/*
    comedi/drivers/amplc_pci230.c
    Driver for Amplicon PCI230 and PCI260 Multifunction I/O boards.

    Copyright (C) 2001 Allan Willcox <allanwillcox@ozemail.com.au>

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 2000 David A. Schleef <ds@schleef.org>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
/*
Driver: amplc_pci230
Description: Amplicon PCI230, PCI260 Multifunction I/O boards
Author: Allan Willcox <allanwillcox@ozemail.com.au>,
  Steve D Sharples <steve.sharples@nottingham.ac.uk>,
  Ian Abbott <abbotti@mev.co.uk>
Updated: Wed, 22 Oct 2008 12:34:49 +0100
Devices: [Amplicon] PCI230 (pci230 or amplc_pci230),
  PCI230+ (pci230+ or amplc_pci230),
  PCI260 (pci260 or amplc_pci230), PCI260+ (pci260+ or amplc_pci230)
Status: works

Configuration options:
  [0] - PCI bus of device (optional).
  [1] - PCI slot of device (optional).
          If bus/slot is not specified, the first available PCI device
          will be used.

Configuring a "amplc_pci230" will match any supported card and it will
choose the best match, picking the "+" models if possible.  Configuring
a "pci230" will match a PCI230 or PCI230+ card and it will be treated as
a PCI230.  Configuring a "pci260" will match a PCI260 or PCI260+ card
and it will be treated as a PCI260.  Configuring a "pci230+" will match
a PCI230+ card.  Configuring a "pci260+" will match a PCI260+ card.

Subdevices:

                PCI230(+)    PCI260(+)
                ---------    ---------
  Subdevices       3            1
        0          AI           AI
        1          AO
        2          DIO

AI Subdevice:

  The AI subdevice has 16 single-ended channels or 8 differential
  channels.

  The PCI230 and PCI260 cards have 12-bit resolution.  The PCI230+ and
  PCI260+ cards have 16-bit resolution.

  For differential mode, use inputs 2N and 2N+1 for channel N (e.g. use
  inputs 14 and 15 for channel 7).  If the card is physically a PCI230
  or PCI260 then it actually uses a "pseudo-differential" mode where the
  inputs are sampled a few microseconds apart.  The PCI230+ and PCI260+
  use true differential sampling.  Another difference is that if the
  card is physically a PCI230 or PCI260, the inverting input is 2N,
  whereas for a PCI230+ or PCI260+ the inverting input is 2N+1.  So if a
  PCI230 is physically replaced by a PCI230+ (or a PCI260 with a
  PCI260+) and differential mode is used, the differential inputs need
  to be physically swapped on the connector.

  The following input ranges are supported:

    0 => [-10, +10] V
    1 => [-5, +5] V
    2 => [-2.5, +2.5] V
    3 => [-1.25, +1.25] V
    4 => [0, 10] V
    5 => [0, 5] V
    6 => [0, 2.5] V

AI Commands:

  +=========+==============+===========+============+==========+
  |start_src|scan_begin_src|convert_src|scan_end_src| stop_src |
  +=========+==============+===========+============+==========+
  |TRIG_NOW | TRIG_FOLLOW  |TRIG_TIMER | TRIG_COUNT |TRIG_NONE |
  |TRIG_INT |              |TRIG_EXT(3)|            |TRIG_COUNT|
  |         |              |TRIG_INT   |            |          |
  |         |--------------|-----------|            |          |
  |         | TRIG_TIMER(1)|TRIG_TIMER |            |          |
  |         | TRIG_EXT(2)  |           |            |          |
  |         | TRIG_INT     |           |            |          |
  +---------+--------------+-----------+------------+----------+

  Note 1: If AI command and AO command are used simultaneously, only
          one may have scan_begin_src == TRIG_TIMER.

  Note 2: For PCI230 and PCI230+, scan_begin_src == TRIG_EXT uses
          DIO channel 16 (pin 49) which will need to be configured as
          a digital input.  For PCI260+, the EXTTRIG/EXTCONVCLK input
          (pin 17) is used instead.  For PCI230, scan_begin_src ==
          TRIG_EXT is not supported.  The trigger is a rising edge
          on the input.

  Note 3: For convert_src == TRIG_EXT, the EXTTRIG/EXTCONVCLK input
          (pin 25 on PCI230(+), pin 17 on PCI260(+)) is used.  The
          convert_arg value is interpreted as follows:

            convert_arg == (CR_EDGE | 0) => rising edge
            convert_arg == (CR_EDGE | CR_INVERT | 0) => falling edge
            convert_arg == 0 => falling edge (backwards compatibility)
            convert_arg == 1 => rising edge (backwards compatibility)

  All entries in the channel list must use the same analogue reference.
  If the analogue reference is not AREF_DIFF (not differential) each
  pair of channel numbers (0 and 1, 2 and 3, etc.) must use the same
  input range.  The input ranges used in the sequence must be all
  bipolar (ranges 0 to 3) or all unipolar (ranges 4 to 6).  The channel
  sequence must consist of 1 or more identical subsequences.  Within the
  subsequence, channels must be in ascending order with no repeated
  channels.  For example, the following sequences are valid: 0 1 2 3
  (single valid subsequence), 0 2 3 5 0 2 3 5 (repeated valid
  subsequence), 1 1 1 1 (repeated valid subsequence).  The following
  sequences are invalid: 0 3 2 1 (invalid subsequence), 0 2 3 5 0 2 3
  (incompletely repeated subsequence).  Some versions of the PCI230+ and
  PCI260+ have a bug that requires a subsequence longer than one entry
  long to include channel 0.

AO Subdevice:

  The AO subdevice has 2 channels with 12-bit resolution.

  The following output ranges are supported:

    0 => [0, 10] V
    1 => [-10, +10] V

AO Commands:

  +=========+==============+===========+============+==========+
  |start_src|scan_begin_src|convert_src|scan_end_src| stop_src |
  +=========+==============+===========+============+==========+
  |TRIG_INT | TRIG_TIMER(1)| TRIG_NOW  | TRIG_COUNT |TRIG_NONE |
  |         | TRIG_EXT(2)  |           |            |TRIG_COUNT|
  |         | TRIG_INT     |           |            |          |
  +---------+--------------+-----------+------------+----------+

  Note 1: If AI command and AO command are used simultaneously, only
          one may have scan_begin_src == TRIG_TIMER.

  Note 2: scan_begin_src == TRIG_EXT is only supported if the card is
          configured as a PCI230+ and is only supported on later
          versions of the card.  As a card configured as a PCI230+ is
          not guaranteed to support external triggering, please consider
          this support to be a bonus.  It uses the EXTTRIG/ EXTCONVCLK
          input (PCI230+ pin 25).  Triggering will be on the rising edge
          unless the CR_INVERT flag is set in scan_begin_arg.

  The channels in the channel sequence must be in ascending order with
  no repeats.  All entries in the channel sequence must use the same
  output range.

DIO Subdevice:

  The DIO subdevice is a 8255 chip providing 24 DIO channels.  The DIO
  channels are configurable as inputs or outputs in four groups:

    Port A  - channels  0 to  7
    Port B  - channels  8 to 15
    Port CL - channels 16 to 19
    Port CH - channels 20 to 23

  Only mode 0 of the 8255 chip is supported.

  Bit 0 of port C (DIO channel 16) is also used as an external scan
  trigger input for AI commands on PCI230 and PCI230+, so would need to
  be configured as an input to use it for that purpose.
*/
/*
Extra triggered scan functionality, interrupt bug-fix added by Steve Sharples.
Support for PCI230+/260+, more triggered scan functionality, and workarounds
for (or detection of) various hardware problems added by Ian Abbott.
*/

#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/interrupt.h>

#include "../comedidev.h"

#include "comedi_fc.h"
#include "8253.h"
#include "8255.h"

/* PCI230 PCI configuration register information */
#define PCI_DEVICE_ID_PCI230 0x0000
#define PCI_DEVICE_ID_PCI260 0x0006
#define PCI_DEVICE_ID_INVALID 0xffff

#define PCI230_IO1_SIZE 32      /* Size of I/O space 1 */
#define PCI230_IO2_SIZE 16      /* Size of I/O space 2 */

/* PCI230 i/o space 1 registers. */
#define PCI230_PPI_X_BASE       0x00    /* User PPI (82C55) base */
#define PCI230_PPI_X_A          0x00    /* User PPI (82C55) port A */
#define PCI230_PPI_X_B          0x01    /* User PPI (82C55) port B */
#define PCI230_PPI_X_C          0x02    /* User PPI (82C55) port C */
#define PCI230_PPI_X_CMD        0x03    /* User PPI (82C55) control word */
#define PCI230_Z2_CT_BASE       0x14    /* 82C54 counter/timer base */
#define PCI230_Z2_CT0           0x14    /* 82C54 counter/timer 0 */
#define PCI230_Z2_CT1           0x15    /* 82C54 counter/timer 1 */
#define PCI230_Z2_CT2           0x16    /* 82C54 counter/timer 2 */
#define PCI230_Z2_CTC           0x17    /* 82C54 counter/timer control word */
#define PCI230_ZCLK_SCE         0x1A    /* Group Z Clock Configuration */
#define PCI230_ZGAT_SCE         0x1D    /* Group Z Gate Configuration */
#define PCI230_INT_SCE          0x1E    /* Interrupt source mask (w) */
#define PCI230_INT_STAT         0x1E    /* Interrupt status (r) */

/* PCI230 i/o space 2 registers. */
#define PCI230_DACCON           0x00    /* DAC control */
#define PCI230_DACOUT1          0x02    /* DAC channel 0 (w) */
#define PCI230_DACOUT2          0x04    /* DAC channel 1 (w) (not FIFO mode) */
#define PCI230_ADCDATA          0x08    /* ADC data (r) */
#define PCI230_ADCSWTRIG        0x08    /* ADC software trigger (w) */
#define PCI230_ADCCON           0x0A    /* ADC control */
#define PCI230_ADCEN            0x0C    /* ADC channel enable bits */
#define PCI230_ADCG             0x0E    /* ADC gain control bits */
/* PCI230+ i/o space 2 additional registers. */
#define PCI230P_ADCTRIG         0x10    /* ADC start acquisition trigger */
#define PCI230P_ADCTH           0x12    /* ADC analog trigger threshold */
#define PCI230P_ADCFFTH         0x14    /* ADC FIFO interrupt threshold */
#define PCI230P_ADCFFLEV        0x16    /* ADC FIFO level (r) */
#define PCI230P_ADCPTSC         0x18    /* ADC pre-trigger sample count (r) */
#define PCI230P_ADCHYST         0x1A    /* ADC analog trigger hysteresys */
#define PCI230P_EXTFUNC         0x1C    /* Extended functions */
#define PCI230P_HWVER           0x1E    /* Hardware version (r) */
/* PCI230+ hardware version 2 onwards. */
#define PCI230P2_DACDATA        0x02    /* DAC data (FIFO mode) (w) */
#define PCI230P2_DACSWTRIG      0x02    /* DAC soft trigger (FIFO mode) (r) */
#define PCI230P2_DACEN          0x06    /* DAC channel enable (FIFO mode) */

/* Convertor related constants. */
#define PCI230_DAC_SETTLE 5     /* Analogue output settling time in µs */
                                /* (DAC itself is 1µs nominally). */
#define PCI230_ADC_SETTLE 1     /* Analogue input settling time in µs */
                                /* (ADC itself is 1.6µs nominally but we poll
                                 * anyway). */
#define PCI230_MUX_SETTLE 10    /* ADC MUX settling time in µS */
                                /* - 10µs for se, 20µs de. */

/* DACCON read-write values. */
#define PCI230_DAC_OR_UNI               (0<<0)  /* Output range unipolar */
#define PCI230_DAC_OR_BIP               (1<<0)  /* Output range bipolar */
#define PCI230_DAC_OR_MASK              (1<<0)
/* The following applies only if DAC FIFO support is enabled in the EXTFUNC
 * register (and only for PCI230+ hardware version 2 onwards). */
#define PCI230P2_DAC_FIFO_EN            (1<<8)  /* FIFO enable */
/* The following apply only if the DAC FIFO is enabled (and only for PCI230+
 * hardware version 2 onwards). */
#define PCI230P2_DAC_TRIG_NONE          (0<<2)  /* No trigger */
#define PCI230P2_DAC_TRIG_SW            (1<<2)  /* Software trigger trigger */
#define PCI230P2_DAC_TRIG_EXTP          (2<<2)  /* EXTTRIG +ve edge trigger */
#define PCI230P2_DAC_TRIG_EXTN          (3<<2)  /* EXTTRIG -ve edge trigger */
#define PCI230P2_DAC_TRIG_Z2CT0         (4<<2)  /* CT0-OUT +ve edge trigger */
#define PCI230P2_DAC_TRIG_Z2CT1         (5<<2)  /* CT1-OUT +ve edge trigger */
#define PCI230P2_DAC_TRIG_Z2CT2         (6<<2)  /* CT2-OUT +ve edge trigger */
#define PCI230P2_DAC_TRIG_MASK          (7<<2)
#define PCI230P2_DAC_FIFO_WRAP          (1<<7)  /* FIFO wraparound mode */
#define PCI230P2_DAC_INT_FIFO_EMPTY     (0<<9)  /* FIFO interrupt empty */
#define PCI230P2_DAC_INT_FIFO_NEMPTY    (1<<9)
#define PCI230P2_DAC_INT_FIFO_NHALF     (2<<9)  /* FIFO intr not half full */
#define PCI230P2_DAC_INT_FIFO_HALF      (3<<9)
#define PCI230P2_DAC_INT_FIFO_NFULL     (4<<9)  /* FIFO interrupt not full */
#define PCI230P2_DAC_INT_FIFO_FULL      (5<<9)
#define PCI230P2_DAC_INT_FIFO_MASK      (7<<9)

/* DACCON read-only values. */
#define PCI230_DAC_BUSY                 (1<<1)  /* DAC busy. */
/* The following apply only if the DAC FIFO is enabled (and only for PCI230+
 * hardware version 2 onwards). */
#define PCI230P2_DAC_FIFO_UNDERRUN_LATCHED      (1<<5)  /* Underrun error */
#define PCI230P2_DAC_FIFO_EMPTY         (1<<13) /* FIFO empty */
#define PCI230P2_DAC_FIFO_FULL          (1<<14) /* FIFO full */
#define PCI230P2_DAC_FIFO_HALF          (1<<15) /* FIFO half full */

/* DACCON write-only, transient values. */
/* The following apply only if the DAC FIFO is enabled (and only for PCI230+
 * hardware version 2 onwards). */
#define PCI230P2_DAC_FIFO_UNDERRUN_CLEAR        (1<<5)  /* Clear underrun */
#define PCI230P2_DAC_FIFO_RESET         (1<<12) /* FIFO reset */

/* PCI230+ hardware version 2 DAC FIFO levels. */
#define PCI230P2_DAC_FIFOLEVEL_HALF     512
#define PCI230P2_DAC_FIFOLEVEL_FULL     1024
/* Free space in DAC FIFO. */
#define PCI230P2_DAC_FIFOROOM_EMPTY             PCI230P2_DAC_FIFOLEVEL_FULL
#define PCI230P2_DAC_FIFOROOM_ONETOHALF         \
        (PCI230P2_DAC_FIFOLEVEL_FULL - PCI230P2_DAC_FIFOLEVEL_HALF)
#define PCI230P2_DAC_FIFOROOM_HALFTOFULL        1
#define PCI230P2_DAC_FIFOROOM_FULL              0

/* ADCCON read/write values. */
#define PCI230_ADC_TRIG_NONE            (0<<0)  /* No trigger */
#define PCI230_ADC_TRIG_SW              (1<<0)  /* Software trigger trigger */
#define PCI230_ADC_TRIG_EXTP            (2<<0)  /* EXTTRIG +ve edge trigger */
#define PCI230_ADC_TRIG_EXTN            (3<<0)  /* EXTTRIG -ve edge trigger */
#define PCI230_ADC_TRIG_Z2CT0           (4<<0)  /* CT0-OUT +ve edge trigger */
#define PCI230_ADC_TRIG_Z2CT1           (5<<0)  /* CT1-OUT +ve edge trigger */
#define PCI230_ADC_TRIG_Z2CT2           (6<<0)  /* CT2-OUT +ve edge trigger */
#define PCI230_ADC_TRIG_MASK            (7<<0)
#define PCI230_ADC_IR_UNI               (0<<3)  /* Input range unipolar */
#define PCI230_ADC_IR_BIP               (1<<3)  /* Input range bipolar */
#define PCI230_ADC_IR_MASK              (1<<3)
#define PCI230_ADC_IM_SE                (0<<4)  /* Input mode single ended */
#define PCI230_ADC_IM_DIF               (1<<4)  /* Input mode differential */
#define PCI230_ADC_IM_MASK              (1<<4)
#define PCI230_ADC_FIFO_EN              (1<<8)  /* FIFO enable */
#define PCI230_ADC_INT_FIFO_EMPTY       (0<<9)
#define PCI230_ADC_INT_FIFO_NEMPTY      (1<<9)  /* FIFO interrupt not empty */
#define PCI230_ADC_INT_FIFO_NHALF       (2<<9)
#define PCI230_ADC_INT_FIFO_HALF        (3<<9)  /* FIFO interrupt half full */
#define PCI230_ADC_INT_FIFO_NFULL       (4<<9)
#define PCI230_ADC_INT_FIFO_FULL        (5<<9)  /* FIFO interrupt full */
#define PCI230P_ADC_INT_FIFO_THRESH     (7<<9)  /* FIFO interrupt threshold */
#define PCI230_ADC_INT_FIFO_MASK        (7<<9)

/* ADCCON write-only, transient values. */
#define PCI230_ADC_FIFO_RESET           (1<<12) /* FIFO reset */
#define PCI230_ADC_GLOB_RESET           (1<<13) /* Global reset */

/* ADCCON read-only values. */
#define PCI230_ADC_BUSY                 (1<<15) /* ADC busy */
#define PCI230_ADC_FIFO_EMPTY           (1<<12) /* FIFO empty */
#define PCI230_ADC_FIFO_FULL            (1<<13) /* FIFO full */
#define PCI230_ADC_FIFO_HALF            (1<<14) /* FIFO half full */
#define PCI230_ADC_FIFO_FULL_LATCHED    (1<<5)  /* Indicates overrun occurred */

/* PCI230 ADC FIFO levels. */
#define PCI230_ADC_FIFOLEVEL_HALFFULL   2049    /* Value for FIFO half full */
#define PCI230_ADC_FIFOLEVEL_FULL       4096    /* FIFO size */

/* Value to write to ADCSWTRIG to trigger ADC conversion in software trigger
 * mode.  Can be anything.  */
#define PCI230_ADC_CONV                 0xffff

/* PCI230+ EXTFUNC values. */
#define PCI230P_EXTFUNC_GAT_EXTTRIG     (1<<0)
                        /* Route EXTTRIG pin to external gate inputs. */
/* PCI230+ hardware version 2 values. */
#define PCI230P2_EXTFUNC_DACFIFO        (1<<1)
                        /* Allow DAC FIFO to be enabled. */

/*
 * Counter/timer clock input configuration sources.
 */
#define CLK_CLK         0       /* reserved (channel-specific clock) */
#define CLK_10MHZ       1       /* internal 10 MHz clock */
#define CLK_1MHZ        2       /* internal 1 MHz clock */
#define CLK_100KHZ      3       /* internal 100 kHz clock */
#define CLK_10KHZ       4       /* internal 10 kHz clock */
#define CLK_1KHZ        5       /* internal 1 kHz clock */
#define CLK_OUTNM1      6       /* output of channel-1 modulo total */
#define CLK_EXT         7       /* external clock */
/* Macro to construct clock input configuration register value. */
#define CLK_CONFIG(chan, src)   ((((chan) & 3) << 3) | ((src) & 7))
/* Timebases in ns. */
#define TIMEBASE_10MHZ          100
#define TIMEBASE_1MHZ           1000
#define TIMEBASE_100KHZ         10000
#define TIMEBASE_10KHZ          100000
#define TIMEBASE_1KHZ           1000000

/*
 * Counter/timer gate input configuration sources.
 */
#define GAT_VCC         0       /* VCC (i.e. enabled) */
#define GAT_GND         1       /* GND (i.e. disabled) */
#define GAT_EXT         2       /* external gate input (PPCn on PCI230) */
#define GAT_NOUTNM2     3       /* inverted output of channel-2 modulo total */
/* Macro to construct gate input configuration register value. */
#define GAT_CONFIG(chan, src)   ((((chan) & 3) << 3) | ((src) & 7))

/*
 * Summary of CLK_OUTNM1 and GAT_NOUTNM2 connections for PCI230 and PCI260:
 *
 *              Channel's       Channel's
 *              clock input     gate input
 * Channel      CLK_OUTNM1      GAT_NOUTNM2
 * -------      ----------      -----------
 * Z2-CT0       Z2-CT2-OUT      /Z2-CT1-OUT
 * Z2-CT1       Z2-CT0-OUT      /Z2-CT2-OUT
 * Z2-CT2       Z2-CT1-OUT      /Z2-CT0-OUT
 */

/* Interrupt enables/status register values. */
#define PCI230_INT_DISABLE              0
#define PCI230_INT_PPI_C0               (1<<0)
#define PCI230_INT_PPI_C3               (1<<1)
#define PCI230_INT_ADC                  (1<<2)
#define PCI230_INT_ZCLK_CT1             (1<<5)
/* For PCI230+ hardware version 2 when DAC FIFO enabled. */
#define PCI230P2_INT_DAC                (1<<4)

#define PCI230_TEST_BIT(val, n) ((val>>n)&1)
                        /* Assumes bits numbered with zero offset, ie. 0-15 */

/* (Potentially) shared resources and their owners */
enum {
        RES_Z2CT0,              /* Z2-CT0 */
        RES_Z2CT1,              /* Z2-CT1 */
        RES_Z2CT2,              /* Z2-CT2 */
        NUM_RESOURCES           /* Number of (potentially) shared resources. */
};

enum {
        OWNER_NONE,             /* Not owned */
        OWNER_AICMD,            /* Owned by AI command */
        OWNER_AOCMD             /* Owned by AO command */
};

/*
 * Handy macros.
 */

/* Combine old and new bits. */
#define COMBINE(old, new, mask) (((old) & ~(mask)) | ((new) & (mask)))

/* Current CPU.  XXX should this be hard_smp_processor_id()? */
#define THISCPU         smp_processor_id()

/* State flags for atomic bit operations */
#define AI_CMD_STARTED  0
#define AO_CMD_STARTED  1

/*
 * Board descriptions for the two boards supported.
 */

struct pci230_board {
        const char *name;
        unsigned short id;
        int ai_chans;
        int ai_bits;
        int ao_chans;
        int ao_bits;
        int have_dio;
        unsigned int min_hwver; /* Minimum hardware version supported. */
};
static const struct pci230_board pci230_boards[] = {
        {
         .name = "pci230+",
         .id = PCI_DEVICE_ID_PCI230,
         .ai_chans = 16,
         .ai_bits = 16,
         .ao_chans = 2,
         .ao_bits = 12,
         .have_dio = 1,
         .min_hwver = 1,
         },
        {
         .name = "pci260+",
         .id = PCI_DEVICE_ID_PCI260,
         .ai_chans = 16,
         .ai_bits = 16,
         .ao_chans = 0,
         .ao_bits = 0,
         .have_dio = 0,
         .min_hwver = 1,
         },
        {
         .name = "pci230",
         .id = PCI_DEVICE_ID_PCI230,
         .ai_chans = 16,
         .ai_bits = 12,
         .ao_chans = 2,
         .ao_bits = 12,
         .have_dio = 1,
         },
        {
         .name = "pci260",
         .id = PCI_DEVICE_ID_PCI260,
         .ai_chans = 16,
         .ai_bits = 12,
         .ao_chans = 0,
         .ao_bits = 0,
         .have_dio = 0,
         },
        {
         .name = "amplc_pci230",        /* Wildcard matches any above */
         .id = PCI_DEVICE_ID_INVALID,
         },
};

/* this structure is for data unique to this hardware driver.  If
   several hardware drivers keep similar information in this structure,
   feel free to suggest moving the variable to the struct comedi_device struct.  */
struct pci230_private {
        spinlock_t isr_spinlock;        /* Interrupt spin lock */
        spinlock_t res_spinlock;        /* Shared resources spin lock */
        spinlock_t ai_stop_spinlock;    /* Spin lock for stopping AI command */
        spinlock_t ao_stop_spinlock;    /* Spin lock for stopping AO command */
        unsigned long state;    /* State flags */
        unsigned long iobase1;  /* PCI230's I/O space 1 */
        unsigned int ao_readback[2];    /* Used for AO readback */
        unsigned int ai_scan_count;     /* Number of analogue input scans
                                         * remaining.  */
        unsigned int ai_scan_pos;       /* Current position within analogue
                                         * input scan */
        unsigned int ao_scan_count;     /* Number of analogue output scans
                                         * remaining.  */
        int intr_cpuid;         /* ID of CPU running interrupt routine. */
        unsigned short hwver;   /* Hardware version (for '+' models). */
        unsigned short adccon;  /* ADCCON register value. */
        unsigned short daccon;  /* DACCON register value. */
        unsigned short adcfifothresh;   /* ADC FIFO programmable interrupt
                                         * level threshold (PCI230+/260+). */
        unsigned short adcg;    /* ADCG register value. */
        unsigned char int_en;   /* Interrupt enables bits. */
        unsigned char ai_continuous;    /* Flag set when cmd->stop_src ==
                                         * TRIG_NONE - user chooses to stop
                                         * continuous conversion by
                                         * cancelation. */
        unsigned char ao_continuous;    /* Flag set when cmd->stop_src ==
                                         * TRIG_NONE - user chooses to stop
                                         * continuous conversion by
                                         * cancelation. */
        unsigned char ai_bipolar;       /* Set if bipolar input range so we
                                         * know to mangle it. */
        unsigned char ao_bipolar;       /* Set if bipolar output range so we
                                         * know to mangle it. */
        unsigned char ier;      /* Copy of interrupt enables/status register. */
        unsigned char intr_running;     /* Flag set in interrupt routine. */
        unsigned char res_owner[NUM_RESOURCES]; /* Shared resource owners. */
};

/* PCI230 clock source periods in ns */
static const unsigned int pci230_timebase[8] = {
        [CLK_10MHZ] = TIMEBASE_10MHZ,
        [CLK_1MHZ] = TIMEBASE_1MHZ,
        [CLK_100KHZ] = TIMEBASE_100KHZ,
        [CLK_10KHZ] = TIMEBASE_10KHZ,
        [CLK_1KHZ] = TIMEBASE_1KHZ,
};

/* PCI230 analogue input range table */
static const struct comedi_lrange pci230_ai_range = { 7, {
                                                          BIP_RANGE(10),
                                                          BIP_RANGE(5),
                                                          BIP_RANGE(2.5),
                                                          BIP_RANGE(1.25),
                                                          UNI_RANGE(10),
                                                          UNI_RANGE(5),
                                                          UNI_RANGE(2.5)
                                                          }
};

/* PCI230 analogue gain bits for each input range. */
static const unsigned char pci230_ai_gain[7] = { 0, 1, 2, 3, 1, 2, 3 };

/* PCI230 adccon bipolar flag for each analogue input range. */
static const unsigned char pci230_ai_bipolar[7] = { 1, 1, 1, 1, 0, 0, 0 };

/* PCI230 analogue output range table */
static const struct comedi_lrange pci230_ao_range = { 2, {
                                                          UNI_RANGE(10),
                                                          BIP_RANGE(10)
                                                          }
};

/* PCI230 daccon bipolar flag for each analogue output range. */
static const unsigned char pci230_ao_bipolar[2] = { 0, 1 };

static short pci230_ai_read(struct comedi_device *dev)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci230_private *devpriv = dev->private;
        short data;

        /* Read sample. */
        data = (short)inw(dev->iobase + PCI230_ADCDATA);
        /* PCI230 is 12 bit - stored in upper bits of 16 bit register (lower
         * four bits reserved for expansion). */
        /* PCI230+ is 16 bit AI. */
        data = data >> (16 - thisboard->ai_bits);

        /* If a bipolar range was specified, mangle it (twos
         * complement->straight binary). */
        if (devpriv->ai_bipolar)
                data ^= 1 << (thisboard->ai_bits - 1);

        return data;
}

static inline unsigned short pci230_ao_mangle_datum(struct comedi_device *dev,
                                                    short datum)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci230_private *devpriv = dev->private;

        /* If a bipolar range was specified, mangle it (straight binary->twos
         * complement). */
        if (devpriv->ao_bipolar)
                datum ^= 1 << (thisboard->ao_bits - 1);

        /* PCI230 is 12 bit - stored in upper bits of 16 bit register (lower
         * four bits reserved for expansion). */
        /* PCI230+ is also 12 bit AO. */
        datum <<= (16 - thisboard->ao_bits);
        return (unsigned short)datum;
}

static inline void pci230_ao_write_nofifo(struct comedi_device *dev,
                                          short datum, unsigned int chan)
{
        struct pci230_private *devpriv = dev->private;

        /* Store unmangled datum to be read back later. */
        devpriv->ao_readback[chan] = datum;

        /* Write mangled datum to appropriate DACOUT register. */
        outw(pci230_ao_mangle_datum(dev, datum), dev->iobase + (((chan) == 0)
                                                                ? PCI230_DACOUT1
                                                                :
                                                                PCI230_DACOUT2));
}

static inline void pci230_ao_write_fifo(struct comedi_device *dev, short datum,
                                        unsigned int chan)
{
        struct pci230_private *devpriv = dev->private;

        /* Store unmangled datum to be read back later. */
        devpriv->ao_readback[chan] = datum;

        /* Write mangled datum to appropriate DACDATA register. */
        outw(pci230_ao_mangle_datum(dev, datum),
             dev->iobase + PCI230P2_DACDATA);
}

static int get_resources(struct comedi_device *dev, unsigned int res_mask,
                         unsigned char owner)
{
        struct pci230_private *devpriv = dev->private;
        int ok;
        unsigned int i;
        unsigned int b;
        unsigned int claimed;
        unsigned long irqflags;

        ok = 1;
        claimed = 0;
        spin_lock_irqsave(&devpriv->res_spinlock, irqflags);
        for (b = 1, i = 0; (i < NUM_RESOURCES)
             && (res_mask != 0); b <<= 1, i++) {
                if ((res_mask & b) != 0) {
                        res_mask &= ~b;
                        if (devpriv->res_owner[i] == OWNER_NONE) {
                                devpriv->res_owner[i] = owner;
                                claimed |= b;
                        } else if (devpriv->res_owner[i] != owner) {
                                for (b = 1, i = 0; claimed != 0; b <<= 1, i++) {
                                        if ((claimed & b) != 0) {
                                                devpriv->res_owner[i]
                                                    = OWNER_NONE;
                                                claimed &= ~b;
                                        }
                                }
                                ok = 0;
                                break;
                        }
                }
        }
        spin_unlock_irqrestore(&devpriv->res_spinlock, irqflags);
        return ok;
}

static inline int get_one_resource(struct comedi_device *dev,
                                   unsigned int resource, unsigned char owner)
{
        return get_resources(dev, (1U << resource), owner);
}

static void put_resources(struct comedi_device *dev, unsigned int res_mask,
                          unsigned char owner)
{
        struct pci230_private *devpriv = dev->private;
        unsigned int i;
        unsigned int b;
        unsigned long irqflags;

        spin_lock_irqsave(&devpriv->res_spinlock, irqflags);
        for (b = 1, i = 0; (i < NUM_RESOURCES)
             && (res_mask != 0); b <<= 1, i++) {
                if ((res_mask & b) != 0) {
                        res_mask &= ~b;
                        if (devpriv->res_owner[i] == owner)
                                devpriv->res_owner[i] = OWNER_NONE;

                }
        }
        spin_unlock_irqrestore(&devpriv->res_spinlock, irqflags);
}

static inline void put_one_resource(struct comedi_device *dev,
                                    unsigned int resource, unsigned char owner)
{
        put_resources(dev, (1U << resource), owner);
}

static inline void put_all_resources(struct comedi_device *dev,
                                     unsigned char owner)
{
        put_resources(dev, (1U << NUM_RESOURCES) - 1, owner);
}

static unsigned int divide_ns(uint64_t ns, unsigned int timebase,
                              unsigned int round_mode)
{
        uint64_t div;
        unsigned int rem;

        div = ns;
        rem = do_div(div, timebase);
        round_mode &= TRIG_ROUND_MASK;
        switch (round_mode) {
        default:
        case TRIG_ROUND_NEAREST:
                div += (rem + (timebase / 2)) / timebase;
                break;
        case TRIG_ROUND_DOWN:
                break;
        case TRIG_ROUND_UP:
                div += (rem + timebase - 1) / timebase;
                break;
        }
        return div > UINT_MAX ? UINT_MAX : (unsigned int)div;
}

/* Given desired period in ns, returns the required internal clock source
 * and gets the initial count. */
static unsigned int pci230_choose_clk_count(uint64_t ns, unsigned int *count,
                                            unsigned int round_mode)
{
        unsigned int clk_src, cnt;

        for (clk_src = CLK_10MHZ;; clk_src++) {
                cnt = divide_ns(ns, pci230_timebase[clk_src], round_mode);
                if ((cnt <= 65536) || (clk_src == CLK_1KHZ))
                        break;

        }
        *count = cnt;
        return clk_src;
}

static void pci230_ns_to_single_timer(unsigned int *ns, unsigned int round)
{
        unsigned int count;
        unsigned int clk_src;

        clk_src = pci230_choose_clk_count(*ns, &count, round);
        *ns = count * pci230_timebase[clk_src];
        return;
}

static void pci230_ct_setup_ns_mode(struct comedi_device *dev, unsigned int ct,
                                    unsigned int mode, uint64_t ns,
                                    unsigned int round)
{
        struct pci230_private *devpriv = dev->private;
        unsigned int clk_src;
        unsigned int count;

        /* Set mode. */
        i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, ct, mode);
        /* Determine clock source and count. */
        clk_src = pci230_choose_clk_count(ns, &count, round);
        /* Program clock source. */
        outb(CLK_CONFIG(ct, clk_src), devpriv->iobase1 + PCI230_ZCLK_SCE);
        /* Set initial count. */
        if (count >= 65536)
                count = 0;

        i8254_write(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, ct, count);
}

static void pci230_cancel_ct(struct comedi_device *dev, unsigned int ct)
{
        struct pci230_private *devpriv = dev->private;

        i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, ct,
                       I8254_MODE1);
        /* Counter ct, 8254 mode 1, initial count not written. */
}

/*
 *  COMEDI_SUBD_AI instruction;
 */
static int pci230_ai_rinsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        struct pci230_private *devpriv = dev->private;
        unsigned int n, i;
        unsigned int chan, range, aref;
        unsigned int gainshift;
        unsigned int status;
        unsigned short adccon, adcen;

        /* Unpack channel and range. */
        chan = CR_CHAN(insn->chanspec);
        range = CR_RANGE(insn->chanspec);
        aref = CR_AREF(insn->chanspec);
        if (aref == AREF_DIFF) {
                /* Differential. */
                if (chan >= s->n_chan / 2) {
                        DPRINTK("comedi%d: amplc_pci230: ai_rinsn: "
                                "differential channel number out of range "
                                "0 to %u\n", dev->minor, (s->n_chan / 2) - 1);
                        return -EINVAL;
                }
        }

        /* Use Z2-CT2 as a conversion trigger instead of the built-in
         * software trigger, as otherwise triggering of differential channels
         * doesn't work properly for some versions of PCI230/260.  Also set
         * FIFO mode because the ADC busy bit only works for software triggers.
         */
        adccon = PCI230_ADC_TRIG_Z2CT2 | PCI230_ADC_FIFO_EN;
        /* Set Z2-CT2 output low to avoid any false triggers. */
        i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, 2, I8254_MODE0);
        devpriv->ai_bipolar = pci230_ai_bipolar[range];
        if (aref == AREF_DIFF) {
                /* Differential. */
                gainshift = chan * 2;
                if (devpriv->hwver == 0) {
                        /* Original PCI230/260 expects both inputs of the
                         * differential channel to be enabled. */
                        adcen = 3 << gainshift;
                } else {
                        /* PCI230+/260+ expects only one input of the
                         * differential channel to be enabled. */
                        adcen = 1 << gainshift;
                }
                adccon |= PCI230_ADC_IM_DIF;
        } else {
                /* Single ended. */
                adcen = 1 << chan;
                gainshift = chan & ~1;
                adccon |= PCI230_ADC_IM_SE;
        }
        devpriv->adcg = (devpriv->adcg & ~(3 << gainshift))
            | (pci230_ai_gain[range] << gainshift);
        if (devpriv->ai_bipolar)
                adccon |= PCI230_ADC_IR_BIP;
        else
                adccon |= PCI230_ADC_IR_UNI;


        /* Enable only this channel in the scan list - otherwise by default
         * we'll get one sample from each channel. */
        outw(adcen, dev->iobase + PCI230_ADCEN);

        /* Set gain for channel. */
        outw(devpriv->adcg, dev->iobase + PCI230_ADCG);

        /* Specify uni/bip, se/diff, conversion source, and reset FIFO. */
        devpriv->adccon = adccon;
        outw(adccon | PCI230_ADC_FIFO_RESET, dev->iobase + PCI230_ADCCON);

        /* Convert n samples */
        for (n = 0; n < insn->n; n++) {
                /* Trigger conversion by toggling Z2-CT2 output (finish with
                 * output high). */
                i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, 2,
                               I8254_MODE0);
                i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, 2,
                               I8254_MODE1);

#define TIMEOUT 100
                /* wait for conversion to end */
                for (i = 0; i < TIMEOUT; i++) {
                        status = inw(dev->iobase + PCI230_ADCCON);
                        if (!(status & PCI230_ADC_FIFO_EMPTY))
                                break;
                        udelay(1);
                }
                if (i == TIMEOUT) {
                        dev_err(dev->class_dev, "timeout\n");
                        return -ETIMEDOUT;
                }

                /* read data */
                data[n] = pci230_ai_read(dev);
        }

        /* return the number of samples read/written */
        return n;
}

/*
 *  COMEDI_SUBD_AO instructions;
 */
static int pci230_ao_winsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        struct pci230_private *devpriv = dev->private;
        int i;
        int chan, range;

        /* Unpack channel and range. */
        chan = CR_CHAN(insn->chanspec);
        range = CR_RANGE(insn->chanspec);

        /* Set range - see analogue output range table; 0 => unipolar 10V,
         * 1 => bipolar +/-10V range scale */
        devpriv->ao_bipolar = pci230_ao_bipolar[range];
        outw(range, dev->iobase + PCI230_DACCON);

        /* Writing a list of values to an AO channel is probably not
         * very useful, but that's how the interface is defined. */
        for (i = 0; i < insn->n; i++) {
                /* Write value to DAC and store it. */
                pci230_ao_write_nofifo(dev, data[i], chan);
        }

        /* return the number of samples read/written */
        return i;
}

/* AO subdevices should have a read insn as well as a write insn.
 * Usually this means copying a value stored in devpriv. */
static int pci230_ao_rinsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        struct pci230_private *devpriv = dev->private;
        int i;
        int chan = CR_CHAN(insn->chanspec);

        for (i = 0; i < insn->n; i++)
                data[i] = devpriv->ao_readback[chan];

        return i;
}

static int pci230_ao_cmdtest(struct comedi_device *dev,
                             struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci230_private *devpriv = dev->private;
        int err = 0;
        unsigned int tmp;

        /* Step 1 : check if triggers are trivially valid */

        err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT);

        tmp = TRIG_TIMER | TRIG_INT;
        if ((thisboard->min_hwver > 0) && (devpriv->hwver >= 2)) {
                /*
                 * For PCI230+ hardware version 2 onwards, allow external
                 * trigger from EXTTRIG/EXTCONVCLK input (PCI230+ pin 25).
                 *
                 * FIXME: The permitted scan_begin_src values shouldn't depend
                 * on devpriv->hwver (the detected card's actual hardware
                 * version).  They should only depend on thisboard->min_hwver
                 * (the static capabilities of the configured card).  To fix
                 * it, a new card model, e.g. "pci230+2" would have to be
                 * defined with min_hwver set to 2.  It doesn't seem worth it
                 * for this alone.  At the moment, please consider
                 * scan_begin_src==TRIG_EXT support to be a bonus rather than a
                 * guarantee!
                 */
                tmp |= TRIG_EXT;
        }
        err |= cfc_check_trigger_src(&cmd->scan_begin_src, tmp);

        err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
        err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
        err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);

        if (err)
                return 1;

        /* Step 2a : make sure trigger sources are unique */

        err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
        err |= cfc_check_trigger_is_unique(cmd->stop_src);

        /* Step 2b : and mutually compatible */

        if (err)

                return 2;

        /* Step 3: check if arguments are trivially valid */

        err |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);

#define MAX_SPEED_AO    8000    /* 8000 ns => 125 kHz */
#define MIN_SPEED_AO    4294967295u     /* 4294967295ns = 4.29s */
                        /*- Comedi limit due to unsigned int cmd.  Driver limit
                         * = 2^16 (16bit * counter) * 1000000ns (1kHz onboard
                         * clock) = 65.536s */

        switch (cmd->scan_begin_src) {
        case TRIG_TIMER:
                err |= cfc_check_trigger_arg_min(&cmd->scan_begin_arg,
                                                 MAX_SPEED_AO);
                err |= cfc_check_trigger_arg_max(&cmd->scan_begin_arg,
                                                 MIN_SPEED_AO);
                break;
        case TRIG_EXT:
                /* External trigger - for PCI230+ hardware version 2 onwards. */
                /* Trigger number must be 0. */
                if ((cmd->scan_begin_arg & ~CR_FLAGS_MASK) != 0) {
                        cmd->scan_begin_arg = COMBINE(cmd->scan_begin_arg, 0,
                                                      ~CR_FLAGS_MASK);
                        err |= -EINVAL;
                }
                /* The only flags allowed are CR_EDGE and CR_INVERT.  The
                 * CR_EDGE flag is ignored. */
                if ((cmd->scan_begin_arg
                     & (CR_FLAGS_MASK & ~(CR_EDGE | CR_INVERT))) != 0) {
                        cmd->scan_begin_arg = COMBINE(cmd->scan_begin_arg, 0,
                                                      CR_FLAGS_MASK &
                                                      ~(CR_EDGE | CR_INVERT));
                        err |= -EINVAL;
                }
                break;
        default:
                err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
                break;
        }

        err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);

        if (cmd->stop_src == TRIG_NONE)
                err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);

        if (err)
                return 3;

        /* Step 4: fix up any arguments.
         * "argument conflict" returned by comedilib to user mode process
         * if this fails. */

        if (cmd->scan_begin_src == TRIG_TIMER) {
                tmp = cmd->scan_begin_arg;
                pci230_ns_to_single_timer(&cmd->scan_begin_arg,
                                          cmd->flags & TRIG_ROUND_MASK);
                if (tmp != cmd->scan_begin_arg)
                        err++;
        }

        if (err)
                return 4;

        /* Step 5: check channel list if it exists. */

        if (cmd->chanlist && cmd->chanlist_len > 0) {
                enum {
                        seq_err = (1 << 0),
                        range_err = (1 << 1)
                };
                unsigned int errors;
                unsigned int n;
                unsigned int chan, prev_chan;
                unsigned int range, first_range;

                prev_chan = CR_CHAN(cmd->chanlist[0]);
                first_range = CR_RANGE(cmd->chanlist[0]);
                errors = 0;
                for (n = 1; n < cmd->chanlist_len; n++) {
                        chan = CR_CHAN(cmd->chanlist[n]);
                        range = CR_RANGE(cmd->chanlist[n]);
                        /* Channel numbers must strictly increase. */
                        if (chan < prev_chan)
                                errors |= seq_err;

                        /* Ranges must be the same. */
                        if (range != first_range)
                                errors |= range_err;

                        prev_chan = chan;
                }
                if (errors != 0) {
                        err++;
                        if ((errors & seq_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ao_cmdtest: "
                                        "channel numbers must increase\n",
                                        dev->minor);
                        }
                        if ((errors & range_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ao_cmdtest: "
                                        "channels must have the same range\n",
                                        dev->minor);
                        }
                }
        }

        if (err)
                return 5;

        return 0;
}

static void pci230_ao_stop(struct comedi_device *dev,
                           struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        unsigned long irqflags;
        unsigned char intsrc;
        int started;
        struct comedi_cmd *cmd;

        spin_lock_irqsave(&devpriv->ao_stop_spinlock, irqflags);
        started = test_and_clear_bit(AO_CMD_STARTED, &devpriv->state);
        spin_unlock_irqrestore(&devpriv->ao_stop_spinlock, irqflags);
        if (!started)
                return;
        cmd = &s->async->cmd;
        if (cmd->scan_begin_src == TRIG_TIMER) {
                /* Stop scan rate generator. */
                pci230_cancel_ct(dev, 1);
        }
        /* Determine interrupt source. */
        if (devpriv->hwver < 2) {
                /* Not using DAC FIFO.  Using CT1 interrupt. */
                intsrc = PCI230_INT_ZCLK_CT1;
        } else {
                /* Using DAC FIFO interrupt. */
                intsrc = PCI230P2_INT_DAC;
        }
        /* Disable interrupt and wait for interrupt routine to finish running
         * unless we are called from the interrupt routine. */
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        devpriv->int_en &= ~intsrc;
        while (devpriv->intr_running && devpriv->intr_cpuid != THISCPU) {
                spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
                spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        }
        if (devpriv->ier != devpriv->int_en) {
                devpriv->ier = devpriv->int_en;
                outb(devpriv->ier, devpriv->iobase1 + PCI230_INT_SCE);
        }
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
        if (devpriv->hwver >= 2) {
                /* Using DAC FIFO.  Reset FIFO, clear underrun error,
                 * disable FIFO. */
                devpriv->daccon &= PCI230_DAC_OR_MASK;
                outw(devpriv->daccon | PCI230P2_DAC_FIFO_RESET
                     | PCI230P2_DAC_FIFO_UNDERRUN_CLEAR,
                     dev->iobase + PCI230_DACCON);
        }
        /* Release resources. */
        put_all_resources(dev, OWNER_AOCMD);
}

static void pci230_handle_ao_nofifo(struct comedi_device *dev,
                                    struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        short data;
        int i, ret;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;

        if (!devpriv->ao_continuous && (devpriv->ao_scan_count == 0))
                return;
        for (i = 0; i < cmd->chanlist_len; i++) {
                /* Read sample from Comedi's circular buffer. */
                ret = comedi_buf_get(s->async, &data);
                if (ret == 0) {
                        s->async->events |= COMEDI_CB_OVERFLOW;
                        pci230_ao_stop(dev, s);
                        comedi_error(dev, "AO buffer underrun");
                        return;
                }
                /* Write value to DAC. */
                pci230_ao_write_nofifo(dev, data, CR_CHAN(cmd->chanlist[i]));
        }
        async->events |= COMEDI_CB_BLOCK | COMEDI_CB_EOS;
        if (!devpriv->ao_continuous) {
                devpriv->ao_scan_count--;
                if (devpriv->ao_scan_count == 0) {
                        /* End of acquisition. */
                        async->events |= COMEDI_CB_EOA;
                        pci230_ao_stop(dev, s);
                }
        }
}

/* Loads DAC FIFO (if using it) from buffer. */
/* Returns 0 if AO finished due to completion or error, 1 if still going. */
static int pci230_handle_ao_fifo(struct comedi_device *dev,
                                 struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;
        unsigned int num_scans;
        unsigned int room;
        unsigned short dacstat;
        unsigned int i, n;
        unsigned int bytes_per_scan;
        unsigned int events = 0;
        int running;

        /* Get DAC FIFO status. */
        dacstat = inw(dev->iobase + PCI230_DACCON);
        /* Determine number of scans available in buffer. */
        bytes_per_scan = cmd->chanlist_len * sizeof(short);
        num_scans = comedi_buf_read_n_available(async) / bytes_per_scan;
        if (!devpriv->ao_continuous) {
                /* Fixed number of scans. */
                if (num_scans > devpriv->ao_scan_count)
                        num_scans = devpriv->ao_scan_count;
                if (devpriv->ao_scan_count == 0) {
                        /* End of acquisition. */
                        events |= COMEDI_CB_EOA;
                }
        }
        if (events == 0) {
                /* Check for FIFO underrun. */
                if ((dacstat & PCI230P2_DAC_FIFO_UNDERRUN_LATCHED) != 0) {
                        comedi_error(dev, "AO FIFO underrun");
                        events |= COMEDI_CB_OVERFLOW | COMEDI_CB_ERROR;
                }
                /* Check for buffer underrun if FIFO less than half full
                 * (otherwise there will be loads of "DAC FIFO not half full"
                 * interrupts). */
                if ((num_scans == 0)
                    && ((dacstat & PCI230P2_DAC_FIFO_HALF) == 0)) {
                        comedi_error(dev, "AO buffer underrun");
                        events |= COMEDI_CB_OVERFLOW | COMEDI_CB_ERROR;
                }
        }
        if (events == 0) {
                /* Determine how much room is in the FIFO (in samples). */
                if ((dacstat & PCI230P2_DAC_FIFO_FULL) != 0)
                        room = PCI230P2_DAC_FIFOROOM_FULL;
                else if ((dacstat & PCI230P2_DAC_FIFO_HALF) != 0)
                        room = PCI230P2_DAC_FIFOROOM_HALFTOFULL;
                else if ((dacstat & PCI230P2_DAC_FIFO_EMPTY) != 0)
                        room = PCI230P2_DAC_FIFOROOM_EMPTY;
                else
                        room = PCI230P2_DAC_FIFOROOM_ONETOHALF;
                /* Convert room to number of scans that can be added. */
                room /= cmd->chanlist_len;
                /* Determine number of scans to process. */
                if (num_scans > room)
                        num_scans = room;
                /* Process scans. */
                for (n = 0; n < num_scans; n++) {
                        for (i = 0; i < cmd->chanlist_len; i++) {
                                short datum;

                                comedi_buf_get(async, &datum);
                                pci230_ao_write_fifo(dev, datum,
                                                     CR_CHAN(cmd->chanlist[i]));
                        }
                }
                events |= COMEDI_CB_EOS | COMEDI_CB_BLOCK;
                if (!devpriv->ao_continuous) {
                        devpriv->ao_scan_count -= num_scans;
                        if (devpriv->ao_scan_count == 0) {
                                /* All data for the command has been written
                                 * to FIFO.  Set FIFO interrupt trigger level
                                 * to 'empty'. */
                                devpriv->daccon = (devpriv->daccon
                                                   &
                                                   ~PCI230P2_DAC_INT_FIFO_MASK)
                                    | PCI230P2_DAC_INT_FIFO_EMPTY;
                                outw(devpriv->daccon,
                                     dev->iobase + PCI230_DACCON);
                        }
                }
                /* Check if FIFO underrun occurred while writing to FIFO. */
                dacstat = inw(dev->iobase + PCI230_DACCON);
                if ((dacstat & PCI230P2_DAC_FIFO_UNDERRUN_LATCHED) != 0) {
                        comedi_error(dev, "AO FIFO underrun");
                        events |= COMEDI_CB_OVERFLOW | COMEDI_CB_ERROR;
                }
        }
        if ((events & (COMEDI_CB_EOA | COMEDI_CB_ERROR | COMEDI_CB_OVERFLOW))
            != 0) {
                /* Stopping AO due to completion or error. */
                pci230_ao_stop(dev, s);
                running = 0;
        } else {
                running = 1;
        }
        async->events |= events;
        return running;
}

static int pci230_ao_inttrig_scan_begin(struct comedi_device *dev,
                                        struct comedi_subdevice *s,
                                        unsigned int trig_num)
{
        struct pci230_private *devpriv = dev->private;
        unsigned long irqflags;

        if (trig_num != 0)
                return -EINVAL;

        spin_lock_irqsave(&devpriv->ao_stop_spinlock, irqflags);
        if (test_bit(AO_CMD_STARTED, &devpriv->state)) {
                /* Perform scan. */
                if (devpriv->hwver < 2) {
                        /* Not using DAC FIFO. */
                        spin_unlock_irqrestore(&devpriv->ao_stop_spinlock,
                                               irqflags);
                        pci230_handle_ao_nofifo(dev, s);
                        comedi_event(dev, s);
                } else {
                        /* Using DAC FIFO. */
                        /* Read DACSWTRIG register to trigger conversion. */
                        inw(dev->iobase + PCI230P2_DACSWTRIG);
                        spin_unlock_irqrestore(&devpriv->ao_stop_spinlock,
                                               irqflags);
                }
                /* Delay.  Should driver be responsible for this? */
                /* XXX TODO: See if DAC busy bit can be used. */
                udelay(8);
        } else {
                spin_unlock_irqrestore(&devpriv->ao_stop_spinlock, irqflags);
        }

        return 1;
}

static void pci230_ao_start(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;
        unsigned long irqflags;

        set_bit(AO_CMD_STARTED, &devpriv->state);
        if (!devpriv->ao_continuous && (devpriv->ao_scan_count == 0)) {
                /* An empty acquisition! */
                async->events |= COMEDI_CB_EOA;
                pci230_ao_stop(dev, s);
                comedi_event(dev, s);
        } else {
                if (devpriv->hwver >= 2) {
                        /* Using DAC FIFO. */
                        unsigned short scantrig;
                        int run;

                        /* Preload FIFO data. */
                        run = pci230_handle_ao_fifo(dev, s);
                        comedi_event(dev, s);
                        if (!run) {
                                /* Stopped. */
                                return;
                        }
                        /* Set scan trigger source. */
                        switch (cmd->scan_begin_src) {
                        case TRIG_TIMER:
                                scantrig = PCI230P2_DAC_TRIG_Z2CT1;
                                break;
                        case TRIG_EXT:
                                /* Trigger on EXTTRIG/EXTCONVCLK pin. */
                                if ((cmd->scan_begin_arg & CR_INVERT) == 0) {
                                        /* +ve edge */
                                        scantrig = PCI230P2_DAC_TRIG_EXTP;
                                } else {
                                        /* -ve edge */
                                        scantrig = PCI230P2_DAC_TRIG_EXTN;
                                }
                                break;
                        case TRIG_INT:
                                scantrig = PCI230P2_DAC_TRIG_SW;
                                break;
                        default:
                                /* Shouldn't get here. */
                                scantrig = PCI230P2_DAC_TRIG_NONE;
                                break;
                        }
                        devpriv->daccon = (devpriv->daccon
                                           & ~PCI230P2_DAC_TRIG_MASK) |
                            scantrig;
                        outw(devpriv->daccon, dev->iobase + PCI230_DACCON);

                }
                switch (cmd->scan_begin_src) {
                case TRIG_TIMER:
                        if (devpriv->hwver < 2) {
                                /* Not using DAC FIFO. */
                                /* Enable CT1 timer interrupt. */
                                spin_lock_irqsave(&devpriv->isr_spinlock,
                                                  irqflags);
                                devpriv->int_en |= PCI230_INT_ZCLK_CT1;
                                devpriv->ier |= PCI230_INT_ZCLK_CT1;
                                outb(devpriv->ier,
                                     devpriv->iobase1 + PCI230_INT_SCE);
                                spin_unlock_irqrestore(&devpriv->isr_spinlock,
                                                       irqflags);
                        }
                        /* Set CT1 gate high to start counting. */
                        outb(GAT_CONFIG(1, GAT_VCC),
                             devpriv->iobase1 + PCI230_ZGAT_SCE);
                        break;
                case TRIG_INT:
                        async->inttrig = pci230_ao_inttrig_scan_begin;
                        break;
                }
                if (devpriv->hwver >= 2) {
                        /* Using DAC FIFO.  Enable DAC FIFO interrupt. */
                        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
                        devpriv->int_en |= PCI230P2_INT_DAC;
                        devpriv->ier |= PCI230P2_INT_DAC;
                        outb(devpriv->ier, devpriv->iobase1 + PCI230_INT_SCE);
                        spin_unlock_irqrestore(&devpriv->isr_spinlock,
                                               irqflags);
                }
        }
}

static int pci230_ao_inttrig_start(struct comedi_device *dev,
                                   struct comedi_subdevice *s,
                                   unsigned int trig_num)
{
        if (trig_num != 0)
                return -EINVAL;

        s->async->inttrig = NULL;
        pci230_ao_start(dev, s);

        return 1;
}

static int pci230_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        unsigned short daccon;
        unsigned int range;

        /* Get the command. */
        struct comedi_cmd *cmd = &s->async->cmd;

        if (cmd->scan_begin_src == TRIG_TIMER) {
                /* Claim Z2-CT1. */
                if (!get_one_resource(dev, RES_Z2CT1, OWNER_AOCMD))
                        return -EBUSY;

        }

        /* Get number of scans required. */
        if (cmd->stop_src == TRIG_COUNT) {
                devpriv->ao_scan_count = cmd->stop_arg;
                devpriv->ao_continuous = 0;
        } else {
                /* TRIG_NONE, user calls cancel. */
                devpriv->ao_scan_count = 0;
                devpriv->ao_continuous = 1;
        }

        /* Set range - see analogue output range table; 0 => unipolar 10V,
         * 1 => bipolar +/-10V range scale */
        range = CR_RANGE(cmd->chanlist[0]);
        devpriv->ao_bipolar = pci230_ao_bipolar[range];
        daccon = devpriv->ao_bipolar ? PCI230_DAC_OR_BIP : PCI230_DAC_OR_UNI;
        /* Use DAC FIFO for hardware version 2 onwards. */
        if (devpriv->hwver >= 2) {
                unsigned short dacen;
                unsigned int i;

                dacen = 0;
                for (i = 0; i < cmd->chanlist_len; i++)
                        dacen |= 1 << CR_CHAN(cmd->chanlist[i]);

                /* Set channel scan list. */
                outw(dacen, dev->iobase + PCI230P2_DACEN);
                /*
                 * Enable DAC FIFO.
                 * Set DAC scan source to 'none'.
                 * Set DAC FIFO interrupt trigger level to 'not half full'.
                 * Reset DAC FIFO and clear underrun.
                 *
                 * N.B. DAC FIFO interrupts are currently disabled.
                 */
                daccon |= PCI230P2_DAC_FIFO_EN | PCI230P2_DAC_FIFO_RESET
                    | PCI230P2_DAC_FIFO_UNDERRUN_CLEAR
                    | PCI230P2_DAC_TRIG_NONE | PCI230P2_DAC_INT_FIFO_NHALF;
        }

        /* Set DACCON. */
        outw(daccon, dev->iobase + PCI230_DACCON);
        /* Preserve most of DACCON apart from write-only, transient bits. */
        devpriv->daccon = daccon
            & ~(PCI230P2_DAC_FIFO_RESET | PCI230P2_DAC_FIFO_UNDERRUN_CLEAR);

        if (cmd->scan_begin_src == TRIG_TIMER) {
                /* Set the counter timer 1 to the specified scan frequency. */
                /* cmd->scan_begin_arg is sampling period in ns */
                /* gate it off for now. */
                outb(GAT_CONFIG(1, GAT_GND),
                     devpriv->iobase1 + PCI230_ZGAT_SCE);
                pci230_ct_setup_ns_mode(dev, 1, I8254_MODE3,
                                        cmd->scan_begin_arg,
                                        cmd->flags & TRIG_ROUND_MASK);
        }

        /* N.B. cmd->start_src == TRIG_INT */
        s->async->inttrig = pci230_ao_inttrig_start;

        return 0;
}

static int pci230_ao_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        pci230_ao_stop(dev, s);
        return 0;
}

static int pci230_ai_check_scan_period(struct comedi_cmd *cmd)
{
        unsigned int min_scan_period, chanlist_len;
        int err = 0;

        chanlist_len = cmd->chanlist_len;
        if (cmd->chanlist_len == 0)
                chanlist_len = 1;

        min_scan_period = chanlist_len * cmd->convert_arg;
        if ((min_scan_period < chanlist_len)
            || (min_scan_period < cmd->convert_arg)) {
                /* Arithmetic overflow. */
                min_scan_period = UINT_MAX;
                err++;
        }
        if (cmd->scan_begin_arg < min_scan_period) {
                cmd->scan_begin_arg = min_scan_period;
                err++;
        }

        return !err;
}

static int pci230_ai_cmdtest(struct comedi_device *dev,
                             struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci230_private *devpriv = dev->private;
        int err = 0;
        unsigned int tmp;

        /* Step 1 : check if triggers are trivially valid */

        err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);

        tmp = TRIG_FOLLOW | TRIG_TIMER | TRIG_INT;
        if ((thisboard->have_dio) || (thisboard->min_hwver > 0)) {
                /*
                 * Unfortunately, we cannot trigger a scan off an external
                 * source on the PCI260 board, since it uses the PPIC0 (DIO)
                 * input, which isn't present on the PCI260.  For PCI260+
                 * we can use the EXTTRIG/EXTCONVCLK input on pin 17 instead.
                 */
                tmp |= TRIG_EXT;
        }
        err |= cfc_check_trigger_src(&cmd->scan_begin_src, tmp);
        err |= cfc_check_trigger_src(&cmd->convert_src,
                                        TRIG_TIMER | TRIG_INT | TRIG_EXT);
        err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
        err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);

        if (err)
                return 1;

        /* Step 2a : make sure trigger sources are unique */

        err |= cfc_check_trigger_is_unique(cmd->start_src);
        err |= cfc_check_trigger_is_unique(cmd->scan_begin_src);
        err |= cfc_check_trigger_is_unique(cmd->convert_src);
        err |= cfc_check_trigger_is_unique(cmd->stop_src);

        /* Step 2b : and mutually compatible */

        /*
         * If scan_begin_src is not TRIG_FOLLOW, then a monostable will be
         * set up to generate a fixed number of timed conversion pulses.
         */
        if ((cmd->scan_begin_src != TRIG_FOLLOW)
            && (cmd->convert_src != TRIG_TIMER))
                err |= -EINVAL;

        if (err)
                return 2;

        /* Step 3: check if arguments are trivially valid */

        err |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);

#define MAX_SPEED_AI_SE         3200    /* PCI230 SE:   3200 ns => 312.5 kHz */
#define MAX_SPEED_AI_DIFF       8000    /* PCI230 DIFF: 8000 ns => 125 kHz */
#define MAX_SPEED_AI_PLUS       4000    /* PCI230+:     4000 ns => 250 kHz */
#define MIN_SPEED_AI    4294967295u     /* 4294967295ns = 4.29s */
                        /*- Comedi limit due to unsigned int cmd.  Driver limit
                         * = 2^16 (16bit * counter) * 1000000ns (1kHz onboard
                         * clock) = 65.536s */

        if (cmd->convert_src == TRIG_TIMER) {
                unsigned int max_speed_ai;

                if (devpriv->hwver == 0) {
                        /* PCI230 or PCI260.  Max speed depends whether
                         * single-ended or pseudo-differential. */
                        if (cmd->chanlist && (cmd->chanlist_len > 0)) {
                                /* Peek analogue reference of first channel. */
                                if (CR_AREF(cmd->chanlist[0]) == AREF_DIFF)
                                        max_speed_ai = MAX_SPEED_AI_DIFF;
                                else
                                        max_speed_ai = MAX_SPEED_AI_SE;

                        } else {
                                /* No channel list.  Assume single-ended. */
                                max_speed_ai = MAX_SPEED_AI_SE;
                        }
                } else {
                        /* PCI230+ or PCI260+. */
                        max_speed_ai = MAX_SPEED_AI_PLUS;
                }

                err |= cfc_check_trigger_arg_min(&cmd->convert_arg,
                                                 max_speed_ai);
                err |= cfc_check_trigger_arg_max(&cmd->convert_arg,
                                                 MIN_SPEED_AI);
        } else if (cmd->convert_src == TRIG_EXT) {
                /*
                 * external trigger
                 *
                 * convert_arg == (CR_EDGE | 0)
                 *                => trigger on +ve edge.
                 * convert_arg == (CR_EDGE | CR_INVERT | 0)
                 *                => trigger on -ve edge.
                 */
                if ((cmd->convert_arg & CR_FLAGS_MASK) != 0) {
                        /* Trigger number must be 0. */
                        if ((cmd->convert_arg & ~CR_FLAGS_MASK) != 0) {
                                cmd->convert_arg = COMBINE(cmd->convert_arg, 0,
                                                           ~CR_FLAGS_MASK);
                                err |= -EINVAL;
                        }
                        /* The only flags allowed are CR_INVERT and CR_EDGE.
                         * CR_EDGE is required. */
                        if ((cmd->convert_arg & (CR_FLAGS_MASK & ~CR_INVERT))
                            != CR_EDGE) {
                                /* Set CR_EDGE, preserve CR_INVERT. */
                                cmd->convert_arg = COMBINE(cmd->start_arg,
                                                           (CR_EDGE | 0),
                                                           CR_FLAGS_MASK &
                                                           ~CR_INVERT);
                                err |= -EINVAL;
                        }
                } else {
                        /* Backwards compatibility with previous versions. */
                        /* convert_arg == 0 => trigger on -ve edge. */
                        /* convert_arg == 1 => trigger on +ve edge. */
                        err |= cfc_check_trigger_arg_max(&cmd->convert_arg, 1);
                }
        } else {
                err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);
        }

        err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);

        if (cmd->stop_src == TRIG_NONE)
                err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);

        if (cmd->scan_begin_src == TRIG_EXT) {
                /* external "trigger" to begin each scan
                 * scan_begin_arg==0 => use PPC0 input -> gate of CT0 -> gate
                 * of CT2 (sample convert trigger is CT2) */
                if ((cmd->scan_begin_arg & ~CR_FLAGS_MASK) != 0) {
                        cmd->scan_begin_arg = COMBINE(cmd->scan_begin_arg, 0,
                                                      ~CR_FLAGS_MASK);
                        err |= -EINVAL;
                }
                /* The only flag allowed is CR_EDGE, which is ignored. */
                if ((cmd->scan_begin_arg & CR_FLAGS_MASK & ~CR_EDGE) != 0) {
                        cmd->scan_begin_arg = COMBINE(cmd->scan_begin_arg, 0,
                                                      CR_FLAGS_MASK & ~CR_EDGE);
                        err |= -EINVAL;
                }
        } else if (cmd->scan_begin_src == TRIG_TIMER) {
                /* N.B. cmd->convert_arg is also TRIG_TIMER */
                if (!pci230_ai_check_scan_period(cmd))
                        err |= -EINVAL;

        } else {
                err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
        }

        if (err)
                return 3;

        /* Step 4: fix up any arguments.
         * "argument conflict" returned by comedilib to user mode process
         * if this fails. */

        if (cmd->convert_src == TRIG_TIMER) {
                tmp = cmd->convert_arg;
                pci230_ns_to_single_timer(&cmd->convert_arg,
                                          cmd->flags & TRIG_ROUND_MASK);
                if (tmp != cmd->convert_arg)
                        err++;
        }

        if (cmd->scan_begin_src == TRIG_TIMER) {
                /* N.B. cmd->convert_arg is also TRIG_TIMER */
                tmp = cmd->scan_begin_arg;
                pci230_ns_to_single_timer(&cmd->scan_begin_arg,
                                          cmd->flags & TRIG_ROUND_MASK);
                if (!pci230_ai_check_scan_period(cmd)) {
                        /* Was below minimum required.  Round up. */
                        pci230_ns_to_single_timer(&cmd->scan_begin_arg,
                                                  TRIG_ROUND_UP);
                        pci230_ai_check_scan_period(cmd);
                }
                if (tmp != cmd->scan_begin_arg)
                        err++;
        }

        if (err)
                return 4;

        /* Step 5: check channel list if it exists. */

        if (cmd->chanlist && cmd->chanlist_len > 0) {
                enum {
                        seq_err = 1 << 0,
                        rangepair_err = 1 << 1,
                        polarity_err = 1 << 2,
                        aref_err = 1 << 3,
                        diffchan_err = 1 << 4,
                        buggy_chan0_err = 1 << 5
                };
                unsigned int errors;
                unsigned int chan, prev_chan;
                unsigned int range, prev_range;
                unsigned int polarity, prev_polarity;
                unsigned int aref, prev_aref;
                unsigned int subseq_len;
                unsigned int n;

                subseq_len = 0;
                errors = 0;
                prev_chan = prev_aref = prev_range = prev_polarity = 0;
                for (n = 0; n < cmd->chanlist_len; n++) {
                        chan = CR_CHAN(cmd->chanlist[n]);
                        range = CR_RANGE(cmd->chanlist[n]);
                        aref = CR_AREF(cmd->chanlist[n]);
                        polarity = pci230_ai_bipolar[range];
                        /* Only the first half of the channels are available if
                         * differential.  (These are remapped in software.  In
                         * hardware, only the even channels are available.) */
                        if ((aref == AREF_DIFF)
                            && (chan >= (s->n_chan / 2))) {
                                errors |= diffchan_err;
                        }
                        if (n > 0) {
                                /* Channel numbers must strictly increase or
                                 * subsequence must repeat exactly. */
                                if ((chan <= prev_chan)
                                    && (subseq_len == 0)) {
                                        subseq_len = n;
                                }
                                if ((subseq_len > 0)
                                    && (cmd->chanlist[n] !=
                                        cmd->chanlist[n % subseq_len])) {
                                        errors |= seq_err;
                                }
                                /* Channels must have same AREF. */
                                if (aref != prev_aref)
                                        errors |= aref_err;

                                /* Channel ranges must have same polarity. */
                                if (polarity != prev_polarity)
                                        errors |= polarity_err;

                                /* Single-ended channel pairs must have same
                                 * range.  */
                                if ((aref != AREF_DIFF)
                                    && (((chan ^ prev_chan) & ~1) == 0)
                                    && (range != prev_range)) {
                                        errors |= rangepair_err;
                                }
                        }
                        prev_chan = chan;
                        prev_range = range;
                        prev_aref = aref;
                        prev_polarity = polarity;
                }
                if (subseq_len == 0) {
                        /* Subsequence is whole sequence. */
                        subseq_len = n;
                }
                /* If channel list is a repeating subsequence, need a whole
                 * number of repeats. */
                if ((n % subseq_len) != 0)
                        errors |= seq_err;

                if ((devpriv->hwver > 0) && (devpriv->hwver < 4)) {
                        /*
                         * Buggy PCI230+ or PCI260+ requires channel 0 to be
                         * (first) in the sequence if the sequence contains
                         * more than one channel.  Hardware versions 1 and 2
                         * have the bug.  There is no hardware version 3.
                         *
                         * Actually, there are two firmwares that report
                         * themselves as hardware version 1 (the boards
                         * have different ADC chips with slightly different
                         * timing requirements, which was supposed to be
                         * invisible to software).  The first one doesn't
                         * seem to have the bug, but the second one
                         * does, and we can't tell them apart!
                         */
                        if ((subseq_len > 1)
                            && (CR_CHAN(cmd->chanlist[0]) != 0)) {
                                errors |= buggy_chan0_err;
                        }
                }
                if (errors != 0) {
                        err++;
                        if ((errors & seq_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ai_cmdtest: "
                                        "channel numbers must increase or "
                                        "sequence must repeat exactly\n",
                                        dev->minor);
                        }
                        if ((errors & rangepair_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ai_cmdtest: "
                                        "single-ended channel pairs must "
                                        "have the same range\n", dev->minor);
                        }
                        if ((errors & polarity_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ai_cmdtest: "
                                        "channel sequence ranges must be all "
                                        "bipolar or all unipolar\n",
                                        dev->minor);
                        }
                        if ((errors & aref_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ai_cmdtest: "
                                        "channel sequence analogue references "
                                        "must be all the same (single-ended "
                                        "or differential)\n", dev->minor);
                        }
                        if ((errors & diffchan_err) != 0) {
                                DPRINTK("comedi%d: amplc_pci230: ai_cmdtest: "
                                        "differential channel number out of "
                                        "range 0 to %u\n", dev->minor,
                                        (s->n_chan / 2) - 1);
                        }
                        if ((errors & buggy_chan0_err) != 0) {
                                dev_info(dev->class_dev,
                                         "amplc_pci230: ai_cmdtest: Buggy PCI230+/260+ h/w version %u requires first channel of multi-channel sequence to be 0 (corrected in h/w version 4)\n",
                                         devpriv->hwver);
                        }
                }
        }

        if (err)
                return 5;

        return 0;
}

static void pci230_ai_update_fifo_trigger_level(struct comedi_device *dev,
                                                struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        struct comedi_cmd *cmd = &s->async->cmd;
        unsigned int scanlen = cmd->scan_end_arg;
        unsigned int wake;
        unsigned short triglev;
        unsigned short adccon;

        if ((cmd->flags & TRIG_WAKE_EOS) != 0) {
                /* Wake at end of scan. */
                wake = scanlen - devpriv->ai_scan_pos;
        } else {
                if (devpriv->ai_continuous
                    || (devpriv->ai_scan_count >= PCI230_ADC_FIFOLEVEL_HALFFULL)
                    || (scanlen >= PCI230_ADC_FIFOLEVEL_HALFFULL)) {
                        wake = PCI230_ADC_FIFOLEVEL_HALFFULL;
                } else {
                        wake = (devpriv->ai_scan_count * scanlen)
                            - devpriv->ai_scan_pos;
                }
        }
        if (wake >= PCI230_ADC_FIFOLEVEL_HALFFULL) {
                triglev = PCI230_ADC_INT_FIFO_HALF;
        } else {
                if ((wake > 1) && (devpriv->hwver > 0)) {
                        /* PCI230+/260+ programmable FIFO interrupt level. */
                        if (devpriv->adcfifothresh != wake) {
                                devpriv->adcfifothresh = wake;
                                outw(wake, dev->iobase + PCI230P_ADCFFTH);
                        }
                        triglev = PCI230P_ADC_INT_FIFO_THRESH;
                } else {
                        triglev = PCI230_ADC_INT_FIFO_NEMPTY;
                }
        }
        adccon = (devpriv->adccon & ~PCI230_ADC_INT_FIFO_MASK) | triglev;
        if (adccon != devpriv->adccon) {
                devpriv->adccon = adccon;
                outw(adccon, dev->iobase + PCI230_ADCCON);
        }
}

static int pci230_ai_inttrig_convert(struct comedi_device *dev,
                                     struct comedi_subdevice *s,
                                     unsigned int trig_num)
{
        struct pci230_private *devpriv = dev->private;
        unsigned long irqflags;

        if (trig_num != 0)
                return -EINVAL;

        spin_lock_irqsave(&devpriv->ai_stop_spinlock, irqflags);
        if (test_bit(AI_CMD_STARTED, &devpriv->state)) {
                unsigned int delayus;

                /* Trigger conversion by toggling Z2-CT2 output.  Finish
                 * with output high. */
                i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, 2,
                               I8254_MODE0);
                i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, 2,
                               I8254_MODE1);
                /* Delay.  Should driver be responsible for this?  An
                 * alternative would be to wait until conversion is complete,
                 * but we can't tell when it's complete because the ADC busy
                 * bit has a different meaning when FIFO enabled (and when
                 * FIFO not enabled, it only works for software triggers). */
                if (((devpriv->adccon & PCI230_ADC_IM_MASK)
                     == PCI230_ADC_IM_DIF)
                    && (devpriv->hwver == 0)) {
                        /* PCI230/260 in differential mode */
                        delayus = 8;
                } else {
                        /* single-ended or PCI230+/260+ */
                        delayus = 4;
                }
                spin_unlock_irqrestore(&devpriv->ai_stop_spinlock, irqflags);
                udelay(delayus);
        } else {
                spin_unlock_irqrestore(&devpriv->ai_stop_spinlock, irqflags);
        }

        return 1;
}

static int pci230_ai_inttrig_scan_begin(struct comedi_device *dev,
                                        struct comedi_subdevice *s,
                                        unsigned int trig_num)
{
        struct pci230_private *devpriv = dev->private;
        unsigned long irqflags;
        unsigned char zgat;

        if (trig_num != 0)
                return -EINVAL;

        spin_lock_irqsave(&devpriv->ai_stop_spinlock, irqflags);
        if (test_bit(AI_CMD_STARTED, &devpriv->state)) {
                /* Trigger scan by waggling CT0 gate source. */
                zgat = GAT_CONFIG(0, GAT_GND);
                outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
                zgat = GAT_CONFIG(0, GAT_VCC);
                outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
        }
        spin_unlock_irqrestore(&devpriv->ai_stop_spinlock, irqflags);

        return 1;
}

static void pci230_ai_stop(struct comedi_device *dev,
                           struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        unsigned long irqflags;
        struct comedi_cmd *cmd;
        int started;

        spin_lock_irqsave(&devpriv->ai_stop_spinlock, irqflags);
        started = test_and_clear_bit(AI_CMD_STARTED, &devpriv->state);
        spin_unlock_irqrestore(&devpriv->ai_stop_spinlock, irqflags);
        if (!started)
                return;
        cmd = &s->async->cmd;
        if (cmd->convert_src == TRIG_TIMER) {
                /* Stop conversion rate generator. */
                pci230_cancel_ct(dev, 2);
        }
        if (cmd->scan_begin_src != TRIG_FOLLOW) {
                /* Stop scan period monostable. */
                pci230_cancel_ct(dev, 0);
        }
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        /* Disable ADC interrupt and wait for interrupt routine to finish
         * running unless we are called from the interrupt routine. */
        devpriv->int_en &= ~PCI230_INT_ADC;
        while (devpriv->intr_running && devpriv->intr_cpuid != THISCPU) {
                spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
                spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        }
        if (devpriv->ier != devpriv->int_en) {
                devpriv->ier = devpriv->int_en;
                outb(devpriv->ier, devpriv->iobase1 + PCI230_INT_SCE);
        }
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
        /* Reset FIFO, disable FIFO and set start conversion source to none.
         * Keep se/diff and bip/uni settings */
        devpriv->adccon = (devpriv->adccon & (PCI230_ADC_IR_MASK
                                              | PCI230_ADC_IM_MASK)) |
            PCI230_ADC_TRIG_NONE;
        outw(devpriv->adccon | PCI230_ADC_FIFO_RESET,
             dev->iobase + PCI230_ADCCON);
        /* Release resources. */
        put_all_resources(dev, OWNER_AICMD);
}

static void pci230_ai_start(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        unsigned long irqflags;
        unsigned short conv;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;

        set_bit(AI_CMD_STARTED, &devpriv->state);
        if (!devpriv->ai_continuous && (devpriv->ai_scan_count == 0)) {
                /* An empty acquisition! */
                async->events |= COMEDI_CB_EOA;
                pci230_ai_stop(dev, s);
                comedi_event(dev, s);
        } else {
                /* Enable ADC FIFO trigger level interrupt. */
                spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
                devpriv->int_en |= PCI230_INT_ADC;
                devpriv->ier |= PCI230_INT_ADC;
                outb(devpriv->ier, devpriv->iobase1 + PCI230_INT_SCE);
                spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);

                /* Update conversion trigger source which is currently set
                 * to CT2 output, which is currently stuck high. */
                switch (cmd->convert_src) {
                default:
                        conv = PCI230_ADC_TRIG_NONE;
                        break;
                case TRIG_TIMER:
                        /* Using CT2 output. */
                        conv = PCI230_ADC_TRIG_Z2CT2;
                        break;
                case TRIG_EXT:
                        if ((cmd->convert_arg & CR_EDGE) != 0) {
                                if ((cmd->convert_arg & CR_INVERT) == 0) {
                                        /* Trigger on +ve edge. */
                                        conv = PCI230_ADC_TRIG_EXTP;
                                } else {
                                        /* Trigger on -ve edge. */
                                        conv = PCI230_ADC_TRIG_EXTN;
                                }
                        } else {
                                /* Backwards compatibility. */
                                if (cmd->convert_arg != 0) {
                                        /* Trigger on +ve edge. */
                                        conv = PCI230_ADC_TRIG_EXTP;
                                } else {
                                        /* Trigger on -ve edge. */
                                        conv = PCI230_ADC_TRIG_EXTN;
                                }
                        }
                        break;
                case TRIG_INT:
                        /* Use CT2 output for software trigger due to problems
                         * in differential mode on PCI230/260. */
                        conv = PCI230_ADC_TRIG_Z2CT2;
                        break;
                }
                devpriv->adccon = (devpriv->adccon & ~PCI230_ADC_TRIG_MASK)
                    | conv;
                outw(devpriv->adccon, dev->iobase + PCI230_ADCCON);
                if (cmd->convert_src == TRIG_INT)
                        async->inttrig = pci230_ai_inttrig_convert;

                /* Update FIFO interrupt trigger level, which is currently
                 * set to "full".  */
                pci230_ai_update_fifo_trigger_level(dev, s);
                if (cmd->convert_src == TRIG_TIMER) {
                        /* Update timer gates. */
                        unsigned char zgat;

                        if (cmd->scan_begin_src != TRIG_FOLLOW) {
                                /* Conversion timer CT2 needs to be gated by
                                 * inverted output of monostable CT2. */
                                zgat = GAT_CONFIG(2, GAT_NOUTNM2);
                        } else {
                                /* Conversion timer CT2 needs to be gated on
                                 * continuously. */
                                zgat = GAT_CONFIG(2, GAT_VCC);
                        }
                        outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
                        if (cmd->scan_begin_src != TRIG_FOLLOW) {
                                /* Set monostable CT0 trigger source. */
                                switch (cmd->scan_begin_src) {
                                default:
                                        zgat = GAT_CONFIG(0, GAT_VCC);
                                        break;
                                case TRIG_EXT:
                                        /*
                                         * For CT0 on PCI230, the external
                                         * trigger (gate) signal comes from
                                         * PPC0, which is channel 16 of the DIO
                                         * subdevice.  The application needs to
                                         * configure this as an input in order
                                         * to use it as an external scan
                                         * trigger.
                                         */
                                        zgat = GAT_CONFIG(0, GAT_EXT);
                                        break;
                                case TRIG_TIMER:
                                        /*
                                         * Monostable CT0 triggered by rising
                                         * edge on inverted output of CT1
                                         * (falling edge on CT1).
                                         */
                                        zgat = GAT_CONFIG(0, GAT_NOUTNM2);
                                        break;
                                case TRIG_INT:
                                        /*
                                         * Monostable CT0 is triggered by
                                         * inttrig function waggling the CT0
                                         * gate source.
                                         */
                                        zgat = GAT_CONFIG(0, GAT_VCC);
                                        break;
                                }
                                outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
                                switch (cmd->scan_begin_src) {
                                case TRIG_TIMER:
                                        /* Scan period timer CT1 needs to be
                                         * gated on to start counting. */
                                        zgat = GAT_CONFIG(1, GAT_VCC);
                                        outb(zgat, devpriv->iobase1
                                             + PCI230_ZGAT_SCE);
                                        break;
                                case TRIG_INT:
                                        async->inttrig =
                                            pci230_ai_inttrig_scan_begin;
                                        break;
                                }
                        }
                } else if (cmd->convert_src != TRIG_INT) {
                        /* No longer need Z2-CT2. */
                        put_one_resource(dev, RES_Z2CT2, OWNER_AICMD);
                }
        }
}

static int pci230_ai_inttrig_start(struct comedi_device *dev,
                                   struct comedi_subdevice *s,
                                   unsigned int trig_num)
{
        if (trig_num != 0)
                return -EINVAL;

        s->async->inttrig = NULL;
        pci230_ai_start(dev, s);

        return 1;
}

static void pci230_handle_ai(struct comedi_device *dev,
                             struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        unsigned int events = 0;
        unsigned int status_fifo;
        unsigned int i;
        unsigned int todo;
        unsigned int fifoamount;
        struct comedi_async *async = s->async;
        unsigned int scanlen = async->cmd.scan_end_arg;

        /* Determine number of samples to read. */
        if (devpriv->ai_continuous) {
                todo = PCI230_ADC_FIFOLEVEL_HALFFULL;
        } else if (devpriv->ai_scan_count == 0) {
                todo = 0;
        } else if ((devpriv->ai_scan_count > PCI230_ADC_FIFOLEVEL_HALFFULL)
                   || (scanlen > PCI230_ADC_FIFOLEVEL_HALFFULL)) {
                todo = PCI230_ADC_FIFOLEVEL_HALFFULL;
        } else {
                todo = (devpriv->ai_scan_count * scanlen)
                    - devpriv->ai_scan_pos;
                if (todo > PCI230_ADC_FIFOLEVEL_HALFFULL)
                        todo = PCI230_ADC_FIFOLEVEL_HALFFULL;
        }
        if (todo == 0)
                return;
        fifoamount = 0;
        for (i = 0; i < todo; i++) {
                if (fifoamount == 0) {
                        /* Read FIFO state. */
                        status_fifo = inw(dev->iobase + PCI230_ADCCON);
                        if ((status_fifo & PCI230_ADC_FIFO_FULL_LATCHED) != 0) {
                                /* Report error otherwise FIFO overruns will go
                                 * unnoticed by the caller. */
                                comedi_error(dev, "AI FIFO overrun");
                                events |= COMEDI_CB_OVERFLOW | COMEDI_CB_ERROR;
                                break;
                        } else if ((status_fifo & PCI230_ADC_FIFO_EMPTY) != 0) {
                                /* FIFO empty. */
                                break;
                        } else if ((status_fifo & PCI230_ADC_FIFO_HALF) != 0) {
                                /* FIFO half full. */
                                fifoamount = PCI230_ADC_FIFOLEVEL_HALFFULL;
                        } else {
                                /* FIFO not empty. */
                                if (devpriv->hwver > 0) {
                                        /* Read PCI230+/260+ ADC FIFO level. */
                                        fifoamount = inw(dev->iobase
                                                         + PCI230P_ADCFFLEV);
                                        if (fifoamount == 0) {
                                                /* Shouldn't happen. */
                                                break;
                                        }
                                } else {
                                        fifoamount = 1;
                                }
                        }
                }
                /* Read sample and store in Comedi's circular buffer. */
                if (comedi_buf_put(async, pci230_ai_read(dev)) == 0) {
                        events |= COMEDI_CB_ERROR | COMEDI_CB_OVERFLOW;
                        comedi_error(dev, "AI buffer overflow");
                        break;
                }
                fifoamount--;
                devpriv->ai_scan_pos++;
                if (devpriv->ai_scan_pos == scanlen) {
                        /* End of scan. */
                        devpriv->ai_scan_pos = 0;
                        devpriv->ai_scan_count--;
                        async->events |= COMEDI_CB_EOS;
                }
        }
        if (!devpriv->ai_continuous && (devpriv->ai_scan_count == 0)) {
                /* End of acquisition. */
                events |= COMEDI_CB_EOA;
        } else {
                /* More samples required, tell Comedi to block. */
                events |= COMEDI_CB_BLOCK;
        }
        async->events |= events;
        if ((async->events & (COMEDI_CB_EOA | COMEDI_CB_ERROR |
                              COMEDI_CB_OVERFLOW)) != 0) {
                /* disable hardware conversions */
                pci230_ai_stop(dev, s);
        } else {
                /* update FIFO interrupt trigger level */
                pci230_ai_update_fifo_trigger_level(dev, s);
        }
}

static int pci230_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct pci230_private *devpriv = dev->private;
        unsigned int i, chan, range, diff;
        unsigned int res_mask;
        unsigned short adccon, adcen;
        unsigned char zgat;

        /* Get the command. */
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;

        /*
         * Determine which shared resources are needed.
         */
        res_mask = 0;
        /* Need Z2-CT2 to supply a conversion trigger source at a high
         * logic level, even if not doing timed conversions. */
        res_mask |= (1U << RES_Z2CT2);
        if (cmd->scan_begin_src != TRIG_FOLLOW) {
                /* Using Z2-CT0 monostable to gate Z2-CT2 conversion timer */
                res_mask |= (1U << RES_Z2CT0);
                if (cmd->scan_begin_src == TRIG_TIMER) {
                        /* Using Z2-CT1 for scan frequency */
                        res_mask |= (1U << RES_Z2CT1);
                }
        }
        /* Claim resources. */
        if (!get_resources(dev, res_mask, OWNER_AICMD))
                return -EBUSY;


        /* Get number of scans required. */
        if (cmd->stop_src == TRIG_COUNT) {
                devpriv->ai_scan_count = cmd->stop_arg;
                devpriv->ai_continuous = 0;
        } else {
                /* TRIG_NONE, user calls cancel. */
                devpriv->ai_scan_count = 0;
                devpriv->ai_continuous = 1;
        }
        devpriv->ai_scan_pos = 0;       /* Position within scan. */

        /* Steps;
         * - Set channel scan list.
         * - Set channel gains.
         * - Enable and reset FIFO, specify uni/bip, se/diff, and set
         *   start conversion source to point to something at a high logic
         *   level (we use the output of counter/timer 2 for this purpose.
         * - PAUSE to allow things to settle down.
         * - Reset the FIFO again because it needs resetting twice and there
         *   may have been a false conversion trigger on some versions of
         *   PCI230/260 due to the start conversion source being set to a
         *   high logic level.
         * - Enable ADC FIFO level interrupt.
         * - Set actual conversion trigger source and FIFO interrupt trigger
         *   level.
         * - If convert_src is TRIG_TIMER, set up the timers.
         */

        adccon = PCI230_ADC_FIFO_EN;
        adcen = 0;

        if (CR_AREF(cmd->chanlist[0]) == AREF_DIFF) {
                /* Differential - all channels must be differential. */
                diff = 1;
                adccon |= PCI230_ADC_IM_DIF;
        } else {
                /* Single ended - all channels must be single-ended. */
                diff = 0;
                adccon |= PCI230_ADC_IM_SE;
        }

        range = CR_RANGE(cmd->chanlist[0]);
        devpriv->ai_bipolar = pci230_ai_bipolar[range];
        if (devpriv->ai_bipolar)
                adccon |= PCI230_ADC_IR_BIP;
        else
                adccon |= PCI230_ADC_IR_UNI;

        for (i = 0; i < cmd->chanlist_len; i++) {
                unsigned int gainshift;

                chan = CR_CHAN(cmd->chanlist[i]);
                range = CR_RANGE(cmd->chanlist[i]);
                if (diff) {
                        gainshift = 2 * chan;
                        if (devpriv->hwver == 0) {
                                /* Original PCI230/260 expects both inputs of
                                 * the differential channel to be enabled. */
                                adcen |= 3 << gainshift;
                        } else {
                                /* PCI230+/260+ expects only one input of the
                                 * differential channel to be enabled. */
                                adcen |= 1 << gainshift;
                        }
                } else {
                        gainshift = (chan & ~1);
                        adcen |= 1 << chan;
                }
                devpriv->adcg = (devpriv->adcg & ~(3 << gainshift))
                    | (pci230_ai_gain[range] << gainshift);
        }

        /* Set channel scan list. */
        outw(adcen, dev->iobase + PCI230_ADCEN);

        /* Set channel gains. */
        outw(devpriv->adcg, dev->iobase + PCI230_ADCG);

        /* Set counter/timer 2 output high for use as the initial start
         * conversion source. */
        i8254_set_mode(devpriv->iobase1 + PCI230_Z2_CT_BASE, 0, 2, I8254_MODE1);

        /* Temporarily use CT2 output as conversion trigger source and
         * temporarily set FIFO interrupt trigger level to 'full'. */
        adccon |= PCI230_ADC_INT_FIFO_FULL | PCI230_ADC_TRIG_Z2CT2;

        /* Enable and reset FIFO, specify FIFO trigger level full, specify
         * uni/bip, se/diff, and temporarily set the start conversion source
         * to CT2 output.  Note that CT2 output is currently high, and this
         * will produce a false conversion trigger on some versions of the
         * PCI230/260, but that will be dealt with later. */
        devpriv->adccon = adccon;
        outw(adccon | PCI230_ADC_FIFO_RESET, dev->iobase + PCI230_ADCCON);

        /* Delay */
        /* Failure to include this will result in the first few channels'-worth
         * of data being corrupt, normally manifesting itself by large negative
         * voltages. It seems the board needs time to settle between the first
         * FIFO reset (above) and the second FIFO reset (below). Setting the
         * channel gains and scan list _before_ the first FIFO reset also
         * helps, though only slightly. */
        udelay(25);

        /* Reset FIFO again. */
        outw(adccon | PCI230_ADC_FIFO_RESET, dev->iobase + PCI230_ADCCON);

        if (cmd->convert_src == TRIG_TIMER) {
                /* Set up CT2 as conversion timer, but gate it off for now.
                 * Note, counter/timer output 2 can be monitored on the
                 * connector: PCI230 pin 21, PCI260 pin 18. */
                zgat = GAT_CONFIG(2, GAT_GND);
                outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
                /* Set counter/timer 2 to the specified conversion period. */
                pci230_ct_setup_ns_mode(dev, 2, I8254_MODE3, cmd->convert_arg,
                                        cmd->flags & TRIG_ROUND_MASK);
                if (cmd->scan_begin_src != TRIG_FOLLOW) {
                        /*
                         * Set up monostable on CT0 output for scan timing.  A
                         * rising edge on the trigger (gate) input of CT0 will
                         * trigger the monostable, causing its output to go low
                         * for the configured period.  The period depends on
                         * the conversion period and the number of conversions
                         * in the scan.
                         *
                         * Set the trigger high before setting up the
                         * monostable to stop it triggering.  The trigger
                         * source will be changed later.
                         */
                        zgat = GAT_CONFIG(0, GAT_VCC);
                        outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
                        pci230_ct_setup_ns_mode(dev, 0, I8254_MODE1,
                                                ((uint64_t) cmd->convert_arg
                                                 * cmd->scan_end_arg),
                                                TRIG_ROUND_UP);
                        if (cmd->scan_begin_src == TRIG_TIMER) {
                                /*
                                 * Monostable on CT0 will be triggered by
                                 * output of CT1 at configured scan frequency.
                                 *
                                 * Set up CT1 but gate it off for now.
                                 */
                                zgat = GAT_CONFIG(1, GAT_GND);
                                outb(zgat, devpriv->iobase1 + PCI230_ZGAT_SCE);
                                pci230_ct_setup_ns_mode(dev, 1, I8254_MODE3,
                                                        cmd->scan_begin_arg,
                                                        cmd->
                                                        flags &
                                                        TRIG_ROUND_MASK);
                        }
                }
        }

        if (cmd->start_src == TRIG_INT) {
                s->async->inttrig = pci230_ai_inttrig_start;
        } else {
                /* TRIG_NOW */
                pci230_ai_start(dev, s);
        }

        return 0;
}

static int pci230_ai_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        pci230_ai_stop(dev, s);
        return 0;
}

/* Interrupt handler */
static irqreturn_t pci230_interrupt(int irq, void *d)
{
        unsigned char status_int, valid_status_int;
        struct comedi_device *dev = (struct comedi_device *)d;
        struct pci230_private *devpriv = dev->private;
        struct comedi_subdevice *s;
        unsigned long irqflags;

        /* Read interrupt status/enable register. */
        status_int = inb(devpriv->iobase1 + PCI230_INT_STAT);

        if (status_int == PCI230_INT_DISABLE)
                return IRQ_NONE;


        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        valid_status_int = devpriv->int_en & status_int;
        /* Disable triggered interrupts.
         * (Only those interrupts that need re-enabling, are, later in the
         * handler).  */
        devpriv->ier = devpriv->int_en & ~status_int;
        outb(devpriv->ier, devpriv->iobase1 + PCI230_INT_SCE);
        devpriv->intr_running = 1;
        devpriv->intr_cpuid = THISCPU;
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);

        /*
         * Check the source of interrupt and handle it.
         * The PCI230 can cope with concurrent ADC, DAC, PPI C0 and C3
         * interrupts.  However, at present (Comedi-0.7.60) does not allow
         * concurrent execution of commands, instructions or a mixture of the
         * two.
         */

        if ((valid_status_int & PCI230_INT_ZCLK_CT1) != 0) {
                s = dev->write_subdev;
                pci230_handle_ao_nofifo(dev, s);
                comedi_event(dev, s);
        }

        if ((valid_status_int & PCI230P2_INT_DAC) != 0) {
                s = dev->write_subdev;
                pci230_handle_ao_fifo(dev, s);
                comedi_event(dev, s);
        }

        if ((valid_status_int & PCI230_INT_ADC) != 0) {
                s = dev->read_subdev;
                pci230_handle_ai(dev, s);
                comedi_event(dev, s);
        }

        /* Reenable interrupts. */
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        if (devpriv->ier != devpriv->int_en) {
                devpriv->ier = devpriv->int_en;
                outb(devpriv->ier, devpriv->iobase1 + PCI230_INT_SCE);
        }
        devpriv->intr_running = 0;
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);

        return IRQ_HANDLED;
}

/* Check if PCI device matches a specific board. */
static bool pci230_match_pci_board(const struct pci230_board *board,
                                   struct pci_dev *pci_dev)
{
        /* assume pci_dev->device != PCI_DEVICE_ID_INVALID */
        if (board->id != pci_dev->device)
                return false;
        if (board->min_hwver == 0)
                return true;
        /* Looking for a '+' model.  First check length of registers. */
        if (pci_resource_len(pci_dev, 3) < 32)
                return false;   /* Not a '+' model. */
        /* TODO: temporarily enable PCI device and read the hardware version
         * register.  For now, assume it's okay. */
        return true;
}

/* Look for board matching PCI device. */
static const struct pci230_board *pci230_find_pci_board(struct pci_dev *pci_dev)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(pci230_boards); i++)
                if (pci230_match_pci_board(&pci230_boards[i], pci_dev))
                        return &pci230_boards[i];
        return NULL;
}

/* Look for PCI device matching requested board name, bus and slot. */
static struct pci_dev *pci230_find_pci_dev(struct comedi_device *dev,
                                           struct comedi_devconfig *it)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci_dev *pci_dev = NULL;
        int bus = it->options[0];
        int slot = it->options[1];

        for_each_pci_dev(pci_dev) {
                /* Check vendor ID (same for all supported PCI boards). */
                if (pci_dev->vendor != PCI_VENDOR_ID_AMPLICON)
                        continue;
                /* If bus/slot specified, check them. */
                if ((bus || slot) &&
                    (bus != pci_dev->bus->number ||
                     slot != PCI_SLOT(pci_dev->devfn)))
                        continue;
                if (thisboard->id == PCI_DEVICE_ID_INVALID) {
                        /* Wildcard board matches any supported PCI board. */
                        const struct pci230_board *foundboard;

                        foundboard = pci230_find_pci_board(pci_dev);
                        if (foundboard == NULL)
                                continue;
                        /* Replace wildcard board_ptr. */
                        dev->board_ptr = foundboard;
                } else {
                        /* Need to match a specific board. */
                        if (!pci230_match_pci_board(thisboard, pci_dev))
                                continue;
                }
                return pci_dev;
        }
        dev_err(dev->class_dev,
                "No supported board found! (req. bus %d, slot %d)\n",
                bus, slot);
        return NULL;
}

static int pci230_alloc_private(struct comedi_device *dev)
{
        struct pci230_private *devpriv;

        devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
        if (!devpriv)
                return -ENOMEM;
        dev->private = devpriv;

        spin_lock_init(&devpriv->isr_spinlock);
        spin_lock_init(&devpriv->res_spinlock);
        spin_lock_init(&devpriv->ai_stop_spinlock);
        spin_lock_init(&devpriv->ao_stop_spinlock);
        return 0;
}

/* Common part of attach and auto_attach. */
static int pci230_attach_common(struct comedi_device *dev,
                                struct pci_dev *pci_dev)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci230_private *devpriv = dev->private;
        struct comedi_subdevice *s;
        unsigned long iobase1, iobase2;
        /* PCI230's I/O spaces 1 and 2 respectively. */
        int irq_hdl, rc;

        comedi_set_hw_dev(dev, &pci_dev->dev);

        dev->board_name = thisboard->name;

        rc = comedi_pci_enable(dev);
        if (rc)
                return rc;

        /* Read base addresses of the PCI230's two I/O regions from PCI
         * configuration register. */
        iobase1 = pci_resource_start(pci_dev, 2);
        iobase2 = pci_resource_start(pci_dev, 3);
        dev_dbg(dev->class_dev,
                "%s I/O region 1 0x%04lx I/O region 2 0x%04lx\n",
                dev->board_name, iobase1, iobase2);
        devpriv->iobase1 = iobase1;
        dev->iobase = iobase2;
        /* Read bits of DACCON register - only the output range. */
        devpriv->daccon = inw(dev->iobase + PCI230_DACCON) & PCI230_DAC_OR_MASK;
        /* Read hardware version register and set extended function register
         * if they exist. */
        if (pci_resource_len(pci_dev, 3) >= 32) {
                unsigned short extfunc = 0;

                devpriv->hwver = inw(dev->iobase + PCI230P_HWVER);
                if (devpriv->hwver < thisboard->min_hwver) {
                        dev_err(dev->class_dev,
                                "%s - bad hardware version - got %u, need %u\n",
                                dev->board_name, devpriv->hwver,
                                thisboard->min_hwver);
                        return -EIO;
                }
                if (devpriv->hwver > 0) {
                        if (!thisboard->have_dio) {
                                /* No DIO ports.  Route counters' external gates
                                 * to the EXTTRIG signal (PCI260+ pin 17).
                                 * (Otherwise, they would be routed to DIO
                                 * inputs PC0, PC1 and PC2 which don't exist
                                 * on PCI260[+].) */
                                extfunc |= PCI230P_EXTFUNC_GAT_EXTTRIG;
                        }
                        if ((thisboard->ao_chans > 0)
                            && (devpriv->hwver >= 2)) {
                                /* Enable DAC FIFO functionality. */
                                extfunc |= PCI230P2_EXTFUNC_DACFIFO;
                        }
                }
                outw(extfunc, dev->iobase + PCI230P_EXTFUNC);
                if ((extfunc & PCI230P2_EXTFUNC_DACFIFO) != 0) {
                        /* Temporarily enable DAC FIFO, reset it and disable
                         * FIFO wraparound. */
                        outw(devpriv->daccon | PCI230P2_DAC_FIFO_EN
                             | PCI230P2_DAC_FIFO_RESET,
                             dev->iobase + PCI230_DACCON);
                        /* Clear DAC FIFO channel enable register. */
                        outw(0, dev->iobase + PCI230P2_DACEN);
                        /* Disable DAC FIFO. */
                        outw(devpriv->daccon, dev->iobase + PCI230_DACCON);
                }
        }
        /* Disable board's interrupts. */
        outb(0, devpriv->iobase1 + PCI230_INT_SCE);
        /* Set ADC to a reasonable state. */
        devpriv->adcg = 0;
        devpriv->adccon = PCI230_ADC_TRIG_NONE | PCI230_ADC_IM_SE
            | PCI230_ADC_IR_BIP;
        outw(1 << 0, dev->iobase + PCI230_ADCEN);
        outw(devpriv->adcg, dev->iobase + PCI230_ADCG);
        outw(devpriv->adccon | PCI230_ADC_FIFO_RESET,
             dev->iobase + PCI230_ADCCON);
        /* Register the interrupt handler. */
        irq_hdl = request_irq(pci_dev->irq, pci230_interrupt,
                              IRQF_SHARED, "amplc_pci230", dev);
        if (irq_hdl < 0) {
                dev_warn(dev->class_dev,
                         "unable to register irq %u, commands will not be available\n",
                         pci_dev->irq);
        } else {
                dev->irq = pci_dev->irq;
                dev_dbg(dev->class_dev, "registered irq %u\n", pci_dev->irq);
        }

        rc = comedi_alloc_subdevices(dev, 3);
        if (rc)
                return rc;

        s = &dev->subdevices[0];
        /* analog input subdevice */
        s->type = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_DIFF | SDF_GROUND;
        s->n_chan = thisboard->ai_chans;
        s->maxdata = (1 << thisboard->ai_bits) - 1;
        s->range_table = &pci230_ai_range;
        s->insn_read = &pci230_ai_rinsn;
        s->len_chanlist = 256;  /* but there are restrictions. */
        /* Only register commands if the interrupt handler is installed. */
        if (irq_hdl == 0) {
                dev->read_subdev = s;
                s->subdev_flags |= SDF_CMD_READ;
                s->do_cmd = &pci230_ai_cmd;
                s->do_cmdtest = &pci230_ai_cmdtest;
                s->cancel = pci230_ai_cancel;
        }
        s = &dev->subdevices[1];
        /* analog output subdevice */
        if (thisboard->ao_chans > 0) {
                s->type = COMEDI_SUBD_AO;
                s->subdev_flags = SDF_WRITABLE | SDF_GROUND;
                s->n_chan = thisboard->ao_chans;
                s->maxdata = (1 << thisboard->ao_bits) - 1;
                s->range_table = &pci230_ao_range;
                s->insn_write = &pci230_ao_winsn;
                s->insn_read = &pci230_ao_rinsn;
                s->len_chanlist = thisboard->ao_chans;
                /* Only register commands if the interrupt handler is
                 * installed. */
                if (irq_hdl == 0) {
                        dev->write_subdev = s;
                        s->subdev_flags |= SDF_CMD_WRITE;
                        s->do_cmd = &pci230_ao_cmd;
                        s->do_cmdtest = &pci230_ao_cmdtest;
                        s->cancel = pci230_ao_cancel;
                }
        } else {
                s->type = COMEDI_SUBD_UNUSED;
        }
        s = &dev->subdevices[2];
        /* digital i/o subdevice */
        if (thisboard->have_dio) {
                rc = subdev_8255_init(dev, s, NULL,
                                      (devpriv->iobase1 + PCI230_PPI_X_BASE));
                if (rc < 0)
                        return rc;
        } else {
                s->type = COMEDI_SUBD_UNUSED;
        }
        dev_info(dev->class_dev, "attached\n");
        return 1;
}

static int pci230_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        const struct pci230_board *thisboard = comedi_board(dev);
        struct pci_dev *pci_dev;
        int rc;

        dev_info(dev->class_dev, "amplc_pci230: attach %s %d,%d\n",
                 thisboard->name, it->options[0], it->options[1]);

        rc = pci230_alloc_private(dev);
        if (rc)
                return rc;

        pci_dev = pci230_find_pci_dev(dev, it);
        if (!pci_dev)
                return -EIO;
        return pci230_attach_common(dev, pci_dev);
}

static int pci230_auto_attach(struct comedi_device *dev,
                                        unsigned long context_unused)
{
        struct pci_dev *pci_dev = comedi_to_pci_dev(dev);
        int rc;

        dev_info(dev->class_dev, "amplc_pci230: attach pci %s\n",
                 pci_name(pci_dev));

        rc = pci230_alloc_private(dev);
        if (rc)
                return rc;

        dev->board_ptr = pci230_find_pci_board(pci_dev);
        if (dev->board_ptr == NULL) {
                dev_err(dev->class_dev,
                        "amplc_pci230: BUG! cannot determine board type!\n");
                return -EINVAL;
        }
        /*
         * Need to 'get' the PCI device to match the 'put' in pci230_detach().
         * TODO: Remove the pci_dev_get() and matching pci_dev_put() once
         * support for manual attachment of PCI devices via pci230_attach()
         * has been removed.
         */
        pci_dev_get(pci_dev);
        return pci230_attach_common(dev, pci_dev);
}

static void pci230_detach(struct comedi_device *dev)
{
        struct pci_dev *pcidev = comedi_to_pci_dev(dev);

        comedi_spriv_free(dev, 2);
        if (dev->irq)
                free_irq(dev->irq, dev);
        comedi_pci_disable(dev);
        if (pcidev)
                pci_dev_put(pcidev);
}

static struct comedi_driver amplc_pci230_driver = {
        .driver_name    = "amplc_pci230",
        .module         = THIS_MODULE,
        .attach         = pci230_attach,
        .auto_attach    = pci230_auto_attach,
        .detach         = pci230_detach,
        .board_name     = &pci230_boards[0].name,
        .offset         = sizeof(pci230_boards[0]),
        .num_names      = ARRAY_SIZE(pci230_boards),
};

static int amplc_pci230_pci_probe(struct pci_dev *dev,
                                  const struct pci_device_id *id)
{
        return comedi_pci_auto_config(dev, &amplc_pci230_driver,
                                      id->driver_data);
}

static DEFINE_PCI_DEVICE_TABLE(amplc_pci230_pci_table) = {
        { PCI_DEVICE(PCI_VENDOR_ID_AMPLICON, PCI_DEVICE_ID_PCI230) },
        { PCI_DEVICE(PCI_VENDOR_ID_AMPLICON, PCI_DEVICE_ID_PCI260) },
        { 0 }
};
MODULE_DEVICE_TABLE(pci, amplc_pci230_pci_table);

static struct pci_driver amplc_pci230_pci_driver = {
        .name           = "amplc_pci230",
        .id_table       = amplc_pci230_pci_table,
        .probe          = amplc_pci230_pci_probe,
        .remove         = comedi_pci_auto_unconfig,
};
module_comedi_pci_driver(amplc_pci230_driver, amplc_pci230_pci_driver);

MODULE_AUTHOR("Comedi http://www.comedi.org");
MODULE_DESCRIPTION("Comedi low-level driver");
MODULE_LICENSE("GPL");