/*
 * comedi/drivers/amplc_pci224.c
 * Driver for Amplicon PCI224 and PCI234 AO boards.
 *
 * Copyright (C) 2005 MEV Ltd. <http://www.mev.co.uk/>
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1998,2000 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.
 */

/*
 * Driver: amplc_pci224
 * Description: Amplicon PCI224, PCI234
 * Author: Ian Abbott <abbotti@mev.co.uk>
 * Devices: [Amplicon] PCI224 (amplc_pci224), PCI234
 * Updated: Thu, 31 Jul 2014 11:08:03 +0000
 * Status: works, but see caveats
 *
 * Supports:
 *
 *   - ao_insn read/write
 *   - ao_do_cmd mode with the following sources:
 *
 *     - start_src         TRIG_INT        TRIG_EXT
 *     - scan_begin_src    TRIG_TIMER      TRIG_EXT
 *     - convert_src       TRIG_NOW
 *     - scan_end_src      TRIG_COUNT
 *     - stop_src          TRIG_COUNT      TRIG_EXT        TRIG_NONE
 *
 *     The channel list must contain at least one channel with no repeated
 *     channels.  The scan end count must equal the number of channels in
 *     the channel list.
 *
 *     There is only one external trigger source so only one of start_src,
 *     scan_begin_src or stop_src may use TRIG_EXT.
 *
 * Configuration options:
 *   none
 *
 * Manual configuration of PCI cards is not supported; they are configured
 * automatically.
 *
 * Output range selection - PCI224:
 *
 *   Output ranges on PCI224 are partly software-selectable and partly
 *   hardware-selectable according to jumper LK1.  All channels are set
 *   to the same range:
 *
 *   - LK1 position 1-2 (factory default) corresponds to the following
 *     comedi ranges:
 *
 *       0: [-10V,+10V]; 1: [-5V,+5V]; 2: [-2.5V,+2.5V], 3: [-1.25V,+1.25V],
 *       4: [0,+10V],    5: [0,+5V],   6: [0,+2.5V],     7: [0,+1.25V]
 *
 *   - LK1 position 2-3 corresponds to the following Comedi ranges, using
 *     an external voltage reference:
 *
 *       0: [-Vext,+Vext],
 *       1: [0,+Vext]
 *
 * Output range selection - PCI234:
 *
 *   Output ranges on PCI234 are hardware-selectable according to jumper
 *   LK1 which affects all channels, and jumpers LK2, LK3, LK4 and LK5
 *   which affect channels 0, 1, 2 and 3 individually.  LK1 chooses between
 *   an internal 5V reference and an external voltage reference (Vext).
 *   LK2/3/4/5 choose (per channel) to double the reference or not according
 *   to the following table:
 *
 *     LK1 position   LK2/3/4/5 pos  Comedi range
 *     -------------  -------------  --------------
 *     2-3 (factory)  1-2 (factory)  0: [-10V,+10V]
 *     2-3 (factory)  2-3            1: [-5V,+5V]
 *     1-2            1-2 (factory)  2: [-2*Vext,+2*Vext]
 *     1-2            2-3            3: [-Vext,+Vext]
 *
 * Caveats:
 *
 *   1) All channels on the PCI224 share the same range.  Any change to the
 *      range as a result of insn_write or a streaming command will affect
 *      the output voltages of all channels, including those not specified
 *      by the instruction or command.
 *
 *   2) For the analog output command,  the first scan may be triggered
 *      falsely at the start of acquisition.  This occurs when the DAC scan
 *      trigger source is switched from 'none' to 'timer' (scan_begin_src =
 *      TRIG_TIMER) or 'external' (scan_begin_src == TRIG_EXT) at the start
 *      of acquisition and the trigger source is at logic level 1 at the
 *      time of the switch.  This is very likely for TRIG_TIMER.  For
 *      TRIG_EXT, it depends on the state of the external line and whether
 *      the CR_INVERT flag has been set.  The remaining scans are triggered
 *      correctly.
 */

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/slab.h>

#include "../comedidev.h"

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

/*
 * PCI224/234 i/o space 1 (PCIBAR2) registers.
 */
#define PCI224_Z2_CT0   0x14    /* 82C54 counter/timer 0 */
#define PCI224_Z2_CT1   0x15    /* 82C54 counter/timer 1 */
#define PCI224_Z2_CT2   0x16    /* 82C54 counter/timer 2 */
#define PCI224_Z2_CTC   0x17    /* 82C54 counter/timer control word */
#define PCI224_ZCLK_SCE 0x1A    /* Group Z Clock Configuration Register */
#define PCI224_ZGAT_SCE 0x1D    /* Group Z Gate Configuration Register */
#define PCI224_INT_SCE  0x1E    /* ISR Interrupt source mask register */
                                /* /Interrupt status */

/*
 * PCI224/234 i/o space 2 (PCIBAR3) 16-bit registers.
 */
#define PCI224_DACDATA  0x00    /* (w-o) DAC FIFO data. */
#define PCI224_SOFTTRIG 0x00    /* (r-o) DAC software scan trigger. */
#define PCI224_DACCON   0x02    /* (r/w) DAC status/configuration. */
#define PCI224_FIFOSIZ  0x04    /* (w-o) FIFO size for wraparound mode. */
#define PCI224_DACCEN   0x06    /* (w-o) DAC channel enable register. */

/*
 * DACCON values.
 */
/* (r/w) Scan trigger. */
#define PCI224_DACCON_TRIG_MASK         (7 << 0)
#define PCI224_DACCON_TRIG_NONE         (0 << 0)        /* none */
#define PCI224_DACCON_TRIG_SW           (1 << 0)        /* software trig */
#define PCI224_DACCON_TRIG_EXTP         (2 << 0)        /* ext +ve edge */
#define PCI224_DACCON_TRIG_EXTN         (3 << 0)        /* ext -ve edge */
#define PCI224_DACCON_TRIG_Z2CT0        (4 << 0)        /* Z2 CT0 out */
#define PCI224_DACCON_TRIG_Z2CT1        (5 << 0)        /* Z2 CT1 out */
#define PCI224_DACCON_TRIG_Z2CT2        (6 << 0)        /* Z2 CT2 out */
/* (r/w) Polarity (PCI224 only, PCI234 always bipolar!). */
#define PCI224_DACCON_POLAR_MASK        (1 << 3)
#define PCI224_DACCON_POLAR_UNI         (0 << 3)        /* range [0,Vref] */
#define PCI224_DACCON_POLAR_BI          (1 << 3)        /* range [-Vref,Vref] */
/* (r/w) Internal Vref (PCI224 only, when LK1 in position 1-2). */
#define PCI224_DACCON_VREF_MASK         (3 << 4)
#define PCI224_DACCON_VREF_1_25         (0 << 4)        /* Vref = 1.25V */
#define PCI224_DACCON_VREF_2_5          (1 << 4)        /* Vref = 2.5V */
#define PCI224_DACCON_VREF_5            (2 << 4)        /* Vref = 5V */
#define PCI224_DACCON_VREF_10           (3 << 4)        /* Vref = 10V */
/* (r/w) Wraparound mode enable (to play back stored waveform). */
#define PCI224_DACCON_FIFOWRAP          (1 << 7)
/* (r/w) FIFO enable.  It MUST be set! */
#define PCI224_DACCON_FIFOENAB          (1 << 8)
/* (r/w) FIFO interrupt trigger level (most values are not very useful). */
#define PCI224_DACCON_FIFOINTR_MASK     (7 << 9)
#define PCI224_DACCON_FIFOINTR_EMPTY    (0 << 9)        /* when empty */
#define PCI224_DACCON_FIFOINTR_NEMPTY   (1 << 9)        /* when not empty */
#define PCI224_DACCON_FIFOINTR_NHALF    (2 << 9)        /* when not half full */
#define PCI224_DACCON_FIFOINTR_HALF     (3 << 9)        /* when half full */
#define PCI224_DACCON_FIFOINTR_NFULL    (4 << 9)        /* when not full */
#define PCI224_DACCON_FIFOINTR_FULL     (5 << 9)        /* when full */
/* (r-o) FIFO fill level. */
#define PCI224_DACCON_FIFOFL_MASK       (7 << 12)
#define PCI224_DACCON_FIFOFL_EMPTY      (1 << 12)       /* 0 */
#define PCI224_DACCON_FIFOFL_ONETOHALF  (0 << 12)       /* [1,2048] */
#define PCI224_DACCON_FIFOFL_HALFTOFULL (4 << 12)       /* [2049,4095] */
#define PCI224_DACCON_FIFOFL_FULL       (6 << 12)       /* 4096 */
/* (r-o) DAC busy flag. */
#define PCI224_DACCON_BUSY              (1 << 15)
/* (w-o) FIFO reset. */
#define PCI224_DACCON_FIFORESET         (1 << 12)
/* (w-o) Global reset (not sure what it does). */
#define PCI224_DACCON_GLOBALRESET       (1 << 13)

/*
 * DAC FIFO size.
 */
#define PCI224_FIFO_SIZE        4096

/*
 * DAC FIFO guaranteed minimum room available, depending on reported fill level.
 * The maximum room available depends on the reported fill level and how much
 * has been written!
 */
#define PCI224_FIFO_ROOM_EMPTY          PCI224_FIFO_SIZE
#define PCI224_FIFO_ROOM_ONETOHALF      (PCI224_FIFO_SIZE / 2)
#define PCI224_FIFO_ROOM_HALFTOFULL     1
#define PCI224_FIFO_ROOM_FULL           0

/*
 * 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))

/*
 * 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       /* reserved (external gate input) */
#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 PCI224 and PCI234:
 *
 *              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 enable/status bits
 */
#define PCI224_INTR_EXT         0x01    /* rising edge on external input */
#define PCI224_INTR_DAC         0x04    /* DAC (FIFO) interrupt */
#define PCI224_INTR_Z2CT1       0x20    /* rising edge on Z2-CT1 output */

#define PCI224_INTR_EDGE_BITS   (PCI224_INTR_EXT | PCI224_INTR_Z2CT1)
#define PCI224_INTR_LEVEL_BITS  PCI224_INTR_DACFIFO

/*
 * 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 bits for use with atomic bit operations. */
#define AO_CMD_STARTED  0

/*
 * Range tables.
 */

/*
 * The ranges for PCI224.
 *
 * These are partly hardware-selectable by jumper LK1 and partly
 * software-selectable.
 *
 * All channels share the same hardware range.
 */
static const struct comedi_lrange range_pci224 = {
        10, {
                /* jumper LK1 in position 1-2 (factory default) */
                BIP_RANGE(10),
                BIP_RANGE(5),
                BIP_RANGE(2.5),
                BIP_RANGE(1.25),
                UNI_RANGE(10),
                UNI_RANGE(5),
                UNI_RANGE(2.5),
                UNI_RANGE(1.25),
                /* jumper LK1 in position 2-3 */
                RANGE_ext(-1, 1),       /* bipolar [-Vext,+Vext] */
                RANGE_ext(0, 1),        /* unipolar [0,+Vext] */
        }
};

static const unsigned short hwrange_pci224[10] = {
        /* jumper LK1 in position 1-2 (factory default) */
        PCI224_DACCON_POLAR_BI | PCI224_DACCON_VREF_10,
        PCI224_DACCON_POLAR_BI | PCI224_DACCON_VREF_5,
        PCI224_DACCON_POLAR_BI | PCI224_DACCON_VREF_2_5,
        PCI224_DACCON_POLAR_BI | PCI224_DACCON_VREF_1_25,
        PCI224_DACCON_POLAR_UNI | PCI224_DACCON_VREF_10,
        PCI224_DACCON_POLAR_UNI | PCI224_DACCON_VREF_5,
        PCI224_DACCON_POLAR_UNI | PCI224_DACCON_VREF_2_5,
        PCI224_DACCON_POLAR_UNI | PCI224_DACCON_VREF_1_25,
        /* jumper LK1 in position 2-3 */
        PCI224_DACCON_POLAR_BI,
        PCI224_DACCON_POLAR_UNI,
};

/* Used to check all channels set to the same range on PCI224. */
static const unsigned char range_check_pci224[10] = {
        0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
};

/*
 * The ranges for PCI234.
 *
 * These are all hardware-selectable by jumper LK1 affecting all channels,
 * and jumpers LK2, LK3, LK4 and LK5 affecting channels 0, 1, 2 and 3
 * individually.
 */
static const struct comedi_lrange range_pci234 = {
        4, {
                /* LK1: 1-2 (fact def), LK2/3/4/5: 2-3 (fac def) */
                BIP_RANGE(10),
                /* LK1: 1-2 (fact def), LK2/3/4/5: 1-2 */
                BIP_RANGE(5),
                /* LK1: 2-3, LK2/3/4/5: 2-3 (fac def) */
                RANGE_ext(-2, 2),       /* bipolar [-2*Vext,+2*Vext] */
                /* LK1: 2-3, LK2/3/4/5: 1-2 */
                RANGE_ext(-1, 1),       /* bipolar [-Vext,+Vext] */
        }
};

/* N.B. PCI234 ignores the polarity bit, but software uses it. */
static const unsigned short hwrange_pci234[4] = {
        PCI224_DACCON_POLAR_BI,
        PCI224_DACCON_POLAR_BI,
        PCI224_DACCON_POLAR_BI,
        PCI224_DACCON_POLAR_BI,
};

/* Used to check all channels use same LK1 setting on PCI234. */
static const unsigned char range_check_pci234[4] = {
        0, 0, 1, 1,
};

/*
 * Board descriptions.
 */

enum pci224_model { pci224_model, pci234_model };

struct pci224_board {
        const char *name;
        unsigned int ao_chans;
        unsigned int ao_bits;
        const struct comedi_lrange *ao_range;
        const unsigned short *ao_hwrange;
        const unsigned char *ao_range_check;
};

static const struct pci224_board pci224_boards[] = {
        [pci224_model] = {
                .name           = "pci224",
                .ao_chans       = 16,
                .ao_bits        = 12,
                .ao_range       = &range_pci224,
                .ao_hwrange     = &hwrange_pci224[0],
                .ao_range_check = &range_check_pci224[0],
        },
        [pci234_model] = {
                .name           = "pci234",
                .ao_chans       = 4,
                .ao_bits        = 16,
                .ao_range       = &range_pci234,
                .ao_hwrange     = &hwrange_pci234[0],
                .ao_range_check = &range_check_pci234[0],
        },
};

struct pci224_private {
        unsigned long iobase1;
        unsigned long state;
        spinlock_t ao_spinlock; /* spinlock for AO command handling */
        unsigned short *ao_scan_vals;
        unsigned char *ao_scan_order;
        int intr_cpuid;
        short intr_running;
        unsigned short daccon;
        unsigned int cached_div1;
        unsigned int cached_div2;
        unsigned short ao_enab; /* max 16 channels so 'short' will do */
        unsigned char intsce;
};

/*
 * Called from the 'insn_write' function to perform a single write.
 */
static void
pci224_ao_set_data(struct comedi_device *dev, int chan, int range,
                   unsigned int data)
{
        const struct pci224_board *thisboard = dev->board_ptr;
        struct pci224_private *devpriv = dev->private;
        unsigned short mangled;

        /* Enable the channel. */
        outw(1 << chan, dev->iobase + PCI224_DACCEN);
        /* Set range and reset FIFO. */
        devpriv->daccon = COMBINE(devpriv->daccon, thisboard->ao_hwrange[range],
                                  PCI224_DACCON_POLAR_MASK |
                                  PCI224_DACCON_VREF_MASK);
        outw(devpriv->daccon | PCI224_DACCON_FIFORESET,
             dev->iobase + PCI224_DACCON);
        /*
         * Mangle the data.  The hardware expects:
         * - bipolar: 16-bit 2's complement
         * - unipolar: 16-bit unsigned
         */
        mangled = (unsigned short)data << (16 - thisboard->ao_bits);
        if ((devpriv->daccon & PCI224_DACCON_POLAR_MASK) ==
            PCI224_DACCON_POLAR_BI) {
                mangled ^= 0x8000;
        }
        /* Write mangled data to the FIFO. */
        outw(mangled, dev->iobase + PCI224_DACDATA);
        /* Trigger the conversion. */
        inw(dev->iobase + PCI224_SOFTTRIG);
}

static int pci224_ao_insn_write(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
{
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int range = CR_RANGE(insn->chanspec);
        unsigned int val = s->readback[chan];
        int i;

        for (i = 0; i < insn->n; i++) {
                val = data[i];
                pci224_ao_set_data(dev, chan, range, val);
        }
        s->readback[chan] = val;

        return insn->n;
}

/*
 * Kills a command running on the AO subdevice.
 */
static void pci224_ao_stop(struct comedi_device *dev,
                           struct comedi_subdevice *s)
{
        struct pci224_private *devpriv = dev->private;
        unsigned long flags;

        if (!test_and_clear_bit(AO_CMD_STARTED, &devpriv->state))
                return;


        spin_lock_irqsave(&devpriv->ao_spinlock, flags);
        /* Kill the interrupts. */
        devpriv->intsce = 0;
        outb(0, devpriv->iobase1 + PCI224_INT_SCE);
        /*
         * Interrupt routine may or may not be running.  We may or may not
         * have been called from the interrupt routine (directly or
         * indirectly via a comedi_events() callback routine).  It's highly
         * unlikely that we've been called from some other interrupt routine
         * but who knows what strange things coders get up to!
         *
         * If the interrupt routine is currently running, wait for it to
         * finish, unless we appear to have been called via the interrupt
         * routine.
         */
        while (devpriv->intr_running && devpriv->intr_cpuid != THISCPU) {
                spin_unlock_irqrestore(&devpriv->ao_spinlock, flags);
                spin_lock_irqsave(&devpriv->ao_spinlock, flags);
        }
        spin_unlock_irqrestore(&devpriv->ao_spinlock, flags);
        /* Reconfigure DAC for insn_write usage. */
        outw(0, dev->iobase + PCI224_DACCEN);   /* Disable channels. */
        devpriv->daccon =
             COMBINE(devpriv->daccon,
                     PCI224_DACCON_TRIG_SW | PCI224_DACCON_FIFOINTR_EMPTY,
                     PCI224_DACCON_TRIG_MASK | PCI224_DACCON_FIFOINTR_MASK);
        outw(devpriv->daccon | PCI224_DACCON_FIFORESET,
             dev->iobase + PCI224_DACCON);
}

/*
 * Handles start of acquisition for the AO subdevice.
 */
static void pci224_ao_start(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        struct pci224_private *devpriv = dev->private;
        struct comedi_cmd *cmd = &s->async->cmd;
        unsigned long flags;

        set_bit(AO_CMD_STARTED, &devpriv->state);

        /* Enable interrupts. */
        spin_lock_irqsave(&devpriv->ao_spinlock, flags);
        if (cmd->stop_src == TRIG_EXT)
                devpriv->intsce = PCI224_INTR_EXT | PCI224_INTR_DAC;
        else
                devpriv->intsce = PCI224_INTR_DAC;

        outb(devpriv->intsce, devpriv->iobase1 + PCI224_INT_SCE);
        spin_unlock_irqrestore(&devpriv->ao_spinlock, flags);
}

/*
 * Handles interrupts from the DAC FIFO.
 */
static void pci224_ao_handle_fifo(struct comedi_device *dev,
                                  struct comedi_subdevice *s)
{
        struct pci224_private *devpriv = dev->private;
        struct comedi_cmd *cmd = &s->async->cmd;
        unsigned int num_scans = comedi_nscans_left(s, 0);
        unsigned int room;
        unsigned short dacstat;
        unsigned int i, n;

        /* Determine how much room is in the FIFO (in samples). */
        dacstat = inw(dev->iobase + PCI224_DACCON);
        switch (dacstat & PCI224_DACCON_FIFOFL_MASK) {
        case PCI224_DACCON_FIFOFL_EMPTY:
                room = PCI224_FIFO_ROOM_EMPTY;
                if (cmd->stop_src == TRIG_COUNT &&
                    s->async->scans_done >= cmd->stop_arg) {
                        /* FIFO empty at end of counted acquisition. */
                        s->async->events |= COMEDI_CB_EOA;
                        comedi_handle_events(dev, s);
                        return;
                }
                break;
        case PCI224_DACCON_FIFOFL_ONETOHALF:
                room = PCI224_FIFO_ROOM_ONETOHALF;
                break;
        case PCI224_DACCON_FIFOFL_HALFTOFULL:
                room = PCI224_FIFO_ROOM_HALFTOFULL;
                break;
        default:
                room = PCI224_FIFO_ROOM_FULL;
                break;
        }
        if (room >= PCI224_FIFO_ROOM_ONETOHALF) {
                /* FIFO is less than half-full. */
                if (num_scans == 0) {
                        /* Nothing left to put in the FIFO. */
                        dev_err(dev->class_dev, "AO buffer underrun\n");
                        s->async->events |= COMEDI_CB_OVERFLOW;
                }
        }
        /* Determine how many new scans can be put in the FIFO. */
        room /= cmd->chanlist_len;

        /* Determine how many scans to process. */
        if (num_scans > room)
                num_scans = room;

        /* Process scans. */
        for (n = 0; n < num_scans; n++) {
                comedi_buf_read_samples(s, &devpriv->ao_scan_vals[0],
                                        cmd->chanlist_len);
                for (i = 0; i < cmd->chanlist_len; i++) {
                        outw(devpriv->ao_scan_vals[devpriv->ao_scan_order[i]],
                             dev->iobase + PCI224_DACDATA);
                }
        }
        if (cmd->stop_src == TRIG_COUNT &&
            s->async->scans_done >= cmd->stop_arg) {
                /*
                 * Change FIFO interrupt trigger level to wait
                 * until FIFO is empty.
                 */
                devpriv->daccon = COMBINE(devpriv->daccon,
                                          PCI224_DACCON_FIFOINTR_EMPTY,
                                          PCI224_DACCON_FIFOINTR_MASK);
                outw(devpriv->daccon, dev->iobase + PCI224_DACCON);
        }
        if ((devpriv->daccon & PCI224_DACCON_TRIG_MASK) ==
            PCI224_DACCON_TRIG_NONE) {
                unsigned short trig;

                /*
                 * This is the initial DAC FIFO interrupt at the
                 * start of the acquisition.  The DAC's scan trigger
                 * has been set to 'none' up until now.
                 *
                 * Now that data has been written to the FIFO, the
                 * DAC's scan trigger source can be set to the
                 * correct value.
                 *
                 * BUG: The first scan will be triggered immediately
                 * if the scan trigger source is at logic level 1.
                 */
                if (cmd->scan_begin_src == TRIG_TIMER) {
                        trig = PCI224_DACCON_TRIG_Z2CT0;
                } else {
                        /* cmd->scan_begin_src == TRIG_EXT */
                        if (cmd->scan_begin_arg & CR_INVERT)
                                trig = PCI224_DACCON_TRIG_EXTN;
                        else
                                trig = PCI224_DACCON_TRIG_EXTP;
                }
                devpriv->daccon =
                    COMBINE(devpriv->daccon, trig, PCI224_DACCON_TRIG_MASK);
                outw(devpriv->daccon, dev->iobase + PCI224_DACCON);
        }

        comedi_handle_events(dev, s);
}

static int pci224_ao_inttrig_start(struct comedi_device *dev,
                                   struct comedi_subdevice *s,
                                   unsigned int trig_num)
{
        struct comedi_cmd *cmd = &s->async->cmd;

        if (trig_num != cmd->start_arg)
                return -EINVAL;

        s->async->inttrig = NULL;
        pci224_ao_start(dev, s);

        return 1;
}

static int pci224_ao_check_chanlist(struct comedi_device *dev,
                                    struct comedi_subdevice *s,
                                    struct comedi_cmd *cmd)
{
        const struct pci224_board *thisboard = dev->board_ptr;
        unsigned int range_check_0;
        unsigned int chan_mask = 0;
        int i;

        range_check_0 = thisboard->ao_range_check[CR_RANGE(cmd->chanlist[0])];
        for (i = 0; i < cmd->chanlist_len; i++) {
                unsigned int chan = CR_CHAN(cmd->chanlist[i]);

                if (chan_mask & (1 << chan)) {
                        dev_dbg(dev->class_dev,
                                "%s: entries in chanlist must contain no duplicate channels\n",
                                __func__);
                        return -EINVAL;
                }
                chan_mask |= 1 << chan;

                if (thisboard->ao_range_check[CR_RANGE(cmd->chanlist[i])] !=
                    range_check_0) {
                        dev_dbg(dev->class_dev,
                                "%s: entries in chanlist have incompatible ranges\n",
                                __func__);
                        return -EINVAL;
                }
        }

        return 0;
}

#define MAX_SCAN_PERIOD         0xFFFFFFFFU
#define MIN_SCAN_PERIOD         2500
#define CONVERT_PERIOD          625

/*
 * 'do_cmdtest' function for AO subdevice.
 */
static int
pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
                  struct comedi_cmd *cmd)
{
        struct pci224_private *devpriv = dev->private;
        int err = 0;
        unsigned int arg;

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

        err |= cfc_check_trigger_src(&cmd->start_src, TRIG_INT | TRIG_EXT);
        err |= cfc_check_trigger_src(&cmd->scan_begin_src,
                                     TRIG_EXT | TRIG_TIMER);
        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_EXT | 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->stop_src);

        /* Step 2b : and mutually compatible */

        /*
         * There's only one external trigger signal (which makes these
         * tests easier).  Only one thing can use it.
         */
        arg = 0;
        if (cmd->start_src & TRIG_EXT)
                arg++;
        if (cmd->scan_begin_src & TRIG_EXT)
                arg++;
        if (cmd->stop_src & TRIG_EXT)
                arg++;
        if (arg > 1)
                err |= -EINVAL;

        if (err)
                return 2;

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

        switch (cmd->start_src) {
        case TRIG_INT:
                err |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);
                break;
        case TRIG_EXT:
                /* Force to external trigger 0. */
                if (cmd->start_arg & ~CR_FLAGS_MASK) {
                        cmd->start_arg =
                            COMBINE(cmd->start_arg, 0, ~CR_FLAGS_MASK);
                        err |= -EINVAL;
                }
                /* The only flag allowed is CR_EDGE, which is ignored. */
                if (cmd->start_arg & CR_FLAGS_MASK & ~CR_EDGE) {
                        cmd->start_arg = COMBINE(cmd->start_arg, 0,
                                                 CR_FLAGS_MASK & ~CR_EDGE);
                        err |= -EINVAL;
                }
                break;
        }

        switch (cmd->scan_begin_src) {
        case TRIG_TIMER:
                err |= cfc_check_trigger_arg_max(&cmd->scan_begin_arg,
                                                 MAX_SCAN_PERIOD);

                arg = cmd->chanlist_len * CONVERT_PERIOD;
                if (arg < MIN_SCAN_PERIOD)
                        arg = MIN_SCAN_PERIOD;
                err |= cfc_check_trigger_arg_min(&cmd->scan_begin_arg, arg);
                break;
        case TRIG_EXT:
                /* Force to external trigger 0. */
                if (cmd->scan_begin_arg & ~CR_FLAGS_MASK) {
                        cmd->scan_begin_arg =
                            COMBINE(cmd->scan_begin_arg, 0, ~CR_FLAGS_MASK);
                        err |= -EINVAL;
                }
                /* Only allow flags CR_EDGE and CR_INVERT.  Ignore CR_EDGE. */
                if (cmd->scan_begin_arg & CR_FLAGS_MASK &
                    ~(CR_EDGE | CR_INVERT)) {
                        cmd->scan_begin_arg =
                            COMBINE(cmd->scan_begin_arg, 0,
                                    CR_FLAGS_MASK & ~(CR_EDGE | CR_INVERT));
                        err |= -EINVAL;
                }
                break;
        }

        err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);
        err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);

        switch (cmd->stop_src) {
        case TRIG_COUNT:
                err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
                break;
        case TRIG_EXT:
                /* Force to external trigger 0. */
                if (cmd->stop_arg & ~CR_FLAGS_MASK) {
                        cmd->stop_arg =
                            COMBINE(cmd->stop_arg, 0, ~CR_FLAGS_MASK);
                        err |= -EINVAL;
                }
                /* The only flag allowed is CR_EDGE, which is ignored. */
                if (cmd->stop_arg & CR_FLAGS_MASK & ~CR_EDGE) {
                        cmd->stop_arg =
                            COMBINE(cmd->stop_arg, 0, CR_FLAGS_MASK & ~CR_EDGE);
                }
                break;
        case TRIG_NONE:
                err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
                break;
        }

        if (err)
                return 3;

        /* Step 4: fix up any arguments. */

        if (cmd->scan_begin_src == TRIG_TIMER) {
                arg = cmd->scan_begin_arg;
                /* Use two timers. */
                i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
                                          &devpriv->cached_div1,
                                          &devpriv->cached_div2,
                                          &arg, cmd->flags);
                err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
        }

        if (err)
                return 4;

        /* Step 5: check channel list if it exists */
        if (cmd->chanlist && cmd->chanlist_len > 0)
                err |= pci224_ao_check_chanlist(dev, s, cmd);

        if (err)
                return 5;

        return 0;
}

static void pci224_ao_start_pacer(struct comedi_device *dev,
                                  struct comedi_subdevice *s)
{
        struct pci224_private *devpriv = dev->private;
        unsigned long timer_base = devpriv->iobase1 + PCI224_Z2_CT0;

        /*
         * The output of timer Z2-0 will be used as the scan trigger
         * source.
         */
        /* Make sure Z2-0 is gated on.  */
        outb(GAT_CONFIG(0, GAT_VCC), devpriv->iobase1 + PCI224_ZGAT_SCE);
        /* Cascading with Z2-2. */
        /* Make sure Z2-2 is gated on.  */
        outb(GAT_CONFIG(2, GAT_VCC), devpriv->iobase1 + PCI224_ZGAT_SCE);
        /* Z2-2 needs 10 MHz clock. */
        outb(CLK_CONFIG(2, CLK_10MHZ), devpriv->iobase1 + PCI224_ZCLK_SCE);
        /* Load Z2-2 mode (2) and counter (div1). */
        i8254_set_mode(timer_base, 0, 2, I8254_MODE2 | I8254_BINARY);
        i8254_write(timer_base, 0, 2, devpriv->cached_div1);
        /* Z2-0 is clocked from Z2-2's output. */
        outb(CLK_CONFIG(0, CLK_OUTNM1), devpriv->iobase1 + PCI224_ZCLK_SCE);
        /* Load Z2-0 mode (2) and counter (div2). */
        i8254_set_mode(timer_base, 0, 0, I8254_MODE2 | I8254_BINARY);
        i8254_write(timer_base, 0, 0, devpriv->cached_div2);
}

static int pci224_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        const struct pci224_board *thisboard = dev->board_ptr;
        struct pci224_private *devpriv = dev->private;
        struct comedi_cmd *cmd = &s->async->cmd;
        int range;
        unsigned int i, j;
        unsigned int ch;
        unsigned int rank;
        unsigned long flags;

        /* Cannot handle null/empty chanlist. */
        if (cmd->chanlist == NULL || cmd->chanlist_len == 0)
                return -EINVAL;


        /* Determine which channels are enabled and their load order.  */
        devpriv->ao_enab = 0;

        for (i = 0; i < cmd->chanlist_len; i++) {
                ch = CR_CHAN(cmd->chanlist[i]);
                devpriv->ao_enab |= 1U << ch;
                rank = 0;
                for (j = 0; j < cmd->chanlist_len; j++) {
                        if (CR_CHAN(cmd->chanlist[j]) < ch)
                                rank++;
                }
                devpriv->ao_scan_order[rank] = i;
        }

        /* Set enabled channels. */
        outw(devpriv->ao_enab, dev->iobase + PCI224_DACCEN);

        /* Determine range and polarity.  All channels the same.  */
        range = CR_RANGE(cmd->chanlist[0]);

        /*
         * Set DAC range and polarity.
         * Set DAC scan trigger source to 'none'.
         * Set DAC FIFO interrupt trigger level to 'not half full'.
         * Reset DAC FIFO.
         *
         * N.B. DAC FIFO interrupts are currently disabled.
         */
        devpriv->daccon =
            COMBINE(devpriv->daccon,
                    thisboard->ao_hwrange[range] | PCI224_DACCON_TRIG_NONE |
                    PCI224_DACCON_FIFOINTR_NHALF,
                    PCI224_DACCON_POLAR_MASK | PCI224_DACCON_VREF_MASK |
                    PCI224_DACCON_TRIG_MASK | PCI224_DACCON_FIFOINTR_MASK);
        outw(devpriv->daccon | PCI224_DACCON_FIFORESET,
             dev->iobase + PCI224_DACCON);

        if (cmd->scan_begin_src == TRIG_TIMER)
                pci224_ao_start_pacer(dev, s);

        spin_lock_irqsave(&devpriv->ao_spinlock, flags);
        if (cmd->start_src == TRIG_INT) {
                s->async->inttrig = pci224_ao_inttrig_start;
        } else {        /* TRIG_EXT */
                /* Enable external interrupt trigger to start acquisition. */
                devpriv->intsce |= PCI224_INTR_EXT;
                outb(devpriv->intsce, devpriv->iobase1 + PCI224_INT_SCE);
        }
        spin_unlock_irqrestore(&devpriv->ao_spinlock, flags);

        return 0;
}

/*
 * 'cancel' function for AO subdevice.
 */
static int pci224_ao_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        pci224_ao_stop(dev, s);
        return 0;
}

/*
 * 'munge' data for AO command.
 */
static void
pci224_ao_munge(struct comedi_device *dev, struct comedi_subdevice *s,
                void *data, unsigned int num_bytes, unsigned int chan_index)
{
        const struct pci224_board *thisboard = dev->board_ptr;
        struct comedi_cmd *cmd = &s->async->cmd;
        unsigned short *array = data;
        unsigned int length = num_bytes / sizeof(*array);
        unsigned int offset;
        unsigned int shift;
        unsigned int i;

        /* The hardware expects 16-bit numbers. */
        shift = 16 - thisboard->ao_bits;
        /* Channels will be all bipolar or all unipolar. */
        if ((thisboard->ao_hwrange[CR_RANGE(cmd->chanlist[0])] &
             PCI224_DACCON_POLAR_MASK) == PCI224_DACCON_POLAR_UNI) {
                /* Unipolar */
                offset = 0;
        } else {
                /* Bipolar */
                offset = 32768;
        }
        /* Munge the data. */
        for (i = 0; i < length; i++)
                array[i] = (array[i] << shift) - offset;
}

/*
 * Interrupt handler.
 */
static irqreturn_t pci224_interrupt(int irq, void *d)
{
        struct comedi_device *dev = d;
        struct pci224_private *devpriv = dev->private;
        struct comedi_subdevice *s = dev->write_subdev;
        struct comedi_cmd *cmd;
        unsigned char intstat, valid_intstat;
        unsigned char curenab;
        int retval = 0;
        unsigned long flags;

        intstat = inb(devpriv->iobase1 + PCI224_INT_SCE) & 0x3F;
        if (intstat) {
                retval = 1;
                spin_lock_irqsave(&devpriv->ao_spinlock, flags);
                valid_intstat = devpriv->intsce & intstat;
                /* Temporarily disable interrupt sources. */
                curenab = devpriv->intsce & ~intstat;
                outb(curenab, devpriv->iobase1 + PCI224_INT_SCE);
                devpriv->intr_running = 1;
                devpriv->intr_cpuid = THISCPU;
                spin_unlock_irqrestore(&devpriv->ao_spinlock, flags);
                if (valid_intstat) {
                        cmd = &s->async->cmd;
                        if (valid_intstat & PCI224_INTR_EXT) {
                                devpriv->intsce &= ~PCI224_INTR_EXT;
                                if (cmd->start_src == TRIG_EXT)
                                        pci224_ao_start(dev, s);
                                else if (cmd->stop_src == TRIG_EXT)
                                        pci224_ao_stop(dev, s);
                        }
                        if (valid_intstat & PCI224_INTR_DAC)
                                pci224_ao_handle_fifo(dev, s);
                }
                /* Reenable interrupt sources. */
                spin_lock_irqsave(&devpriv->ao_spinlock, flags);
                if (curenab != devpriv->intsce) {
                        outb(devpriv->intsce,
                             devpriv->iobase1 + PCI224_INT_SCE);
                }
                devpriv->intr_running = 0;
                spin_unlock_irqrestore(&devpriv->ao_spinlock, flags);
        }
        return IRQ_RETVAL(retval);
}

static int
pci224_auto_attach(struct comedi_device *dev, unsigned long context_model)
{
        struct pci_dev *pci_dev = comedi_to_pci_dev(dev);
        const struct pci224_board *thisboard = NULL;
        struct pci224_private *devpriv;
        struct comedi_subdevice *s;
        unsigned int irq;
        int ret;

        if (context_model < ARRAY_SIZE(pci224_boards))
                thisboard = &pci224_boards[context_model];
        if (!thisboard || !thisboard->name) {
                dev_err(dev->class_dev,
                        "amplc_pci224: BUG! cannot determine board type!\n");
                return -EINVAL;
        }
        dev->board_ptr = thisboard;
        dev->board_name = thisboard->name;

        dev_info(dev->class_dev, "amplc_pci224: attach pci %s - %s\n",
                 pci_name(pci_dev), dev->board_name);

        devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
        if (!devpriv)
                return -ENOMEM;

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

        spin_lock_init(&devpriv->ao_spinlock);

        devpriv->iobase1 = pci_resource_start(pci_dev, 2);
        dev->iobase = pci_resource_start(pci_dev, 3);
        irq = pci_dev->irq;

        /* Allocate buffer to hold values for AO channel scan. */
        devpriv->ao_scan_vals = kmalloc(sizeof(devpriv->ao_scan_vals[0]) *
                                        thisboard->ao_chans, GFP_KERNEL);
        if (!devpriv->ao_scan_vals)
                return -ENOMEM;


        /* Allocate buffer to hold AO channel scan order. */
        devpriv->ao_scan_order = kmalloc(sizeof(devpriv->ao_scan_order[0]) *
                                         thisboard->ao_chans, GFP_KERNEL);
        if (!devpriv->ao_scan_order)
                return -ENOMEM;


        /* Disable interrupt sources. */
        devpriv->intsce = 0;
        outb(0, devpriv->iobase1 + PCI224_INT_SCE);

        /* Initialize the DAC hardware. */
        outw(PCI224_DACCON_GLOBALRESET, dev->iobase + PCI224_DACCON);
        outw(0, dev->iobase + PCI224_DACCEN);
        outw(0, dev->iobase + PCI224_FIFOSIZ);
        devpriv->daccon = PCI224_DACCON_TRIG_SW | PCI224_DACCON_POLAR_BI |
                          PCI224_DACCON_FIFOENAB | PCI224_DACCON_FIFOINTR_EMPTY;
        outw(devpriv->daccon | PCI224_DACCON_FIFORESET,
             dev->iobase + PCI224_DACCON);

        ret = comedi_alloc_subdevices(dev, 1);
        if (ret)
                return ret;

        s = &dev->subdevices[0];
        /* Analog output subdevice. */
        s->type = COMEDI_SUBD_AO;
        s->subdev_flags = SDF_WRITABLE | SDF_GROUND | SDF_CMD_WRITE;
        s->n_chan = thisboard->ao_chans;
        s->maxdata = (1 << thisboard->ao_bits) - 1;
        s->range_table = thisboard->ao_range;
        s->insn_write = pci224_ao_insn_write;
        s->len_chanlist = s->n_chan;
        dev->write_subdev = s;
        s->do_cmd = pci224_ao_cmd;
        s->do_cmdtest = pci224_ao_cmdtest;
        s->cancel = pci224_ao_cancel;
        s->munge = pci224_ao_munge;

        ret = comedi_alloc_subdev_readback(s);
        if (ret)
                return ret;

        if (irq) {
                ret = request_irq(irq, pci224_interrupt, IRQF_SHARED,
                                  dev->board_name, dev);
                if (ret < 0) {
                        dev_err(dev->class_dev,
                                "error! unable to allocate irq %u\n", irq);
                        return ret;
                }
                dev->irq = irq;
        }

        return 0;
}

static void pci224_detach(struct comedi_device *dev)
{
        struct pci224_private *devpriv = dev->private;

        comedi_pci_detach(dev);
        if (devpriv) {
                kfree(devpriv->ao_scan_vals);
                kfree(devpriv->ao_scan_order);
        }
}

static struct comedi_driver amplc_pci224_driver = {
        .driver_name    = "amplc_pci224",
        .module         = THIS_MODULE,
        .detach         = pci224_detach,
        .auto_attach    = pci224_auto_attach,
        .board_name     = &pci224_boards[0].name,
        .offset         = sizeof(struct pci224_board),
        .num_names      = ARRAY_SIZE(pci224_boards),
};

static int amplc_pci224_pci_probe(struct pci_dev *dev,
                                  const struct pci_device_id *id)
{
        return comedi_pci_auto_config(dev, &amplc_pci224_driver,
                                      id->driver_data);
}

static const struct pci_device_id amplc_pci224_pci_table[] = {
        { PCI_VDEVICE(AMPLICON, 0x0007), pci224_model },
        { PCI_VDEVICE(AMPLICON, 0x0008), pci234_model },
        { 0 }
};
MODULE_DEVICE_TABLE(pci, amplc_pci224_pci_table);

static struct pci_driver amplc_pci224_pci_driver = {
        .name           = "amplc_pci224",
        .id_table       = amplc_pci224_pci_table,
        .probe          = amplc_pci224_pci_probe,
        .remove         = comedi_pci_auto_unconfig,
};
module_comedi_pci_driver(amplc_pci224_driver, amplc_pci224_pci_driver);

MODULE_AUTHOR("Comedi http://www.comedi.org");
MODULE_DESCRIPTION("Comedi driver for Amplicon PCI224 and PCI234 AO boards");
MODULE_LICENSE("GPL");