/*
 * comedi/drivers/rtd520.c
 * Comedi driver for Real Time Devices (RTD) PCI4520/DM7520
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 2001 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: rtd520
 * Description: Real Time Devices PCI4520/DM7520
 * Devices: [Real Time Devices] DM7520HR-1 (DM7520), DM7520HR-8,
 *   PCI4520 (PCI4520), PCI4520-8
 * Author: Dan Christian
 * Status: Works. Only tested on DM7520-8. Not SMP safe.
 *
 * Configuration options: not applicable, uses PCI auto config
 */

/*
 * Created by Dan Christian, NASA Ames Research Center.
 *
 * The PCI4520 is a PCI card. The DM7520 is a PC/104-plus card.
 * Both have:
 *   8/16 12 bit ADC with FIFO and channel gain table
 *   8 bits high speed digital out (for external MUX) (or 8 in or 8 out)
 *   8 bits high speed digital in with FIFO and interrupt on change (or 8 IO)
 *   2 12 bit DACs with FIFOs
 *   2 bits output
 *   2 bits input
 *   bus mastering DMA
 *   timers: ADC sample, pacer, burst, about, delay, DA1, DA2
 *   sample counter
 *   3 user timer/counters (8254)
 *   external interrupt
 *
 * The DM7520 has slightly fewer features (fewer gain steps).
 *
 * These boards can support external multiplexors and multi-board
 * synchronization, but this driver doesn't support that.
 *
 * Board docs: http://www.rtdusa.com/PC104/DM/analog%20IO/dm7520.htm
 * Data sheet: http://www.rtdusa.com/pdf/dm7520.pdf
 * Example source: http://www.rtdusa.com/examples/dm/dm7520.zip
 * Call them and ask for the register level manual.
 * PCI chip: http://www.plxtech.com/products/io/pci9080
 *
 * Notes:
 * This board is memory mapped. There is some IO stuff, but it isn't needed.
 *
 * I use a pretty loose naming style within the driver (rtd_blah).
 * All externally visible names should be rtd520_blah.
 * I use camelCase for structures (and inside them).
 * I may also use upper CamelCase for function names (old habit).
 *
 * This board is somewhat related to the RTD PCI4400 board.
 *
 * I borrowed heavily from the ni_mio_common, ni_atmio16d, mite, and
 * das1800, since they have the best documented code. Driver cb_pcidas64.c
 * uses the same DMA controller.
 *
 * As far as I can tell, the About interrupt doesn't work if Sample is
 * also enabled. It turns out that About really isn't needed, since
 * we always count down samples read.
 */

/*
 * driver status:
 *
 * Analog-In supports instruction and command mode.
 *
 * With DMA, you can sample at 1.15Mhz with 70% idle on a 400Mhz K6-2
 * (single channel, 64K read buffer). I get random system lockups when
 * using DMA with ALI-15xx based systems. I haven't been able to test
 * any other chipsets. The lockups happen soon after the start of an
 * acquistion, not in the middle of a long run.
 *
 * Without DMA, you can do 620Khz sampling with 20% idle on a 400Mhz K6-2
 * (with a 256K read buffer).
 *
 * Digital-IO and Analog-Out only support instruction mode.
 */

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

#include "../comedi_pci.h"

#include "comedi_8254.h"
#include "plx9080.h"

/*
 * Local Address Space 0 Offsets
 */
#define LAS0_USER_IO            0x0008  /* User I/O */
#define LAS0_ADC                0x0010  /* FIFO Status/Software A/D Start */
#define FS_DAC1_NOT_EMPTY       BIT(0)  /* DAC1 FIFO not empty */
#define FS_DAC1_HEMPTY          BIT(1)  /* DAC1 FIFO half empty */
#define FS_DAC1_NOT_FULL        BIT(2)  /* DAC1 FIFO not full */
#define FS_DAC2_NOT_EMPTY       BIT(4)  /* DAC2 FIFO not empty */
#define FS_DAC2_HEMPTY          BIT(5)  /* DAC2 FIFO half empty */
#define FS_DAC2_NOT_FULL        BIT(6)  /* DAC2 FIFO not full */
#define FS_ADC_NOT_EMPTY        BIT(8)  /* ADC FIFO not empty */
#define FS_ADC_HEMPTY           BIT(9)  /* ADC FIFO half empty */
#define FS_ADC_NOT_FULL         BIT(10) /* ADC FIFO not full */
#define FS_DIN_NOT_EMPTY        BIT(12) /* DIN FIFO not empty */
#define FS_DIN_HEMPTY           BIT(13) /* DIN FIFO half empty */
#define FS_DIN_NOT_FULL         BIT(14) /* DIN FIFO not full */
#define LAS0_UPDATE_DAC(x)      (0x0014 + ((x) * 0x4))  /* D/Ax Update (w) */
#define LAS0_DAC                0x0024  /* Software Simultaneous Update (w) */
#define LAS0_PACER              0x0028  /* Software Pacer Start/Stop */
#define LAS0_TIMER              0x002c  /* Timer Status/HDIN Software Trig. */
#define LAS0_IT                 0x0030  /* Interrupt Status/Enable */
#define IRQM_ADC_FIFO_WRITE     BIT(0)  /* ADC FIFO Write */
#define IRQM_CGT_RESET          BIT(1)  /* Reset CGT */
#define IRQM_CGT_PAUSE          BIT(3)  /* Pause CGT */
#define IRQM_ADC_ABOUT_CNT      BIT(4)  /* About Counter out */
#define IRQM_ADC_DELAY_CNT      BIT(5)  /* Delay Counter out */
#define IRQM_ADC_SAMPLE_CNT     BIT(6)  /* ADC Sample Counter */
#define IRQM_DAC1_UCNT          BIT(7)  /* DAC1 Update Counter */
#define IRQM_DAC2_UCNT          BIT(8)  /* DAC2 Update Counter */
#define IRQM_UTC1               BIT(9)  /* User TC1 out */
#define IRQM_UTC1_INV           BIT(10) /* User TC1 out, inverted */
#define IRQM_UTC2               BIT(11) /* User TC2 out */
#define IRQM_DIGITAL_IT         BIT(12) /* Digital Interrupt */
#define IRQM_EXTERNAL_IT        BIT(13) /* External Interrupt */
#define IRQM_ETRIG_RISING       BIT(14) /* Ext Trigger rising-edge */
#define IRQM_ETRIG_FALLING      BIT(15) /* Ext Trigger falling-edge */
#define LAS0_CLEAR              0x0034  /* Clear/Set Interrupt Clear Mask */
#define LAS0_OVERRUN            0x0038  /* Pending interrupts/Clear Overrun */
#define LAS0_PCLK               0x0040  /* Pacer Clock (24bit) */
#define LAS0_BCLK               0x0044  /* Burst Clock (10bit) */
#define LAS0_ADC_SCNT           0x0048  /* A/D Sample counter (10bit) */
#define LAS0_DAC1_UCNT          0x004c  /* D/A1 Update counter (10 bit) */
#define LAS0_DAC2_UCNT          0x0050  /* D/A2 Update counter (10 bit) */
#define LAS0_DCNT               0x0054  /* Delay counter (16 bit) */
#define LAS0_ACNT               0x0058  /* About counter (16 bit) */
#define LAS0_DAC_CLK            0x005c  /* DAC clock (16bit) */
#define LAS0_8254_TIMER_BASE    0x0060  /* 8254 timer/counter base */
#define LAS0_DIO0               0x0070  /* Digital I/O Port 0 */
#define LAS0_DIO1               0x0074  /* Digital I/O Port 1 */
#define LAS0_DIO0_CTRL          0x0078  /* Digital I/O Control */
#define LAS0_DIO_STATUS         0x007c  /* Digital I/O Status */
#define LAS0_BOARD_RESET        0x0100  /* Board reset */
#define LAS0_DMA0_SRC           0x0104  /* DMA 0 Sources select */
#define LAS0_DMA1_SRC           0x0108  /* DMA 1 Sources select */
#define LAS0_ADC_CONVERSION     0x010c  /* A/D Conversion Signal select */
#define LAS0_BURST_START        0x0110  /* Burst Clock Start Trigger select */
#define LAS0_PACER_START        0x0114  /* Pacer Clock Start Trigger select */
#define LAS0_PACER_STOP         0x0118  /* Pacer Clock Stop Trigger select */
#define LAS0_ACNT_STOP_ENABLE   0x011c  /* About Counter Stop Enable */
#define LAS0_PACER_REPEAT       0x0120  /* Pacer Start Trigger Mode select */
#define LAS0_DIN_START          0x0124  /* HiSpd DI Sampling Signal select */
#define LAS0_DIN_FIFO_CLEAR     0x0128  /* Digital Input FIFO Clear */
#define LAS0_ADC_FIFO_CLEAR     0x012c  /* A/D FIFO Clear */
#define LAS0_CGT_WRITE          0x0130  /* Channel Gain Table Write */
#define LAS0_CGL_WRITE          0x0134  /* Channel Gain Latch Write */
#define LAS0_CG_DATA            0x0138  /* Digital Table Write */
#define LAS0_CGT_ENABLE         0x013c  /* Channel Gain Table Enable */
#define LAS0_CG_ENABLE          0x0140  /* Digital Table Enable */
#define LAS0_CGT_PAUSE          0x0144  /* Table Pause Enable */
#define LAS0_CGT_RESET          0x0148  /* Reset Channel Gain Table */
#define LAS0_CGT_CLEAR          0x014c  /* Clear Channel Gain Table */
#define LAS0_DAC_CTRL(x)        (0x0150 + ((x) * 0x14)) /* D/Ax type/range */
#define LAS0_DAC_SRC(x)         (0x0154 + ((x) * 0x14)) /* D/Ax update source */
#define LAS0_DAC_CYCLE(x)       (0x0158 + ((x) * 0x14)) /* D/Ax cycle mode */
#define LAS0_DAC_RESET(x)       (0x015c + ((x) * 0x14)) /* D/Ax FIFO reset */
#define LAS0_DAC_FIFO_CLEAR(x)  (0x0160 + ((x) * 0x14)) /* D/Ax FIFO clear */
#define LAS0_ADC_SCNT_SRC       0x0178  /* A/D Sample Counter Source select */
#define LAS0_PACER_SELECT       0x0180  /* Pacer Clock select */
#define LAS0_SBUS0_SRC          0x0184  /* SyncBus 0 Source select */
#define LAS0_SBUS0_ENABLE       0x0188  /* SyncBus 0 enable */
#define LAS0_SBUS1_SRC          0x018c  /* SyncBus 1 Source select */
#define LAS0_SBUS1_ENABLE       0x0190  /* SyncBus 1 enable */
#define LAS0_SBUS2_SRC          0x0198  /* SyncBus 2 Source select */
#define LAS0_SBUS2_ENABLE       0x019c  /* SyncBus 2 enable */
#define LAS0_ETRG_POLARITY      0x01a4  /* Ext. Trigger polarity select */
#define LAS0_EINT_POLARITY      0x01a8  /* Ext. Interrupt polarity select */
#define LAS0_8254_CLK_SEL(x)    (0x01ac + ((x) * 0x8))  /* 8254 clock select */
#define LAS0_8254_GATE_SEL(x)   (0x01b0 + ((x) * 0x8))  /* 8254 gate select */
#define LAS0_UOUT0_SELECT       0x01c4  /* User Output 0 source select */
#define LAS0_UOUT1_SELECT       0x01c8  /* User Output 1 source select */
#define LAS0_DMA0_RESET         0x01cc  /* DMA0 Request state machine reset */
#define LAS0_DMA1_RESET         0x01d0  /* DMA1 Request state machine reset */

/*
 * Local Address Space 1 Offsets
 */
#define LAS1_ADC_FIFO           0x0000  /* A/D FIFO (16bit) */
#define LAS1_HDIO_FIFO          0x0004  /* HiSpd DI FIFO (16bit) */
#define LAS1_DAC_FIFO(x)        (0x0008 + ((x) * 0x4))  /* D/Ax FIFO (16bit) */

/*
 * Driver specific stuff (tunable)
 */

/*
 * We really only need 2 buffers.  More than that means being much
 * smarter about knowing which ones are full.
 */
#define DMA_CHAIN_COUNT 2       /* max DMA segments/buffers in a ring (min 2) */

/* Target period for periodic transfers.  This sets the user read latency. */
/* Note: There are certain rates where we give this up and transfer 1/2 FIFO */
/* If this is too low, efficiency is poor */
#define TRANS_TARGET_PERIOD 10000000    /* 10 ms (in nanoseconds) */

/* Set a practical limit on how long a list to support (affects memory use) */
/* The board support a channel list up to the FIFO length (1K or 8K) */
#define RTD_MAX_CHANLIST        128     /* max channel list that we allow */

/*
 * Board specific stuff
 */

#define RTD_CLOCK_RATE  8000000 /* 8Mhz onboard clock */
#define RTD_CLOCK_BASE  125     /* clock period in ns */

/* Note: these speed are slower than the spec, but fit the counter resolution*/
#define RTD_MAX_SPEED   1625    /* when sampling, in nanoseconds */
/* max speed if we don't have to wait for settling */
#define RTD_MAX_SPEED_1 875     /* if single channel, in nanoseconds */

#define RTD_MIN_SPEED   2097151875      /* (24bit counter) in nanoseconds */
/* min speed when only 1 channel (no burst counter) */
#define RTD_MIN_SPEED_1 5000000 /* 200Hz, in nanoseconds */

/* Setup continuous ring of 1/2 FIFO transfers.  See RTD manual p91 */
#define DMA_MODE_BITS (\
                       PLX_LOCAL_BUS_16_WIDE_BITS \
                       | PLX_DMA_EN_READYIN_BIT \
                       | PLX_DMA_LOCAL_BURST_EN_BIT \
                       | PLX_EN_CHAIN_BIT \
                       | PLX_DMA_INTR_PCI_BIT \
                       | PLX_LOCAL_ADDR_CONST_BIT \
                       | PLX_DEMAND_MODE_BIT)

#define DMA_TRANSFER_BITS (\
/* descriptors in PCI memory*/  PLX_DESC_IN_PCI_BIT \
/* interrupt at end of block */ | PLX_INTR_TERM_COUNT \
/* from board to PCI */         | PLX_XFER_LOCAL_TO_PCI)

/*
 * Comedi specific stuff
 */

/*
 * The board has 3 input modes and the gains of 1,2,4,...32 (, 64, 128)
 */
static const struct comedi_lrange rtd_ai_7520_range = {
        18, {
                /* +-5V input range gain steps */
                BIP_RANGE(5.0),
                BIP_RANGE(5.0 / 2),
                BIP_RANGE(5.0 / 4),
                BIP_RANGE(5.0 / 8),
                BIP_RANGE(5.0 / 16),
                BIP_RANGE(5.0 / 32),
                /* +-10V input range gain steps */
                BIP_RANGE(10.0),
                BIP_RANGE(10.0 / 2),
                BIP_RANGE(10.0 / 4),
                BIP_RANGE(10.0 / 8),
                BIP_RANGE(10.0 / 16),
                BIP_RANGE(10.0 / 32),
                /* +10V input range gain steps */
                UNI_RANGE(10.0),
                UNI_RANGE(10.0 / 2),
                UNI_RANGE(10.0 / 4),
                UNI_RANGE(10.0 / 8),
                UNI_RANGE(10.0 / 16),
                UNI_RANGE(10.0 / 32),
        }
};

/* PCI4520 has two more gains (6 more entries) */
static const struct comedi_lrange rtd_ai_4520_range = {
        24, {
                /* +-5V input range gain steps */
                BIP_RANGE(5.0),
                BIP_RANGE(5.0 / 2),
                BIP_RANGE(5.0 / 4),
                BIP_RANGE(5.0 / 8),
                BIP_RANGE(5.0 / 16),
                BIP_RANGE(5.0 / 32),
                BIP_RANGE(5.0 / 64),
                BIP_RANGE(5.0 / 128),
                /* +-10V input range gain steps */
                BIP_RANGE(10.0),
                BIP_RANGE(10.0 / 2),
                BIP_RANGE(10.0 / 4),
                BIP_RANGE(10.0 / 8),
                BIP_RANGE(10.0 / 16),
                BIP_RANGE(10.0 / 32),
                BIP_RANGE(10.0 / 64),
                BIP_RANGE(10.0 / 128),
                /* +10V input range gain steps */
                UNI_RANGE(10.0),
                UNI_RANGE(10.0 / 2),
                UNI_RANGE(10.0 / 4),
                UNI_RANGE(10.0 / 8),
                UNI_RANGE(10.0 / 16),
                UNI_RANGE(10.0 / 32),
                UNI_RANGE(10.0 / 64),
                UNI_RANGE(10.0 / 128),
        }
};

/* Table order matches range values */
static const struct comedi_lrange rtd_ao_range = {
        4, {
                UNI_RANGE(5),
                UNI_RANGE(10),
                BIP_RANGE(5),
                BIP_RANGE(10),
        }
};

enum rtd_boardid {
        BOARD_DM7520,
        BOARD_PCI4520,
};

struct rtd_boardinfo {
        const char *name;
        int range_bip10;        /* start of +-10V range */
        int range_uni10;        /* start of +10V range */
        const struct comedi_lrange *ai_range;
};

static const struct rtd_boardinfo rtd520_boards[] = {
        [BOARD_DM7520] = {
                .name           = "DM7520",
                .range_bip10    = 6,
                .range_uni10    = 12,
                .ai_range       = &rtd_ai_7520_range,
        },
        [BOARD_PCI4520] = {
                .name           = "PCI4520",
                .range_bip10    = 8,
                .range_uni10    = 16,
                .ai_range       = &rtd_ai_4520_range,
        },
};

struct rtd_private {
        /* memory mapped board structures */
        void __iomem *las1;
        void __iomem *lcfg;

        long ai_count;          /* total transfer size (samples) */
        int xfer_count;         /* # to transfer data. 0->1/2FIFO */
        int flags;              /* flag event modes */
        unsigned fifosz;

        /* 8254 Timer/Counter gate and clock sources */
        unsigned char timer_gate_src[3];
        unsigned char timer_clk_src[3];
};

/* bit defines for "flags" */
#define SEND_EOS        0x01    /* send End Of Scan events */
#define DMA0_ACTIVE     0x02    /* DMA0 is active */
#define DMA1_ACTIVE     0x04    /* DMA1 is active */

/*
 * Given a desired period and the clock period (both in ns), return the
 * proper counter value (divider-1). Sets the original period to be the
 * true value.
 * Note: you have to check if the value is larger than the counter range!
 */
static int rtd_ns_to_timer_base(unsigned int *nanosec,
                                unsigned int flags, int base)
{
        int divider;

        switch (flags & CMDF_ROUND_MASK) {
        case CMDF_ROUND_NEAREST:
        default:
                divider = DIV_ROUND_CLOSEST(*nanosec, base);
                break;
        case CMDF_ROUND_DOWN:
                divider = (*nanosec) / base;
                break;
        case CMDF_ROUND_UP:
                divider = DIV_ROUND_UP(*nanosec, base);
                break;
        }
        if (divider < 2)
                divider = 2;    /* min is divide by 2 */

        /*
         * Note: we don't check for max, because different timers
         * have different ranges
         */

        *nanosec = base * divider;
        return divider - 1;     /* countdown is divisor+1 */
}

/*
 * Given a desired period (in ns), return the proper counter value
 * (divider-1) for the internal clock. Sets the original period to
 * be the true value.
 */
static int rtd_ns_to_timer(unsigned int *ns, unsigned int flags)
{
        return rtd_ns_to_timer_base(ns, flags, RTD_CLOCK_BASE);
}

/* Convert a single comedi channel-gain entry to a RTD520 table entry */
static unsigned short rtd_convert_chan_gain(struct comedi_device *dev,
                                            unsigned int chanspec, int index)
{
        const struct rtd_boardinfo *board = dev->board_ptr;
        unsigned int chan = CR_CHAN(chanspec);
        unsigned int range = CR_RANGE(chanspec);
        unsigned int aref = CR_AREF(chanspec);
        unsigned short r = 0;

        r |= chan & 0xf;

        /* Note: we also setup the channel list bipolar flag array */
        if (range < board->range_bip10) {
                /* +-5 range */
                r |= 0x000;
                r |= (range & 0x7) << 4;
        } else if (range < board->range_uni10) {
                /* +-10 range */
                r |= 0x100;
                r |= ((range - board->range_bip10) & 0x7) << 4;
        } else {
                /* +10 range */
                r |= 0x200;
                r |= ((range - board->range_uni10) & 0x7) << 4;
        }

        switch (aref) {
        case AREF_GROUND:       /* on-board ground */
                break;

        case AREF_COMMON:
                r |= 0x80;      /* ref external analog common */
                break;

        case AREF_DIFF:
                r |= 0x400;     /* differential inputs */
                break;

        case AREF_OTHER:        /* ??? */
                break;
        }
        return r;
}

/* Setup the channel-gain table from a comedi list */
static void rtd_load_channelgain_list(struct comedi_device *dev,
                                      unsigned int n_chan, unsigned int *list)
{
        if (n_chan > 1) {       /* setup channel gain table */
                int ii;

                writel(0, dev->mmio + LAS0_CGT_CLEAR);
                writel(1, dev->mmio + LAS0_CGT_ENABLE);
                for (ii = 0; ii < n_chan; ii++) {
                        writel(rtd_convert_chan_gain(dev, list[ii], ii),
                               dev->mmio + LAS0_CGT_WRITE);
                }
        } else {                /* just use the channel gain latch */
                writel(0, dev->mmio + LAS0_CGT_ENABLE);
                writel(rtd_convert_chan_gain(dev, list[0], 0),
                       dev->mmio + LAS0_CGL_WRITE);
        }
}

/*
 * Determine fifo size by doing adc conversions until the fifo half
 * empty status flag clears.
 */
static int rtd520_probe_fifo_depth(struct comedi_device *dev)
{
        unsigned int chanspec = CR_PACK(0, 0, AREF_GROUND);
        unsigned i;
        static const unsigned limit = 0x2000;
        unsigned fifo_size = 0;

        writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
        rtd_load_channelgain_list(dev, 1, &chanspec);
        /* ADC conversion trigger source: SOFTWARE */
        writel(0, dev->mmio + LAS0_ADC_CONVERSION);
        /* convert  samples */
        for (i = 0; i < limit; ++i) {
                unsigned fifo_status;
                /* trigger conversion */
                writew(0, dev->mmio + LAS0_ADC);
                usleep_range(1, 1000);
                fifo_status = readl(dev->mmio + LAS0_ADC);
                if ((fifo_status & FS_ADC_HEMPTY) == 0) {
                        fifo_size = 2 * i;
                        break;
                }
        }
        if (i == limit) {
                dev_info(dev->class_dev, "failed to probe fifo size.\n");
                return -EIO;
        }
        writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
        if (fifo_size != 0x400 && fifo_size != 0x2000) {
                dev_info(dev->class_dev,
                         "unexpected fifo size of %i, expected 1024 or 8192.\n",
                         fifo_size);
                return -EIO;
        }
        return fifo_size;
}

static int rtd_ai_eoc(struct comedi_device *dev,
                      struct comedi_subdevice *s,
                      struct comedi_insn *insn,
                      unsigned long context)
{
        unsigned int status;

        status = readl(dev->mmio + LAS0_ADC);
        if (status & FS_ADC_NOT_EMPTY)
                return 0;
        return -EBUSY;
}

static int rtd_ai_rinsn(struct comedi_device *dev,
                        struct comedi_subdevice *s, struct comedi_insn *insn,
                        unsigned int *data)
{
        struct rtd_private *devpriv = dev->private;
        unsigned int range = CR_RANGE(insn->chanspec);
        int ret;
        int n;

        /* clear any old fifo data */
        writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);

        /* write channel to multiplexer and clear channel gain table */
        rtd_load_channelgain_list(dev, 1, &insn->chanspec);

        /* ADC conversion trigger source: SOFTWARE */
        writel(0, dev->mmio + LAS0_ADC_CONVERSION);

        /* convert n samples */
        for (n = 0; n < insn->n; n++) {
                unsigned short d;
                /* trigger conversion */
                writew(0, dev->mmio + LAS0_ADC);

                ret = comedi_timeout(dev, s, insn, rtd_ai_eoc, 0);
                if (ret)
                        return ret;

                /* read data */
                d = readw(devpriv->las1 + LAS1_ADC_FIFO);
                d >>= 3;        /* low 3 bits are marker lines */

                /* convert bipolar data to comedi unsigned data */
                if (comedi_range_is_bipolar(s, range))
                        d = comedi_offset_munge(s, d);

                data[n] = d & s->maxdata;
        }

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

static int ai_read_n(struct comedi_device *dev, struct comedi_subdevice *s,
                     int count)
{
        struct rtd_private *devpriv = dev->private;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;
        int ii;

        for (ii = 0; ii < count; ii++) {
                unsigned int range = CR_RANGE(cmd->chanlist[async->cur_chan]);
                unsigned short d;

                if (devpriv->ai_count == 0) {   /* done */
                        d = readw(devpriv->las1 + LAS1_ADC_FIFO);
                        continue;
                }

                d = readw(devpriv->las1 + LAS1_ADC_FIFO);
                d >>= 3;        /* low 3 bits are marker lines */

                /* convert bipolar data to comedi unsigned data */
                if (comedi_range_is_bipolar(s, range))
                        d = comedi_offset_munge(s, d);
                d &= s->maxdata;

                if (!comedi_buf_write_samples(s, &d, 1))
                        return -1;

                if (devpriv->ai_count > 0)      /* < 0, means read forever */
                        devpriv->ai_count--;
        }
        return 0;
}

static irqreturn_t rtd_interrupt(int irq, void *d)
{
        struct comedi_device *dev = d;
        struct comedi_subdevice *s = dev->read_subdev;
        struct rtd_private *devpriv = dev->private;
        u32 overrun;
        u16 status;
        u16 fifo_status;

        if (!dev->attached)
                return IRQ_NONE;

        fifo_status = readl(dev->mmio + LAS0_ADC);
        /* check for FIFO full, this automatically halts the ADC! */
        if (!(fifo_status & FS_ADC_NOT_FULL))   /* 0 -> full */
                goto xfer_abort;

        status = readw(dev->mmio + LAS0_IT);
        /* if interrupt was not caused by our board, or handled above */
        if (status == 0)
                return IRQ_HANDLED;

        if (status & IRQM_ADC_ABOUT_CNT) {      /* sample count -> read FIFO */
                /*
                 * since the priority interrupt controller may have queued
                 * a sample counter interrupt, even though we have already
                 * finished, we must handle the possibility that there is
                 * no data here
                 */
                if (!(fifo_status & FS_ADC_HEMPTY)) {
                        /* FIFO half full */
                        if (ai_read_n(dev, s, devpriv->fifosz / 2) < 0)
                                goto xfer_abort;

                        if (devpriv->ai_count == 0)
                                goto xfer_done;
                } else if (devpriv->xfer_count > 0) {
                        if (fifo_status & FS_ADC_NOT_EMPTY) {
                                /* FIFO not empty */
                                if (ai_read_n(dev, s, devpriv->xfer_count) < 0)
                                        goto xfer_abort;

                                if (devpriv->ai_count == 0)
                                        goto xfer_done;
                        }
                }
        }

        overrun = readl(dev->mmio + LAS0_OVERRUN) & 0xffff;
        if (overrun)
                goto xfer_abort;

        /* clear the interrupt */
        writew(status, dev->mmio + LAS0_CLEAR);
        readw(dev->mmio + LAS0_CLEAR);

        comedi_handle_events(dev, s);

        return IRQ_HANDLED;

xfer_abort:
        s->async->events |= COMEDI_CB_ERROR;

xfer_done:
        s->async->events |= COMEDI_CB_EOA;

        /* clear the interrupt */
        status = readw(dev->mmio + LAS0_IT);
        writew(status, dev->mmio + LAS0_CLEAR);
        readw(dev->mmio + LAS0_CLEAR);

        fifo_status = readl(dev->mmio + LAS0_ADC);
        overrun = readl(dev->mmio + LAS0_OVERRUN) & 0xffff;

        comedi_handle_events(dev, s);

        return IRQ_HANDLED;
}

static int rtd_ai_cmdtest(struct comedi_device *dev,
                          struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
        int err = 0;
        unsigned int arg;

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

        err |= comedi_check_trigger_src(&cmd->start_src, TRIG_NOW);
        err |= comedi_check_trigger_src(&cmd->scan_begin_src,
                                        TRIG_TIMER | TRIG_EXT);
        err |= comedi_check_trigger_src(&cmd->convert_src,
                                        TRIG_TIMER | TRIG_EXT);
        err |= comedi_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
        err |= comedi_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);

        if (err)
                return 1;

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

        err |= comedi_check_trigger_is_unique(cmd->scan_begin_src);
        err |= comedi_check_trigger_is_unique(cmd->convert_src);
        err |= comedi_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 |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);

        if (cmd->scan_begin_src == TRIG_TIMER) {
                /* Note: these are time periods, not actual rates */
                if (cmd->chanlist_len == 1) {   /* no scanning */
                        if (comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
                                                         RTD_MAX_SPEED_1)) {
                                rtd_ns_to_timer(&cmd->scan_begin_arg,
                                                CMDF_ROUND_UP);
                                err |= -EINVAL;
                        }
                        if (comedi_check_trigger_arg_max(&cmd->scan_begin_arg,
                                                         RTD_MIN_SPEED_1)) {
                                rtd_ns_to_timer(&cmd->scan_begin_arg,
                                                CMDF_ROUND_DOWN);
                                err |= -EINVAL;
                        }
                } else {
                        if (comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
                                                         RTD_MAX_SPEED)) {
                                rtd_ns_to_timer(&cmd->scan_begin_arg,
                                                CMDF_ROUND_UP);
                                err |= -EINVAL;
                        }
                        if (comedi_check_trigger_arg_max(&cmd->scan_begin_arg,
                                                         RTD_MIN_SPEED)) {
                                rtd_ns_to_timer(&cmd->scan_begin_arg,
                                                CMDF_ROUND_DOWN);
                                err |= -EINVAL;
                        }
                }
        } else {
                /* external trigger */
                /* should be level/edge, hi/lo specification here */
                /* should specify multiple external triggers */
                err |= comedi_check_trigger_arg_max(&cmd->scan_begin_arg, 9);
        }

        if (cmd->convert_src == TRIG_TIMER) {
                if (cmd->chanlist_len == 1) {   /* no scanning */
                        if (comedi_check_trigger_arg_min(&cmd->convert_arg,
                                                         RTD_MAX_SPEED_1)) {
                                rtd_ns_to_timer(&cmd->convert_arg,
                                                CMDF_ROUND_UP);
                                err |= -EINVAL;
                        }
                        if (comedi_check_trigger_arg_max(&cmd->convert_arg,
                                                         RTD_MIN_SPEED_1)) {
                                rtd_ns_to_timer(&cmd->convert_arg,
                                                CMDF_ROUND_DOWN);
                                err |= -EINVAL;
                        }
                } else {
                        if (comedi_check_trigger_arg_min(&cmd->convert_arg,
                                                         RTD_MAX_SPEED)) {
                                rtd_ns_to_timer(&cmd->convert_arg,
                                                CMDF_ROUND_UP);
                                err |= -EINVAL;
                        }
                        if (comedi_check_trigger_arg_max(&cmd->convert_arg,
                                                         RTD_MIN_SPEED)) {
                                rtd_ns_to_timer(&cmd->convert_arg,
                                                CMDF_ROUND_DOWN);
                                err |= -EINVAL;
                        }
                }
        } else {
                /* external trigger */
                /* see above */
                err |= comedi_check_trigger_arg_max(&cmd->convert_arg, 9);
        }

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

        if (cmd->stop_src == TRIG_COUNT)
                err |= comedi_check_trigger_arg_min(&cmd->stop_arg, 1);
        else    /* TRIG_NONE */
                err |= comedi_check_trigger_arg_is(&cmd->stop_arg, 0);

        if (err)
                return 3;

        /* step 4: fix up any arguments */

        if (cmd->scan_begin_src == TRIG_TIMER) {
                arg = cmd->scan_begin_arg;
                rtd_ns_to_timer(&arg, cmd->flags);
                err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
        }

        if (cmd->convert_src == TRIG_TIMER) {
                arg = cmd->convert_arg;
                rtd_ns_to_timer(&arg, cmd->flags);
                err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);

                if (cmd->scan_begin_src == TRIG_TIMER) {
                        arg = cmd->convert_arg * cmd->scan_end_arg;
                        err |= comedi_check_trigger_arg_min(&cmd->
                                                            scan_begin_arg,
                                                            arg);
                }
        }

        if (err)
                return 4;

        return 0;
}

static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct rtd_private *devpriv = dev->private;
        struct comedi_cmd *cmd = &s->async->cmd;
        int timer;

        /* stop anything currently running */
        /* pacer stop source: SOFTWARE */
        writel(0, dev->mmio + LAS0_PACER_STOP);
        writel(0, dev->mmio + LAS0_PACER);      /* stop pacer */
        writel(0, dev->mmio + LAS0_ADC_CONVERSION);
        writew(0, dev->mmio + LAS0_IT);
        writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
        writel(0, dev->mmio + LAS0_OVERRUN);

        /* start configuration */
        /* load channel list and reset CGT */
        rtd_load_channelgain_list(dev, cmd->chanlist_len, cmd->chanlist);

        /* setup the common case and override if needed */
        if (cmd->chanlist_len > 1) {
                /* pacer start source: SOFTWARE */
                writel(0, dev->mmio + LAS0_PACER_START);
                /* burst trigger source: PACER */
                writel(1, dev->mmio + LAS0_BURST_START);
                /* ADC conversion trigger source: BURST */
                writel(2, dev->mmio + LAS0_ADC_CONVERSION);
        } else {                /* single channel */
                /* pacer start source: SOFTWARE */
                writel(0, dev->mmio + LAS0_PACER_START);
                /* ADC conversion trigger source: PACER */
                writel(1, dev->mmio + LAS0_ADC_CONVERSION);
        }
        writel((devpriv->fifosz / 2 - 1) & 0xffff, dev->mmio + LAS0_ACNT);

        if (cmd->scan_begin_src == TRIG_TIMER) {
                /* scan_begin_arg is in nanoseconds */
                /* find out how many samples to wait before transferring */
                if (cmd->flags & CMDF_WAKE_EOS) {
                        /*
                         * this may generate un-sustainable interrupt rates
                         * the application is responsible for doing the
                         * right thing
                         */
                        devpriv->xfer_count = cmd->chanlist_len;
                        devpriv->flags |= SEND_EOS;
                } else {
                        /* arrange to transfer data periodically */
                        devpriv->xfer_count =
                            (TRANS_TARGET_PERIOD * cmd->chanlist_len) /
                            cmd->scan_begin_arg;
                        if (devpriv->xfer_count < cmd->chanlist_len) {
                                /* transfer after each scan (and avoid 0) */
                                devpriv->xfer_count = cmd->chanlist_len;
                        } else {        /* make a multiple of scan length */
                                devpriv->xfer_count =
                                    DIV_ROUND_UP(devpriv->xfer_count,
                                                 cmd->chanlist_len);
                                devpriv->xfer_count *= cmd->chanlist_len;
                        }
                        devpriv->flags |= SEND_EOS;
                }
                if (devpriv->xfer_count >= (devpriv->fifosz / 2)) {
                        /* out of counter range, use 1/2 fifo instead */
                        devpriv->xfer_count = 0;
                        devpriv->flags &= ~SEND_EOS;
                } else {
                        /* interrupt for each transfer */
                        writel((devpriv->xfer_count - 1) & 0xffff,
                               dev->mmio + LAS0_ACNT);
                }
        } else {                /* unknown timing, just use 1/2 FIFO */
                devpriv->xfer_count = 0;
                devpriv->flags &= ~SEND_EOS;
        }
        /* pacer clock source: INTERNAL 8MHz */
        writel(1, dev->mmio + LAS0_PACER_SELECT);
        /* just interrupt, don't stop */
        writel(1, dev->mmio + LAS0_ACNT_STOP_ENABLE);

        /* BUG??? these look like enumerated values, but they are bit fields */

        /* First, setup when to stop */
        switch (cmd->stop_src) {
        case TRIG_COUNT:        /* stop after N scans */
                devpriv->ai_count = cmd->stop_arg * cmd->chanlist_len;
                if ((devpriv->xfer_count > 0) &&
                    (devpriv->xfer_count > devpriv->ai_count)) {
                        devpriv->xfer_count = devpriv->ai_count;
                }
                break;

        case TRIG_NONE: /* stop when cancel is called */
                devpriv->ai_count = -1; /* read forever */
                break;
        }

        /* Scan timing */
        switch (cmd->scan_begin_src) {
        case TRIG_TIMER:        /* periodic scanning */
                timer = rtd_ns_to_timer(&cmd->scan_begin_arg,
                                        CMDF_ROUND_NEAREST);
                /* set PACER clock */
                writel(timer & 0xffffff, dev->mmio + LAS0_PCLK);

                break;

        case TRIG_EXT:
                /* pacer start source: EXTERNAL */
                writel(1, dev->mmio + LAS0_PACER_START);
                break;
        }

        /* Sample timing within a scan */
        switch (cmd->convert_src) {
        case TRIG_TIMER:        /* periodic */
                if (cmd->chanlist_len > 1) {
                        /* only needed for multi-channel */
                        timer = rtd_ns_to_timer(&cmd->convert_arg,
                                                CMDF_ROUND_NEAREST);
                        /* setup BURST clock */
                        writel(timer & 0x3ff, dev->mmio + LAS0_BCLK);
                }

                break;

        case TRIG_EXT:          /* external */
                /* burst trigger source: EXTERNAL */
                writel(2, dev->mmio + LAS0_BURST_START);
                break;
        }
        /* end configuration */

        /*
         * This doesn't seem to work.  There is no way to clear an interrupt
         * that the priority controller has queued!
         */
        writew(~0, dev->mmio + LAS0_CLEAR);
        readw(dev->mmio + LAS0_CLEAR);

        /* TODO: allow multiple interrupt sources */
        /* transfer every N samples */
        writew(IRQM_ADC_ABOUT_CNT, dev->mmio + LAS0_IT);

        /* BUG: start_src is ASSUMED to be TRIG_NOW */
        /* BUG? it seems like things are running before the "start" */
        readl(dev->mmio + LAS0_PACER);  /* start pacer */
        return 0;
}

static int rtd_ai_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct rtd_private *devpriv = dev->private;

        /* pacer stop source: SOFTWARE */
        writel(0, dev->mmio + LAS0_PACER_STOP);
        writel(0, dev->mmio + LAS0_PACER);      /* stop pacer */
        writel(0, dev->mmio + LAS0_ADC_CONVERSION);
        writew(0, dev->mmio + LAS0_IT);
        devpriv->ai_count = 0;  /* stop and don't transfer any more */
        writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
        return 0;

}

static int rtd_ao_eoc(struct comedi_device *dev,
                      struct comedi_subdevice *s,
                      struct comedi_insn *insn,
                      unsigned long context)
{
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int bit = (chan == 0) ? FS_DAC1_NOT_EMPTY : FS_DAC2_NOT_EMPTY;
        unsigned int status;

        status = readl(dev->mmio + LAS0_ADC);
        if (status & bit)
                return 0;
        return -EBUSY;
}

static int rtd_ao_insn_write(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_insn *insn,
                             unsigned int *data)
{
        struct rtd_private *devpriv = dev->private;
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int range = CR_RANGE(insn->chanspec);
        int ret;
        int i;

        /* Configure the output range (table index matches the range values) */
        writew(range & 7, dev->mmio + LAS0_DAC_CTRL(chan));

        for (i = 0; i < insn->n; ++i) {
                unsigned int val = data[i];

                /* bipolar uses 2's complement values with an extended sign */
                if (comedi_range_is_bipolar(s, range)) {
                        val = comedi_offset_munge(s, val);
                        val |= (val & ((s->maxdata + 1) >> 1)) << 1;
                }

                /* shift the 12-bit data (+ sign) to match the register */
                val <<= 3;

                writew(val, devpriv->las1 + LAS1_DAC_FIFO(chan));
                writew(0, dev->mmio + LAS0_UPDATE_DAC(chan));

                ret = comedi_timeout(dev, s, insn, rtd_ao_eoc, 0);
                if (ret)
                        return ret;

                s->readback[chan] = data[i];
        }

        return insn->n;
}

static int rtd_dio_insn_bits(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_insn *insn,
                             unsigned int *data)
{
        if (comedi_dio_update_state(s, data))
                writew(s->state & 0xff, dev->mmio + LAS0_DIO0);

        data[1] = readw(dev->mmio + LAS0_DIO0) & 0xff;

        return insn->n;
}

static int rtd_dio_insn_config(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn,
                               unsigned int *data)
{
        int ret;

        ret = comedi_dio_insn_config(dev, s, insn, data, 0);
        if (ret)
                return ret;

        /* TODO support digital match interrupts and strobes */

        /* set direction */
        writew(0x01, dev->mmio + LAS0_DIO_STATUS);
        writew(s->io_bits & 0xff, dev->mmio + LAS0_DIO0_CTRL);

        /* clear interrupts */
        writew(0x00, dev->mmio + LAS0_DIO_STATUS);

        /* port1 can only be all input or all output */

        /* there are also 2 user input lines and 2 user output lines */

        return insn->n;
}

static int rtd_counter_insn_config(struct comedi_device *dev,
                                   struct comedi_subdevice *s,
                                   struct comedi_insn *insn,
                                   unsigned int *data)
{
        struct rtd_private *devpriv = dev->private;
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int max_src;
        unsigned int src;

        switch (data[0]) {
        case INSN_CONFIG_SET_GATE_SRC:
                /*
                 * 8254 Timer/Counter gate sources:
                 *
                 * 0 = Not gated, free running (reset state)
                 * 1 = Gated, off
                 * 2 = Ext. TC Gate 1
                 * 3 = Ext. TC Gate 2
                 * 4 = Previous TC out (chan 1 and 2 only)
                 */
                src = data[2];
                max_src = (chan == 0) ? 3 : 4;
                if (src > max_src)
                        return -EINVAL;

                devpriv->timer_gate_src[chan] = src;
                writeb(src, dev->mmio + LAS0_8254_GATE_SEL(chan));
                break;
        case INSN_CONFIG_GET_GATE_SRC:
                data[2] = devpriv->timer_gate_src[chan];
                break;
        case INSN_CONFIG_SET_CLOCK_SRC:
                /*
                 * 8254 Timer/Counter clock sources:
                 *
                 * 0 = 8 MHz (reset state)
                 * 1 = Ext. TC Clock 1
                 * 2 = Ext. TX Clock 2
                 * 3 = Ext. Pacer Clock
                 * 4 = Previous TC out (chan 1 and 2 only)
                 * 5 = High-Speed Digital Input Sampling signal (chan 1 only)
                 */
                src = data[1];
                switch (chan) {
                case 0:
                        max_src = 3;
                        break;
                case 1:
                        max_src = 5;
                        break;
                case 2:
                        max_src = 4;
                        break;
                default:
                        return -EINVAL;
                }
                if (src > max_src)
                        return -EINVAL;

                devpriv->timer_clk_src[chan] = src;
                writeb(src, dev->mmio + LAS0_8254_CLK_SEL(chan));
                break;
        case INSN_CONFIG_GET_CLOCK_SRC:
                src = devpriv->timer_clk_src[chan];
                data[1] = devpriv->timer_clk_src[chan];
                data[2] = (src == 0) ? RTD_CLOCK_BASE : 0;
                break;
        default:
                return -EINVAL;
        }

        return insn->n;
}

static void rtd_reset(struct comedi_device *dev)
{
        struct rtd_private *devpriv = dev->private;

        writel(0, dev->mmio + LAS0_BOARD_RESET);
        usleep_range(100, 1000);        /* needed? */
        writel(0, devpriv->lcfg + PLX_INTRCS_REG);
        writew(0, dev->mmio + LAS0_IT);
        writew(~0, dev->mmio + LAS0_CLEAR);
        readw(dev->mmio + LAS0_CLEAR);
}

/*
 * initialize board, per RTD spec
 * also, initialize shadow registers
 */
static void rtd_init_board(struct comedi_device *dev)
{
        rtd_reset(dev);

        writel(0, dev->mmio + LAS0_OVERRUN);
        writel(0, dev->mmio + LAS0_CGT_CLEAR);
        writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
        writel(0, dev->mmio + LAS0_DAC_RESET(0));
        writel(0, dev->mmio + LAS0_DAC_RESET(1));
        /* clear digital IO fifo */
        writew(0, dev->mmio + LAS0_DIO_STATUS);
        /* TODO: set user out source ??? */
}

/* The RTD driver does this */
static void rtd_pci_latency_quirk(struct comedi_device *dev,
                                  struct pci_dev *pcidev)
{
        unsigned char pci_latency;

        pci_read_config_byte(pcidev, PCI_LATENCY_TIMER, &pci_latency);
        if (pci_latency < 32) {
                dev_info(dev->class_dev,
                         "PCI latency changed from %d to %d\n",
                         pci_latency, 32);
                pci_write_config_byte(pcidev, PCI_LATENCY_TIMER, 32);
        }
}

static int rtd_auto_attach(struct comedi_device *dev,
                           unsigned long context)
{
        struct pci_dev *pcidev = comedi_to_pci_dev(dev);
        const struct rtd_boardinfo *board = NULL;
        struct rtd_private *devpriv;
        struct comedi_subdevice *s;
        int ret;

        if (context < ARRAY_SIZE(rtd520_boards))
                board = &rtd520_boards[context];
        if (!board)
                return -ENODEV;
        dev->board_ptr = board;
        dev->board_name = board->name;

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

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

        dev->mmio = pci_ioremap_bar(pcidev, 2);
        devpriv->las1 = pci_ioremap_bar(pcidev, 3);
        devpriv->lcfg = pci_ioremap_bar(pcidev, 0);
        if (!dev->mmio || !devpriv->las1 || !devpriv->lcfg)
                return -ENOMEM;

        rtd_pci_latency_quirk(dev, pcidev);

        if (pcidev->irq) {
                ret = request_irq(pcidev->irq, rtd_interrupt, IRQF_SHARED,
                                  dev->board_name, dev);
                if (ret == 0)
                        dev->irq = pcidev->irq;
        }

        ret = comedi_alloc_subdevices(dev, 4);
        if (ret)
                return ret;

        s = &dev->subdevices[0];
        /* analog input subdevice */
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_GROUND | SDF_COMMON | SDF_DIFF;
        s->n_chan       = 16;
        s->maxdata      = 0x0fff;
        s->range_table  = board->ai_range;
        s->len_chanlist = RTD_MAX_CHANLIST;
        s->insn_read    = rtd_ai_rinsn;
        if (dev->irq) {
                dev->read_subdev = s;
                s->subdev_flags |= SDF_CMD_READ;
                s->do_cmd       = rtd_ai_cmd;
                s->do_cmdtest   = rtd_ai_cmdtest;
                s->cancel       = rtd_ai_cancel;
        }

        s = &dev->subdevices[1];
        /* analog output subdevice */
        s->type         = COMEDI_SUBD_AO;
        s->subdev_flags = SDF_WRITABLE;
        s->n_chan       = 2;
        s->maxdata      = 0x0fff;
        s->range_table  = &rtd_ao_range;
        s->insn_write   = rtd_ao_insn_write;

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

        s = &dev->subdevices[2];
        /* digital i/o subdevice */
        s->type         = COMEDI_SUBD_DIO;
        s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
        /* we only support port 0 right now.  Ignoring port 1 and user IO */
        s->n_chan       = 8;
        s->maxdata      = 1;
        s->range_table  = &range_digital;
        s->insn_bits    = rtd_dio_insn_bits;
        s->insn_config  = rtd_dio_insn_config;

        /* 8254 Timer/Counter subdevice */
        s = &dev->subdevices[3];
        dev->pacer = comedi_8254_mm_init(dev->mmio + LAS0_8254_TIMER_BASE,
                                         RTD_CLOCK_BASE, I8254_IO8, 2);
        if (!dev->pacer)
                return -ENOMEM;

        comedi_8254_subdevice_init(s, dev->pacer);
        dev->pacer->insn_config = rtd_counter_insn_config;

        rtd_init_board(dev);

        ret = rtd520_probe_fifo_depth(dev);
        if (ret < 0)
                return ret;
        devpriv->fifosz = ret;

        if (dev->irq)
                writel(ICS_PIE | ICS_PLIE, devpriv->lcfg + PLX_INTRCS_REG);

        return 0;
}

static void rtd_detach(struct comedi_device *dev)
{
        struct rtd_private *devpriv = dev->private;

        if (devpriv) {
                /* Shut down any board ops by resetting it */
                if (dev->mmio && devpriv->lcfg)
                        rtd_reset(dev);
                if (dev->irq)
                        free_irq(dev->irq, dev);
                if (dev->mmio)
                        iounmap(dev->mmio);
                if (devpriv->las1)
                        iounmap(devpriv->las1);
                if (devpriv->lcfg)
                        iounmap(devpriv->lcfg);
        }
        comedi_pci_disable(dev);
}

static struct comedi_driver rtd520_driver = {
        .driver_name    = "rtd520",
        .module         = THIS_MODULE,
        .auto_attach    = rtd_auto_attach,
        .detach         = rtd_detach,
};

static int rtd520_pci_probe(struct pci_dev *dev,
                            const struct pci_device_id *id)
{
        return comedi_pci_auto_config(dev, &rtd520_driver, id->driver_data);
}

static const struct pci_device_id rtd520_pci_table[] = {
        { PCI_VDEVICE(RTD, 0x7520), BOARD_DM7520 },
        { PCI_VDEVICE(RTD, 0x4520), BOARD_PCI4520 },
        { 0 }
};
MODULE_DEVICE_TABLE(pci, rtd520_pci_table);

static struct pci_driver rtd520_pci_driver = {
        .name           = "rtd520",
        .id_table       = rtd520_pci_table,
        .probe          = rtd520_pci_probe,
        .remove         = comedi_pci_auto_unconfig,
};
module_comedi_pci_driver(rtd520_driver, rtd520_pci_driver);

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