/*
   comedi/drivers/dt282x.c
   Hardware driver for Data Translation DT2821 series

   COMEDI - Linux Control and Measurement Device Interface
   Copyright (C) 1997-8 David A. Schleef <ds@schleef.org>

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

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

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */
/*
Driver: dt282x
Description: Data Translation DT2821 series (including DT-EZ)
Author: ds
Devices: [Data Translation] DT2821 (dt2821),
  DT2821-F-16SE (dt2821-f), DT2821-F-8DI (dt2821-f),
  DT2821-G-16SE (dt2821-f), DT2821-G-8DI (dt2821-g),
  DT2823 (dt2823),
  DT2824-PGH (dt2824-pgh), DT2824-PGL (dt2824-pgl), DT2825 (dt2825),
  DT2827 (dt2827), DT2828 (dt2828), DT21-EZ (dt21-ez), DT23-EZ (dt23-ez),
  DT24-EZ (dt24-ez), DT24-EZ-PGL (dt24-ez-pgl)
Status: complete
Updated: Wed, 22 Aug 2001 17:11:34 -0700

Configuration options:
  [0] - I/O port base address
  [1] - IRQ
  [2] - DMA 1
  [3] - DMA 2
  [4] - AI jumpered for 0=single ended, 1=differential
  [5] - AI jumpered for 0=straight binary, 1=2's complement
  [6] - AO 0 jumpered for 0=straight binary, 1=2's complement
  [7] - AO 1 jumpered for 0=straight binary, 1=2's complement
  [8] - AI jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5]
  [9] - AO 0 jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5],
        4=[-2.5,2.5]
  [10]- A0 1 jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5],
        4=[-2.5,2.5]

Notes:
  - AO commands might be broken.
  - If you try to run a command on both the AI and AO subdevices
    simultaneously, bad things will happen.  The driver needs to
    be fixed to check for this situation and return an error.
*/

#include "../comedidev.h"

#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <asm/dma.h>
#include "comedi_fc.h"

#define DEBUG

#define DT2821_TIMEOUT          100     /* 500 us */
#define DT2821_SIZE 0x10

/*
 *    Registers in the DT282x
 */

#define DT2821_ADCSR    0x00    /* A/D Control/Status             */
#define DT2821_CHANCSR  0x02    /* Channel Control/Status */
#define DT2821_ADDAT    0x04    /* A/D data                       */
#define DT2821_DACSR    0x06    /* D/A Control/Status             */
#define DT2821_DADAT    0x08    /* D/A data                       */
#define DT2821_DIODAT   0x0a    /* digital data                   */
#define DT2821_SUPCSR   0x0c    /* Supervisor Control/Status      */
#define DT2821_TMRCTR   0x0e    /* Timer/Counter          */

/*
 *  At power up, some registers are in a well-known state.  The
 *  masks and values are as follows:
 */

#define DT2821_ADCSR_MASK 0xfff0
#define DT2821_ADCSR_VAL 0x7c00

#define DT2821_CHANCSR_MASK 0xf0f0
#define DT2821_CHANCSR_VAL 0x70f0

#define DT2821_DACSR_MASK 0x7c93
#define DT2821_DACSR_VAL 0x7c90

#define DT2821_SUPCSR_MASK 0xf8ff
#define DT2821_SUPCSR_VAL 0x0000

#define DT2821_TMRCTR_MASK 0xff00
#define DT2821_TMRCTR_VAL 0xf000

/*
 *    Bit fields of each register
 */

/* ADCSR */

#define DT2821_ADERR    0x8000  /* (R)   1 for A/D error  */
#define DT2821_ADCLK    0x0200  /* (R/W) A/D clock enable */
                /*      0x7c00           read as 1's            */
#define DT2821_MUXBUSY  0x0100  /* (R)   multiplexer busy */
#define DT2821_ADDONE   0x0080  /* (R)   A/D done         */
#define DT2821_IADDONE  0x0040  /* (R/W) interrupt on A/D done    */
                /*      0x0030           gain select            */
                /*      0x000f           channel select         */

/* CHANCSR */

#define DT2821_LLE      0x8000  /* (R/W) Load List Enable */
                /*      0x7000           read as 1's            */
                /*      0x0f00     (R)   present address        */
                /*      0x00f0           read as 1's            */
                /*      0x000f     (R)   number of entries - 1  */

/* DACSR */

#define DT2821_DAERR    0x8000  /* (R)   D/A error                */
#define DT2821_YSEL     0x0200  /* (R/W) DAC 1 select             */
#define DT2821_SSEL     0x0100  /* (R/W) single channel select    */
#define DT2821_DACRDY   0x0080  /* (R)   DAC ready                */
#define DT2821_IDARDY   0x0040  /* (R/W) interrupt on DAC ready   */
#define DT2821_DACLK    0x0020  /* (R/W) D/A clock enable */
#define DT2821_HBOE     0x0002  /* (R/W) DIO high byte output enable      */
#define DT2821_LBOE     0x0001  /* (R/W) DIO low byte output enable       */

/* SUPCSR */

#define DT2821_DMAD     0x8000  /* (R)   DMA done                 */
#define DT2821_ERRINTEN 0x4000  /* (R/W) interrupt on error               */
#define DT2821_CLRDMADNE 0x2000 /* (W)   clear DMA done                   */
#define DT2821_DDMA     0x1000  /* (R/W) dual DMA                 */
#define DT2821_DS1      0x0800  /* (R/W) DMA select 1                     */
#define DT2821_DS0      0x0400  /* (R/W) DMA select 0                     */
#define DT2821_BUFFB    0x0200  /* (R/W) buffer B selected                */
#define DT2821_SCDN     0x0100  /* (R)   scan done                        */
#define DT2821_DACON    0x0080  /* (W)   DAC single conversion            */
#define DT2821_ADCINIT  0x0040  /* (W)   A/D initialize                   */
#define DT2821_DACINIT  0x0020  /* (W)   D/A initialize                   */
#define DT2821_PRLD     0x0010  /* (W)   preload multiplexer              */
#define DT2821_STRIG    0x0008  /* (W)   software trigger         */
#define DT2821_XTRIG    0x0004  /* (R/W) external trigger enable  */
#define DT2821_XCLK     0x0002  /* (R/W) external clock enable            */
#define DT2821_BDINIT   0x0001  /* (W)   initialize board         */

static const struct comedi_lrange range_dt282x_ai_lo_bipolar = { 4, {
                                                                     RANGE(-10,
                                                                           10),
                                                                     RANGE(-5,
                                                                           5),
                                                                     RANGE(-2.5,
                                                                           2.5),
                                                                     RANGE
                                                                     (-1.25,
                                                                      1.25)
                                                                     }
};

static const struct comedi_lrange range_dt282x_ai_lo_unipolar = { 4, {
                                                                      RANGE(0,
                                                                            10),
                                                                      RANGE(0,
                                                                            5),
                                                                      RANGE(0,
                                                                            2.5),
                                                                      RANGE(0,
                                                                            1.25)
                                                                      }
};

static const struct comedi_lrange range_dt282x_ai_5_bipolar = { 4, {
                                                                    RANGE(-5,
                                                                          5),
                                                                    RANGE(-2.5,
                                                                          2.5),
                                                                    RANGE(-1.25,
                                                                          1.25),
                                                                    RANGE
                                                                    (-0.625,
                                                                     0.625),
                                                                    }
};

static const struct comedi_lrange range_dt282x_ai_5_unipolar = { 4, {
                                                                     RANGE(0,
                                                                           5),
                                                                     RANGE(0,
                                                                           2.5),
                                                                     RANGE(0,
                                                                           1.25),
                                                                     RANGE(0,
                                                                           0.625),
                                                                     }
};

static const struct comedi_lrange range_dt282x_ai_hi_bipolar = { 4, {
                                                                     RANGE(-10,
                                                                           10),
                                                                     RANGE(-1,
                                                                           1),
                                                                     RANGE(-0.1,
                                                                           0.1),
                                                                     RANGE
                                                                     (-0.02,
                                                                      0.02)
                                                                     }
};

static const struct comedi_lrange range_dt282x_ai_hi_unipolar = { 4, {
                                                                      RANGE(0,
                                                                            10),
                                                                      RANGE(0,
                                                                            1),
                                                                      RANGE(0,
                                                                            0.1),
                                                                      RANGE(0,
                                                                            0.02)
                                                                      }
};

struct dt282x_board {
        const char *name;
        int adbits;
        int adchan_se;
        int adchan_di;
        int ai_speed;
        int ispgl;
        int dachan;
        int dabits;
};

static const struct dt282x_board boardtypes[] = {
        {.name = "dt2821",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 20000,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt2821-f",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 6500,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt2821-g",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 4000,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt2823",
         .adbits = 16,
         .adchan_se = 0,
         .adchan_di = 4,
         .ai_speed = 10000,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 16,
         },
        {.name = "dt2824-pgh",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 20000,
         .ispgl = 0,
         .dachan = 0,
         .dabits = 0,
         },
        {.name = "dt2824-pgl",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 20000,
         .ispgl = 1,
         .dachan = 0,
         .dabits = 0,
         },
        {.name = "dt2825",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 20000,
         .ispgl = 1,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt2827",
         .adbits = 16,
         .adchan_se = 0,
         .adchan_di = 4,
         .ai_speed = 10000,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt2828",
         .adbits = 12,
         .adchan_se = 4,
         .adchan_di = 0,
         .ai_speed = 10000,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt2829",
         .adbits = 16,
         .adchan_se = 8,
         .adchan_di = 0,
         .ai_speed = 33250,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 16,
         },
        {.name = "dt21-ez",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 10000,
         .ispgl = 0,
         .dachan = 2,
         .dabits = 12,
         },
        {.name = "dt23-ez",
         .adbits = 16,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 10000,
         .ispgl = 0,
         .dachan = 0,
         .dabits = 0,
         },
        {.name = "dt24-ez",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 10000,
         .ispgl = 0,
         .dachan = 0,
         .dabits = 0,
         },
        {.name = "dt24-ez-pgl",
         .adbits = 12,
         .adchan_se = 16,
         .adchan_di = 8,
         .ai_speed = 10000,
         .ispgl = 1,
         .dachan = 0,
         .dabits = 0,
         },
};

#define n_boardtypes sizeof(boardtypes)/sizeof(struct dt282x_board)
#define this_board ((const struct dt282x_board *)dev->board_ptr)

struct dt282x_private {
        int ad_2scomp;          /* we have 2's comp jumper set  */
        int da0_2scomp;         /* same, for DAC0               */
        int da1_2scomp;         /* same, for DAC1               */

        const struct comedi_lrange *darangelist[2];

        short ao[2];

        volatile int dacsr;     /* software copies of registers */
        volatile int adcsr;
        volatile int supcsr;

        volatile int ntrig;
        volatile int nread;

        struct {
                int chan;
                short *buf;     /* DMA buffer */
                volatile int size;      /* size of current transfer */
        } dma[2];
        int dma_maxsize;        /* max size of DMA transfer (in bytes) */
        int usedma;             /* driver uses DMA              */
        volatile int current_dma_index;
        int dma_dir;
};

#define devpriv ((struct dt282x_private *)dev->private)
#define boardtype (*(const struct dt282x_board *)dev->board_ptr)

/*
 *    Some useless abstractions
 */
#define chan_to_DAC(a)  ((a)&1)
#define update_dacsr(a) outw(devpriv->dacsr|(a), dev->iobase+DT2821_DACSR)
#define update_adcsr(a) outw(devpriv->adcsr|(a), dev->iobase+DT2821_ADCSR)
#define mux_busy() (inw(dev->iobase+DT2821_ADCSR)&DT2821_MUXBUSY)
#define ad_done() (inw(dev->iobase+DT2821_ADCSR)&DT2821_ADDONE)
#define update_supcsr(a)        outw(devpriv->supcsr|(a), dev->iobase+DT2821_SUPCSR)

/*
 *    danger! macro abuse... a is the expression to wait on, and b is
 *      the statement(s) to execute if it doesn't happen.
 */
#define wait_for(a, b)                                  \
        do{                                             \
                int _i;                                 \
                for (_i=0;_i<DT2821_TIMEOUT;_i++){      \
                        if (a){_i=0;break;}             \
                        udelay(5);                      \
                }                                       \
                if (_i){b}                              \
        }while (0)

static int dt282x_attach(struct comedi_device *dev,
                         struct comedi_devconfig *it);
static int dt282x_detach(struct comedi_device *dev);
static struct comedi_driver driver_dt282x = {
        .driver_name = "dt282x",
        .module = THIS_MODULE,
        .attach = dt282x_attach,
        .detach = dt282x_detach,
        .board_name = &boardtypes[0].name,
        .num_names = n_boardtypes,
        .offset = sizeof(struct dt282x_board),
};

COMEDI_INITCLEANUP(driver_dt282x);

static void free_resources(struct comedi_device *dev);
static int prep_ai_dma(struct comedi_device *dev, int chan, int size);
static int prep_ao_dma(struct comedi_device *dev, int chan, int size);
static int dt282x_ai_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s);
static int dt282x_ao_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s);
static int dt282x_ns_to_timer(int *nanosec, int round_mode);
static void dt282x_disable_dma(struct comedi_device *dev);

static int dt282x_grab_dma(struct comedi_device *dev, int dma1, int dma2);

static void dt282x_munge(struct comedi_device *dev, short *buf,
                         unsigned int nbytes)
{
        unsigned int i;
        unsigned short mask = (1 << boardtype.adbits) - 1;
        unsigned short sign = 1 << (boardtype.adbits - 1);
        int n;

        if (devpriv->ad_2scomp) {
                sign = 1 << (boardtype.adbits - 1);
        } else {
                sign = 0;
        }

        if (nbytes % 2)
                comedi_error(dev, "bug! odd number of bytes from dma xfer");
        n = nbytes / 2;
        for (i = 0; i < n; i++) {
                buf[i] = (buf[i] & mask) ^ sign;
        }
}

static void dt282x_ao_dma_interrupt(struct comedi_device *dev)
{
        void *ptr;
        int size;
        int i;
        struct comedi_subdevice *s = dev->subdevices + 1;

        update_supcsr(DT2821_CLRDMADNE);

        if (!s->async->prealloc_buf) {
                printk("async->data disappeared.  dang!\n");
                return;
        }

        i = devpriv->current_dma_index;
        ptr = devpriv->dma[i].buf;

        disable_dma(devpriv->dma[i].chan);

        devpriv->current_dma_index = 1 - i;

        size = cfc_read_array_from_buffer(s, ptr, devpriv->dma_maxsize);
        if (size == 0) {
                printk("dt282x: AO underrun\n");
                dt282x_ao_cancel(dev, s);
                s->async->events |= COMEDI_CB_OVERFLOW;
                return;
        }
        prep_ao_dma(dev, i, size);
        return;
}

static void dt282x_ai_dma_interrupt(struct comedi_device *dev)
{
        void *ptr;
        int size;
        int i;
        int ret;
        struct comedi_subdevice *s = dev->subdevices;

        update_supcsr(DT2821_CLRDMADNE);

        if (!s->async->prealloc_buf) {
                printk("async->data disappeared.  dang!\n");
                return;
        }

        i = devpriv->current_dma_index;
        ptr = devpriv->dma[i].buf;
        size = devpriv->dma[i].size;

        disable_dma(devpriv->dma[i].chan);

        devpriv->current_dma_index = 1 - i;

        dt282x_munge(dev, ptr, size);
        ret = cfc_write_array_to_buffer(s, ptr, size);
        if (ret != size) {
                dt282x_ai_cancel(dev, s);
                return;
        }
        devpriv->nread -= size / 2;

        if (devpriv->nread < 0) {
                printk("dt282x: off by one\n");
                devpriv->nread = 0;
        }
        if (!devpriv->nread) {
                dt282x_ai_cancel(dev, s);
                s->async->events |= COMEDI_CB_EOA;
                return;
        }
#if 0
        /* clear the dual dma flag, making this the last dma segment */
        /* XXX probably wrong */
        if (!devpriv->ntrig) {
                devpriv->supcsr &= ~(DT2821_DDMA);
                update_supcsr(0);
        }
#endif
        /* restart the channel */
        prep_ai_dma(dev, i, 0);
}

static int prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
{
        int dma_chan;
        unsigned long dma_ptr;
        unsigned long flags;

        if (!devpriv->ntrig)
                return 0;

        if (n == 0)
                n = devpriv->dma_maxsize;
        if (n > devpriv->ntrig * 2)
                n = devpriv->ntrig * 2;
        devpriv->ntrig -= n / 2;

        devpriv->dma[dma_index].size = n;
        dma_chan = devpriv->dma[dma_index].chan;
        dma_ptr = virt_to_bus(devpriv->dma[dma_index].buf);

        set_dma_mode(dma_chan, DMA_MODE_READ);
        flags = claim_dma_lock();
        clear_dma_ff(dma_chan);
        set_dma_addr(dma_chan, dma_ptr);
        set_dma_count(dma_chan, n);
        release_dma_lock(flags);

        enable_dma(dma_chan);

        return n;
}

static int prep_ao_dma(struct comedi_device *dev, int dma_index, int n)
{
        int dma_chan;
        unsigned long dma_ptr;
        unsigned long flags;

        devpriv->dma[dma_index].size = n;
        dma_chan = devpriv->dma[dma_index].chan;
        dma_ptr = virt_to_bus(devpriv->dma[dma_index].buf);

        set_dma_mode(dma_chan, DMA_MODE_WRITE);
        flags = claim_dma_lock();
        clear_dma_ff(dma_chan);
        set_dma_addr(dma_chan, dma_ptr);
        set_dma_count(dma_chan, n);
        release_dma_lock(flags);

        enable_dma(dma_chan);

        return n;
}

static irqreturn_t dt282x_interrupt(int irq, void *d)
{
        struct comedi_device *dev = d;
        struct comedi_subdevice *s;
        struct comedi_subdevice *s_ao;
        unsigned int supcsr, adcsr, dacsr;
        int handled = 0;

        if (!dev->attached) {
                comedi_error(dev, "spurious interrupt");
                return IRQ_HANDLED;
        }

        s = dev->subdevices + 0;
        s_ao = dev->subdevices + 1;
        adcsr = inw(dev->iobase + DT2821_ADCSR);
        dacsr = inw(dev->iobase + DT2821_DACSR);
        supcsr = inw(dev->iobase + DT2821_SUPCSR);
        if (supcsr & DT2821_DMAD) {
                if (devpriv->dma_dir == DMA_MODE_READ)
                        dt282x_ai_dma_interrupt(dev);
                else
                        dt282x_ao_dma_interrupt(dev);
                handled = 1;
        }
        if (adcsr & DT2821_ADERR) {
                if (devpriv->nread != 0) {
                        comedi_error(dev, "A/D error");
                        dt282x_ai_cancel(dev, s);
                        s->async->events |= COMEDI_CB_ERROR;
                }
                handled = 1;
        }
        if (dacsr & DT2821_DAERR) {
#if 0
                static int warn = 5;
                if (--warn <= 0) {
                        disable_irq(dev->irq);
                        printk("disabling irq\n");
                }
#endif
                comedi_error(dev, "D/A error");
                dt282x_ao_cancel(dev, s_ao);
                s->async->events |= COMEDI_CB_ERROR;
                handled = 1;
        }
#if 0
        if (adcsr & DT2821_ADDONE) {
                int ret;
                short data;

                data = (short)inw(dev->iobase + DT2821_ADDAT);
                data &= (1 << boardtype.adbits) - 1;
                if (devpriv->ad_2scomp) {
                        data ^= 1 << (boardtype.adbits - 1);
                }
                ret = comedi_buf_put(s->async, data);
                if (ret == 0) {
                        s->async->events |= COMEDI_CB_OVERFLOW;
                }

                devpriv->nread--;
                if (!devpriv->nread) {
                        s->async->events |= COMEDI_CB_EOA;
                } else {
                        if (supcsr & DT2821_SCDN)
                                update_supcsr(DT2821_STRIG);
                }
                handled = 1;
        }
#endif
        comedi_event(dev, s);
        /* printk("adcsr=0x%02x dacsr-0x%02x supcsr=0x%02x\n", adcsr, dacsr, supcsr); */
        return IRQ_RETVAL(handled);
}

static void dt282x_load_changain(struct comedi_device *dev, int n,
                                 unsigned int *chanlist)
{
        unsigned int i;
        unsigned int chan, range;

        outw(DT2821_LLE | (n - 1), dev->iobase + DT2821_CHANCSR);
        for (i = 0; i < n; i++) {
                chan = CR_CHAN(chanlist[i]);
                range = CR_RANGE(chanlist[i]);
                update_adcsr((range << 4) | (chan));
        }
        outw(n - 1, dev->iobase + DT2821_CHANCSR);
}

/*
 *    Performs a single A/D conversion.
 *      - Put channel/gain into channel-gain list
 *      - preload multiplexer
 *      - trigger conversion and wait for it to finish
 */
static int dt282x_ai_insn_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn, unsigned int *data)
{
        int i;

        /* XXX should we really be enabling the ad clock here? */
        devpriv->adcsr = DT2821_ADCLK;
        update_adcsr(0);

        dt282x_load_changain(dev, 1, &insn->chanspec);

        update_supcsr(DT2821_PRLD);
        wait_for(!mux_busy(), comedi_error(dev, "timeout\n"); return -ETIME;);

        for (i = 0; i < insn->n; i++) {
                update_supcsr(DT2821_STRIG);
                wait_for(ad_done(), comedi_error(dev, "timeout\n");
                         return -ETIME;);

                data[i] =
                    inw(dev->iobase +
                        DT2821_ADDAT) & ((1 << boardtype.adbits) - 1);
                if (devpriv->ad_2scomp)
                        data[i] ^= (1 << (boardtype.adbits - 1));
        }

        return i;
}

static int dt282x_ai_cmdtest(struct comedi_device *dev,
                             struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
        int err = 0;
        int tmp;

        /* step 1: make sure trigger sources are trivially valid */

        tmp = cmd->start_src;
        cmd->start_src &= TRIG_NOW;
        if (!cmd->start_src || tmp != cmd->start_src)
                err++;

        tmp = cmd->scan_begin_src;
        cmd->scan_begin_src &= TRIG_FOLLOW | TRIG_EXT;
        if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
                err++;

        tmp = cmd->convert_src;
        cmd->convert_src &= TRIG_TIMER;
        if (!cmd->convert_src || tmp != cmd->convert_src)
                err++;

        tmp = cmd->scan_end_src;
        cmd->scan_end_src &= TRIG_COUNT;
        if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
                err++;

        tmp = cmd->stop_src;
        cmd->stop_src &= TRIG_COUNT | TRIG_NONE;
        if (!cmd->stop_src || tmp != cmd->stop_src)
                err++;

        if (err)
                return 1;

        /* step 2: make sure trigger sources are unique and mutually compatible */

        /* note that mutual compatiblity is not an issue here */
        if (cmd->scan_begin_src != TRIG_FOLLOW &&
            cmd->scan_begin_src != TRIG_EXT)
                err++;
        if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
                err++;

        if (err)
                return 2;

        /* step 3: make sure arguments are trivially compatible */

        if (cmd->start_arg != 0) {
                cmd->start_arg = 0;
                err++;
        }
        if (cmd->scan_begin_src == TRIG_FOLLOW) {
                /* internal trigger */
                if (cmd->scan_begin_arg != 0) {
                        cmd->scan_begin_arg = 0;
                        err++;
                }
        } else {
                /* external trigger */
                /* should be level/edge, hi/lo specification here */
                if (cmd->scan_begin_arg != 0) {
                        cmd->scan_begin_arg = 0;
                        err++;
                }
        }
        if (cmd->convert_arg < 4000) {
                /* XXX board dependent */
                cmd->convert_arg = 4000;
                err++;
        }
#define SLOWEST_TIMER   (250*(1<<15)*255)
        if (cmd->convert_arg > SLOWEST_TIMER) {
                cmd->convert_arg = SLOWEST_TIMER;
                err++;
        }
        if (cmd->convert_arg < this_board->ai_speed) {
                cmd->convert_arg = this_board->ai_speed;
                err++;
        }
        if (cmd->scan_end_arg != cmd->chanlist_len) {
                cmd->scan_end_arg = cmd->chanlist_len;
                err++;
        }
        if (cmd->stop_src == TRIG_COUNT) {
                /* any count is allowed */
        } else {
                /* TRIG_NONE */
                if (cmd->stop_arg != 0) {
                        cmd->stop_arg = 0;
                        err++;
                }
        }

        if (err)
                return 3;

        /* step 4: fix up any arguments */

        tmp = cmd->convert_arg;
        dt282x_ns_to_timer(&cmd->convert_arg, cmd->flags & TRIG_ROUND_MASK);
        if (tmp != cmd->convert_arg)
                err++;

        if (err)
                return 4;

        return 0;
}

static int dt282x_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct comedi_cmd *cmd = &s->async->cmd;
        int timer;

        if (devpriv->usedma == 0) {
                comedi_error(dev,
                             "driver requires 2 dma channels to execute command");
                return -EIO;
        }

        dt282x_disable_dma(dev);

        if (cmd->convert_arg < this_board->ai_speed)
                cmd->convert_arg = this_board->ai_speed;
        timer = dt282x_ns_to_timer(&cmd->convert_arg, TRIG_ROUND_NEAREST);
        outw(timer, dev->iobase + DT2821_TMRCTR);

        if (cmd->scan_begin_src == TRIG_FOLLOW) {
                /* internal trigger */
                devpriv->supcsr = DT2821_ERRINTEN | DT2821_DS0;
        } else {
                /* external trigger */
                devpriv->supcsr = DT2821_ERRINTEN | DT2821_DS0 | DT2821_DS1;
        }
        update_supcsr(DT2821_CLRDMADNE | DT2821_BUFFB | DT2821_ADCINIT);

        devpriv->ntrig = cmd->stop_arg * cmd->scan_end_arg;
        devpriv->nread = devpriv->ntrig;

        devpriv->dma_dir = DMA_MODE_READ;
        devpriv->current_dma_index = 0;
        prep_ai_dma(dev, 0, 0);
        if (devpriv->ntrig) {
                prep_ai_dma(dev, 1, 0);
                devpriv->supcsr |= DT2821_DDMA;
                update_supcsr(0);
        }

        devpriv->adcsr = 0;

        dt282x_load_changain(dev, cmd->chanlist_len, cmd->chanlist);

        devpriv->adcsr = DT2821_ADCLK | DT2821_IADDONE;
        update_adcsr(0);

        update_supcsr(DT2821_PRLD);
        wait_for(!mux_busy(), comedi_error(dev, "timeout\n"); return -ETIME;);

        if (cmd->scan_begin_src == TRIG_FOLLOW) {
                update_supcsr(DT2821_STRIG);
        } else {
                devpriv->supcsr |= DT2821_XTRIG;
                update_supcsr(0);
        }

        return 0;
}

static void dt282x_disable_dma(struct comedi_device *dev)
{
        if (devpriv->usedma) {
                disable_dma(devpriv->dma[0].chan);
                disable_dma(devpriv->dma[1].chan);
        }
}

static int dt282x_ai_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        dt282x_disable_dma(dev);

        devpriv->adcsr = 0;
        update_adcsr(0);

        devpriv->supcsr = 0;
        update_supcsr(DT2821_ADCINIT);

        return 0;
}

static int dt282x_ns_to_timer(int *nanosec, int round_mode)
{
        int prescale, base, divider;

        for (prescale = 0; prescale < 16; prescale++) {
                if (prescale == 1)
                        continue;
                base = 250 * (1 << prescale);
                switch (round_mode) {
                case TRIG_ROUND_NEAREST:
                default:
                        divider = (*nanosec + base / 2) / base;
                        break;
                case TRIG_ROUND_DOWN:
                        divider = (*nanosec) / base;
                        break;
                case TRIG_ROUND_UP:
                        divider = (*nanosec + base - 1) / base;
                        break;
                }
                if (divider < 256) {
                        *nanosec = divider * base;
                        return (prescale << 8) | (255 - divider);
                }
        }
        base = 250 * (1 << 15);
        divider = 255;
        *nanosec = divider * base;
        return (15 << 8) | (255 - divider);
}

/*
 *    Analog output routine.  Selects single channel conversion,
 *      selects correct channel, converts from 2's compliment to
 *      offset binary if necessary, loads the data into the DAC
 *      data register, and performs the conversion.
 */
static int dt282x_ao_insn_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn, unsigned int *data)
{
        data[0] = devpriv->ao[CR_CHAN(insn->chanspec)];

        return 1;
}

static int dt282x_ao_insn_write(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn, unsigned int *data)
{
        short d;
        unsigned int chan;

        chan = CR_CHAN(insn->chanspec);
        d = data[0];
        d &= (1 << boardtype.dabits) - 1;
        devpriv->ao[chan] = d;

        devpriv->dacsr |= DT2821_SSEL;

        if (chan) {
                /* select channel */
                devpriv->dacsr |= DT2821_YSEL;
                if (devpriv->da0_2scomp)
                        d ^= (1 << (boardtype.dabits - 1));
        } else {

                devpriv->dacsr &= ~DT2821_YSEL;
                if (devpriv->da1_2scomp)
                        d ^= (1 << (boardtype.dabits - 1));
        }

        update_dacsr(0);

        outw(d, dev->iobase + DT2821_DADAT);

        update_supcsr(DT2821_DACON);

        return 1;
}

static int dt282x_ao_cmdtest(struct comedi_device *dev,
                             struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
        int err = 0;
        int tmp;

        /* step 1: make sure trigger sources are trivially valid */

        tmp = cmd->start_src;
        cmd->start_src &= TRIG_INT;
        if (!cmd->start_src || tmp != cmd->start_src)
                err++;

        tmp = cmd->scan_begin_src;
        cmd->scan_begin_src &= TRIG_TIMER;
        if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
                err++;

        tmp = cmd->convert_src;
        cmd->convert_src &= TRIG_NOW;
        if (!cmd->convert_src || tmp != cmd->convert_src)
                err++;

        tmp = cmd->scan_end_src;
        cmd->scan_end_src &= TRIG_COUNT;
        if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
                err++;

        tmp = cmd->stop_src;
        cmd->stop_src &= TRIG_NONE;
        if (!cmd->stop_src || tmp != cmd->stop_src)
                err++;

        if (err)
                return 1;

        /* step 2: make sure trigger sources are unique and mutually compatible */

        /* note that mutual compatiblity is not an issue here */
        if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
                err++;

        if (err)
                return 2;

        /* step 3: make sure arguments are trivially compatible */

        if (cmd->start_arg != 0) {
                cmd->start_arg = 0;
                err++;
        }
        if (cmd->scan_begin_arg < 5000 /* XXX unknown */ ) {
                cmd->scan_begin_arg = 5000;
                err++;
        }
        if (cmd->convert_arg != 0) {
                cmd->convert_arg = 0;
                err++;
        }
        if (cmd->scan_end_arg > 2) {
                /* XXX chanlist stuff? */
                cmd->scan_end_arg = 2;
                err++;
        }
        if (cmd->stop_src == TRIG_COUNT) {
                /* any count is allowed */
        } else {
                /* TRIG_NONE */
                if (cmd->stop_arg != 0) {
                        cmd->stop_arg = 0;
                        err++;
                }
        }

        if (err)
                return 3;

        /* step 4: fix up any arguments */

        tmp = cmd->scan_begin_arg;
        dt282x_ns_to_timer(&cmd->scan_begin_arg, cmd->flags & TRIG_ROUND_MASK);
        if (tmp != cmd->scan_begin_arg)
                err++;

        if (err)
                return 4;

        return 0;

}

static int dt282x_ao_inttrig(struct comedi_device *dev,
                             struct comedi_subdevice *s, unsigned int x)
{
        int size;

        if (x != 0)
                return -EINVAL;

        size = cfc_read_array_from_buffer(s, devpriv->dma[0].buf,
                                          devpriv->dma_maxsize);
        if (size == 0) {
                printk("dt282x: AO underrun\n");
                return -EPIPE;
        }
        prep_ao_dma(dev, 0, size);

        size = cfc_read_array_from_buffer(s, devpriv->dma[1].buf,
                                          devpriv->dma_maxsize);
        if (size == 0) {
                printk("dt282x: AO underrun\n");
                return -EPIPE;
        }
        prep_ao_dma(dev, 1, size);

        update_supcsr(DT2821_STRIG);
        s->async->inttrig = NULL;

        return 1;
}

static int dt282x_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        int timer;
        struct comedi_cmd *cmd = &s->async->cmd;

        if (devpriv->usedma == 0) {
                comedi_error(dev,
                             "driver requires 2 dma channels to execute command");
                return -EIO;
        }

        dt282x_disable_dma(dev);

        devpriv->supcsr = DT2821_ERRINTEN | DT2821_DS1 | DT2821_DDMA;
        update_supcsr(DT2821_CLRDMADNE | DT2821_BUFFB | DT2821_DACINIT);

        devpriv->ntrig = cmd->stop_arg * cmd->chanlist_len;
        devpriv->nread = devpriv->ntrig;

        devpriv->dma_dir = DMA_MODE_WRITE;
        devpriv->current_dma_index = 0;

        timer = dt282x_ns_to_timer(&cmd->scan_begin_arg, TRIG_ROUND_NEAREST);
        outw(timer, dev->iobase + DT2821_TMRCTR);

        devpriv->dacsr = DT2821_SSEL | DT2821_DACLK | DT2821_IDARDY;
        update_dacsr(0);

        s->async->inttrig = dt282x_ao_inttrig;

        return 0;
}

static int dt282x_ao_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        dt282x_disable_dma(dev);

        devpriv->dacsr = 0;
        update_dacsr(0);

        devpriv->supcsr = 0;
        update_supcsr(DT2821_DACINIT);

        return 0;
}

static int dt282x_dio_insn_bits(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn, unsigned int *data)
{
        if (data[0]) {
                s->state &= ~data[0];
                s->state |= (data[0] & data[1]);

                outw(s->state, dev->iobase + DT2821_DIODAT);
        }
        data[1] = inw(dev->iobase + DT2821_DIODAT);

        return 2;
}

static int dt282x_dio_insn_config(struct comedi_device *dev,
                                  struct comedi_subdevice *s,
                                  struct comedi_insn *insn, unsigned int *data)
{
        int mask;

        mask = (CR_CHAN(insn->chanspec) < 8) ? 0x00ff : 0xff00;
        if (data[0])
                s->io_bits |= mask;
        else
                s->io_bits &= ~mask;

        if (s->io_bits & 0x00ff)
                devpriv->dacsr |= DT2821_LBOE;
        else
                devpriv->dacsr &= ~DT2821_LBOE;
        if (s->io_bits & 0xff00)
                devpriv->dacsr |= DT2821_HBOE;
        else
                devpriv->dacsr &= ~DT2821_HBOE;

        outw(devpriv->dacsr, dev->iobase + DT2821_DACSR);

        return 1;
}

static const struct comedi_lrange *const ai_range_table[] = {
        &range_dt282x_ai_lo_bipolar,
        &range_dt282x_ai_lo_unipolar,
        &range_dt282x_ai_5_bipolar,
        &range_dt282x_ai_5_unipolar
};

static const struct comedi_lrange *const ai_range_pgl_table[] = {
        &range_dt282x_ai_hi_bipolar,
        &range_dt282x_ai_hi_unipolar
};

static const struct comedi_lrange *opt_ai_range_lkup(int ispgl, int x)
{
        if (ispgl) {
                if (x < 0 || x >= 2)
                        x = 0;
                return ai_range_pgl_table[x];
        } else {
                if (x < 0 || x >= 4)
                        x = 0;
                return ai_range_table[x];
        }
}

static const struct comedi_lrange *const ao_range_table[] = {
        &range_bipolar10,
        &range_unipolar10,
        &range_bipolar5,
        &range_unipolar5,
        &range_bipolar2_5
};

static const struct comedi_lrange *opt_ao_range_lkup(int x)
{
        if (x < 0 || x >= 5)
                x = 0;
        return ao_range_table[x];
}

enum { opt_iobase = 0, opt_irq, opt_dma1, opt_dma2,     /* i/o base, irq, dma channels */
        opt_diff,               /* differential */
        opt_ai_twos, opt_ao0_twos, opt_ao1_twos,        /* twos comp */
        opt_ai_range, opt_ao0_range, opt_ao1_range,     /* range */
};

/*
   options:
   0    i/o base
   1    irq
   2    dma1
   3    dma2
   4    0=single ended, 1=differential
   5    ai 0=straight binary, 1=2's comp
   6    ao0 0=straight binary, 1=2's comp
   7    ao1 0=straight binary, 1=2's comp
   8    ai 0=±10 V, 1=0-10 V, 2=±5 V, 3=0-5 V
   9    ao0 0=±10 V, 1=0-10 V, 2=±5 V, 3=0-5 V, 4=±2.5 V
   10   ao1 0=±10 V, 1=0-10 V, 2=±5 V, 3=0-5 V, 4=±2.5 V
 */
static int dt282x_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        int i, irq;
        int ret;
        struct comedi_subdevice *s;
        unsigned long iobase;

        dev->board_name = this_board->name;

        iobase = it->options[opt_iobase];
        if (!iobase)
                iobase = 0x240;

        printk("comedi%d: dt282x: 0x%04lx", dev->minor, iobase);
        if (!request_region(iobase, DT2821_SIZE, "dt282x")) {
                printk(" I/O port conflict\n");
                return -EBUSY;
        }
        dev->iobase = iobase;

        outw(DT2821_BDINIT, dev->iobase + DT2821_SUPCSR);
        i = inw(dev->iobase + DT2821_ADCSR);
#ifdef DEBUG
        printk(" fingerprint=%x,%x,%x,%x,%x",
               inw(dev->iobase + DT2821_ADCSR),
               inw(dev->iobase + DT2821_CHANCSR),
               inw(dev->iobase + DT2821_DACSR),
               inw(dev->iobase + DT2821_SUPCSR),
               inw(dev->iobase + DT2821_TMRCTR));
#endif

        if (((inw(dev->iobase + DT2821_ADCSR) & DT2821_ADCSR_MASK)
             != DT2821_ADCSR_VAL) ||
            ((inw(dev->iobase + DT2821_CHANCSR) & DT2821_CHANCSR_MASK)
             != DT2821_CHANCSR_VAL) ||
            ((inw(dev->iobase + DT2821_DACSR) & DT2821_DACSR_MASK)
             != DT2821_DACSR_VAL) ||
            ((inw(dev->iobase + DT2821_SUPCSR) & DT2821_SUPCSR_MASK)
             != DT2821_SUPCSR_VAL) ||
            ((inw(dev->iobase + DT2821_TMRCTR) & DT2821_TMRCTR_MASK)
             != DT2821_TMRCTR_VAL)) {
                printk(" board not found");
                return -EIO;
        }
        /* should do board test */

        irq = it->options[opt_irq];
#if 0
        if (irq < 0) {
                unsigned long flags;
                int irqs;

                save_flags(flags);
                sti();
                irqs = probe_irq_on();

                /* trigger interrupt */

                udelay(100);

                irq = probe_irq_off(irqs);
                restore_flags(flags);
                if (0 /* error */ ) {
                        printk(" error probing irq (bad)");
                }
        }
#endif
        if (irq > 0) {
                printk(" ( irq = %d )", irq);
                ret = request_irq(irq, dt282x_interrupt, 0, "dt282x", dev);
                if (ret < 0) {
                        printk(" failed to get irq\n");
                        return -EIO;
                }
                dev->irq = irq;
        } else if (irq == 0) {
                printk(" (no irq)");
        } else {
#if 0
                printk(" (probe returned multiple irqs--bad)");
#else
                printk(" (irq probe not implemented)");
#endif
        }

        ret = alloc_private(dev, sizeof(struct dt282x_private));
        if (ret < 0)
                return ret;

        ret = dt282x_grab_dma(dev, it->options[opt_dma1],
                              it->options[opt_dma2]);
        if (ret < 0)
                return ret;

        ret = alloc_subdevices(dev, 3);
        if (ret < 0)
                return ret;

        s = dev->subdevices + 0;

        dev->read_subdev = s;
        /* ai subdevice */
        s->type = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_CMD_READ |
            ((it->options[opt_diff]) ? SDF_DIFF : SDF_COMMON);
        s->n_chan =
            (it->options[opt_diff]) ? boardtype.adchan_di : boardtype.adchan_se;
        s->insn_read = dt282x_ai_insn_read;
        s->do_cmdtest = dt282x_ai_cmdtest;
        s->do_cmd = dt282x_ai_cmd;
        s->cancel = dt282x_ai_cancel;
        s->maxdata = (1 << boardtype.adbits) - 1;
        s->len_chanlist = 16;
        s->range_table =
            opt_ai_range_lkup(boardtype.ispgl, it->options[opt_ai_range]);
        devpriv->ad_2scomp = it->options[opt_ai_twos];

        s++;

        s->n_chan = boardtype.dachan;
        if (s->n_chan) {
                /* ao subsystem */
                s->type = COMEDI_SUBD_AO;
                dev->write_subdev = s;
                s->subdev_flags = SDF_WRITABLE | SDF_CMD_WRITE;
                s->insn_read = dt282x_ao_insn_read;
                s->insn_write = dt282x_ao_insn_write;
                s->do_cmdtest = dt282x_ao_cmdtest;
                s->do_cmd = dt282x_ao_cmd;
                s->cancel = dt282x_ao_cancel;
                s->maxdata = (1 << boardtype.dabits) - 1;
                s->len_chanlist = 2;
                s->range_table_list = devpriv->darangelist;
                devpriv->darangelist[0] =
                    opt_ao_range_lkup(it->options[opt_ao0_range]);
                devpriv->darangelist[1] =
                    opt_ao_range_lkup(it->options[opt_ao1_range]);
                devpriv->da0_2scomp = it->options[opt_ao0_twos];
                devpriv->da1_2scomp = it->options[opt_ao1_twos];
        } else {
                s->type = COMEDI_SUBD_UNUSED;
        }

        s++;
        /* dio subsystem */
        s->type = COMEDI_SUBD_DIO;
        s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
        s->n_chan = 16;
        s->insn_bits = dt282x_dio_insn_bits;
        s->insn_config = dt282x_dio_insn_config;
        s->maxdata = 1;
        s->range_table = &range_digital;

        printk("\n");

        return 0;
}

static void free_resources(struct comedi_device *dev)
{
        if (dev->irq) {
                free_irq(dev->irq, dev);
        }
        if (dev->iobase)
                release_region(dev->iobase, DT2821_SIZE);
        if (dev->private) {
                if (devpriv->dma[0].chan)
                        free_dma(devpriv->dma[0].chan);
                if (devpriv->dma[1].chan)
                        free_dma(devpriv->dma[1].chan);
                if (devpriv->dma[0].buf)
                        free_page((unsigned long)devpriv->dma[0].buf);
                if (devpriv->dma[1].buf)
                        free_page((unsigned long)devpriv->dma[1].buf);
        }
}

static int dt282x_detach(struct comedi_device *dev)
{
        printk("comedi%d: dt282x: remove\n", dev->minor);

        free_resources(dev);

        return 0;
}

static int dt282x_grab_dma(struct comedi_device *dev, int dma1, int dma2)
{
        int ret;

        devpriv->usedma = 0;

        if (!dma1 && !dma2) {
                printk(" (no dma)");
                return 0;
        }

        if (dma1 == dma2 || dma1 < 5 || dma2 < 5 || dma1 > 7 || dma2 > 7)
                return -EINVAL;

        if (dma2 < dma1) {
                int i;
                i = dma1;
                dma1 = dma2;
                dma2 = i;
        }

        ret = request_dma(dma1, "dt282x A");
        if (ret)
                return -EBUSY;
        devpriv->dma[0].chan = dma1;

        ret = request_dma(dma2, "dt282x B");
        if (ret)
                return -EBUSY;
        devpriv->dma[1].chan = dma2;

        devpriv->dma_maxsize = PAGE_SIZE;
        devpriv->dma[0].buf = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
        devpriv->dma[1].buf = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
        if (!devpriv->dma[0].buf || !devpriv->dma[1].buf) {
                printk(" can't get DMA memory");
                return -ENOMEM;
        }

        printk(" (dma=%d,%d)", dma1, dma2);

        devpriv->usedma = 1;

        return 0;
}