// SPDX-License-Identifier: GPL-2.0+
/*
 * dt282x.c
 * Comedi driver for Data Translation DT2821 series
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1997-8 David A. Schleef <ds@schleef.org>
 */

/*
 * 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-g),
 *   DT2821-G-8DI (dt2821-g), DT2823 (dt2823), DT2824-PGH (dt2824-pgh),
 *   DT2824-PGL (dt2824-pgl), DT2825 (dt2825), DT2827 (dt2827),
 *   DT2828 (dt2828), DT2928 (dt2829), 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 (optional, required for async command support)
 *   [2] - DMA 1 (optional, required for async command support)
 *   [3] - DMA 2 (optional, required for async command support)
 *   [4] - AI jumpered for 0=single ended, 1=differential
 *   [5] - AI jumpered for 0=straight binary, 1=2's complement
 *   [6] - AO 0 data format (deprecated, see below)
 *   [7] - AO 1 data format (deprecated, see below)
 *   [8] - AI jumpered for 0=[-10,10]V, 1=[0,10], 2=[-5,5], 3=[0,5]
 *   [9] - AO channel 0 range (deprecated, see below)
 *   [10]- AO channel 1 range (deprecated, see below)
 *
 * 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.
 *   - AO range is not programmable. The AO subdevice has a range_table
 *     containing all the possible analog output ranges. Use the range
 *     that matches your board configuration to convert between data
 *     values and physical units. The format of the data written to the
 *     board is handled automatically based on the unipolar/bipolar
 *     range that is selected.
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/gfp.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/comedi/comedidev.h>
#include <linux/comedi/comedi_isadma.h>

/*
 * Register map
 */
#define DT2821_ADCSR_REG                0x00
#define DT2821_ADCSR_ADERR              BIT(15)
#define DT2821_ADCSR_ADCLK              BIT(9)
#define DT2821_ADCSR_MUXBUSY            BIT(8)
#define DT2821_ADCSR_ADDONE             BIT(7)
#define DT2821_ADCSR_IADDONE            BIT(6)
#define DT2821_ADCSR_GS(x)              (((x) & 0x3) << 4)
#define DT2821_ADCSR_CHAN(x)            (((x) & 0xf) << 0)
#define DT2821_CHANCSR_REG              0x02
#define DT2821_CHANCSR_LLE              BIT(15)
#define DT2821_CHANCSR_TO_PRESLA(x)     (((x) >> 8) & 0xf)
#define DT2821_CHANCSR_NUMB(x)          ((((x) - 1) & 0xf) << 0)
#define DT2821_ADDAT_REG                0x04
#define DT2821_DACSR_REG                0x06
#define DT2821_DACSR_DAERR              BIT(15)
#define DT2821_DACSR_YSEL(x)            ((x) << 9)
#define DT2821_DACSR_SSEL               BIT(8)
#define DT2821_DACSR_DACRDY             BIT(7)
#define DT2821_DACSR_IDARDY             BIT(6)
#define DT2821_DACSR_DACLK              BIT(5)
#define DT2821_DACSR_HBOE               BIT(1)
#define DT2821_DACSR_LBOE               BIT(0)
#define DT2821_DADAT_REG                0x08
#define DT2821_DIODAT_REG               0x0a
#define DT2821_SUPCSR_REG               0x0c
#define DT2821_SUPCSR_DMAD              BIT(15)
#define DT2821_SUPCSR_ERRINTEN          BIT(14)
#define DT2821_SUPCSR_CLRDMADNE         BIT(13)
#define DT2821_SUPCSR_DDMA              BIT(12)
#define DT2821_SUPCSR_DS(x)             (((x) & 0x3) << 10)
#define DT2821_SUPCSR_DS_PIO            DT2821_SUPCSR_DS(0)
#define DT2821_SUPCSR_DS_AD_CLK         DT2821_SUPCSR_DS(1)
#define DT2821_SUPCSR_DS_DA_CLK         DT2821_SUPCSR_DS(2)
#define DT2821_SUPCSR_DS_AD_TRIG        DT2821_SUPCSR_DS(3)
#define DT2821_SUPCSR_BUFFB             BIT(9)
#define DT2821_SUPCSR_SCDN              BIT(8)
#define DT2821_SUPCSR_DACON             BIT(7)
#define DT2821_SUPCSR_ADCINIT           BIT(6)
#define DT2821_SUPCSR_DACINIT           BIT(5)
#define DT2821_SUPCSR_PRLD              BIT(4)
#define DT2821_SUPCSR_STRIG             BIT(3)
#define DT2821_SUPCSR_XTRIG             BIT(2)
#define DT2821_SUPCSR_XCLK              BIT(1)
#define DT2821_SUPCSR_BDINIT            BIT(0)
#define DT2821_TMRCTR_REG               0x0e
#define DT2821_TMRCTR_PRESCALE(x)       (((x) & 0xf) << 8)
#define DT2821_TMRCTR_DIVIDER(x)        ((255 - ((x) & 0xff)) << 0)

/* Pacer Clock */
#define DT2821_OSC_BASE         250     /* 4 MHz (in nanoseconds) */
#define DT2821_PRESCALE(x)      BIT(x)
#define DT2821_PRESCALE_MAX     15
#define DT2821_DIVIDER_MAX      255
#define DT2821_OSC_MAX          (DT2821_OSC_BASE *                      \
                                 DT2821_PRESCALE(DT2821_PRESCALE_MAX) * \
                                 DT2821_DIVIDER_MAX)

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

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

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

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

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

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

/*
 * The Analog Output range is set per-channel using jumpers on the board.
 * All of these ranges may not be available on some DT2821 series boards.
 * The default jumper setting has both channels set for +/-10V output.
 */
static const struct comedi_lrange dt282x_ao_range = {
        5, {
                BIP_RANGE(10),
                BIP_RANGE(5),
                BIP_RANGE(2.5),
                UNI_RANGE(10),
                UNI_RANGE(5),
        }
};

struct dt282x_board {
        const char *name;
        unsigned int ai_maxdata;
        int adchan_se;
        int adchan_di;
        int ai_speed;
        int ispgl;
        int dachan;
        unsigned int ao_maxdata;
};

static const struct dt282x_board boardtypes[] = {
        {
                .name           = "dt2821",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 20000,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt2821-f",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 6500,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt2821-g",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 4000,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt2823",
                .ai_maxdata     = 0xffff,
                .adchan_di      = 4,
                .ai_speed       = 10000,
                .dachan         = 2,
                .ao_maxdata     = 0xffff,
        }, {
                .name           = "dt2824-pgh",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 20000,
        }, {
                .name           = "dt2824-pgl",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 20000,
                .ispgl          = 1,
        }, {
                .name           = "dt2825",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 20000,
                .ispgl          = 1,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt2827",
                .ai_maxdata     = 0xffff,
                .adchan_di      = 4,
                .ai_speed       = 10000,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt2828",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 4,
                .ai_speed       = 10000,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt2829",
                .ai_maxdata     = 0xffff,
                .adchan_se      = 8,
                .ai_speed       = 33250,
                .dachan         = 2,
                .ao_maxdata     = 0xffff,
        }, {
                .name           = "dt21-ez",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 10000,
                .dachan         = 2,
                .ao_maxdata     = 0x0fff,
        }, {
                .name           = "dt23-ez",
                .ai_maxdata     = 0xffff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 10000,
        }, {
                .name           = "dt24-ez",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 10000,
        }, {
                .name           = "dt24-ez-pgl",
                .ai_maxdata     = 0x0fff,
                .adchan_se      = 16,
                .adchan_di      = 8,
                .ai_speed       = 10000,
                .ispgl          = 1,
        },
};

struct dt282x_private {
        struct comedi_isadma *dma;
        unsigned int ad_2scomp:1;
        unsigned int divisor;
        int dacsr;      /* software copies of registers */
        int adcsr;
        int supcsr;
        int ntrig;
        int nread;
        int dma_dir;
};

static int dt282x_prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc = &dma->desc[dma_index];

        if (!devpriv->ntrig)
                return 0;

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

        desc->size = n;
        comedi_isadma_set_mode(desc, devpriv->dma_dir);

        comedi_isadma_program(desc);

        return n;
}

static int dt282x_prep_ao_dma(struct comedi_device *dev, int dma_index, int n)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc = &dma->desc[dma_index];

        desc->size = n;
        comedi_isadma_set_mode(desc, devpriv->dma_dir);

        comedi_isadma_program(desc);

        return n;
}

static void dt282x_disable_dma(struct comedi_device *dev)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc;
        int i;

        for (i = 0; i < 2; i++) {
                desc = &dma->desc[i];
                comedi_isadma_disable(desc->chan);
        }
}

static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags)
{
        unsigned int prescale, base, divider;

        for (prescale = 0; prescale <= DT2821_PRESCALE_MAX; prescale++) {
                if (prescale == 1)      /* 0 and 1 are both divide by 1 */
                        continue;
                base = DT2821_OSC_BASE * DT2821_PRESCALE(prescale);
                switch (flags & CMDF_ROUND_MASK) {
                case CMDF_ROUND_NEAREST:
                default:
                        divider = DIV_ROUND_CLOSEST(*ns, base);
                        break;
                case CMDF_ROUND_DOWN:
                        divider = (*ns) / base;
                        break;
                case CMDF_ROUND_UP:
                        divider = DIV_ROUND_UP(*ns, base);
                        break;
                }
                if (divider <= DT2821_DIVIDER_MAX)
                        break;
        }
        if (divider > DT2821_DIVIDER_MAX) {
                prescale = DT2821_PRESCALE_MAX;
                divider = DT2821_DIVIDER_MAX;
                base = DT2821_OSC_BASE * DT2821_PRESCALE(prescale);
        }
        *ns = divider * base;
        return DT2821_TMRCTR_PRESCALE(prescale) |
               DT2821_TMRCTR_DIVIDER(divider);
}

static void dt282x_munge(struct comedi_device *dev,
                         struct comedi_subdevice *s,
                         unsigned short *buf,
                         unsigned int nbytes)
{
        struct dt282x_private *devpriv = dev->private;
        unsigned int val;
        int i;

        if (nbytes % 2)
                dev_err(dev->class_dev,
                        "bug! odd number of bytes from dma xfer\n");

        for (i = 0; i < nbytes / 2; i++) {
                val = buf[i];
                val &= s->maxdata;
                if (devpriv->ad_2scomp)
                        val = comedi_offset_munge(s, val);

                buf[i] = val;
        }
}

static unsigned int dt282x_ao_setup_dma(struct comedi_device *dev,
                                        struct comedi_subdevice *s,
                                        int cur_dma)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc = &dma->desc[cur_dma];
        unsigned int nsamples = comedi_bytes_to_samples(s, desc->maxsize);
        unsigned int nbytes;

        nbytes = comedi_buf_read_samples(s, desc->virt_addr, nsamples);
        if (nbytes)
                dt282x_prep_ao_dma(dev, cur_dma, nbytes);
        else
                dev_err(dev->class_dev, "AO underrun\n");

        return nbytes;
}

static void dt282x_ao_dma_interrupt(struct comedi_device *dev,
                                    struct comedi_subdevice *s)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];

        outw(devpriv->supcsr | DT2821_SUPCSR_CLRDMADNE,
             dev->iobase + DT2821_SUPCSR_REG);

        comedi_isadma_disable(desc->chan);

        if (!dt282x_ao_setup_dma(dev, s, dma->cur_dma))
                s->async->events |= COMEDI_CB_OVERFLOW;

        dma->cur_dma = 1 - dma->cur_dma;
}

static void dt282x_ai_dma_interrupt(struct comedi_device *dev,
                                    struct comedi_subdevice *s)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
        unsigned int nsamples = comedi_bytes_to_samples(s, desc->size);
        int ret;

        outw(devpriv->supcsr | DT2821_SUPCSR_CLRDMADNE,
             dev->iobase + DT2821_SUPCSR_REG);

        comedi_isadma_disable(desc->chan);

        dt282x_munge(dev, s, desc->virt_addr, desc->size);
        ret = comedi_buf_write_samples(s, desc->virt_addr, nsamples);
        if (ret != desc->size)
                return;

        devpriv->nread -= nsamples;
        if (devpriv->nread < 0) {
                dev_info(dev->class_dev, "nread off by one\n");
                devpriv->nread = 0;
        }
        if (!devpriv->nread) {
                s->async->events |= COMEDI_CB_EOA;
                return;
        }

        /* restart the channel */
        dt282x_prep_ai_dma(dev, dma->cur_dma, 0);

        dma->cur_dma = 1 - dma->cur_dma;
}

static irqreturn_t dt282x_interrupt(int irq, void *d)
{
        struct comedi_device *dev = d;
        struct dt282x_private *devpriv = dev->private;
        struct comedi_subdevice *s = dev->read_subdev;
        struct comedi_subdevice *s_ao = dev->write_subdev;
        unsigned int supcsr, adcsr, dacsr;
        int handled = 0;

        if (!dev->attached) {
                dev_err(dev->class_dev, "spurious interrupt\n");
                return IRQ_HANDLED;
        }

        adcsr = inw(dev->iobase + DT2821_ADCSR_REG);
        dacsr = inw(dev->iobase + DT2821_DACSR_REG);
        supcsr = inw(dev->iobase + DT2821_SUPCSR_REG);
        if (supcsr & DT2821_SUPCSR_DMAD) {
                if (devpriv->dma_dir == COMEDI_ISADMA_READ)
                        dt282x_ai_dma_interrupt(dev, s);
                else
                        dt282x_ao_dma_interrupt(dev, s_ao);
                handled = 1;
        }
        if (adcsr & DT2821_ADCSR_ADERR) {
                if (devpriv->nread != 0) {
                        dev_err(dev->class_dev, "A/D error\n");
                        s->async->events |= COMEDI_CB_ERROR;
                }
                handled = 1;
        }
        if (dacsr & DT2821_DACSR_DAERR) {
                dev_err(dev->class_dev, "D/A error\n");
                s_ao->async->events |= COMEDI_CB_ERROR;
                handled = 1;
        }

        comedi_handle_events(dev, s);
        if (s_ao)
                comedi_handle_events(dev, s_ao);

        return IRQ_RETVAL(handled);
}

static void dt282x_load_changain(struct comedi_device *dev, int n,
                                 unsigned int *chanlist)
{
        struct dt282x_private *devpriv = dev->private;
        int i;

        outw(DT2821_CHANCSR_LLE | DT2821_CHANCSR_NUMB(n),
             dev->iobase + DT2821_CHANCSR_REG);
        for (i = 0; i < n; i++) {
                unsigned int chan = CR_CHAN(chanlist[i]);
                unsigned int range = CR_RANGE(chanlist[i]);

                outw(devpriv->adcsr |
                     DT2821_ADCSR_GS(range) |
                     DT2821_ADCSR_CHAN(chan),
                     dev->iobase + DT2821_ADCSR_REG);
        }
        outw(DT2821_CHANCSR_NUMB(n), dev->iobase + DT2821_CHANCSR_REG);
}

static int dt282x_ai_timeout(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_insn *insn,
                             unsigned long context)
{
        unsigned int status;

        status = inw(dev->iobase + DT2821_ADCSR_REG);
        switch (context) {
        case DT2821_ADCSR_MUXBUSY:
                if ((status & DT2821_ADCSR_MUXBUSY) == 0)
                        return 0;
                break;
        case DT2821_ADCSR_ADDONE:
                if (status & DT2821_ADCSR_ADDONE)
                        return 0;
                break;
        default:
                return -EINVAL;
        }
        return -EBUSY;
}

/*
 *    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)
{
        struct dt282x_private *devpriv = dev->private;
        unsigned int val;
        int ret;
        int i;

        /* XXX should we really be enabling the ad clock here? */
        devpriv->adcsr = DT2821_ADCSR_ADCLK;
        outw(devpriv->adcsr, dev->iobase + DT2821_ADCSR_REG);

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

        outw(devpriv->supcsr | DT2821_SUPCSR_PRLD,
             dev->iobase + DT2821_SUPCSR_REG);
        ret = comedi_timeout(dev, s, insn,
                             dt282x_ai_timeout, DT2821_ADCSR_MUXBUSY);
        if (ret)
                return ret;

        for (i = 0; i < insn->n; i++) {
                outw(devpriv->supcsr | DT2821_SUPCSR_STRIG,
                     dev->iobase + DT2821_SUPCSR_REG);

                ret = comedi_timeout(dev, s, insn,
                                     dt282x_ai_timeout, DT2821_ADCSR_ADDONE);
                if (ret)
                        return ret;

                val = inw(dev->iobase + DT2821_ADDAT_REG);
                val &= s->maxdata;
                if (devpriv->ad_2scomp)
                        val = comedi_offset_munge(s, val);

                data[i] = val;
        }

        return i;
}

static int dt282x_ai_cmdtest(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_cmd *cmd)
{
        const struct dt282x_board *board = dev->board_ptr;
        struct dt282x_private *devpriv = dev->private;
        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_FOLLOW | TRIG_EXT);
        err |= comedi_check_trigger_src(&cmd->convert_src, TRIG_TIMER);
        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->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);
        err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
        err |= comedi_check_trigger_arg_max(&cmd->convert_arg, DT2821_OSC_MAX);
        err |= comedi_check_trigger_arg_min(&cmd->convert_arg, board->ai_speed);
        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_EXT | TRIG_NONE */
                err |= comedi_check_trigger_arg_is(&cmd->stop_arg, 0);

        if (err)
                return 3;

        /* step 4: fix up any arguments */

        arg = cmd->convert_arg;
        devpriv->divisor = dt282x_ns_to_timer(&arg, cmd->flags);
        err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);

        if (err)
                return 4;

        return 0;
}

static int dt282x_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_cmd *cmd = &s->async->cmd;
        int ret;

        dt282x_disable_dma(dev);

        outw(devpriv->divisor, dev->iobase + DT2821_TMRCTR_REG);

        devpriv->supcsr = DT2821_SUPCSR_ERRINTEN;
        if (cmd->scan_begin_src == TRIG_FOLLOW)
                devpriv->supcsr = DT2821_SUPCSR_DS_AD_CLK;
        else
                devpriv->supcsr = DT2821_SUPCSR_DS_AD_TRIG;
        outw(devpriv->supcsr |
             DT2821_SUPCSR_CLRDMADNE |
             DT2821_SUPCSR_BUFFB |
             DT2821_SUPCSR_ADCINIT,
             dev->iobase + DT2821_SUPCSR_REG);

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

        devpriv->dma_dir = COMEDI_ISADMA_READ;
        dma->cur_dma = 0;
        dt282x_prep_ai_dma(dev, 0, 0);
        if (devpriv->ntrig) {
                dt282x_prep_ai_dma(dev, 1, 0);
                devpriv->supcsr |= DT2821_SUPCSR_DDMA;
                outw(devpriv->supcsr, dev->iobase + DT2821_SUPCSR_REG);
        }

        devpriv->adcsr = 0;

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

        devpriv->adcsr = DT2821_ADCSR_ADCLK | DT2821_ADCSR_IADDONE;
        outw(devpriv->adcsr, dev->iobase + DT2821_ADCSR_REG);

        outw(devpriv->supcsr | DT2821_SUPCSR_PRLD,
             dev->iobase + DT2821_SUPCSR_REG);
        ret = comedi_timeout(dev, s, NULL,
                             dt282x_ai_timeout, DT2821_ADCSR_MUXBUSY);
        if (ret)
                return ret;

        if (cmd->scan_begin_src == TRIG_FOLLOW) {
                outw(devpriv->supcsr | DT2821_SUPCSR_STRIG,
                     dev->iobase + DT2821_SUPCSR_REG);
        } else {
                devpriv->supcsr |= DT2821_SUPCSR_XTRIG;
                outw(devpriv->supcsr, dev->iobase + DT2821_SUPCSR_REG);
        }

        return 0;
}

static int dt282x_ai_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        struct dt282x_private *devpriv = dev->private;

        dt282x_disable_dma(dev);

        devpriv->adcsr = 0;
        outw(devpriv->adcsr, dev->iobase + DT2821_ADCSR_REG);

        devpriv->supcsr = 0;
        outw(devpriv->supcsr | DT2821_SUPCSR_ADCINIT,
             dev->iobase + DT2821_SUPCSR_REG);

        return 0;
}

static int dt282x_ao_insn_write(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
{
        struct dt282x_private *devpriv = dev->private;
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int range = CR_RANGE(insn->chanspec);
        int i;

        devpriv->dacsr |= DT2821_DACSR_SSEL | DT2821_DACSR_YSEL(chan);

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

                s->readback[chan] = val;

                if (comedi_range_is_bipolar(s, range))
                        val = comedi_offset_munge(s, val);

                outw(devpriv->dacsr, dev->iobase + DT2821_DACSR_REG);

                outw(val, dev->iobase + DT2821_DADAT_REG);

                outw(devpriv->supcsr | DT2821_SUPCSR_DACON,
                     dev->iobase + DT2821_SUPCSR_REG);
        }

        return insn->n;
}

static int dt282x_ao_cmdtest(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_cmd *cmd)
{
        struct dt282x_private *devpriv = dev->private;
        int err = 0;
        unsigned int arg;

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

        err |= comedi_check_trigger_src(&cmd->start_src, TRIG_INT);
        err |= comedi_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
        err |= comedi_check_trigger_src(&cmd->convert_src, TRIG_NOW);
        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->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);
        err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg, 5000);
        err |= comedi_check_trigger_arg_is(&cmd->convert_arg, 0);
        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_EXT | TRIG_NONE */
                err |= comedi_check_trigger_arg_is(&cmd->stop_arg, 0);

        if (err)
                return 3;

        /* step 4: fix up any arguments */

        arg = cmd->scan_begin_arg;
        devpriv->divisor = dt282x_ns_to_timer(&arg, cmd->flags);
        err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);

        if (err)
                return 4;

        return 0;
}

static int dt282x_ao_inttrig(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             unsigned int trig_num)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_cmd *cmd = &s->async->cmd;

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

        if (!dt282x_ao_setup_dma(dev, s, 0))
                return -EPIPE;

        if (!dt282x_ao_setup_dma(dev, s, 1))
                return -EPIPE;

        outw(devpriv->supcsr | DT2821_SUPCSR_STRIG,
             dev->iobase + DT2821_SUPCSR_REG);
        s->async->inttrig = NULL;

        return 1;
}

static int dt282x_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct dt282x_private *devpriv = dev->private;
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_cmd *cmd = &s->async->cmd;

        dt282x_disable_dma(dev);

        devpriv->supcsr = DT2821_SUPCSR_ERRINTEN |
                          DT2821_SUPCSR_DS_DA_CLK |
                          DT2821_SUPCSR_DDMA;
        outw(devpriv->supcsr |
             DT2821_SUPCSR_CLRDMADNE |
             DT2821_SUPCSR_BUFFB |
             DT2821_SUPCSR_DACINIT,
             dev->iobase + DT2821_SUPCSR_REG);

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

        devpriv->dma_dir = COMEDI_ISADMA_WRITE;
        dma->cur_dma = 0;

        outw(devpriv->divisor, dev->iobase + DT2821_TMRCTR_REG);

        /* clear all bits but the DIO direction bits */
        devpriv->dacsr &= (DT2821_DACSR_LBOE | DT2821_DACSR_HBOE);

        devpriv->dacsr |= (DT2821_DACSR_SSEL |
                           DT2821_DACSR_DACLK |
                           DT2821_DACSR_IDARDY);
        outw(devpriv->dacsr, dev->iobase + DT2821_DACSR_REG);

        s->async->inttrig = dt282x_ao_inttrig;

        return 0;
}

static int dt282x_ao_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        struct dt282x_private *devpriv = dev->private;

        dt282x_disable_dma(dev);

        /* clear all bits but the DIO direction bits */
        devpriv->dacsr &= (DT2821_DACSR_LBOE | DT2821_DACSR_HBOE);

        outw(devpriv->dacsr, dev->iobase + DT2821_DACSR_REG);

        devpriv->supcsr = 0;
        outw(devpriv->supcsr | DT2821_SUPCSR_DACINIT,
             dev->iobase + DT2821_SUPCSR_REG);

        return 0;
}

static int dt282x_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))
                outw(s->state, dev->iobase + DT2821_DIODAT_REG);

        data[1] = inw(dev->iobase + DT2821_DIODAT_REG);

        return insn->n;
}

static int dt282x_dio_insn_config(struct comedi_device *dev,
                                  struct comedi_subdevice *s,
                                  struct comedi_insn *insn,
                                  unsigned int *data)
{
        struct dt282x_private *devpriv = dev->private;
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int mask;
        int ret;

        if (chan < 8)
                mask = 0x00ff;
        else
                mask = 0xff00;

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

        devpriv->dacsr &= ~(DT2821_DACSR_LBOE | DT2821_DACSR_HBOE);
        if (s->io_bits & 0x00ff)
                devpriv->dacsr |= DT2821_DACSR_LBOE;
        if (s->io_bits & 0xff00)
                devpriv->dacsr |= DT2821_DACSR_HBOE;

        outw(devpriv->dacsr, dev->iobase + DT2821_DACSR_REG);

        return insn->n;
}

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];
        }

        if (x < 0 || x >= 4)
                x = 0;
        return ai_range_table[x];
}

static void dt282x_alloc_dma(struct comedi_device *dev,
                             struct comedi_devconfig *it)
{
        struct dt282x_private *devpriv = dev->private;
        unsigned int irq_num = it->options[1];
        unsigned int dma_chan[2];

        if (it->options[2] < it->options[3]) {
                dma_chan[0] = it->options[2];
                dma_chan[1] = it->options[3];
        } else {
                dma_chan[0] = it->options[3];
                dma_chan[1] = it->options[2];
        }

        if (!irq_num || dma_chan[0] == dma_chan[1] ||
            dma_chan[0] < 5 || dma_chan[0] > 7 ||
            dma_chan[1] < 5 || dma_chan[1] > 7)
                return;

        if (request_irq(irq_num, dt282x_interrupt, 0, dev->board_name, dev))
                return;

        /* DMA uses two 4K buffers with separate DMA channels */
        devpriv->dma = comedi_isadma_alloc(dev, 2, dma_chan[0], dma_chan[1],
                                           PAGE_SIZE, 0);
        if (!devpriv->dma)
                free_irq(irq_num, dev);
        else
                dev->irq = irq_num;
}

static void dt282x_free_dma(struct comedi_device *dev)
{
        struct dt282x_private *devpriv = dev->private;

        if (devpriv)
                comedi_isadma_free(devpriv->dma);
}

static int dt282x_initialize(struct comedi_device *dev)
{
        /* Initialize board */
        outw(DT2821_SUPCSR_BDINIT, dev->iobase + DT2821_SUPCSR_REG);
        inw(dev->iobase + DT2821_ADCSR_REG);

        /*
         * At power up, some registers are in a well-known state.
         * Check them to see if a DT2821 series board is present.
         */
        if (((inw(dev->iobase + DT2821_ADCSR_REG) & 0xfff0) != 0x7c00) ||
            ((inw(dev->iobase + DT2821_CHANCSR_REG) & 0xf0f0) != 0x70f0) ||
            ((inw(dev->iobase + DT2821_DACSR_REG) & 0x7c93) != 0x7c90) ||
            ((inw(dev->iobase + DT2821_SUPCSR_REG) & 0xf8ff) != 0x0000) ||
            ((inw(dev->iobase + DT2821_TMRCTR_REG) & 0xff00) != 0xf000)) {
                dev_err(dev->class_dev, "board not found\n");
                return -EIO;
        }
        return 0;
}

static int dt282x_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        const struct dt282x_board *board = dev->board_ptr;
        struct dt282x_private *devpriv;
        struct comedi_subdevice *s;
        int ret;

        ret = comedi_request_region(dev, it->options[0], 0x10);
        if (ret)
                return ret;

        ret = dt282x_initialize(dev);
        if (ret)
                return ret;

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

        /* an IRQ and 2 DMA channels are required for async command support */
        dt282x_alloc_dma(dev, it);

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

        /* Analog Input subdevice */
        s = &dev->subdevices[0];
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE;
        if ((it->options[4] && board->adchan_di) || board->adchan_se == 0) {
                s->subdev_flags |= SDF_DIFF;
                s->n_chan       = board->adchan_di;
        } else {
                s->subdev_flags |= SDF_COMMON;
                s->n_chan       = board->adchan_se;
        }
        s->maxdata      = board->ai_maxdata;

        s->range_table = opt_ai_range_lkup(board->ispgl, it->options[8]);
        devpriv->ad_2scomp = it->options[5] ? 1 : 0;

        s->insn_read    = dt282x_ai_insn_read;
        if (dev->irq) {
                dev->read_subdev = s;
                s->subdev_flags |= SDF_CMD_READ;
                s->len_chanlist = s->n_chan;
                s->do_cmdtest   = dt282x_ai_cmdtest;
                s->do_cmd       = dt282x_ai_cmd;
                s->cancel       = dt282x_ai_cancel;
        }

        /* Analog Output subdevice */
        s = &dev->subdevices[1];
        if (board->dachan) {
                s->type         = COMEDI_SUBD_AO;
                s->subdev_flags = SDF_WRITABLE;
                s->n_chan       = board->dachan;
                s->maxdata      = board->ao_maxdata;
                /* ranges are per-channel, set by jumpers on the board */
                s->range_table  = &dt282x_ao_range;
                s->insn_write   = dt282x_ao_insn_write;
                if (dev->irq) {
                        dev->write_subdev = s;
                        s->subdev_flags |= SDF_CMD_WRITE;
                        s->len_chanlist = s->n_chan;
                        s->do_cmdtest   = dt282x_ao_cmdtest;
                        s->do_cmd       = dt282x_ao_cmd;
                        s->cancel       = dt282x_ao_cancel;
                }

                ret = comedi_alloc_subdev_readback(s);
                if (ret)
                        return ret;
        } else {
                s->type         = COMEDI_SUBD_UNUSED;
        }

        /* Digital I/O subdevice */
        s = &dev->subdevices[2];
        s->type         = COMEDI_SUBD_DIO;
        s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
        s->n_chan       = 16;
        s->maxdata      = 1;
        s->range_table  = &range_digital;
        s->insn_bits    = dt282x_dio_insn_bits;
        s->insn_config  = dt282x_dio_insn_config;

        return 0;
}

static void dt282x_detach(struct comedi_device *dev)
{
        dt282x_free_dma(dev);
        comedi_legacy_detach(dev);
}

static struct comedi_driver dt282x_driver = {
        .driver_name    = "dt282x",
        .module         = THIS_MODULE,
        .attach         = dt282x_attach,
        .detach         = dt282x_detach,
        .board_name     = &boardtypes[0].name,
        .num_names      = ARRAY_SIZE(boardtypes),
        .offset         = sizeof(struct dt282x_board),
};
module_comedi_driver(dt282x_driver);

MODULE_AUTHOR("Comedi https://www.comedi.org");
MODULE_DESCRIPTION("Comedi driver for Data Translation DT2821 series");
MODULE_LICENSE("GPL");