// SPDX-License-Identifier: GPL-2.0+
/*
 * comedi/drivers/dt2814.c
 * Hardware driver for Data Translation DT2814
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
 */
/*
 * Driver: dt2814
 * Description: Data Translation DT2814
 * Author: ds
 * Status: complete
 * Devices: [Data Translation] DT2814 (dt2814)
 *
 * Configuration options:
 * [0] - I/O port base address
 * [1] - IRQ
 *
 * This card has 16 analog inputs multiplexed onto a 12 bit ADC.  There
 * is a minimally useful onboard clock.  The base frequency for the
 * clock is selected by jumpers, and the clock divider can be selected
 * via programmed I/O.  Unfortunately, the clock divider can only be
 * a power of 10, from 1 to 10^7, of which only 3 or 4 are useful.  In
 * addition, the clock does not seem to be very accurate.
 */

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

#define DT2814_CSR 0
#define DT2814_DATA 1

/*
 * flags
 */

#define DT2814_FINISH 0x80
#define DT2814_ERR 0x40
#define DT2814_BUSY 0x20
#define DT2814_ENB 0x10
#define DT2814_CHANMASK 0x0f

#define DT2814_TIMEOUT 10
#define DT2814_MAX_SPEED 100000 /* Arbitrary 10 khz limit */

static int dt2814_ai_notbusy(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_insn *insn,
                             unsigned long context)
{
        unsigned int status;

        status = inb(dev->iobase + DT2814_CSR);
        if (context)
                *(unsigned int *)context = status;
        if (status & DT2814_BUSY)
                return -EBUSY;
        return 0;
}

static int dt2814_ai_clear(struct comedi_device *dev)
{
        unsigned int status = 0;
        int ret;

        /* Wait until not busy and get status register value. */
        ret = comedi_timeout(dev, NULL, NULL, dt2814_ai_notbusy,
                             (unsigned long)&status);
        if (ret)
                return ret;

        if (status & (DT2814_FINISH | DT2814_ERR)) {
                /*
                 * There unread data, or the error flag is set.
                 * Read the data register twice to clear the condition.
                 */
                inb(dev->iobase + DT2814_DATA);
                inb(dev->iobase + DT2814_DATA);
        }
        return 0;
}

static int dt2814_ai_eoc(struct comedi_device *dev,
                         struct comedi_subdevice *s,
                         struct comedi_insn *insn,
                         unsigned long context)
{
        unsigned int status;

        status = inb(dev->iobase + DT2814_CSR);
        if (status & DT2814_FINISH)
                return 0;
        return -EBUSY;
}

static int dt2814_ai_insn_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn, unsigned int *data)
{
        int n, hi, lo;
        int chan;
        int ret;

        dt2814_ai_clear(dev);   /* clear stale data or error */
        for (n = 0; n < insn->n; n++) {
                chan = CR_CHAN(insn->chanspec);

                outb(chan, dev->iobase + DT2814_CSR);

                ret = comedi_timeout(dev, s, insn, dt2814_ai_eoc, 0);
                if (ret)
                        return ret;

                hi = inb(dev->iobase + DT2814_DATA);
                lo = inb(dev->iobase + DT2814_DATA);

                data[n] = (hi << 4) | (lo >> 4);
        }

        return n;
}

static int dt2814_ns_to_timer(unsigned int *ns, unsigned int flags)
{
        int i;
        unsigned int f;

        /* XXX ignores flags */

        f = 10000;              /* ns */
        for (i = 0; i < 8; i++) {
                if ((2 * (*ns)) < (f * 11))
                        break;
                f *= 10;
        }

        *ns = f;

        return i;
}

static int dt2814_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);
        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_max(&cmd->scan_begin_arg, 1000000000);
        err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
                                            DT2814_MAX_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, 2);
        else    /* 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;
        dt2814_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 dt2814_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct comedi_cmd *cmd = &s->async->cmd;
        int chan;
        int trigvar;

        dt2814_ai_clear(dev);   /* clear stale data or error */
        trigvar = dt2814_ns_to_timer(&cmd->scan_begin_arg, cmd->flags);

        chan = CR_CHAN(cmd->chanlist[0]);

        outb(chan | DT2814_ENB | (trigvar << 5), dev->iobase + DT2814_CSR);

        return 0;
}

static int dt2814_ai_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
{
        unsigned int status;
        unsigned long flags;

        spin_lock_irqsave(&dev->spinlock, flags);
        status = inb(dev->iobase + DT2814_CSR);
        if (status & DT2814_ENB) {
                /*
                 * Clear the timed trigger enable bit.
                 *
                 * Note: turning off timed mode triggers another
                 * sample.  This will be mopped up by the calls to
                 * dt2814_ai_clear().
                 */
                outb(status & DT2814_CHANMASK, dev->iobase + DT2814_CSR);
        }
        spin_unlock_irqrestore(&dev->spinlock, flags);
        return 0;
}

static irqreturn_t dt2814_interrupt(int irq, void *d)
{
        struct comedi_device *dev = d;
        struct comedi_subdevice *s = dev->read_subdev;
        struct comedi_async *async;
        unsigned int lo, hi;
        unsigned short data;
        unsigned int status;

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

        async = s->async;

        spin_lock(&dev->spinlock);

        status = inb(dev->iobase + DT2814_CSR);
        if (!(status & DT2814_ENB)) {
                /* Timed acquisition not enabled.  Nothing to do. */
                spin_unlock(&dev->spinlock);
                return IRQ_HANDLED;
        }

        if (!(status & (DT2814_FINISH | DT2814_ERR))) {
                /* Spurious interrupt? */
                spin_unlock(&dev->spinlock);
                return IRQ_HANDLED;
        }

        /* Read data or clear error. */
        hi = inb(dev->iobase + DT2814_DATA);
        lo = inb(dev->iobase + DT2814_DATA);

        data = (hi << 4) | (lo >> 4);

        if (status & DT2814_ERR) {
                async->events |= COMEDI_CB_ERROR;
        } else {
                comedi_buf_write_samples(s, &data, 1);
                if (async->cmd.stop_src == TRIG_COUNT &&
                    async->scans_done >=  async->cmd.stop_arg) {
                        async->events |= COMEDI_CB_EOA;
                }
        }
        if (async->events & COMEDI_CB_CANCEL_MASK) {
                /*
                 * Disable timed mode.
                 *
                 * Note: turning off timed mode triggers another
                 * sample.  This will be mopped up by the calls to
                 * dt2814_ai_clear().
                 */
                outb(status & DT2814_CHANMASK, dev->iobase + DT2814_CSR);
        }

        spin_unlock(&dev->spinlock);

        comedi_handle_events(dev, s);
        return IRQ_HANDLED;
}

static int dt2814_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        struct comedi_subdevice *s;
        int ret;

        ret = comedi_request_region(dev, it->options[0], 0x2);
        if (ret)
                return ret;

        outb(0, dev->iobase + DT2814_CSR);
        if (dt2814_ai_clear(dev)) {
                dev_err(dev->class_dev, "reset error (fatal)\n");
                return -EIO;
        }

        if (it->options[1]) {
                ret = request_irq(it->options[1], dt2814_interrupt, 0,
                                  dev->board_name, dev);
                if (ret == 0)
                        dev->irq = it->options[1];
        }

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

        s = &dev->subdevices[0];
        s->type = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_GROUND;
        s->n_chan = 16;         /* XXX */
        s->insn_read = dt2814_ai_insn_read;
        s->maxdata = 0xfff;
        s->range_table = &range_unknown;        /* XXX */
        if (dev->irq) {
                dev->read_subdev = s;
                s->subdev_flags |= SDF_CMD_READ;
                s->len_chanlist = 1;
                s->do_cmd = dt2814_ai_cmd;
                s->do_cmdtest = dt2814_ai_cmdtest;
                s->cancel = dt2814_ai_cancel;
        }

        return 0;
}

static void dt2814_detach(struct comedi_device *dev)
{
        if (dev->irq) {
                /*
                 * An extra conversion triggered on termination of an
                 * asynchronous command may still be in progress.  Wait for
                 * it to finish and clear the data or error status.
                 */
                dt2814_ai_clear(dev);
        }
        comedi_legacy_detach(dev);
}

static struct comedi_driver dt2814_driver = {
        .driver_name    = "dt2814",
        .module         = THIS_MODULE,
        .attach         = dt2814_attach,
        .detach         = dt2814_detach,
};
module_comedi_driver(dt2814_driver);

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