// SPDX-License-Identifier: GPL-2.0+
/*
 * Comedi driver for CIO-DAS16/M1
 * Author: Frank Mori Hess, based on code from the das16 driver.
 * Copyright (C) 2001 Frank Mori Hess <fmhess@users.sourceforge.net>
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 2000 David A. Schleef <ds@schleef.org>
 */

/*
 * Driver: das16m1
 * Description: CIO-DAS16/M1
 * Author: Frank Mori Hess <fmhess@users.sourceforge.net>
 * Devices: [Measurement Computing] CIO-DAS16/M1 (das16m1)
 * Status: works
 *
 * This driver supports a single board - the CIO-DAS16/M1. As far as I know,
 * there are no other boards that have the same register layout. Even the
 * CIO-DAS16/M1/16 is significantly different.
 *
 * I was _barely_ able to reach the full 1 MHz capability of this board, using
 * a hard real-time interrupt (set the TRIG_RT flag in your struct comedi_cmd
 * and use rtlinux or RTAI). The board can't do dma, so the bottleneck is
 * pulling the data across the ISA bus. I timed the interrupt handler, and it
 * took my computer ~470 microseconds to pull 512 samples from the board. So
 * at 1 Mhz sampling rate, expect your CPU to be spending almost all of its
 * time in the interrupt handler.
 *
 * This board has some unusual restrictions for its channel/gain list.  If the
 * list has 2 or more channels in it, then two conditions must be satisfied:
 * (1) - even/odd channels must appear at even/odd indices in the list
 * (2) - the list must have an even number of entries.
 *
 * Configuration options:
 *   [0] - base io address
 *   [1] - irq (optional, but you probably want it)
 *
 * irq can be omitted, although the cmd interface will not work without it.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include "../comedidev.h"

#include "8255.h"
#include "comedi_8254.h"

/*
 * Register map (dev->iobase)
 */
#define DAS16M1_AI_REG                  0x00    /* 16-bit register */
#define DAS16M1_AI_TO_CHAN(x)           (((x) >> 0) & 0xf)
#define DAS16M1_AI_TO_SAMPLE(x)         (((x) >> 4) & 0xfff)
#define DAS16M1_CS_REG                  0x02
#define DAS16M1_CS_EXT_TRIG             BIT(0)
#define DAS16M1_CS_OVRUN                BIT(5)
#define DAS16M1_CS_IRQDATA              BIT(7)
#define DAS16M1_DI_REG                  0x03
#define DAS16M1_DO_REG                  0x03
#define DAS16M1_CLR_INTR_REG            0x04
#define DAS16M1_INTR_CTRL_REG           0x05
#define DAS16M1_INTR_CTRL_PACER(x)      (((x) & 0x3) << 0)
#define DAS16M1_INTR_CTRL_PACER_EXT     DAS16M1_INTR_CTRL_PACER(2)
#define DAS16M1_INTR_CTRL_PACER_INT     DAS16M1_INTR_CTRL_PACER(3)
#define DAS16M1_INTR_CTRL_PACER_MASK    DAS16M1_INTR_CTRL_PACER(3)
#define DAS16M1_INTR_CTRL_IRQ(x)        (((x) & 0x7) << 4)
#define DAS16M1_INTR_CTRL_INTE          BIT(7)
#define DAS16M1_Q_ADDR_REG              0x06
#define DAS16M1_Q_REG                   0x07
#define DAS16M1_Q_CHAN(x)              (((x) & 0x7) << 0)
#define DAS16M1_Q_RANGE(x)             (((x) & 0xf) << 4)
#define DAS16M1_8254_IOBASE1            0x08
#define DAS16M1_8254_IOBASE2            0x0c
#define DAS16M1_8255_IOBASE             0x400
#define DAS16M1_8254_IOBASE3            0x404

#define DAS16M1_SIZE2                   0x08

#define DAS16M1_AI_FIFO_SZ              1024    /* # samples */

static const struct comedi_lrange range_das16m1 = {
        9, {
                BIP_RANGE(5),
                BIP_RANGE(2.5),
                BIP_RANGE(1.25),
                BIP_RANGE(0.625),
                UNI_RANGE(10),
                UNI_RANGE(5),
                UNI_RANGE(2.5),
                UNI_RANGE(1.25),
                BIP_RANGE(10)
        }
};

struct das16m1_private {
        struct comedi_8254 *counter;
        unsigned int intr_ctrl;
        unsigned int adc_count;
        u16 initial_hw_count;
        unsigned short ai_buffer[DAS16M1_AI_FIFO_SZ];
        unsigned long extra_iobase;
};

static void das16m1_ai_set_queue(struct comedi_device *dev,
                                 unsigned int *chanspec, unsigned int len)
{
        unsigned int i;

        for (i = 0; i < len; i++) {
                unsigned int chan = CR_CHAN(chanspec[i]);
                unsigned int range = CR_RANGE(chanspec[i]);

                outb(i, dev->iobase + DAS16M1_Q_ADDR_REG);
                outb(DAS16M1_Q_CHAN(chan) | DAS16M1_Q_RANGE(range),
                     dev->iobase + DAS16M1_Q_REG);
        }
}

static void das16m1_ai_munge(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             void *data, unsigned int num_bytes,
                             unsigned int start_chan_index)
{
        unsigned short *array = data;
        unsigned int nsamples = comedi_bytes_to_samples(s, num_bytes);
        unsigned int i;

        /*
         * The fifo values have the channel number in the lower 4-bits and
         * the sample in the upper 12-bits. This just shifts the values
         * to remove the channel numbers.
         */
        for (i = 0; i < nsamples; i++)
                array[i] = DAS16M1_AI_TO_SAMPLE(array[i]);
}

static int das16m1_ai_check_chanlist(struct comedi_device *dev,
                                     struct comedi_subdevice *s,
                                     struct comedi_cmd *cmd)
{
        int i;

        if (cmd->chanlist_len == 1)
                return 0;

        if ((cmd->chanlist_len % 2) != 0) {
                dev_dbg(dev->class_dev,
                        "chanlist must be of even length or length 1\n");
                return -EINVAL;
        }

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

                if ((i % 2) != (chan % 2)) {
                        dev_dbg(dev->class_dev,
                                "even/odd channels must go have even/odd chanlist indices\n");
                        return -EINVAL;
                }
        }

        return 0;
}

static int das16m1_ai_cmdtest(struct comedi_device *dev,
                              struct comedi_subdevice *s,
                              struct comedi_cmd *cmd)
{
        int err = 0;

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

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

        if (err)
                return 1;

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

        err |= comedi_check_trigger_is_unique(cmd->start_src);
        err |= comedi_check_trigger_is_unique(cmd->convert_src);
        err |= comedi_check_trigger_is_unique(cmd->stop_src);

        /* Step 2b : and mutually compatible */

        if (err)
                return 2;

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

        err |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);

        if (cmd->scan_begin_src == TRIG_FOLLOW) /* internal trigger */
                err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, 0);

        if (cmd->convert_src == TRIG_TIMER)
                err |= comedi_check_trigger_arg_min(&cmd->convert_arg, 1000);

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

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

        if (err)
                return 3;

        /* step 4: fix up arguments */

        if (cmd->convert_src == TRIG_TIMER) {
                unsigned int arg = cmd->convert_arg;

                comedi_8254_cascade_ns_to_timer(dev->pacer, &arg, cmd->flags);
                err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);
        }

        if (err)
                return 4;

        /* Step 5: check channel list if it exists */
        if (cmd->chanlist && cmd->chanlist_len > 0)
                err |= das16m1_ai_check_chanlist(dev, s, cmd);

        if (err)
                return 5;

        return 0;
}

static int das16m1_ai_cmd(struct comedi_device *dev,
                          struct comedi_subdevice *s)
{
        struct das16m1_private *devpriv = dev->private;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;
        unsigned int byte;

        /*  set software count */
        devpriv->adc_count = 0;

        /*
         * Initialize lower half of hardware counter, used to determine how
         * many samples are in fifo.  Value doesn't actually load into counter
         * until counter's next clock (the next a/d conversion).
         */
        comedi_8254_set_mode(devpriv->counter, 1, I8254_MODE2 | I8254_BINARY);
        comedi_8254_write(devpriv->counter, 1, 0);

        /*
         * Remember current reading of counter so we know when counter has
         * actually been loaded.
         */
        devpriv->initial_hw_count = comedi_8254_read(devpriv->counter, 1);

        das16m1_ai_set_queue(dev, cmd->chanlist, cmd->chanlist_len);

        /* enable interrupts and set internal pacer counter mode and counts */
        devpriv->intr_ctrl &= ~DAS16M1_INTR_CTRL_PACER_MASK;
        if (cmd->convert_src == TRIG_TIMER) {
                comedi_8254_update_divisors(dev->pacer);
                comedi_8254_pacer_enable(dev->pacer, 1, 2, true);
                devpriv->intr_ctrl |= DAS16M1_INTR_CTRL_PACER_INT;
        } else {        /* TRIG_EXT */
                devpriv->intr_ctrl |= DAS16M1_INTR_CTRL_PACER_EXT;
        }

        /*  set control & status register */
        byte = 0;
        /*
         * If we are using external start trigger (also board dislikes having
         * both start and conversion triggers external simultaneously).
         */
        if (cmd->start_src == TRIG_EXT && cmd->convert_src != TRIG_EXT)
                byte |= DAS16M1_CS_EXT_TRIG;

        outb(byte, dev->iobase + DAS16M1_CS_REG);

        /* clear interrupt */
        outb(0, dev->iobase + DAS16M1_CLR_INTR_REG);

        devpriv->intr_ctrl |= DAS16M1_INTR_CTRL_INTE;
        outb(devpriv->intr_ctrl, dev->iobase + DAS16M1_INTR_CTRL_REG);

        return 0;
}

static int das16m1_ai_cancel(struct comedi_device *dev,
                             struct comedi_subdevice *s)
{
        struct das16m1_private *devpriv = dev->private;

        /* disable interrupts and pacer */
        devpriv->intr_ctrl &= ~(DAS16M1_INTR_CTRL_INTE |
                                DAS16M1_INTR_CTRL_PACER_MASK);
        outb(devpriv->intr_ctrl, dev->iobase + DAS16M1_INTR_CTRL_REG);

        return 0;
}

static int das16m1_ai_eoc(struct comedi_device *dev,
                          struct comedi_subdevice *s,
                          struct comedi_insn *insn,
                          unsigned long context)
{
        unsigned int status;

        status = inb(dev->iobase + DAS16M1_CS_REG);
        if (status & DAS16M1_CS_IRQDATA)
                return 0;
        return -EBUSY;
}

static int das16m1_ai_insn_read(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
{
        int ret;
        int i;

        das16m1_ai_set_queue(dev, &insn->chanspec, 1);

        for (i = 0; i < insn->n; i++) {
                unsigned short val;

                /* clear interrupt */
                outb(0, dev->iobase + DAS16M1_CLR_INTR_REG);
                /* trigger conversion */
                outb(0, dev->iobase + DAS16M1_AI_REG);

                ret = comedi_timeout(dev, s, insn, das16m1_ai_eoc, 0);
                if (ret)
                        return ret;

                val = inw(dev->iobase + DAS16M1_AI_REG);
                data[i] = DAS16M1_AI_TO_SAMPLE(val);
        }

        return insn->n;
}

static int das16m1_di_insn_bits(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
{
        data[1] = inb(dev->iobase + DAS16M1_DI_REG) & 0xf;

        return insn->n;
}

static int das16m1_do_insn_bits(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
{
        if (comedi_dio_update_state(s, data))
                outb(s->state, dev->iobase + DAS16M1_DO_REG);

        data[1] = s->state;

        return insn->n;
}

static void das16m1_handler(struct comedi_device *dev, unsigned int status)
{
        struct das16m1_private *devpriv = dev->private;
        struct comedi_subdevice *s = dev->read_subdev;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;
        u16 num_samples;
        u16 hw_counter;

        /* figure out how many samples are in fifo */
        hw_counter = comedi_8254_read(devpriv->counter, 1);
        /*
         * Make sure hardware counter reading is not bogus due to initial
         * value not having been loaded yet.
         */
        if (devpriv->adc_count == 0 &&
            hw_counter == devpriv->initial_hw_count) {
                num_samples = 0;
        } else {
                /*
                 * The calculation of num_samples looks odd, but it uses the
                 * following facts. 16 bit hardware counter is initialized with
                 * value of zero (which really means 0x1000).  The counter
                 * decrements by one on each conversion (when the counter
                 * decrements from zero it goes to 0xffff).  num_samples is a
                 * 16 bit variable, so it will roll over in a similar fashion
                 * to the hardware counter.  Work it out, and this is what you
                 * get.
                 */
                num_samples = -hw_counter - devpriv->adc_count;
        }
        /*  check if we only need some of the points */
        if (cmd->stop_src == TRIG_COUNT) {
                if (num_samples > cmd->stop_arg * cmd->chanlist_len)
                        num_samples = cmd->stop_arg * cmd->chanlist_len;
        }
        /*  make sure we don't try to get too many points if fifo has overrun */
        if (num_samples > DAS16M1_AI_FIFO_SZ)
                num_samples = DAS16M1_AI_FIFO_SZ;
        insw(dev->iobase, devpriv->ai_buffer, num_samples);
        comedi_buf_write_samples(s, devpriv->ai_buffer, num_samples);
        devpriv->adc_count += num_samples;

        if (cmd->stop_src == TRIG_COUNT) {
                if (devpriv->adc_count >= cmd->stop_arg * cmd->chanlist_len) {
                        /* end of acquisition */
                        async->events |= COMEDI_CB_EOA;
                }
        }

        /*
         * This probably won't catch overruns since the card doesn't generate
         * overrun interrupts, but we might as well try.
         */
        if (status & DAS16M1_CS_OVRUN) {
                async->events |= COMEDI_CB_ERROR;
                dev_err(dev->class_dev, "fifo overflow\n");
        }

        comedi_handle_events(dev, s);
}

static int das16m1_ai_poll(struct comedi_device *dev,
                           struct comedi_subdevice *s)
{
        unsigned long flags;
        unsigned int status;

        /*  prevent race with interrupt handler */
        spin_lock_irqsave(&dev->spinlock, flags);
        status = inb(dev->iobase + DAS16M1_CS_REG);
        das16m1_handler(dev, status);
        spin_unlock_irqrestore(&dev->spinlock, flags);

        return comedi_buf_n_bytes_ready(s);
}

static irqreturn_t das16m1_interrupt(int irq, void *d)
{
        int status;
        struct comedi_device *dev = d;

        if (!dev->attached) {
                dev_err(dev->class_dev, "premature interrupt\n");
                return IRQ_HANDLED;
        }
        /*  prevent race with comedi_poll() */
        spin_lock(&dev->spinlock);

        status = inb(dev->iobase + DAS16M1_CS_REG);

        if ((status & (DAS16M1_CS_IRQDATA | DAS16M1_CS_OVRUN)) == 0) {
                dev_err(dev->class_dev, "spurious interrupt\n");
                spin_unlock(&dev->spinlock);
                return IRQ_NONE;
        }

        das16m1_handler(dev, status);

        /* clear interrupt */
        outb(0, dev->iobase + DAS16M1_CLR_INTR_REG);

        spin_unlock(&dev->spinlock);
        return IRQ_HANDLED;
}

static int das16m1_irq_bits(unsigned int irq)
{
        switch (irq) {
        case 10:
                return 0x0;
        case 11:
                return 0x1;
        case 12:
                return 0x2;
        case 15:
                return 0x3;
        case 2:
                return 0x4;
        case 3:
                return 0x5;
        case 5:
                return 0x6;
        case 7:
                return 0x7;
        default:
                return 0x0;
        }
}

static int das16m1_attach(struct comedi_device *dev,
                          struct comedi_devconfig *it)
{
        struct das16m1_private *devpriv;
        struct comedi_subdevice *s;
        int ret;

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

        ret = comedi_request_region(dev, it->options[0], 0x10);
        if (ret)
                return ret;
        /* Request an additional region for the 8255 and 3rd 8254 */
        ret = __comedi_request_region(dev, dev->iobase + DAS16M1_8255_IOBASE,
                                      DAS16M1_SIZE2);
        if (ret)
                return ret;
        devpriv->extra_iobase = dev->iobase + DAS16M1_8255_IOBASE;

        /* only irqs 2, 3, 4, 5, 6, 7, 10, 11, 12, 14, and 15 are valid */
        if ((1 << it->options[1]) & 0xdcfc) {
                ret = request_irq(it->options[1], das16m1_interrupt, 0,
                                  dev->board_name, dev);
                if (ret == 0)
                        dev->irq = it->options[1];
        }

        dev->pacer = comedi_8254_init(dev->iobase + DAS16M1_8254_IOBASE2,
                                      I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
        if (!dev->pacer)
                return -ENOMEM;

        devpriv->counter = comedi_8254_init(dev->iobase + DAS16M1_8254_IOBASE1,
                                            0, I8254_IO8, 0);
        if (!devpriv->counter)
                return -ENOMEM;

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

        /* Analog Input subdevice */
        s = &dev->subdevices[0];
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_DIFF;
        s->n_chan       = 8;
        s->maxdata      = 0x0fff;
        s->range_table  = &range_das16m1;
        s->insn_read    = das16m1_ai_insn_read;
        if (dev->irq) {
                dev->read_subdev = s;
                s->subdev_flags |= SDF_CMD_READ;
                s->len_chanlist = 256;
                s->do_cmdtest   = das16m1_ai_cmdtest;
                s->do_cmd       = das16m1_ai_cmd;
                s->cancel       = das16m1_ai_cancel;
                s->poll         = das16m1_ai_poll;
                s->munge        = das16m1_ai_munge;
        }

        /* Digital Input subdevice */
        s = &dev->subdevices[1];
        s->type         = COMEDI_SUBD_DI;
        s->subdev_flags = SDF_READABLE;
        s->n_chan       = 4;
        s->maxdata      = 1;
        s->range_table  = &range_digital;
        s->insn_bits    = das16m1_di_insn_bits;

        /* Digital Output subdevice */
        s = &dev->subdevices[2];
        s->type         = COMEDI_SUBD_DO;
        s->subdev_flags = SDF_WRITABLE;
        s->n_chan       = 4;
        s->maxdata      = 1;
        s->range_table  = &range_digital;
        s->insn_bits    = das16m1_do_insn_bits;

        /* Digital I/O subdevice (8255) */
        s = &dev->subdevices[3];
        ret = subdev_8255_init(dev, s, NULL, DAS16M1_8255_IOBASE);
        if (ret)
                return ret;

        /*  initialize digital output lines */
        outb(0, dev->iobase + DAS16M1_DO_REG);

        /* set the interrupt level */
        devpriv->intr_ctrl = DAS16M1_INTR_CTRL_IRQ(das16m1_irq_bits(dev->irq));
        outb(devpriv->intr_ctrl, dev->iobase + DAS16M1_INTR_CTRL_REG);

        return 0;
}

static void das16m1_detach(struct comedi_device *dev)
{
        struct das16m1_private *devpriv = dev->private;

        if (devpriv) {
                if (devpriv->extra_iobase)
                        release_region(devpriv->extra_iobase, DAS16M1_SIZE2);
                kfree(devpriv->counter);
        }
        comedi_legacy_detach(dev);
}

static struct comedi_driver das16m1_driver = {
        .driver_name    = "das16m1",
        .module         = THIS_MODULE,
        .attach         = das16m1_attach,
        .detach         = das16m1_detach,
};
module_comedi_driver(das16m1_driver);

MODULE_AUTHOR("Comedi http://www.comedi.org");
MODULE_DESCRIPTION("Comedi driver for CIO-DAS16/M1 ISA cards");
MODULE_LICENSE("GPL");