/*
   Some comments on the code..

   - it shouldn't be necessary to use outb_p().

   - ignoreirq creates a race condition.  It needs to be fixed.

 */

/*
   comedi/drivers/das6402.c
   An experimental driver for Computerboards' DAS6402 I/O card

   Copyright (C) 1999 Oystein Svendsen <svendsen@pvv.org>

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

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 */
/*
Driver: das6402
Description: Keithley Metrabyte DAS6402 (& compatibles)
Author: Oystein Svendsen <svendsen@pvv.org>
Status: bitrotten
Devices: [Keithley Metrabyte] DAS6402 (das6402)

This driver has suffered bitrot.
*/

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

#define DAS6402_SIZE 16

#define N_WORDS (3000*64)

#define STOP    0
#define START   1

#define SCANL 0x3f00
#define BYTE unsigned char
#define WORD unsigned short

/*----- register 8 ----*/
#define CLRINT 0x01
#define CLRXTR 0x02
#define CLRXIN 0x04
#define EXTEND 0x10
#define ARMED 0x20		/* enable conting of post sample conv */
#define POSTMODE 0x40
#define MHZ 0x80		/* 10 MHz clock */
/*---------------------*/

/*----- register 9 ----*/
#define IRQ (0x04 << 4)		/* these two are                         */
#define IRQV 10			/*               dependent on each other */

#define CONVSRC 0x03		/* trig src is Intarnal pacer */
#define BURSTEN 0x04		/* enable burst */
#define XINTE 0x08		/* use external int. trig */
#define INTE 0x80		/* enable analog interrupts */
/*---------------------*/

/*----- register 10 ---*/
#define TGEN 0x01		/* Use pin DI1 for externl trigging? */
#define TGSEL 0x02		/* Use edge triggering */
#define TGPOL 0x04		/* active edge is falling */
#define PRETRIG 0x08		/* pretrig */
/*---------------------*/

/*----- register 11 ---*/
#define EOB 0x0c
#define FIFOHFULL 0x08
#define GAIN 0x01
#define FIFONEPTY 0x04
#define MODE 0x10
#define SEM 0x20
#define BIP 0x40
/*---------------------*/

#define M0 0x00
#define M2 0x04

#define	C0 0x00
#define	C1 0x40
#define	C2 0x80
#define	RWLH 0x30

struct das6402_private {
	int ai_bytes_to_read;

	int das6402_ignoreirq;
};

static void das6402_ai_fifo_dregs(struct comedi_device *dev,
				  struct comedi_subdevice *s)
{
	while (1) {
		if (!(inb(dev->iobase + 8) & 0x01))
			return;
		comedi_buf_put(s->async, inw(dev->iobase));
	}
}

static void das6402_setcounter(struct comedi_device *dev)
{
	BYTE p;
	unsigned short ctrlwrd;

	/* set up counter0 first, mode 0 */
	p = M0 | C0 | RWLH;
	outb_p(p, dev->iobase + 15);
	ctrlwrd = 2000;
	p = (BYTE) (0xff & ctrlwrd);
	outb_p(p, dev->iobase + 12);
	p = (BYTE) (0xff & (ctrlwrd >> 8));
	outb_p(p, dev->iobase + 12);

	/* set up counter1, mode 2 */
	p = M2 | C1 | RWLH;
	outb_p(p, dev->iobase + 15);
	ctrlwrd = 10;
	p = (BYTE) (0xff & ctrlwrd);
	outb_p(p, dev->iobase + 13);
	p = (BYTE) (0xff & (ctrlwrd >> 8));
	outb_p(p, dev->iobase + 13);

	/* set up counter1, mode 2 */
	p = M2 | C2 | RWLH;
	outb_p(p, dev->iobase + 15);
	ctrlwrd = 1000;
	p = (BYTE) (0xff & ctrlwrd);
	outb_p(p, dev->iobase + 14);
	p = (BYTE) (0xff & (ctrlwrd >> 8));
	outb_p(p, dev->iobase + 14);
}

static irqreturn_t intr_handler(int irq, void *d)
{
	struct comedi_device *dev = d;
	struct das6402_private *devpriv = dev->private;
	struct comedi_subdevice *s = &dev->subdevices[0];

	if (!dev->attached || devpriv->das6402_ignoreirq) {
		dev_warn(dev->class_dev, "BUG: spurious interrupt\n");
		return IRQ_HANDLED;
	}

	das6402_ai_fifo_dregs(dev, s);

	if (s->async->buf_write_count >= devpriv->ai_bytes_to_read) {
		outw_p(SCANL, dev->iobase + 2);	/* clears the fifo */
		outb(0x07, dev->iobase + 8);	/* clears all flip-flops */
		s->async->events |= COMEDI_CB_EOA;
		comedi_event(dev, s);
	}

	outb(0x01, dev->iobase + 8);	/* clear only the interrupt flip-flop */

	comedi_event(dev, s);
	return IRQ_HANDLED;
}

#if 0
static void das6402_ai_fifo_read(struct comedi_device *dev, short *data, int n)
{
	int i;

	for (i = 0; i < n; i++)
		data[i] = inw(dev->iobase);
}
#endif

static int das6402_ai_cancel(struct comedi_device *dev,
			     struct comedi_subdevice *s)
{
	struct das6402_private *devpriv = dev->private;

	/*
	 *  This function should reset the board from whatever condition it
	 *  is in (i.e., acquiring data), to a non-active state.
	 */

	devpriv->das6402_ignoreirq = 1;
	dev_dbg(dev->class_dev, "Stopping acquisition\n");
	devpriv->das6402_ignoreirq = 1;
	outb_p(0x02, dev->iobase + 10);	/* disable external trigging */
	outw_p(SCANL, dev->iobase + 2);	/* resets the card fifo */
	outb_p(0, dev->iobase + 9);	/* disables interrupts */

	outw_p(SCANL, dev->iobase + 2);

	return 0;
}

#ifdef unused
static int das6402_ai_mode2(struct comedi_device *dev,
			    struct comedi_subdevice *s, comedi_trig *it)
{
	struct das6402_private *devpriv = dev->private;

	devpriv->das6402_ignoreirq = 1;
	dev_dbg(dev->class_dev, "Starting acquisition\n");
	outb_p(0x03, dev->iobase + 10);	/* enable external trigging */
	outw_p(SCANL, dev->iobase + 2);	/* resets the card fifo */
	outb_p(IRQ | CONVSRC | BURSTEN | INTE, dev->iobase + 9);

	devpriv->ai_bytes_to_read = it->n * sizeof(short);

	/* um... ignoreirq is a nasty race condition */
	devpriv->das6402_ignoreirq = 0;

	outw_p(SCANL, dev->iobase + 2);

	return 0;
}
#endif

static int board_init(struct comedi_device *dev)
{
	struct das6402_private *devpriv = dev->private;
	BYTE b;

	devpriv->das6402_ignoreirq = 1;

	outb(0x07, dev->iobase + 8);

	/* register 11  */
	outb_p(MODE, dev->iobase + 11);
	b = BIP | SEM | MODE | GAIN | FIFOHFULL;
	outb_p(b, dev->iobase + 11);

	/* register 8   */
	outb_p(EXTEND, dev->iobase + 8);
	b = EXTEND | MHZ;
	outb_p(b, dev->iobase + 8);
	b = MHZ | CLRINT | CLRXTR | CLRXIN;
	outb_p(b, dev->iobase + 8);

	/* register 9    */
	b = IRQ | CONVSRC | BURSTEN | INTE;
	outb_p(b, dev->iobase + 9);

	/* register 10   */
	b = TGSEL | TGEN;
	outb_p(b, dev->iobase + 10);

	b = 0x07;
	outb_p(b, dev->iobase + 8);

	das6402_setcounter(dev);

	outw_p(SCANL, dev->iobase + 2);	/* reset card fifo */

	devpriv->das6402_ignoreirq = 0;

	return 0;
}

static int das6402_attach(struct comedi_device *dev,
			  struct comedi_devconfig *it)
{
	struct das6402_private *devpriv;
	unsigned int irq;
	int ret;
	struct comedi_subdevice *s;

	ret = comedi_request_region(dev, it->options[0], DAS6402_SIZE);
	if (ret)
		return ret;

	irq = it->options[0];
	dev_dbg(dev->class_dev, "( irq = %u )\n", irq);
	ret = request_irq(irq, intr_handler, 0, "das6402", dev);
	if (ret < 0)
		return ret;

	dev->irq = irq;

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

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

	/* ai subdevice */
	s = &dev->subdevices[0];
	s->type = COMEDI_SUBD_AI;
	s->subdev_flags = SDF_READABLE | SDF_GROUND;
	s->n_chan = 8;
	/* s->trig[2]=das6402_ai_mode2; */
	s->cancel = das6402_ai_cancel;
	s->maxdata = (1 << 12) - 1;
	s->len_chanlist = 16;	/* ? */
	s->range_table = &range_unknown;

	board_init(dev);

	return 0;
}

static struct comedi_driver das6402_driver = {
	.driver_name	= "das6402",
	.module		= THIS_MODULE,
	.attach		= das6402_attach,
	.detach		= comedi_legacy_detach,
};
module_comedi_driver(das6402_driver)

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