drivers/staging/comedi/drivers/pcmad.c

/*
    comedi/drivers/pcmad.c
    Hardware driver for Winsystems PCM-A/D12 and PCM-A/D16

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 2000,2001 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: pcmad
Description: Winsystems PCM-A/D12, PCM-A/D16
Author: ds
Devices: [Winsystems] PCM-A/D12 (pcmad12), PCM-A/D16 (pcmad16)
Status: untested

This driver was written on a bet that I couldn't write a driver
in less than 2 hours.  I won the bet, but never got paid.  =(

Configuration options:
  [0] - I/O port base
  [1] - unused
  [2] - Analog input reference
	0 = single ended
	1 = differential
  [3] - Analog input encoding (must match jumpers)
	0 = straight binary
	1 = two's complement
*/

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

#include <linux/ioport.h>

#define PCMAD_SIZE		4

#define PCMAD_STATUS		0
#define PCMAD_LSB		1
#define PCMAD_MSB		2
#define PCMAD_CONVERT		1

struct pcmad_board_struct {
	const char *name;
	int n_ai_bits;
};

struct pcmad_priv_struct {
	int differential;
	int twos_comp;
};

#define TIMEOUT	100

static int pcmad_ai_insn_read(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      struct comedi_insn *insn, unsigned int *data)
{
	const struct pcmad_board_struct *board = comedi_board(dev);
	struct pcmad_priv_struct *devpriv = dev->private;
	int i;
	int chan;
	int n;

	chan = CR_CHAN(insn->chanspec);

	for (n = 0; n < insn->n; n++) {
		outb(chan, dev->iobase + PCMAD_CONVERT);

		for (i = 0; i < TIMEOUT; i++) {
			if ((inb(dev->iobase + PCMAD_STATUS) & 0x3) == 0x3)
				break;
		}
		data[n] = inb(dev->iobase + PCMAD_LSB);
		data[n] |= (inb(dev->iobase + PCMAD_MSB) << 8);

		if (devpriv->twos_comp)
			data[n] ^= (1 << (board->n_ai_bits - 1));
	}

	return n;
}

/*
 * options:
 * 0	i/o base
 * 1	unused
 * 2	0=single ended 1=differential
 * 3	0=straight binary 1=two's comp
 */
static int pcmad_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
	const struct pcmad_board_struct *board = comedi_board(dev);
	struct pcmad_priv_struct *devpriv;
	struct comedi_subdevice *s;
	int ret;

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

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

	devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
	if (!devpriv)
		return -ENOMEM;
	dev->private = devpriv;

	s = &dev->subdevices[0];
	s->type = COMEDI_SUBD_AI;
	s->subdev_flags = SDF_READABLE | AREF_GROUND;
	s->n_chan = 16;		/* XXX */
	s->len_chanlist = 1;
	s->insn_read = pcmad_ai_insn_read;
	s->maxdata = (1 << board->n_ai_bits) - 1;
	s->range_table = &range_unknown;

	return 0;
}

static const struct pcmad_board_struct pcmad_boards[] = {
	{
		.name		= "pcmad12",
		.n_ai_bits	= 12,
	}, {
		.name		= "pcmad16",
		.n_ai_bits	= 16,
	},
};
static struct comedi_driver pcmad_driver = {
	.driver_name	= "pcmad",
	.module		= THIS_MODULE,
	.attach		= pcmad_attach,
	.detach		= comedi_legacy_detach,
	.board_name	= &pcmad_boards[0].name,
	.num_names	= ARRAY_SIZE(pcmad_boards),
	.offset		= sizeof(pcmad_boards[0]),
};
module_comedi_driver(pcmad_driver);

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