xref: /drivers/staging/comedi/drivers/pcmuio.c

/*
 * pcmuio.c
 * Comedi driver for Winsystems PC-104 based 48/96-channel DIO boards.
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 2006 Calin A. Culianu <calin@ajvar.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: pcmuio
 * Description: Winsystems PC-104 based 48/96-channel DIO boards.
 * Devices: (Winsystems) PCM-UIO48A [pcmuio48]
 *	    (Winsystems) PCM-UIO96A [pcmuio96]
 * Author: Calin Culianu <calin@ajvar.org>
 * Updated: Fri, 13 Jan 2006 12:01:01 -0500
 * Status: works
 *
 * A driver for the relatively straightforward-to-program PCM-UIO48A and
 * PCM-UIO96A boards from Winsystems. These boards use either one or two
 * (in the 96-DIO version) WS16C48 ASIC HighDensity I/O Chips (HDIO). This
 * chip is interesting in that each I/O line is individually programmable
 * for INPUT or OUTPUT (thus comedi_dio_config can be done on a per-channel
 * basis). Also, each chip supports edge-triggered interrupts for the first
 * 24 I/O lines. Of course, since the 96-channel version of the board has
 * two ASICs, it can detect polarity changes on up to 48 I/O lines. Since
 * this is essentially an (non-PnP) ISA board, I/O Address and IRQ selection
 * are done through jumpers on the board. You need to pass that information
 * to this driver as the first and second comedi_config option, respectively.
 * Note that the 48-channel version uses 16 bytes of IO memory and the 96-
 * channel version uses 32-bytes (in case you are worried about conflicts).
 * The 48-channel board is split into two 24-channel comedi subdevices. The
 * 96-channel board is split into 4 24-channel DIO subdevices.
 *
 * Note that IRQ support has been added, but it is untested.
 *
 * To use edge-detection IRQ support, pass the IRQs of both ASICS (for the
 * 96 channel version) or just 1 ASIC (for 48-channel version). Then, use
 * comedi_commands with TRIG_NOW. Your callback will be called each time an
 * edge is triggered, and the data values will be two sample_t's, which
 * should be concatenated to form one 32-bit unsigned int.  This value is
 * the mask of channels that had edges detected from your channel list. Note
 * that the bits positions in the mask correspond to positions in your
 * chanlist when you specified the command and *not* channel id's!
 *
 * To set the polarity of the edge-detection interrupts pass a nonzero value
 * for either CR_RANGE or CR_AREF for edge-up polarity, or a zero value for
 * both CR_RANGE and CR_AREF if you want edge-down polarity.
 *
 * In the 48-channel version:
 *
 * On subdev 0, the first 24 channels channels are edge-detect channels.
 *
 * In the 96-channel board you have the following channels that can do edge
 * detection:
 *
 * subdev 0, channels 0-24  (first 24 channels of 1st ASIC)
 * subdev 2, channels 0-24  (first 24 channels of 2nd ASIC)
 *
 * Configuration Options:
 *  [0] - I/O port base address
 *  [1] - IRQ (for first ASIC, or first 24 channels)
 *  [2] - IRQ (for second ASIC, pcmuio96 only - IRQ for chans 48-72
 *             can be the same as first irq!)
 */

#include <linux/interrupt.h>
#include <linux/slab.h>

#include "../comedidev.h"

#include "comedi_fc.h"

#define CHANS_PER_PORT		8
#define PORTS_PER_ASIC		6
#define INTR_PORTS_PER_ASIC	3
/* number of channels per comedi subdevice */
#define MAX_CHANS_PER_SUBDEV	24
#define PORTS_PER_SUBDEV	(MAX_CHANS_PER_SUBDEV / CHANS_PER_PORT)
#define CHANS_PER_ASIC		(CHANS_PER_PORT * PORTS_PER_ASIC)
#define INTR_CHANS_PER_ASIC	24
#define INTR_PORTS_PER_SUBDEV	(INTR_CHANS_PER_ASIC / CHANS_PER_PORT)
#define MAX_DIO_CHANS		(PORTS_PER_ASIC * 2 * CHANS_PER_PORT)
#define MAX_ASICS		(MAX_DIO_CHANS / CHANS_PER_ASIC)

/* IO Memory sizes */
#define ASIC_IOSIZE		0x10
#define PCMUIO48_IOSIZE		ASIC_IOSIZE
#define PCMUIO96_IOSIZE		(ASIC_IOSIZE * 2)

/*
 * Some offsets - these are all in the 16byte IO memory offset from
 * the base address.  Note that there is a paging scheme to swap out
 * offsets 0x8-0xA using the PAGELOCK register.  See the table below.
 *
 * Register(s)       Pages        R/W?        Description
 * --------------------------------------------------------------------------
 * REG_PORTx         All          R/W         Read/Write/Configure IO
 * REG_INT_PENDING   All          ReadOnly    Which INT_IDx has int.
 * REG_PAGELOCK      All          WriteOnly   Select a page
 * REG_POLx          Pg. 1 only   WriteOnly   Select edge-detection polarity
 * REG_ENABx         Pg. 2 only   WriteOnly   Enable/Disable edge-detect int.
 * REG_INT_IDx       Pg. 3 only   R/W         See which ports/bits have ints.
 */
#define REG_PORT0		0x0
#define REG_PORT1		0x1
#define REG_PORT2		0x2
#define REG_PORT3		0x3
#define REG_PORT4		0x4
#define REG_PORT5		0x5
#define REG_INT_PENDING		0x6
/*
 * page selector register
 * Upper 2 bits select a page and bits 0-5 are used to
 * 'lock down' a particular port above to make it readonly.
 */
#define REG_PAGELOCK		0x7
#define REG_POL0		0x8
#define REG_POL1		0x9
#define REG_POL2		0xa
#define REG_ENAB0		0x8
#define REG_ENAB1		0x9
#define REG_ENAB2		0xa
#define REG_INT_ID0		0x8
#define REG_INT_ID1		0x9
#define REG_INT_ID2		0xa

#define NUM_PAGED_REGS		3
#define NUM_PAGES		4
#define FIRST_PAGED_REG		0x8
#define REG_PAGE_BITOFFSET	6
#define REG_LOCK_BITOFFSET	0
#define REG_PAGE_MASK		(~((0x1 << REG_PAGE_BITOFFSET) - 1))
#define REG_LOCK_MASK		~(REG_PAGE_MASK)
#define PAGE_POL		1
#define PAGE_ENAB		2
#define PAGE_INT_ID		3

struct pcmuio_board {
	const char *name;
	const int num_asics;
	const int num_channels_per_port;
	const int num_ports;
};

static const struct pcmuio_board pcmuio_boards[] = {
	{
		.name		= "pcmuio48",
		.num_asics	= 1,
		.num_ports	= 6,
	}, {
		.name		= "pcmuio96",
		.num_asics	= 2,
		.num_ports	= 12,
	},
};

/* this structure is for data unique to this subdevice.  */
struct pcmuio_subdev_private {
	/* mapping of halfwords (bytes) in port/chanarray to iobase */
	unsigned long iobases[PORTS_PER_SUBDEV];

	/* The below is only used for intr subdevices */
	struct {
		int asic;	/* if non-negative, this subdev has an interrupt asic */
		int first_chan;	/* if nonnegative, the first channel id for
				   interrupts. */
		int num_asic_chans;	/* the number of asic channels in this subdev
					   that have interrutps */
		int asic_chan;	/* if nonnegative, the first channel id with
				   respect to the asic that has interrupts */
		int enabled_mask;	/* subdev-relative channel mask for channels
					   we are interested in */
		int active;
		int stop_count;
		int continuous;
		spinlock_t spinlock;
	} intr;
};

/* this structure is for data unique to this hardware driver.  If
   several hardware drivers keep similar information in this structure,
   feel free to suggest moving the variable to the struct comedi_device struct.  */
struct pcmuio_private {
	struct {
		unsigned char pagelock;	/* current page and lock */
		unsigned char pol[NUM_PAGED_REGS];	/* shadow of POLx registers */
		unsigned char enab[NUM_PAGED_REGS];	/* shadow of ENABx registers */
		int num;
		unsigned long iobase;
		unsigned int irq;
		spinlock_t spinlock;
	} asics[MAX_ASICS];
	struct pcmuio_subdev_private *sprivs;
};

/* DIO devices are slightly special.  Although it is possible to
 * implement the insn_read/insn_write interface, it is much more
 * useful to applications if you implement the insn_bits interface.
 * This allows packed reading/writing of the DIO channels.  The
 * comedi core can convert between insn_bits and insn_read/write */
static int pcmuio_dio_insn_bits(struct comedi_device *dev,
				struct comedi_subdevice *s,
				struct comedi_insn *insn, unsigned int *data)
{
	struct pcmuio_subdev_private *subpriv = s->private;
	int byte_no;

	/* NOTE:
	   reading a 0 means this channel was high
	   writine a 0 sets the channel high
	   reading a 1 means this channel was low
	   writing a 1 means set this channel low

	   Therefore everything is always inverted. */

	/* The insn data is a mask in data[0] and the new data
	 * in data[1], each channel cooresponding to a bit. */

#ifdef DAMMIT_ITS_BROKEN
	/* DEBUG */
	dev_dbg(dev->class_dev, "write mask: %08x  data: %08x\n", data[0],
		data[1]);
#endif

	s->state = 0;

	for (byte_no = 0; byte_no < s->n_chan / CHANS_PER_PORT; ++byte_no) {
		/* address of 8-bit port */
		unsigned long ioaddr = subpriv->iobases[byte_no],
		    /* bit offset of port in 32-bit doubleword */
		    offset = byte_no * 8;
		/* this 8-bit port's data */
		unsigned char byte = 0,
		    /* The write mask for this port (if any) */
		    write_mask_byte = (data[0] >> offset) & 0xff,
		    /* The data byte for this port */
		    data_byte = (data[1] >> offset) & 0xff;

		byte = inb(ioaddr);	/* read all 8-bits for this port */

#ifdef DAMMIT_ITS_BROKEN
		/* DEBUG */
		printk
		    ("byte %d wmb %02x db %02x offset %02d io %04x, data_in %02x ",
		     byte_no, (unsigned)write_mask_byte, (unsigned)data_byte,
		     offset, ioaddr, (unsigned)byte);
#endif

		if (write_mask_byte) {
			/* this byte has some write_bits -- so set the output lines */
			byte &= ~write_mask_byte;	/* clear bits for write mask */
			byte |= ~data_byte & write_mask_byte;	/* set to inverted data_byte */
			/* Write out the new digital output state */
			outb(byte, ioaddr);
		}
#ifdef DAMMIT_ITS_BROKEN
		/* DEBUG */
		dev_dbg(dev->class_dev, "data_out_byte %02x\n", (unsigned)byte);
#endif
		/* save the digital input lines for this byte.. */
		s->state |= ((unsigned int)byte) << offset;
	}

	/* now return the DIO lines to data[1] - note they came inverted! */
	data[1] = ~s->state;

#ifdef DAMMIT_ITS_BROKEN
	/* DEBUG */
	dev_dbg(dev->class_dev, "s->state %08x data_out %08x\n", s->state,
		data[1]);
#endif

	return insn->n;
}

/* The input or output configuration of each digital line is
 * configured by a special insn_config instruction.  chanspec
 * contains the channel to be changed, and data[0] contains the
 * value COMEDI_INPUT or COMEDI_OUTPUT. */
static int pcmuio_dio_insn_config(struct comedi_device *dev,
				  struct comedi_subdevice *s,
				  struct comedi_insn *insn, unsigned int *data)
{
	struct pcmuio_subdev_private *subpriv = s->private;
	int chan = CR_CHAN(insn->chanspec), byte_no = chan / 8, bit_no =
	    chan % 8;
	unsigned long ioaddr;
	unsigned char byte;

	/* Compute ioaddr for this channel */
	ioaddr = subpriv->iobases[byte_no];

	/* NOTE:
	   writing a 0 an IO channel's bit sets the channel to INPUT
	   and pulls the line high as well

	   writing a 1 to an IO channel's  bit pulls the line low

	   All channels are implicitly always in OUTPUT mode -- but when
	   they are high they can be considered to be in INPUT mode..

	   Thus, we only force channels low if the config request was INPUT,
	   otherwise we do nothing to the hardware.    */

	switch (data[0]) {
	case INSN_CONFIG_DIO_OUTPUT:
		/* save to io_bits -- don't actually do anything since
		   all input channels are also output channels... */
		s->io_bits |= 1 << chan;
		break;
	case INSN_CONFIG_DIO_INPUT:
		/* write a 0 to the actual register representing the channel
		   to set it to 'input'.  0 means "float high". */
		byte = inb(ioaddr);
		byte &= ~(1 << bit_no);
				/**< set input channel to '0' */

		/* write out byte -- this is the only time we actually affect the
		   hardware as all channels are implicitly output -- but input
		   channels are set to float-high */
		outb(byte, ioaddr);

		/* save to io_bits */
		s->io_bits &= ~(1 << chan);
		break;

	case INSN_CONFIG_DIO_QUERY:
		/* retrieve from shadow register */
		data[1] =
		    (s->io_bits & (1 << chan)) ? COMEDI_OUTPUT : COMEDI_INPUT;
		return insn->n;
		break;

	default:
		return -EINVAL;
		break;
	}

	return insn->n;
}

static void switch_page(struct comedi_device *dev, int asic, int page)
{
	const struct pcmuio_board *board = comedi_board(dev);
	struct pcmuio_private *devpriv = dev->private;

	if (asic < 0 || asic >= board->num_asics)
		return;		/* paranoia */
	if (page < 0 || page >= NUM_PAGES)
		return;		/* more paranoia */

	devpriv->asics[asic].pagelock &= ~REG_PAGE_MASK;
	devpriv->asics[asic].pagelock |= page << REG_PAGE_BITOFFSET;

	/* now write out the shadow register */
	outb(devpriv->asics[asic].pagelock,
	     dev->iobase + ASIC_IOSIZE * asic + REG_PAGELOCK);
}

static void init_asics(struct comedi_device *dev)
{				/* sets up an
				   ASIC chip to defaults */
	const struct pcmuio_board *board = comedi_board(dev);
	int asic;

	for (asic = 0; asic < board->num_asics; ++asic) {
		int port, page;
		unsigned long baseaddr = dev->iobase + asic * ASIC_IOSIZE;

		switch_page(dev, asic, 0);	/* switch back to page 0 */

		/* first, clear all the DIO port bits */
		for (port = 0; port < PORTS_PER_ASIC; ++port)
			outb(0, baseaddr + REG_PORT0 + port);

		/* Next, clear all the paged registers for each page */
		for (page = 1; page < NUM_PAGES; ++page) {
			int reg;
			/* now clear all the paged registers */
			switch_page(dev, asic, page);
			for (reg = FIRST_PAGED_REG;
			     reg < FIRST_PAGED_REG + NUM_PAGED_REGS; ++reg)
				outb(0, baseaddr + reg);
		}

		/* DEBUG  set rising edge interrupts on port0 of both asics */
		/*switch_page(dev, asic, PAGE_POL);
		   outb(0xff, baseaddr + REG_POL0);
		   switch_page(dev, asic, PAGE_ENAB);
		   outb(0xff, baseaddr + REG_ENAB0); */
		/* END DEBUG */

		switch_page(dev, asic, 0);	/* switch back to default page 0 */

	}
}

#ifdef notused
static void lock_port(struct comedi_device *dev, int asic, int port)
{
	const struct pcmuio_board *board = comedi_board(dev);
	struct pcmuio_private *devpriv = dev->private;

	if (asic < 0 || asic >= board->num_asics)
		return;		/* paranoia */
	if (port < 0 || port >= PORTS_PER_ASIC)
		return;		/* more paranoia */

	devpriv->asics[asic].pagelock |= 0x1 << port;
	/* now write out the shadow register */
	outb(devpriv->asics[asic].pagelock,
	     dev->iobase + ASIC_IOSIZE * asic + REG_PAGELOCK);
}

static void unlock_port(struct comedi_device *dev, int asic, int port)
{
	const struct pcmuio_board *board = comedi_board(dev);
	struct pcmuio_private *devpriv = dev->private;

	if (asic < 0 || asic >= board->num_asics)
		return;		/* paranoia */
	if (port < 0 || port >= PORTS_PER_ASIC)
		return;		/* more paranoia */
	devpriv->asics[asic].pagelock &= ~(0x1 << port) | REG_LOCK_MASK;
	/* now write out the shadow register */
	outb(devpriv->asics[asic].pagelock,
	     dev->iobase + ASIC_IOSIZE * asic + REG_PAGELOCK);
}
#endif /* notused */

static void pcmuio_stop_intr(struct comedi_device *dev,
			     struct comedi_subdevice *s)
{
	struct pcmuio_private *devpriv = dev->private;
	struct pcmuio_subdev_private *subpriv = s->private;
	int nports, firstport, asic, port;

	asic = subpriv->intr.asic;
	if (asic < 0)
		return;		/* not an interrupt subdev */

	subpriv->intr.enabled_mask = 0;
	subpriv->intr.active = 0;
	s->async->inttrig = NULL;
	nports = subpriv->intr.num_asic_chans / CHANS_PER_PORT;
	firstport = subpriv->intr.asic_chan / CHANS_PER_PORT;
	switch_page(dev, asic, PAGE_ENAB);
	for (port = firstport; port < firstport + nports; ++port) {
		/* disable all intrs for this subdev.. */
		outb(0, devpriv->asics[asic].iobase + REG_ENAB0 + port);
	}
}

static void pcmuio_handle_intr_subdev(struct comedi_device *dev,
				      struct comedi_subdevice *s,
				      unsigned triggered)
{
	struct pcmuio_subdev_private *subpriv = s->private;
	unsigned int len = s->async->cmd.chanlist_len;
	unsigned oldevents = s->async->events;
	unsigned int val = 0;
	unsigned long flags;
	unsigned mytrig;
	unsigned int i;

	spin_lock_irqsave(&subpriv->intr.spinlock, flags);

	if (!subpriv->intr.active)
		goto done;

	mytrig = triggered >> subpriv->intr.asic_chan;
	mytrig &= ((0x1 << subpriv->intr.num_asic_chans) - 1);
	mytrig <<= subpriv->intr.first_chan;

	if (!(mytrig & subpriv->intr.enabled_mask))
		goto done;

	for (i = 0; i < len; i++) {
		unsigned int chan = CR_CHAN(s->async->cmd.chanlist[i]);
		if (mytrig & (1U << chan))
			val |= (1U << i);
	}

	/* Write the scan to the buffer. */
	if (comedi_buf_put(s->async, ((short *)&val)[0]) &&
	    comedi_buf_put(s->async, ((short *)&val)[1])) {
		s->async->events |= (COMEDI_CB_BLOCK | COMEDI_CB_EOS);
	} else {
		/* Overflow! Stop acquisition!! */
		/* TODO: STOP_ACQUISITION_CALL_HERE!! */
		pcmuio_stop_intr(dev, s);
	}

	/* Check for end of acquisition. */
	if (!subpriv->intr.continuous) {
		/* stop_src == TRIG_COUNT */
		if (subpriv->intr.stop_count > 0) {
			subpriv->intr.stop_count--;
			if (subpriv->intr.stop_count == 0) {
				s->async->events |= COMEDI_CB_EOA;
				/* TODO: STOP_ACQUISITION_CALL_HERE!! */
				pcmuio_stop_intr(dev, s);
			}
		}
	}

done:
	spin_unlock_irqrestore(&subpriv->intr.spinlock, flags);

	if (oldevents != s->async->events)
		comedi_event(dev, s);
}

static int pcmuio_handle_asic_interrupt(struct comedi_device *dev, int asic)
{
	struct pcmuio_private *devpriv = dev->private;
	struct pcmuio_subdev_private *subpriv;
	unsigned long iobase = devpriv->asics[asic].iobase;
	unsigned triggered = 0;
	int got1 = 0;
	unsigned long flags;
	unsigned char int_pend;
	int i;

	spin_lock_irqsave(&devpriv->asics[asic].spinlock, flags);

	int_pend = inb(iobase + REG_INT_PENDING) & 0x07;
	if (int_pend) {
		for (i = 0; i < INTR_PORTS_PER_ASIC; ++i) {
			if (int_pend & (0x1 << i)) {
				unsigned char val;

				switch_page(dev, asic, PAGE_INT_ID);
				val = inb(iobase + REG_INT_ID0 + i);
				if (val)
					/* clear pending interrupt */
					outb(0, iobase + REG_INT_ID0 + i);

					triggered |= (val << (i * 8));
			}
		}

		++got1;
	}

	spin_unlock_irqrestore(&devpriv->asics[asic].spinlock, flags);

	if (triggered) {
		struct comedi_subdevice *s;
		/* TODO here: dispatch io lines to subdevs with commands.. */
		for (i = 0; i < dev->n_subdevices; i++) {
			s = &dev->subdevices[i];
			subpriv = s->private;
			if (subpriv->intr.asic == asic) {
				/*
				 * This is an interrupt subdev, and it
				 * matches this asic!
				 */
				pcmuio_handle_intr_subdev(dev, s,
							  triggered);
			}
		}
	}
	return got1;
}

static irqreturn_t interrupt_pcmuio(int irq, void *d)
{
	struct comedi_device *dev = d;
	struct pcmuio_private *devpriv = dev->private;
	int got1 = 0;
	int asic;

	for (asic = 0; asic < MAX_ASICS; ++asic) {
		if (irq == devpriv->asics[asic].irq) {
			/* it is an interrupt for ASIC #asic */
			if (pcmuio_handle_asic_interrupt(dev, asic))
				got1++;
		}
	}
	if (!got1)
		return IRQ_NONE;	/* interrupt from other source */
	return IRQ_HANDLED;
}

static int pcmuio_start_intr(struct comedi_device *dev,
			     struct comedi_subdevice *s)
{
	struct pcmuio_private *devpriv = dev->private;
	struct pcmuio_subdev_private *subpriv = s->private;

	if (!subpriv->intr.continuous && subpriv->intr.stop_count == 0) {
		/* An empty acquisition! */
		s->async->events |= COMEDI_CB_EOA;
		subpriv->intr.active = 0;
		return 1;
	} else {
		unsigned bits = 0, pol_bits = 0, n;
		int nports, firstport, asic, port;
		struct comedi_cmd *cmd = &s->async->cmd;

		asic = subpriv->intr.asic;
		if (asic < 0)
			return 1;	/* not an interrupt
					   subdev */
		subpriv->intr.enabled_mask = 0;
		subpriv->intr.active = 1;
		nports = subpriv->intr.num_asic_chans / CHANS_PER_PORT;
		firstport = subpriv->intr.asic_chan / CHANS_PER_PORT;
		if (cmd->chanlist) {
			for (n = 0; n < cmd->chanlist_len; n++) {
				bits |= (1U << CR_CHAN(cmd->chanlist[n]));
				pol_bits |= (CR_AREF(cmd->chanlist[n])
					     || CR_RANGE(cmd->
							 chanlist[n]) ? 1U : 0U)
				    << CR_CHAN(cmd->chanlist[n]);
			}
		}
		bits &= ((0x1 << subpriv->intr.num_asic_chans) -
			 1) << subpriv->intr.first_chan;
		subpriv->intr.enabled_mask = bits;

		switch_page(dev, asic, PAGE_ENAB);
		for (port = firstport; port < firstport + nports; ++port) {
			unsigned enab =
			    bits >> (subpriv->intr.first_chan + (port -
								 firstport) *
				     8) & 0xff, pol =
			    pol_bits >> (subpriv->intr.first_chan +
					 (port - firstport) * 8) & 0xff;
			/* set enab intrs for this subdev.. */
			outb(enab,
			     devpriv->asics[asic].iobase + REG_ENAB0 + port);
			switch_page(dev, asic, PAGE_POL);
			outb(pol,
			     devpriv->asics[asic].iobase + REG_ENAB0 + port);
		}
	}
	return 0;
}

static int pcmuio_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
{
	struct pcmuio_subdev_private *subpriv = s->private;
	unsigned long flags;

	spin_lock_irqsave(&subpriv->intr.spinlock, flags);
	if (subpriv->intr.active)
		pcmuio_stop_intr(dev, s);
	spin_unlock_irqrestore(&subpriv->intr.spinlock, flags);

	return 0;
}

/*
 * Internal trigger function to start acquisition for an 'INTERRUPT' subdevice.
 */
static int
pcmuio_inttrig_start_intr(struct comedi_device *dev, struct comedi_subdevice *s,
			  unsigned int trignum)
{
	struct pcmuio_subdev_private *subpriv = s->private;
	unsigned long flags;
	int event = 0;

	if (trignum != 0)
		return -EINVAL;

	spin_lock_irqsave(&subpriv->intr.spinlock, flags);
	s->async->inttrig = NULL;
	if (subpriv->intr.active)
		event = pcmuio_start_intr(dev, s);

	spin_unlock_irqrestore(&subpriv->intr.spinlock, flags);

	if (event)
		comedi_event(dev, s);

	return 1;
}

/*
 * 'do_cmd' function for an 'INTERRUPT' subdevice.
 */
static int pcmuio_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
	struct pcmuio_subdev_private *subpriv = s->private;
	struct comedi_cmd *cmd = &s->async->cmd;
	unsigned long flags;
	int event = 0;

	spin_lock_irqsave(&subpriv->intr.spinlock, flags);
	subpriv->intr.active = 1;

	/* Set up end of acquisition. */
	switch (cmd->stop_src) {
	case TRIG_COUNT:
		subpriv->intr.continuous = 0;
		subpriv->intr.stop_count = cmd->stop_arg;
		break;
	default:
		/* TRIG_NONE */
		subpriv->intr.continuous = 1;
		subpriv->intr.stop_count = 0;
		break;
	}

	/* Set up start of acquisition. */
	switch (cmd->start_src) {
	case TRIG_INT:
		s->async->inttrig = pcmuio_inttrig_start_intr;
		break;
	default:
		/* TRIG_NOW */
		event = pcmuio_start_intr(dev, s);
		break;
	}
	spin_unlock_irqrestore(&subpriv->intr.spinlock, flags);

	if (event)
		comedi_event(dev, s);

	return 0;
}

static int pcmuio_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 |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW | TRIG_INT);
	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_EXT);
	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW);
	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);

	if (err)
		return 1;

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

	err |= cfc_check_trigger_is_unique(cmd->start_src);
	err |= cfc_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 |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);
	err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
	err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);
	err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);

	switch (cmd->stop_src) {
	case TRIG_COUNT:
		/* any count allowed */
		break;
	case TRIG_NONE:
		err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
		break;
	default:
		break;
	}

	if (err)
		return 3;

	/* step 4: fix up any arguments */

	/* if (err) return 4; */

	return 0;
}

static int pcmuio_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
	const struct pcmuio_board *board = comedi_board(dev);
	struct comedi_subdevice *s;
	struct pcmuio_private *devpriv;
	struct pcmuio_subdev_private *subpriv;
	int sdev_no, chans_left, n_subdevs, port, asic, thisasic_chanct = 0;
	unsigned int irq[MAX_ASICS];
	int ret;

	irq[0] = it->options[1];
	irq[1] = it->options[2];

	ret = comedi_request_region(dev, it->options[0],
				    board->num_asics * ASIC_IOSIZE);
	if (ret)
		return ret;

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

	for (asic = 0; asic < MAX_ASICS; ++asic) {
		devpriv->asics[asic].num = asic;
		devpriv->asics[asic].iobase = dev->iobase + asic * ASIC_IOSIZE;
		devpriv->asics[asic].irq = 0;	/* this gets actually set at the end of
						   this function when we
						   request_irqs */
		spin_lock_init(&devpriv->asics[asic].spinlock);
	}

	chans_left = CHANS_PER_ASIC * board->num_asics;
	n_subdevs = (chans_left / MAX_CHANS_PER_SUBDEV) +
		    (!!(chans_left % MAX_CHANS_PER_SUBDEV));
	devpriv->sprivs = kcalloc(n_subdevs,
				  sizeof(struct pcmuio_subdev_private),
				  GFP_KERNEL);
	if (!devpriv->sprivs)
		return -ENOMEM;

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

	port = 0;
	asic = 0;
	for (sdev_no = 0; sdev_no < (int)dev->n_subdevices; ++sdev_no) {
		int byte_no;

		s = &dev->subdevices[sdev_no];
		subpriv = &devpriv->sprivs[sdev_no];
		s->private = subpriv;
		s->maxdata = 1;
		s->range_table = &range_digital;
		s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
		s->type = COMEDI_SUBD_DIO;
		s->insn_bits = pcmuio_dio_insn_bits;
		s->insn_config = pcmuio_dio_insn_config;
		s->n_chan = min(chans_left, MAX_CHANS_PER_SUBDEV);
		subpriv->intr.asic = -1;
		subpriv->intr.first_chan = -1;
		subpriv->intr.asic_chan = -1;
		subpriv->intr.num_asic_chans = -1;
		subpriv->intr.active = 0;
		s->len_chanlist = 1;

		/* save the ioport address for each 'port' of 8 channels in the
		   subdevice */
		for (byte_no = 0; byte_no < PORTS_PER_SUBDEV; ++byte_no, ++port) {
			if (port >= PORTS_PER_ASIC) {
				port = 0;
				++asic;
				thisasic_chanct = 0;
			}
			subpriv->iobases[byte_no] =
			    devpriv->asics[asic].iobase + port;

			if (thisasic_chanct <
			    CHANS_PER_PORT * INTR_PORTS_PER_ASIC
			    && subpriv->intr.asic < 0) {
				/* this is an interrupt subdevice, so setup the struct */
				subpriv->intr.asic = asic;
				subpriv->intr.active = 0;
				subpriv->intr.stop_count = 0;
				subpriv->intr.first_chan = byte_no * 8;
				subpriv->intr.asic_chan = thisasic_chanct;
				subpriv->intr.num_asic_chans =
				    s->n_chan - subpriv->intr.first_chan;
				dev->read_subdev = s;
				s->subdev_flags |= SDF_CMD_READ;
				s->cancel = pcmuio_cancel;
				s->do_cmd = pcmuio_cmd;
				s->do_cmdtest = pcmuio_cmdtest;
				s->len_chanlist = subpriv->intr.num_asic_chans;
			}
			thisasic_chanct += CHANS_PER_PORT;
		}
		spin_lock_init(&subpriv->intr.spinlock);

		chans_left -= s->n_chan;

		if (!chans_left) {
			asic = 0;	/* reset the asic to our first asic, to do intr subdevs */
			port = 0;
		}

	}

	init_asics(dev);	/* clear out all the registers, basically */

	for (asic = 0; irq[0] && asic < MAX_ASICS; ++asic) {
		if (irq[asic]
		    && request_irq(irq[asic], interrupt_pcmuio,
				   IRQF_SHARED, board->name, dev)) {
			int i;
			/* unroll the allocated irqs.. */
			for (i = asic - 1; i >= 0; --i) {
				free_irq(irq[i], dev);
				devpriv->asics[i].irq = irq[i] = 0;
			}
			irq[asic] = 0;
		}
		devpriv->asics[asic].irq = irq[asic];
	}

	if (irq[0]) {
		dev_dbg(dev->class_dev, "irq: %u\n", irq[0]);
		if (irq[1] && board->num_asics == 2)
			dev_dbg(dev->class_dev, "second ASIC irq: %u\n",
				irq[1]);
	} else {
		dev_dbg(dev->class_dev, "(IRQ mode disabled)\n");
	}


	return 1;
}

static void pcmuio_detach(struct comedi_device *dev)
{
	struct pcmuio_private *devpriv = dev->private;
	int i;

	for (i = 0; i < MAX_ASICS; ++i) {
		if (devpriv->asics[i].irq)
			free_irq(devpriv->asics[i].irq, dev);
	}
	if (devpriv && devpriv->sprivs)
		kfree(devpriv->sprivs);
	comedi_legacy_detach(dev);
}

static struct comedi_driver pcmuio_driver = {
	.driver_name	= "pcmuio",
	.module		= THIS_MODULE,
	.attach		= pcmuio_attach,
	.detach		= pcmuio_detach,
	.board_name	= &pcmuio_boards[0].name,
	.offset		= sizeof(struct pcmuio_board),
	.num_names	= ARRAY_SIZE(pcmuio_boards),
};
module_comedi_driver(pcmuio_driver);

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