// SPDX-License-Identifier: GPL-2.0+
/*
 * comedi/drivers/rtd520.c
 * Comedi driver for Real Time Devices (RTD) PCI4520/DM7520
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 2001 David A. Schleef <ds@schleef.org>
 */

/*
 * Driver: rtd520
 * Description: Real Time Devices PCI4520/DM7520
 * Devices: [Real Time Devices] DM7520HR-1 (DM7520), DM7520HR-8,
 *   PCI4520 (PCI4520), PCI4520-8
 * Author: Dan Christian
 * Status: Works. Only tested on DM7520-8. Not SMP safe.
 *
 * Configuration options: not applicable, uses PCI auto config
 */

/*
 * Created by Dan Christian, NASA Ames Research Center.
 *
 * The PCI4520 is a PCI card. The DM7520 is a PC/104-plus card.
 * Both have:
 *   8/16 12 bit ADC with FIFO and channel gain table
 *   8 bits high speed digital out (for external MUX) (or 8 in or 8 out)
 *   8 bits high speed digital in with FIFO and interrupt on change (or 8 IO)
 *   2 12 bit DACs with FIFOs
 *   2 bits output
 *   2 bits input
 *   bus mastering DMA
 *   timers: ADC sample, pacer, burst, about, delay, DA1, DA2
 *   sample counter
 *   3 user timer/counters (8254)
 *   external interrupt
 *
 * The DM7520 has slightly fewer features (fewer gain steps).
 *
 * These boards can support external multiplexors and multi-board
 * synchronization, but this driver doesn't support that.
 *
 * Board docs: http://www.rtdusa.com/PC104/DM/analog%20IO/dm7520.htm
 * Data sheet: http://www.rtdusa.com/pdf/dm7520.pdf
 * Example source: http://www.rtdusa.com/examples/dm/dm7520.zip
 * Call them and ask for the register level manual.
 * PCI chip: http://www.plxtech.com/products/io/pci9080
 *
 * Notes:
 * This board is memory mapped. There is some IO stuff, but it isn't needed.
 *
 * I use a pretty loose naming style within the driver (rtd_blah).
 * All externally visible names should be rtd520_blah.
 * I use camelCase for structures (and inside them).
 * I may also use upper CamelCase for function names (old habit).
 *
 * This board is somewhat related to the RTD PCI4400 board.
 *
 * I borrowed heavily from the ni_mio_common, ni_atmio16d, mite, and
 * das1800, since they have the best documented code. Driver cb_pcidas64.c
 * uses the same DMA controller.
 *
 * As far as I can tell, the About interrupt doesn't work if Sample is
 * also enabled. It turns out that About really isn't needed, since
 * we always count down samples read.
 */

/*
 * driver status:
 *
 * Analog-In supports instruction and command mode.
 *
 * With DMA, you can sample at 1.15Mhz with 70% idle on a 400Mhz K6-2
 * (single channel, 64K read buffer). I get random system lockups when
 * using DMA with ALI-15xx based systems. I haven't been able to test
 * any other chipsets. The lockups happen soon after the start of an
 * acquistion, not in the middle of a long run.
 *
 * Without DMA, you can do 620Khz sampling with 20% idle on a 400Mhz K6-2
 * (with a 256K read buffer).
 *
 * Digital-IO and Analog-Out only support instruction mode.
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/comedi/comedi_pci.h>
#include <linux/comedi/comedi_8254.h>

#include "plx9080.h"

/*
 * Local Address Space 0 Offsets
 */
#define LAS0_USER_IO		0x0008	/* User I/O */
#define LAS0_ADC		0x0010	/* FIFO Status/Software A/D Start */
#define FS_DAC1_NOT_EMPTY	BIT(0)	/* DAC1 FIFO not empty */
#define FS_DAC1_HEMPTY		BIT(1)	/* DAC1 FIFO half empty */
#define FS_DAC1_NOT_FULL	BIT(2)	/* DAC1 FIFO not full */
#define FS_DAC2_NOT_EMPTY	BIT(4)	/* DAC2 FIFO not empty */
#define FS_DAC2_HEMPTY		BIT(5)	/* DAC2 FIFO half empty */
#define FS_DAC2_NOT_FULL	BIT(6)	/* DAC2 FIFO not full */
#define FS_ADC_NOT_EMPTY	BIT(8)	/* ADC FIFO not empty */
#define FS_ADC_HEMPTY		BIT(9)	/* ADC FIFO half empty */
#define FS_ADC_NOT_FULL		BIT(10)	/* ADC FIFO not full */
#define FS_DIN_NOT_EMPTY	BIT(12)	/* DIN FIFO not empty */
#define FS_DIN_HEMPTY		BIT(13)	/* DIN FIFO half empty */
#define FS_DIN_NOT_FULL		BIT(14)	/* DIN FIFO not full */
#define LAS0_UPDATE_DAC(x)	(0x0014 + ((x) * 0x4))	/* D/Ax Update (w) */
#define LAS0_DAC		0x0024	/* Software Simultaneous Update (w) */
#define LAS0_PACER		0x0028	/* Software Pacer Start/Stop */
#define LAS0_TIMER		0x002c	/* Timer Status/HDIN Software Trig. */
#define LAS0_IT			0x0030	/* Interrupt Status/Enable */
#define IRQM_ADC_FIFO_WRITE	BIT(0)	/* ADC FIFO Write */
#define IRQM_CGT_RESET		BIT(1)	/* Reset CGT */
#define IRQM_CGT_PAUSE		BIT(3)	/* Pause CGT */
#define IRQM_ADC_ABOUT_CNT	BIT(4)	/* About Counter out */
#define IRQM_ADC_DELAY_CNT	BIT(5)	/* Delay Counter out */
#define IRQM_ADC_SAMPLE_CNT	BIT(6)	/* ADC Sample Counter */
#define IRQM_DAC1_UCNT		BIT(7)	/* DAC1 Update Counter */
#define IRQM_DAC2_UCNT		BIT(8)	/* DAC2 Update Counter */
#define IRQM_UTC1		BIT(9)	/* User TC1 out */
#define IRQM_UTC1_INV		BIT(10)	/* User TC1 out, inverted */
#define IRQM_UTC2		BIT(11)	/* User TC2 out */
#define IRQM_DIGITAL_IT		BIT(12)	/* Digital Interrupt */
#define IRQM_EXTERNAL_IT	BIT(13)	/* External Interrupt */
#define IRQM_ETRIG_RISING	BIT(14)	/* Ext Trigger rising-edge */
#define IRQM_ETRIG_FALLING	BIT(15)	/* Ext Trigger falling-edge */
#define LAS0_CLEAR		0x0034	/* Clear/Set Interrupt Clear Mask */
#define LAS0_OVERRUN		0x0038	/* Pending interrupts/Clear Overrun */
#define LAS0_PCLK		0x0040	/* Pacer Clock (24bit) */
#define LAS0_BCLK		0x0044	/* Burst Clock (10bit) */
#define LAS0_ADC_SCNT		0x0048	/* A/D Sample counter (10bit) */
#define LAS0_DAC1_UCNT		0x004c	/* D/A1 Update counter (10 bit) */
#define LAS0_DAC2_UCNT		0x0050	/* D/A2 Update counter (10 bit) */
#define LAS0_DCNT		0x0054	/* Delay counter (16 bit) */
#define LAS0_ACNT		0x0058	/* About counter (16 bit) */
#define LAS0_DAC_CLK		0x005c	/* DAC clock (16bit) */
#define LAS0_8254_TIMER_BASE	0x0060	/* 8254 timer/counter base */
#define LAS0_DIO0		0x0070	/* Digital I/O Port 0 */
#define LAS0_DIO1		0x0074	/* Digital I/O Port 1 */
#define LAS0_DIO0_CTRL		0x0078	/* Digital I/O Control */
#define LAS0_DIO_STATUS		0x007c	/* Digital I/O Status */
#define LAS0_BOARD_RESET	0x0100	/* Board reset */
#define LAS0_DMA0_SRC		0x0104	/* DMA 0 Sources select */
#define LAS0_DMA1_SRC		0x0108	/* DMA 1 Sources select */
#define LAS0_ADC_CONVERSION	0x010c	/* A/D Conversion Signal select */
#define LAS0_BURST_START	0x0110	/* Burst Clock Start Trigger select */
#define LAS0_PACER_START	0x0114	/* Pacer Clock Start Trigger select */
#define LAS0_PACER_STOP		0x0118	/* Pacer Clock Stop Trigger select */
#define LAS0_ACNT_STOP_ENABLE	0x011c	/* About Counter Stop Enable */
#define LAS0_PACER_REPEAT	0x0120	/* Pacer Start Trigger Mode select */
#define LAS0_DIN_START		0x0124	/* HiSpd DI Sampling Signal select */
#define LAS0_DIN_FIFO_CLEAR	0x0128	/* Digital Input FIFO Clear */
#define LAS0_ADC_FIFO_CLEAR	0x012c	/* A/D FIFO Clear */
#define LAS0_CGT_WRITE		0x0130	/* Channel Gain Table Write */
#define LAS0_CGL_WRITE		0x0134	/* Channel Gain Latch Write */
#define LAS0_CG_DATA		0x0138	/* Digital Table Write */
#define LAS0_CGT_ENABLE		0x013c	/* Channel Gain Table Enable */
#define LAS0_CG_ENABLE		0x0140	/* Digital Table Enable */
#define LAS0_CGT_PAUSE		0x0144	/* Table Pause Enable */
#define LAS0_CGT_RESET		0x0148	/* Reset Channel Gain Table */
#define LAS0_CGT_CLEAR		0x014c	/* Clear Channel Gain Table */
#define LAS0_DAC_CTRL(x)	(0x0150	+ ((x) * 0x14))	/* D/Ax type/range */
#define LAS0_DAC_SRC(x)		(0x0154 + ((x) * 0x14))	/* D/Ax update source */
#define LAS0_DAC_CYCLE(x)	(0x0158 + ((x) * 0x14))	/* D/Ax cycle mode */
#define LAS0_DAC_RESET(x)	(0x015c + ((x) * 0x14))	/* D/Ax FIFO reset */
#define LAS0_DAC_FIFO_CLEAR(x)	(0x0160 + ((x) * 0x14))	/* D/Ax FIFO clear */
#define LAS0_ADC_SCNT_SRC	0x0178	/* A/D Sample Counter Source select */
#define LAS0_PACER_SELECT	0x0180	/* Pacer Clock select */
#define LAS0_SBUS0_SRC		0x0184	/* SyncBus 0 Source select */
#define LAS0_SBUS0_ENABLE	0x0188	/* SyncBus 0 enable */
#define LAS0_SBUS1_SRC		0x018c	/* SyncBus 1 Source select */
#define LAS0_SBUS1_ENABLE	0x0190	/* SyncBus 1 enable */
#define LAS0_SBUS2_SRC		0x0198	/* SyncBus 2 Source select */
#define LAS0_SBUS2_ENABLE	0x019c	/* SyncBus 2 enable */
#define LAS0_ETRG_POLARITY	0x01a4	/* Ext. Trigger polarity select */
#define LAS0_EINT_POLARITY	0x01a8	/* Ext. Interrupt polarity select */
#define LAS0_8254_CLK_SEL(x)	(0x01ac + ((x) * 0x8))	/* 8254 clock select */
#define LAS0_8254_GATE_SEL(x)	(0x01b0 + ((x) * 0x8))	/* 8254 gate select */
#define LAS0_UOUT0_SELECT	0x01c4	/* User Output 0 source select */
#define LAS0_UOUT1_SELECT	0x01c8	/* User Output 1 source select */
#define LAS0_DMA0_RESET		0x01cc	/* DMA0 Request state machine reset */
#define LAS0_DMA1_RESET		0x01d0	/* DMA1 Request state machine reset */

/*
 * Local Address Space 1 Offsets
 */
#define LAS1_ADC_FIFO		0x0000	/* A/D FIFO (16bit) */
#define LAS1_HDIO_FIFO		0x0004	/* HiSpd DI FIFO (16bit) */
#define LAS1_DAC_FIFO(x)	(0x0008 + ((x) * 0x4))	/* D/Ax FIFO (16bit) */

/*
 * Driver specific stuff (tunable)
 */

/*
 * We really only need 2 buffers.  More than that means being much
 * smarter about knowing which ones are full.
 */
#define DMA_CHAIN_COUNT 2	/* max DMA segments/buffers in a ring (min 2) */

/* Target period for periodic transfers.  This sets the user read latency. */
/* Note: There are certain rates where we give this up and transfer 1/2 FIFO */
/* If this is too low, efficiency is poor */
#define TRANS_TARGET_PERIOD 10000000	/* 10 ms (in nanoseconds) */

/* Set a practical limit on how long a list to support (affects memory use) */
/* The board support a channel list up to the FIFO length (1K or 8K) */
#define RTD_MAX_CHANLIST	128	/* max channel list that we allow */

/*
 * Board specific stuff
 */

#define RTD_CLOCK_RATE	8000000	/* 8Mhz onboard clock */
#define RTD_CLOCK_BASE	125	/* clock period in ns */

/* Note: these speed are slower than the spec, but fit the counter resolution*/
#define RTD_MAX_SPEED	1625	/* when sampling, in nanoseconds */
/* max speed if we don't have to wait for settling */
#define RTD_MAX_SPEED_1	875	/* if single channel, in nanoseconds */

#define RTD_MIN_SPEED	2097151875	/* (24bit counter) in nanoseconds */
/* min speed when only 1 channel (no burst counter) */
#define RTD_MIN_SPEED_1	5000000	/* 200Hz, in nanoseconds */

/* Setup continuous ring of 1/2 FIFO transfers.  See RTD manual p91 */
#define DMA_MODE_BITS (\
		       PLX_LOCAL_BUS_16_WIDE_BITS \
		       | PLX_DMA_EN_READYIN_BIT \
		       | PLX_DMA_LOCAL_BURST_EN_BIT \
		       | PLX_EN_CHAIN_BIT \
		       | PLX_DMA_INTR_PCI_BIT \
		       | PLX_LOCAL_ADDR_CONST_BIT \
		       | PLX_DEMAND_MODE_BIT)

#define DMA_TRANSFER_BITS (\
/* descriptors in PCI memory*/  PLX_DESC_IN_PCI_BIT \
/* interrupt at end of block */ | PLX_INTR_TERM_COUNT \
/* from board to PCI */		| PLX_XFER_LOCAL_TO_PCI)

/*
 * Comedi specific stuff
 */

/*
 * The board has 3 input modes and the gains of 1,2,4,...32 (, 64, 128)
 */
static const struct comedi_lrange rtd_ai_7520_range = {
	18, {
		/* +-5V input range gain steps */
		BIP_RANGE(5.0),
		BIP_RANGE(5.0 / 2),
		BIP_RANGE(5.0 / 4),
		BIP_RANGE(5.0 / 8),
		BIP_RANGE(5.0 / 16),
		BIP_RANGE(5.0 / 32),
		/* +-10V input range gain steps */
		BIP_RANGE(10.0),
		BIP_RANGE(10.0 / 2),
		BIP_RANGE(10.0 / 4),
		BIP_RANGE(10.0 / 8),
		BIP_RANGE(10.0 / 16),
		BIP_RANGE(10.0 / 32),
		/* +10V input range gain steps */
		UNI_RANGE(10.0),
		UNI_RANGE(10.0 / 2),
		UNI_RANGE(10.0 / 4),
		UNI_RANGE(10.0 / 8),
		UNI_RANGE(10.0 / 16),
		UNI_RANGE(10.0 / 32),
	}
};

/* PCI4520 has two more gains (6 more entries) */
static const struct comedi_lrange rtd_ai_4520_range = {
	24, {
		/* +-5V input range gain steps */
		BIP_RANGE(5.0),
		BIP_RANGE(5.0 / 2),
		BIP_RANGE(5.0 / 4),
		BIP_RANGE(5.0 / 8),
		BIP_RANGE(5.0 / 16),
		BIP_RANGE(5.0 / 32),
		BIP_RANGE(5.0 / 64),
		BIP_RANGE(5.0 / 128),
		/* +-10V input range gain steps */
		BIP_RANGE(10.0),
		BIP_RANGE(10.0 / 2),
		BIP_RANGE(10.0 / 4),
		BIP_RANGE(10.0 / 8),
		BIP_RANGE(10.0 / 16),
		BIP_RANGE(10.0 / 32),
		BIP_RANGE(10.0 / 64),
		BIP_RANGE(10.0 / 128),
		/* +10V input range gain steps */
		UNI_RANGE(10.0),
		UNI_RANGE(10.0 / 2),
		UNI_RANGE(10.0 / 4),
		UNI_RANGE(10.0 / 8),
		UNI_RANGE(10.0 / 16),
		UNI_RANGE(10.0 / 32),
		UNI_RANGE(10.0 / 64),
		UNI_RANGE(10.0 / 128),
	}
};

/* Table order matches range values */
static const struct comedi_lrange rtd_ao_range = {
	4, {
		UNI_RANGE(5),
		UNI_RANGE(10),
		BIP_RANGE(5),
		BIP_RANGE(10),
	}
};

enum rtd_boardid {
	BOARD_DM7520,
	BOARD_PCI4520,
};

struct rtd_boardinfo {
	const char *name;
	int range_bip10;	/* start of +-10V range */
	int range_uni10;	/* start of +10V range */
	const struct comedi_lrange *ai_range;
};

static const struct rtd_boardinfo rtd520_boards[] = {
	[BOARD_DM7520] = {
		.name		= "DM7520",
		.range_bip10	= 6,
		.range_uni10	= 12,
		.ai_range	= &rtd_ai_7520_range,
	},
	[BOARD_PCI4520] = {
		.name		= "PCI4520",
		.range_bip10	= 8,
		.range_uni10	= 16,
		.ai_range	= &rtd_ai_4520_range,
	},
};

struct rtd_private {
	/* memory mapped board structures */
	void __iomem *las1;
	void __iomem *lcfg;

	long ai_count;		/* total transfer size (samples) */
	int xfer_count;		/* # to transfer data. 0->1/2FIFO */
	int flags;		/* flag event modes */
	unsigned int fifosz;

	/* 8254 Timer/Counter gate and clock sources */
	unsigned char timer_gate_src[3];
	unsigned char timer_clk_src[3];
};

/* bit defines for "flags" */
#define SEND_EOS	0x01	/* send End Of Scan events */
#define DMA0_ACTIVE	0x02	/* DMA0 is active */
#define DMA1_ACTIVE	0x04	/* DMA1 is active */

/*
 * Given a desired period and the clock period (both in ns), return the
 * proper counter value (divider-1). Sets the original period to be the
 * true value.
 * Note: you have to check if the value is larger than the counter range!
 */
static int rtd_ns_to_timer_base(unsigned int *nanosec,
				unsigned int flags, int base)
{
	int divider;

	switch (flags & CMDF_ROUND_MASK) {
	case CMDF_ROUND_NEAREST:
	default:
		divider = DIV_ROUND_CLOSEST(*nanosec, base);
		break;
	case CMDF_ROUND_DOWN:
		divider = (*nanosec) / base;
		break;
	case CMDF_ROUND_UP:
		divider = DIV_ROUND_UP(*nanosec, base);
		break;
	}
	if (divider < 2)
		divider = 2;	/* min is divide by 2 */

	/*
	 * Note: we don't check for max, because different timers
	 * have different ranges
	 */

	*nanosec = base * divider;
	return divider - 1;	/* countdown is divisor+1 */
}

/*
 * Given a desired period (in ns), return the proper counter value
 * (divider-1) for the internal clock. Sets the original period to
 * be the true value.
 */
static int rtd_ns_to_timer(unsigned int *ns, unsigned int flags)
{
	return rtd_ns_to_timer_base(ns, flags, RTD_CLOCK_BASE);
}

/* Convert a single comedi channel-gain entry to a RTD520 table entry */
static unsigned short rtd_convert_chan_gain(struct comedi_device *dev,
					    unsigned int chanspec, int index)
{
	const struct rtd_boardinfo *board = dev->board_ptr;
	unsigned int chan = CR_CHAN(chanspec);
	unsigned int range = CR_RANGE(chanspec);
	unsigned int aref = CR_AREF(chanspec);
	unsigned short r = 0;

	r |= chan & 0xf;

	/* Note: we also setup the channel list bipolar flag array */
	if (range < board->range_bip10) {
		/* +-5 range */
		r |= 0x000;
		r |= (range & 0x7) << 4;
	} else if (range < board->range_uni10) {
		/* +-10 range */
		r |= 0x100;
		r |= ((range - board->range_bip10) & 0x7) << 4;
	} else {
		/* +10 range */
		r |= 0x200;
		r |= ((range - board->range_uni10) & 0x7) << 4;
	}

	switch (aref) {
	case AREF_GROUND:	/* on-board ground */
		break;

	case AREF_COMMON:
		r |= 0x80;	/* ref external analog common */
		break;

	case AREF_DIFF:
		r |= 0x400;	/* differential inputs */
		break;

	case AREF_OTHER:	/* ??? */
		break;
	}
	return r;
}

/* Setup the channel-gain table from a comedi list */
static void rtd_load_channelgain_list(struct comedi_device *dev,
				      unsigned int n_chan, unsigned int *list)
{
	if (n_chan > 1) {	/* setup channel gain table */
		int ii;

		writel(0, dev->mmio + LAS0_CGT_CLEAR);
		writel(1, dev->mmio + LAS0_CGT_ENABLE);
		for (ii = 0; ii < n_chan; ii++) {
			writel(rtd_convert_chan_gain(dev, list[ii], ii),
			       dev->mmio + LAS0_CGT_WRITE);
		}
	} else {		/* just use the channel gain latch */
		writel(0, dev->mmio + LAS0_CGT_ENABLE);
		writel(rtd_convert_chan_gain(dev, list[0], 0),
		       dev->mmio + LAS0_CGL_WRITE);
	}
}

/*
 * Determine fifo size by doing adc conversions until the fifo half
 * empty status flag clears.
 */
static int rtd520_probe_fifo_depth(struct comedi_device *dev)
{
	unsigned int chanspec = CR_PACK(0, 0, AREF_GROUND);
	unsigned int i;
	static const unsigned int limit = 0x2000;
	unsigned int fifo_size = 0;

	writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
	rtd_load_channelgain_list(dev, 1, &chanspec);
	/* ADC conversion trigger source: SOFTWARE */
	writel(0, dev->mmio + LAS0_ADC_CONVERSION);
	/* convert  samples */
	for (i = 0; i < limit; ++i) {
		unsigned int fifo_status;
		/* trigger conversion */
		writew(0, dev->mmio + LAS0_ADC);
		usleep_range(1, 1000);
		fifo_status = readl(dev->mmio + LAS0_ADC);
		if ((fifo_status & FS_ADC_HEMPTY) == 0) {
			fifo_size = 2 * i;
			break;
		}
	}
	if (i == limit) {
		dev_info(dev->class_dev, "failed to probe fifo size.\n");
		return -EIO;
	}
	writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
	if (fifo_size != 0x400 && fifo_size != 0x2000) {
		dev_info(dev->class_dev,
			 "unexpected fifo size of %i, expected 1024 or 8192.\n",
			 fifo_size);
		return -EIO;
	}
	return fifo_size;
}

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

	status = readl(dev->mmio + LAS0_ADC);
	if (status & FS_ADC_NOT_EMPTY)
		return 0;
	return -EBUSY;
}

static int rtd_ai_rinsn(struct comedi_device *dev,
			struct comedi_subdevice *s, struct comedi_insn *insn,
			unsigned int *data)
{
	struct rtd_private *devpriv = dev->private;
	unsigned int range = CR_RANGE(insn->chanspec);
	int ret;
	int n;

	/* clear any old fifo data */
	writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);

	/* write channel to multiplexer and clear channel gain table */
	rtd_load_channelgain_list(dev, 1, &insn->chanspec);

	/* ADC conversion trigger source: SOFTWARE */
	writel(0, dev->mmio + LAS0_ADC_CONVERSION);

	/* convert n samples */
	for (n = 0; n < insn->n; n++) {
		unsigned short d;
		/* trigger conversion */
		writew(0, dev->mmio + LAS0_ADC);

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

		/* read data */
		d = readw(devpriv->las1 + LAS1_ADC_FIFO);
		d >>= 3;	/* low 3 bits are marker lines */

		/* convert bipolar data to comedi unsigned data */
		if (comedi_range_is_bipolar(s, range))
			d = comedi_offset_munge(s, d);

		data[n] = d & s->maxdata;
	}

	/* return the number of samples read/written */
	return n;
}

static int ai_read_n(struct comedi_device *dev, struct comedi_subdevice *s,
		     int count)
{
	struct rtd_private *devpriv = dev->private;
	struct comedi_async *async = s->async;
	struct comedi_cmd *cmd = &async->cmd;
	int ii;

	for (ii = 0; ii < count; ii++) {
		unsigned int range = CR_RANGE(cmd->chanlist[async->cur_chan]);
		unsigned short d;

		if (devpriv->ai_count == 0) {	/* done */
			d = readw(devpriv->las1 + LAS1_ADC_FIFO);
			continue;
		}

		d = readw(devpriv->las1 + LAS1_ADC_FIFO);
		d >>= 3;	/* low 3 bits are marker lines */

		/* convert bipolar data to comedi unsigned data */
		if (comedi_range_is_bipolar(s, range))
			d = comedi_offset_munge(s, d);
		d &= s->maxdata;

		if (!comedi_buf_write_samples(s, &d, 1))
			return -1;

		if (devpriv->ai_count > 0)	/* < 0, means read forever */
			devpriv->ai_count--;
	}
	return 0;
}

static irqreturn_t rtd_interrupt(int irq, void *d)
{
	struct comedi_device *dev = d;
	struct comedi_subdevice *s = dev->read_subdev;
	struct rtd_private *devpriv = dev->private;
	u32 overrun;
	u16 status;
	u16 fifo_status;

	if (!dev->attached)
		return IRQ_NONE;

	fifo_status = readl(dev->mmio + LAS0_ADC);
	/* check for FIFO full, this automatically halts the ADC! */
	if (!(fifo_status & FS_ADC_NOT_FULL))	/* 0 -> full */
		goto xfer_abort;

	status = readw(dev->mmio + LAS0_IT);
	/* if interrupt was not caused by our board, or handled above */
	if (status == 0)
		return IRQ_HANDLED;

	if (status & IRQM_ADC_ABOUT_CNT) {	/* sample count -> read FIFO */
		/*
		 * since the priority interrupt controller may have queued
		 * a sample counter interrupt, even though we have already
		 * finished, we must handle the possibility that there is
		 * no data here
		 */
		if (!(fifo_status & FS_ADC_HEMPTY)) {
			/* FIFO half full */
			if (ai_read_n(dev, s, devpriv->fifosz / 2) < 0)
				goto xfer_abort;

			if (devpriv->ai_count == 0)
				goto xfer_done;
		} else if (devpriv->xfer_count > 0) {
			if (fifo_status & FS_ADC_NOT_EMPTY) {
				/* FIFO not empty */
				if (ai_read_n(dev, s, devpriv->xfer_count) < 0)
					goto xfer_abort;

				if (devpriv->ai_count == 0)
					goto xfer_done;
			}
		}
	}

	overrun = readl(dev->mmio + LAS0_OVERRUN) & 0xffff;
	if (overrun)
		goto xfer_abort;

	/* clear the interrupt */
	writew(status, dev->mmio + LAS0_CLEAR);
	readw(dev->mmio + LAS0_CLEAR);

	comedi_handle_events(dev, s);

	return IRQ_HANDLED;

xfer_abort:
	s->async->events |= COMEDI_CB_ERROR;

xfer_done:
	s->async->events |= COMEDI_CB_EOA;

	/* clear the interrupt */
	status = readw(dev->mmio + LAS0_IT);
	writew(status, dev->mmio + LAS0_CLEAR);
	readw(dev->mmio + LAS0_CLEAR);

	fifo_status = readl(dev->mmio + LAS0_ADC);
	overrun = readl(dev->mmio + LAS0_OVERRUN) & 0xffff;

	comedi_handle_events(dev, s);

	return IRQ_HANDLED;
}

static int rtd_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 | TRIG_EXT);
	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->scan_begin_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_TIMER) {
		/* Note: these are time periods, not actual rates */
		if (cmd->chanlist_len == 1) {	/* no scanning */
			if (comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
							 RTD_MAX_SPEED_1)) {
				rtd_ns_to_timer(&cmd->scan_begin_arg,
						CMDF_ROUND_UP);
				err |= -EINVAL;
			}
			if (comedi_check_trigger_arg_max(&cmd->scan_begin_arg,
							 RTD_MIN_SPEED_1)) {
				rtd_ns_to_timer(&cmd->scan_begin_arg,
						CMDF_ROUND_DOWN);
				err |= -EINVAL;
			}
		} else {
			if (comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
							 RTD_MAX_SPEED)) {
				rtd_ns_to_timer(&cmd->scan_begin_arg,
						CMDF_ROUND_UP);
				err |= -EINVAL;
			}
			if (comedi_check_trigger_arg_max(&cmd->scan_begin_arg,
							 RTD_MIN_SPEED)) {
				rtd_ns_to_timer(&cmd->scan_begin_arg,
						CMDF_ROUND_DOWN);
				err |= -EINVAL;
			}
		}
	} else {
		/* external trigger */
		/* should be level/edge, hi/lo specification here */
		/* should specify multiple external triggers */
		err |= comedi_check_trigger_arg_max(&cmd->scan_begin_arg, 9);
	}

	if (cmd->convert_src == TRIG_TIMER) {
		if (cmd->chanlist_len == 1) {	/* no scanning */
			if (comedi_check_trigger_arg_min(&cmd->convert_arg,
							 RTD_MAX_SPEED_1)) {
				rtd_ns_to_timer(&cmd->convert_arg,
						CMDF_ROUND_UP);
				err |= -EINVAL;
			}
			if (comedi_check_trigger_arg_max(&cmd->convert_arg,
							 RTD_MIN_SPEED_1)) {
				rtd_ns_to_timer(&cmd->convert_arg,
						CMDF_ROUND_DOWN);
				err |= -EINVAL;
			}
		} else {
			if (comedi_check_trigger_arg_min(&cmd->convert_arg,
							 RTD_MAX_SPEED)) {
				rtd_ns_to_timer(&cmd->convert_arg,
						CMDF_ROUND_UP);
				err |= -EINVAL;
			}
			if (comedi_check_trigger_arg_max(&cmd->convert_arg,
							 RTD_MIN_SPEED)) {
				rtd_ns_to_timer(&cmd->convert_arg,
						CMDF_ROUND_DOWN);
				err |= -EINVAL;
			}
		}
	} else {
		/* external trigger */
		/* see above */
		err |= comedi_check_trigger_arg_max(&cmd->convert_arg, 9);
	}

	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 any arguments */

	if (cmd->scan_begin_src == TRIG_TIMER) {
		arg = cmd->scan_begin_arg;
		rtd_ns_to_timer(&arg, cmd->flags);
		err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
	}

	if (cmd->convert_src == TRIG_TIMER) {
		arg = cmd->convert_arg;
		rtd_ns_to_timer(&arg, cmd->flags);
		err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);

		if (cmd->scan_begin_src == TRIG_TIMER) {
			arg = cmd->convert_arg * cmd->scan_end_arg;
			err |= comedi_check_trigger_arg_min(
					&cmd->scan_begin_arg, arg);
		}
	}

	if (err)
		return 4;

	return 0;
}

static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
	struct rtd_private *devpriv = dev->private;
	struct comedi_cmd *cmd = &s->async->cmd;
	int timer;

	/* stop anything currently running */
	/* pacer stop source: SOFTWARE */
	writel(0, dev->mmio + LAS0_PACER_STOP);
	writel(0, dev->mmio + LAS0_PACER);	/* stop pacer */
	writel(0, dev->mmio + LAS0_ADC_CONVERSION);
	writew(0, dev->mmio + LAS0_IT);
	writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
	writel(0, dev->mmio + LAS0_OVERRUN);

	/* start configuration */
	/* load channel list and reset CGT */
	rtd_load_channelgain_list(dev, cmd->chanlist_len, cmd->chanlist);

	/* setup the common case and override if needed */
	if (cmd->chanlist_len > 1) {
		/* pacer start source: SOFTWARE */
		writel(0, dev->mmio + LAS0_PACER_START);
		/* burst trigger source: PACER */
		writel(1, dev->mmio + LAS0_BURST_START);
		/* ADC conversion trigger source: BURST */
		writel(2, dev->mmio + LAS0_ADC_CONVERSION);
	} else {		/* single channel */
		/* pacer start source: SOFTWARE */
		writel(0, dev->mmio + LAS0_PACER_START);
		/* ADC conversion trigger source: PACER */
		writel(1, dev->mmio + LAS0_ADC_CONVERSION);
	}
	writel((devpriv->fifosz / 2 - 1) & 0xffff, dev->mmio + LAS0_ACNT);

	if (cmd->scan_begin_src == TRIG_TIMER) {
		/* scan_begin_arg is in nanoseconds */
		/* find out how many samples to wait before transferring */
		if (cmd->flags & CMDF_WAKE_EOS) {
			/*
			 * this may generate un-sustainable interrupt rates
			 * the application is responsible for doing the
			 * right thing
			 */
			devpriv->xfer_count = cmd->chanlist_len;
			devpriv->flags |= SEND_EOS;
		} else {
			/* arrange to transfer data periodically */
			devpriv->xfer_count =
			    (TRANS_TARGET_PERIOD * cmd->chanlist_len) /
			    cmd->scan_begin_arg;
			if (devpriv->xfer_count < cmd->chanlist_len) {
				/* transfer after each scan (and avoid 0) */
				devpriv->xfer_count = cmd->chanlist_len;
			} else {	/* make a multiple of scan length */
				devpriv->xfer_count =
				    DIV_ROUND_UP(devpriv->xfer_count,
						 cmd->chanlist_len);
				devpriv->xfer_count *= cmd->chanlist_len;
			}
			devpriv->flags |= SEND_EOS;
		}
		if (devpriv->xfer_count >= (devpriv->fifosz / 2)) {
			/* out of counter range, use 1/2 fifo instead */
			devpriv->xfer_count = 0;
			devpriv->flags &= ~SEND_EOS;
		} else {
			/* interrupt for each transfer */
			writel((devpriv->xfer_count - 1) & 0xffff,
			       dev->mmio + LAS0_ACNT);
		}
	} else {		/* unknown timing, just use 1/2 FIFO */
		devpriv->xfer_count = 0;
		devpriv->flags &= ~SEND_EOS;
	}
	/* pacer clock source: INTERNAL 8MHz */
	writel(1, dev->mmio + LAS0_PACER_SELECT);
	/* just interrupt, don't stop */
	writel(1, dev->mmio + LAS0_ACNT_STOP_ENABLE);

	/* BUG??? these look like enumerated values, but they are bit fields */

	/* First, setup when to stop */
	switch (cmd->stop_src) {
	case TRIG_COUNT:	/* stop after N scans */
		devpriv->ai_count = cmd->stop_arg * cmd->chanlist_len;
		if ((devpriv->xfer_count > 0) &&
		    (devpriv->xfer_count > devpriv->ai_count)) {
			devpriv->xfer_count = devpriv->ai_count;
		}
		break;

	case TRIG_NONE:	/* stop when cancel is called */
		devpriv->ai_count = -1;	/* read forever */
		break;
	}

	/* Scan timing */
	switch (cmd->scan_begin_src) {
	case TRIG_TIMER:	/* periodic scanning */
		timer = rtd_ns_to_timer(&cmd->scan_begin_arg,
					CMDF_ROUND_NEAREST);
		/* set PACER clock */
		writel(timer & 0xffffff, dev->mmio + LAS0_PCLK);

		break;

	case TRIG_EXT:
		/* pacer start source: EXTERNAL */
		writel(1, dev->mmio + LAS0_PACER_START);
		break;
	}

	/* Sample timing within a scan */
	switch (cmd->convert_src) {
	case TRIG_TIMER:	/* periodic */
		if (cmd->chanlist_len > 1) {
			/* only needed for multi-channel */
			timer = rtd_ns_to_timer(&cmd->convert_arg,
						CMDF_ROUND_NEAREST);
			/* setup BURST clock */
			writel(timer & 0x3ff, dev->mmio + LAS0_BCLK);
		}

		break;

	case TRIG_EXT:		/* external */
		/* burst trigger source: EXTERNAL */
		writel(2, dev->mmio + LAS0_BURST_START);
		break;
	}
	/* end configuration */

	/*
	 * This doesn't seem to work.  There is no way to clear an interrupt
	 * that the priority controller has queued!
	 */
	writew(~0, dev->mmio + LAS0_CLEAR);
	readw(dev->mmio + LAS0_CLEAR);

	/* TODO: allow multiple interrupt sources */
	/* transfer every N samples */
	writew(IRQM_ADC_ABOUT_CNT, dev->mmio + LAS0_IT);

	/* BUG: start_src is ASSUMED to be TRIG_NOW */
	/* BUG? it seems like things are running before the "start" */
	readl(dev->mmio + LAS0_PACER);	/* start pacer */
	return 0;
}

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

	/* pacer stop source: SOFTWARE */
	writel(0, dev->mmio + LAS0_PACER_STOP);
	writel(0, dev->mmio + LAS0_PACER);	/* stop pacer */
	writel(0, dev->mmio + LAS0_ADC_CONVERSION);
	writew(0, dev->mmio + LAS0_IT);
	devpriv->ai_count = 0;	/* stop and don't transfer any more */
	writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
	return 0;
}

static int rtd_ao_eoc(struct comedi_device *dev,
		      struct comedi_subdevice *s,
		      struct comedi_insn *insn,
		      unsigned long context)
{
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int bit = (chan == 0) ? FS_DAC1_NOT_EMPTY : FS_DAC2_NOT_EMPTY;
	unsigned int status;

	status = readl(dev->mmio + LAS0_ADC);
	if (status & bit)
		return 0;
	return -EBUSY;
}

static int rtd_ao_insn_write(struct comedi_device *dev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn,
			     unsigned int *data)
{
	struct rtd_private *devpriv = dev->private;
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int range = CR_RANGE(insn->chanspec);
	int ret;
	int i;

	/* Configure the output range (table index matches the range values) */
	writew(range & 7, dev->mmio + LAS0_DAC_CTRL(chan));

	for (i = 0; i < insn->n; ++i) {
		unsigned int val = data[i];

		/* bipolar uses 2's complement values with an extended sign */
		if (comedi_range_is_bipolar(s, range)) {
			val = comedi_offset_munge(s, val);
			val |= (val & ((s->maxdata + 1) >> 1)) << 1;
		}

		/* shift the 12-bit data (+ sign) to match the register */
		val <<= 3;

		writew(val, devpriv->las1 + LAS1_DAC_FIFO(chan));
		writew(0, dev->mmio + LAS0_UPDATE_DAC(chan));

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

		s->readback[chan] = data[i];
	}

	return insn->n;
}

static int rtd_dio_insn_bits(struct comedi_device *dev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn,
			     unsigned int *data)
{
	if (comedi_dio_update_state(s, data))
		writew(s->state & 0xff, dev->mmio + LAS0_DIO0);

	data[1] = readw(dev->mmio + LAS0_DIO0) & 0xff;

	return insn->n;
}

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

	ret = comedi_dio_insn_config(dev, s, insn, data, 0);
	if (ret)
		return ret;

	/* TODO support digital match interrupts and strobes */

	/* set direction */
	writew(0x01, dev->mmio + LAS0_DIO_STATUS);
	writew(s->io_bits & 0xff, dev->mmio + LAS0_DIO0_CTRL);

	/* clear interrupts */
	writew(0x00, dev->mmio + LAS0_DIO_STATUS);

	/* port1 can only be all input or all output */

	/* there are also 2 user input lines and 2 user output lines */

	return insn->n;
}

static int rtd_counter_insn_config(struct comedi_device *dev,
				   struct comedi_subdevice *s,
				   struct comedi_insn *insn,
				   unsigned int *data)
{
	struct rtd_private *devpriv = dev->private;
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int max_src;
	unsigned int src;

	switch (data[0]) {
	case INSN_CONFIG_SET_GATE_SRC:
		/*
		 * 8254 Timer/Counter gate sources:
		 *
		 * 0 = Not gated, free running (reset state)
		 * 1 = Gated, off
		 * 2 = Ext. TC Gate 1
		 * 3 = Ext. TC Gate 2
		 * 4 = Previous TC out (chan 1 and 2 only)
		 */
		src = data[2];
		max_src = (chan == 0) ? 3 : 4;
		if (src > max_src)
			return -EINVAL;

		devpriv->timer_gate_src[chan] = src;
		writeb(src, dev->mmio + LAS0_8254_GATE_SEL(chan));
		break;
	case INSN_CONFIG_GET_GATE_SRC:
		data[2] = devpriv->timer_gate_src[chan];
		break;
	case INSN_CONFIG_SET_CLOCK_SRC:
		/*
		 * 8254 Timer/Counter clock sources:
		 *
		 * 0 = 8 MHz (reset state)
		 * 1 = Ext. TC Clock 1
		 * 2 = Ext. TX Clock 2
		 * 3 = Ext. Pacer Clock
		 * 4 = Previous TC out (chan 1 and 2 only)
		 * 5 = High-Speed Digital Input Sampling signal (chan 1 only)
		 */
		src = data[1];
		switch (chan) {
		case 0:
			max_src = 3;
			break;
		case 1:
			max_src = 5;
			break;
		case 2:
			max_src = 4;
			break;
		default:
			return -EINVAL;
		}
		if (src > max_src)
			return -EINVAL;

		devpriv->timer_clk_src[chan] = src;
		writeb(src, dev->mmio + LAS0_8254_CLK_SEL(chan));
		break;
	case INSN_CONFIG_GET_CLOCK_SRC:
		src = devpriv->timer_clk_src[chan];
		data[1] = devpriv->timer_clk_src[chan];
		data[2] = (src == 0) ? RTD_CLOCK_BASE : 0;
		break;
	default:
		return -EINVAL;
	}

	return insn->n;
}

static void rtd_reset(struct comedi_device *dev)
{
	struct rtd_private *devpriv = dev->private;

	writel(0, dev->mmio + LAS0_BOARD_RESET);
	usleep_range(100, 1000);	/* needed? */
	writel(0, devpriv->lcfg + PLX_REG_INTCSR);
	writew(0, dev->mmio + LAS0_IT);
	writew(~0, dev->mmio + LAS0_CLEAR);
	readw(dev->mmio + LAS0_CLEAR);
}

/*
 * initialize board, per RTD spec
 * also, initialize shadow registers
 */
static void rtd_init_board(struct comedi_device *dev)
{
	rtd_reset(dev);

	writel(0, dev->mmio + LAS0_OVERRUN);
	writel(0, dev->mmio + LAS0_CGT_CLEAR);
	writel(0, dev->mmio + LAS0_ADC_FIFO_CLEAR);
	writel(0, dev->mmio + LAS0_DAC_RESET(0));
	writel(0, dev->mmio + LAS0_DAC_RESET(1));
	/* clear digital IO fifo */
	writew(0, dev->mmio + LAS0_DIO_STATUS);
	/* TODO: set user out source ??? */
}

/* The RTD driver does this */
static void rtd_pci_latency_quirk(struct comedi_device *dev,
				  struct pci_dev *pcidev)
{
	unsigned char pci_latency;

	pci_read_config_byte(pcidev, PCI_LATENCY_TIMER, &pci_latency);
	if (pci_latency < 32) {
		dev_info(dev->class_dev,
			 "PCI latency changed from %d to %d\n",
			 pci_latency, 32);
		pci_write_config_byte(pcidev, PCI_LATENCY_TIMER, 32);
	}
}

static int rtd_auto_attach(struct comedi_device *dev,
			   unsigned long context)
{
	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
	const struct rtd_boardinfo *board = NULL;
	struct rtd_private *devpriv;
	struct comedi_subdevice *s;
	int ret;

	if (context < ARRAY_SIZE(rtd520_boards))
		board = &rtd520_boards[context];
	if (!board)
		return -ENODEV;
	dev->board_ptr = board;
	dev->board_name = board->name;

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

	ret = comedi_pci_enable(dev);
	if (ret)
		return ret;

	dev->mmio = pci_ioremap_bar(pcidev, 2);
	devpriv->las1 = pci_ioremap_bar(pcidev, 3);
	devpriv->lcfg = pci_ioremap_bar(pcidev, 0);
	if (!dev->mmio || !devpriv->las1 || !devpriv->lcfg)
		return -ENOMEM;

	rtd_pci_latency_quirk(dev, pcidev);

	if (pcidev->irq) {
		ret = request_irq(pcidev->irq, rtd_interrupt, IRQF_SHARED,
				  dev->board_name, dev);
		if (ret == 0)
			dev->irq = pcidev->irq;
	}

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

	s = &dev->subdevices[0];
	/* analog input subdevice */
	s->type		= COMEDI_SUBD_AI;
	s->subdev_flags	= SDF_READABLE | SDF_GROUND | SDF_COMMON | SDF_DIFF;
	s->n_chan	= 16;
	s->maxdata	= 0x0fff;
	s->range_table	= board->ai_range;
	s->len_chanlist	= RTD_MAX_CHANLIST;
	s->insn_read	= rtd_ai_rinsn;
	if (dev->irq) {
		dev->read_subdev = s;
		s->subdev_flags	|= SDF_CMD_READ;
		s->do_cmd	= rtd_ai_cmd;
		s->do_cmdtest	= rtd_ai_cmdtest;
		s->cancel	= rtd_ai_cancel;
	}

	s = &dev->subdevices[1];
	/* analog output subdevice */
	s->type		= COMEDI_SUBD_AO;
	s->subdev_flags	= SDF_WRITABLE;
	s->n_chan	= 2;
	s->maxdata	= 0x0fff;
	s->range_table	= &rtd_ao_range;
	s->insn_write	= rtd_ao_insn_write;

	ret = comedi_alloc_subdev_readback(s);
	if (ret)
		return ret;

	s = &dev->subdevices[2];
	/* digital i/o subdevice */
	s->type		= COMEDI_SUBD_DIO;
	s->subdev_flags	= SDF_READABLE | SDF_WRITABLE;
	/* we only support port 0 right now.  Ignoring port 1 and user IO */
	s->n_chan	= 8;
	s->maxdata	= 1;
	s->range_table	= &range_digital;
	s->insn_bits	= rtd_dio_insn_bits;
	s->insn_config	= rtd_dio_insn_config;

	/* 8254 Timer/Counter subdevice */
	s = &dev->subdevices[3];
	dev->pacer = comedi_8254_mm_init(dev->mmio + LAS0_8254_TIMER_BASE,
					 RTD_CLOCK_BASE, I8254_IO8, 2);
	if (!dev->pacer)
		return -ENOMEM;

	comedi_8254_subdevice_init(s, dev->pacer);
	dev->pacer->insn_config = rtd_counter_insn_config;

	rtd_init_board(dev);

	ret = rtd520_probe_fifo_depth(dev);
	if (ret < 0)
		return ret;
	devpriv->fifosz = ret;

	if (dev->irq)
		writel(PLX_INTCSR_PIEN | PLX_INTCSR_PLIEN,
		       devpriv->lcfg + PLX_REG_INTCSR);

	return 0;
}

static void rtd_detach(struct comedi_device *dev)
{
	struct rtd_private *devpriv = dev->private;

	if (devpriv) {
		/* Shut down any board ops by resetting it */
		if (dev->mmio && devpriv->lcfg)
			rtd_reset(dev);
		if (dev->irq)
			free_irq(dev->irq, dev);
		if (dev->mmio)
			iounmap(dev->mmio);
		if (devpriv->las1)
			iounmap(devpriv->las1);
		if (devpriv->lcfg)
			iounmap(devpriv->lcfg);
	}
	comedi_pci_disable(dev);
}

static struct comedi_driver rtd520_driver = {
	.driver_name	= "rtd520",
	.module		= THIS_MODULE,
	.auto_attach	= rtd_auto_attach,
	.detach		= rtd_detach,
};

static int rtd520_pci_probe(struct pci_dev *dev,
			    const struct pci_device_id *id)
{
	return comedi_pci_auto_config(dev, &rtd520_driver, id->driver_data);
}

static const struct pci_device_id rtd520_pci_table[] = {
	{ PCI_VDEVICE(RTD, 0x7520), BOARD_DM7520 },
	{ PCI_VDEVICE(RTD, 0x4520), BOARD_PCI4520 },
	{ 0 }
};
MODULE_DEVICE_TABLE(pci, rtd520_pci_table);

static struct pci_driver rtd520_pci_driver = {
	.name		= "rtd520",
	.id_table	= rtd520_pci_table,
	.probe		= rtd520_pci_probe,
	.remove		= comedi_pci_auto_unconfig,
};
module_comedi_pci_driver(rtd520_driver, rtd520_pci_driver);

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