1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * quatech_daqp_cs.c
4  * Quatech DAQP PCMCIA data capture cards COMEDI client driver
5  * Copyright (C) 2000, 2003 Brent Baccala <baccala@freesoft.org>
6  * The DAQP interface code in this file is released into the public domain.
7  *
8  * COMEDI - Linux Control and Measurement Device Interface
9  * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
10  * https://www.comedi.org/
11  *
12  * Documentation for the DAQP PCMCIA cards can be found on Quatech's site:
13  *	ftp://ftp.quatech.com/Manuals/daqp-208.pdf
14  *
15  * This manual is for both the DAQP-208 and the DAQP-308.
16  *
17  * What works:
18  * - A/D conversion
19  *	- 8 channels
20  *	- 4 gain ranges
21  *	- ground ref or differential
22  *	- single-shot and timed both supported
23  * - D/A conversion, single-shot
24  * - digital I/O
25  *
26  * What doesn't:
27  * - any kind of triggering - external or D/A channel 1
28  * - the card's optional expansion board
29  * - the card's timer (for anything other than A/D conversion)
30  * - D/A update modes other than immediate (i.e, timed)
31  * - fancier timing modes
32  * - setting card's FIFO buffer thresholds to anything but default
33  */
34 
35 /*
36  * Driver: quatech_daqp_cs
37  * Description: Quatech DAQP PCMCIA data capture cards
38  * Devices: [Quatech] DAQP-208 (daqp), DAQP-308
39  * Author: Brent Baccala <baccala@freesoft.org>
40  * Status: works
41  */
42 
43 #include <linux/module.h>
44 
45 #include "../comedi_pcmcia.h"
46 
47 /*
48  * Register I/O map
49  *
50  * The D/A and timer registers can be accessed with 16-bit or 8-bit I/O
51  * instructions. All other registers can only use 8-bit instructions.
52  *
53  * The FIFO and scanlist registers require two 8-bit instructions to
54  * access the 16-bit data. Data is transferred LSB then MSB.
55  */
56 #define DAQP_AI_FIFO_REG		0x00
57 
58 #define DAQP_SCANLIST_REG		0x01
59 #define DAQP_SCANLIST_DIFFERENTIAL	BIT(14)
60 #define DAQP_SCANLIST_GAIN(x)		(((x) & 0x3) << 12)
61 #define DAQP_SCANLIST_CHANNEL(x)	(((x) & 0xf) << 8)
62 #define DAQP_SCANLIST_START		BIT(7)
63 #define DAQP_SCANLIST_EXT_GAIN(x)	(((x) & 0x3) << 4)
64 #define DAQP_SCANLIST_EXT_CHANNEL(x)	(((x) & 0xf) << 0)
65 
66 #define DAQP_CTRL_REG			0x02
67 #define DAQP_CTRL_PACER_CLK(x)		(((x) & 0x3) << 6)
68 #define DAQP_CTRL_PACER_CLK_EXT		DAQP_CTRL_PACER_CLK(0)
69 #define DAQP_CTRL_PACER_CLK_5MHZ	DAQP_CTRL_PACER_CLK(1)
70 #define DAQP_CTRL_PACER_CLK_1MHZ	DAQP_CTRL_PACER_CLK(2)
71 #define DAQP_CTRL_PACER_CLK_100KHZ	DAQP_CTRL_PACER_CLK(3)
72 #define DAQP_CTRL_EXPANSION		BIT(5)
73 #define DAQP_CTRL_EOS_INT_ENA		BIT(4)
74 #define DAQP_CTRL_FIFO_INT_ENA		BIT(3)
75 #define DAQP_CTRL_TRIG_MODE		BIT(2)	/* 0=one-shot; 1=continuous */
76 #define DAQP_CTRL_TRIG_SRC		BIT(1)	/* 0=internal; 1=external */
77 #define DAQP_CTRL_TRIG_EDGE		BIT(0)	/* 0=rising; 1=falling */
78 
79 #define DAQP_STATUS_REG			0x02
80 #define DAQP_STATUS_IDLE		BIT(7)
81 #define DAQP_STATUS_RUNNING		BIT(6)
82 #define DAQP_STATUS_DATA_LOST		BIT(5)
83 #define DAQP_STATUS_END_OF_SCAN		BIT(4)
84 #define DAQP_STATUS_FIFO_THRESHOLD	BIT(3)
85 #define DAQP_STATUS_FIFO_FULL		BIT(2)
86 #define DAQP_STATUS_FIFO_NEARFULL	BIT(1)
87 #define DAQP_STATUS_FIFO_EMPTY		BIT(0)
88 /* these bits clear when the status register is read */
89 #define DAQP_STATUS_EVENTS		(DAQP_STATUS_DATA_LOST |	\
90 					 DAQP_STATUS_END_OF_SCAN |	\
91 					 DAQP_STATUS_FIFO_THRESHOLD)
92 
93 #define DAQP_DI_REG			0x03
94 #define DAQP_DO_REG			0x03
95 
96 #define DAQP_PACER_LOW_REG		0x04
97 #define DAQP_PACER_MID_REG		0x05
98 #define DAQP_PACER_HIGH_REG		0x06
99 
100 #define DAQP_CMD_REG			0x07
101 /* the monostable bits are self-clearing after the function is complete */
102 #define DAQP_CMD_ARM			BIT(7)	/* monostable */
103 #define DAQP_CMD_RSTF			BIT(6)	/* monostable */
104 #define DAQP_CMD_RSTQ			BIT(5)	/* monostable */
105 #define DAQP_CMD_STOP			BIT(4)	/* monostable */
106 #define DAQP_CMD_LATCH			BIT(3)	/* monostable */
107 #define DAQP_CMD_SCANRATE(x)		(((x) & 0x3) << 1)
108 #define DAQP_CMD_SCANRATE_100KHZ	DAQP_CMD_SCANRATE(0)
109 #define DAQP_CMD_SCANRATE_50KHZ		DAQP_CMD_SCANRATE(1)
110 #define DAQP_CMD_SCANRATE_25KHZ		DAQP_CMD_SCANRATE(2)
111 #define DAQP_CMD_FIFO_DATA		BIT(0)
112 
113 #define DAQP_AO_REG			0x08	/* and 0x09 (16-bit) */
114 
115 #define DAQP_TIMER_REG			0x0a	/* and 0x0b (16-bit) */
116 
117 #define DAQP_AUX_REG			0x0f
118 /* Auxiliary Control register bits (write) */
119 #define DAQP_AUX_EXT_ANALOG_TRIG	BIT(7)
120 #define DAQP_AUX_PRETRIG		BIT(6)
121 #define DAQP_AUX_TIMER_INT_ENA		BIT(5)
122 #define DAQP_AUX_TIMER_MODE(x)		(((x) & 0x3) << 3)
123 #define DAQP_AUX_TIMER_MODE_RELOAD	DAQP_AUX_TIMER_MODE(0)
124 #define DAQP_AUX_TIMER_MODE_PAUSE	DAQP_AUX_TIMER_MODE(1)
125 #define DAQP_AUX_TIMER_MODE_GO		DAQP_AUX_TIMER_MODE(2)
126 #define DAQP_AUX_TIMER_MODE_EXT		DAQP_AUX_TIMER_MODE(3)
127 #define DAQP_AUX_TIMER_CLK_SRC_EXT	BIT(2)
128 #define DAQP_AUX_DA_UPDATE(x)		(((x) & 0x3) << 0)
129 #define DAQP_AUX_DA_UPDATE_DIRECT	DAQP_AUX_DA_UPDATE(0)
130 #define DAQP_AUX_DA_UPDATE_OVERFLOW	DAQP_AUX_DA_UPDATE(1)
131 #define DAQP_AUX_DA_UPDATE_EXTERNAL	DAQP_AUX_DA_UPDATE(2)
132 #define DAQP_AUX_DA_UPDATE_PACER	DAQP_AUX_DA_UPDATE(3)
133 /* Auxiliary Status register bits (read) */
134 #define DAQP_AUX_RUNNING		BIT(7)
135 #define DAQP_AUX_TRIGGERED		BIT(6)
136 #define DAQP_AUX_DA_BUFFER		BIT(5)
137 #define DAQP_AUX_TIMER_OVERFLOW		BIT(4)
138 #define DAQP_AUX_CONVERSION		BIT(3)
139 #define DAQP_AUX_DATA_LOST		BIT(2)
140 #define DAQP_AUX_FIFO_NEARFULL		BIT(1)
141 #define DAQP_AUX_FIFO_EMPTY		BIT(0)
142 
143 #define DAQP_FIFO_SIZE			4096
144 
145 #define DAQP_MAX_TIMER_SPEED		10000	/* 100 kHz in nanoseconds */
146 
147 struct daqp_private {
148 	unsigned int pacer_div;
149 	int stop;
150 };
151 
152 static const struct comedi_lrange range_daqp_ai = {
153 	4, {
154 		BIP_RANGE(10),
155 		BIP_RANGE(5),
156 		BIP_RANGE(2.5),
157 		BIP_RANGE(1.25)
158 	}
159 };
160 
161 static int daqp_clear_events(struct comedi_device *dev, int loops)
162 {
163 	unsigned int status;
164 
165 	/*
166 	 * Reset any pending interrupts (my card has a tendency to require
167 	 * multiple reads on the status register to achieve this).
168 	 */
169 	while (--loops) {
170 		status = inb(dev->iobase + DAQP_STATUS_REG);
171 		if ((status & DAQP_STATUS_EVENTS) == 0)
172 			return 0;
173 	}
174 	dev_err(dev->class_dev, "couldn't clear events in status register\n");
175 	return -EBUSY;
176 }
177 
178 static int daqp_ai_cancel(struct comedi_device *dev,
179 			  struct comedi_subdevice *s)
180 {
181 	struct daqp_private *devpriv = dev->private;
182 
183 	if (devpriv->stop)
184 		return -EIO;
185 
186 	/*
187 	 * Stop any conversions, disable interrupts, and clear
188 	 * the status event flags.
189 	 */
190 	outb(DAQP_CMD_STOP, dev->iobase + DAQP_CMD_REG);
191 	outb(0, dev->iobase + DAQP_CTRL_REG);
192 	inb(dev->iobase + DAQP_STATUS_REG);
193 
194 	return 0;
195 }
196 
197 static unsigned int daqp_ai_get_sample(struct comedi_device *dev,
198 				       struct comedi_subdevice *s)
199 {
200 	unsigned int val;
201 
202 	/*
203 	 * Get a two's complement sample from the FIFO and
204 	 * return the munged offset binary value.
205 	 */
206 	val = inb(dev->iobase + DAQP_AI_FIFO_REG);
207 	val |= inb(dev->iobase + DAQP_AI_FIFO_REG) << 8;
208 	return comedi_offset_munge(s, val);
209 }
210 
211 static irqreturn_t daqp_interrupt(int irq, void *dev_id)
212 {
213 	struct comedi_device *dev = dev_id;
214 	struct comedi_subdevice *s = dev->read_subdev;
215 	struct comedi_cmd *cmd = &s->async->cmd;
216 	int loop_limit = 10000;
217 	int status;
218 
219 	if (!dev->attached)
220 		return IRQ_NONE;
221 
222 	status = inb(dev->iobase + DAQP_STATUS_REG);
223 	if (!(status & DAQP_STATUS_EVENTS))
224 		return IRQ_NONE;
225 
226 	while (!(status & DAQP_STATUS_FIFO_EMPTY)) {
227 		unsigned short data;
228 
229 		if (status & DAQP_STATUS_DATA_LOST) {
230 			s->async->events |= COMEDI_CB_OVERFLOW;
231 			dev_warn(dev->class_dev, "data lost\n");
232 			break;
233 		}
234 
235 		data = daqp_ai_get_sample(dev, s);
236 		comedi_buf_write_samples(s, &data, 1);
237 
238 		if (cmd->stop_src == TRIG_COUNT &&
239 		    s->async->scans_done >= cmd->stop_arg) {
240 			s->async->events |= COMEDI_CB_EOA;
241 			break;
242 		}
243 
244 		if ((loop_limit--) <= 0)
245 			break;
246 
247 		status = inb(dev->iobase + DAQP_STATUS_REG);
248 	}
249 
250 	if (loop_limit <= 0) {
251 		dev_warn(dev->class_dev,
252 			 "loop_limit reached in %s()\n", __func__);
253 		s->async->events |= COMEDI_CB_ERROR;
254 	}
255 
256 	comedi_handle_events(dev, s);
257 
258 	return IRQ_HANDLED;
259 }
260 
261 static void daqp_ai_set_one_scanlist_entry(struct comedi_device *dev,
262 					   unsigned int chanspec,
263 					   int start)
264 {
265 	unsigned int chan = CR_CHAN(chanspec);
266 	unsigned int range = CR_RANGE(chanspec);
267 	unsigned int aref = CR_AREF(chanspec);
268 	unsigned int val;
269 
270 	val = DAQP_SCANLIST_CHANNEL(chan) | DAQP_SCANLIST_GAIN(range);
271 
272 	if (aref == AREF_DIFF)
273 		val |= DAQP_SCANLIST_DIFFERENTIAL;
274 
275 	if (start)
276 		val |= DAQP_SCANLIST_START;
277 
278 	outb(val & 0xff, dev->iobase + DAQP_SCANLIST_REG);
279 	outb((val >> 8) & 0xff, dev->iobase + DAQP_SCANLIST_REG);
280 }
281 
282 static int daqp_ai_eos(struct comedi_device *dev,
283 		       struct comedi_subdevice *s,
284 		       struct comedi_insn *insn,
285 		       unsigned long context)
286 {
287 	unsigned int status;
288 
289 	status = inb(dev->iobase + DAQP_AUX_REG);
290 	if (status & DAQP_AUX_CONVERSION)
291 		return 0;
292 	return -EBUSY;
293 }
294 
295 static int daqp_ai_insn_read(struct comedi_device *dev,
296 			     struct comedi_subdevice *s,
297 			     struct comedi_insn *insn,
298 			     unsigned int *data)
299 {
300 	struct daqp_private *devpriv = dev->private;
301 	int ret = 0;
302 	int i;
303 
304 	if (devpriv->stop)
305 		return -EIO;
306 
307 	outb(0, dev->iobase + DAQP_AUX_REG);
308 
309 	/* Reset scan list queue */
310 	outb(DAQP_CMD_RSTQ, dev->iobase + DAQP_CMD_REG);
311 
312 	/* Program one scan list entry */
313 	daqp_ai_set_one_scanlist_entry(dev, insn->chanspec, 1);
314 
315 	/* Reset data FIFO (see page 28 of DAQP User's Manual) */
316 	outb(DAQP_CMD_RSTF, dev->iobase + DAQP_CMD_REG);
317 
318 	/* Set trigger - one-shot, internal, no interrupts */
319 	outb(DAQP_CTRL_PACER_CLK_100KHZ, dev->iobase + DAQP_CTRL_REG);
320 
321 	ret = daqp_clear_events(dev, 10000);
322 	if (ret)
323 		return ret;
324 
325 	for (i = 0; i < insn->n; i++) {
326 		/* Start conversion */
327 		outb(DAQP_CMD_ARM | DAQP_CMD_FIFO_DATA,
328 		     dev->iobase + DAQP_CMD_REG);
329 
330 		ret = comedi_timeout(dev, s, insn, daqp_ai_eos, 0);
331 		if (ret)
332 			break;
333 
334 		/* clear the status event flags */
335 		inb(dev->iobase + DAQP_STATUS_REG);
336 
337 		data[i] = daqp_ai_get_sample(dev, s);
338 	}
339 
340 	/* stop any conversions and clear the status event flags */
341 	outb(DAQP_CMD_STOP, dev->iobase + DAQP_CMD_REG);
342 	inb(dev->iobase + DAQP_STATUS_REG);
343 
344 	return ret ? ret : insn->n;
345 }
346 
347 /* This function converts ns nanoseconds to a counter value suitable
348  * for programming the device.  We always use the DAQP's 5 MHz clock,
349  * which with its 24-bit counter, allows values up to 84 seconds.
350  * Also, the function adjusts ns so that it cooresponds to the actual
351  * time that the device will use.
352  */
353 
354 static int daqp_ns_to_timer(unsigned int *ns, unsigned int flags)
355 {
356 	int timer;
357 
358 	timer = *ns / 200;
359 	*ns = timer * 200;
360 
361 	return timer;
362 }
363 
364 static void daqp_set_pacer(struct comedi_device *dev, unsigned int val)
365 {
366 	outb(val & 0xff, dev->iobase + DAQP_PACER_LOW_REG);
367 	outb((val >> 8) & 0xff, dev->iobase + DAQP_PACER_MID_REG);
368 	outb((val >> 16) & 0xff, dev->iobase + DAQP_PACER_HIGH_REG);
369 }
370 
371 static int daqp_ai_cmdtest(struct comedi_device *dev,
372 			   struct comedi_subdevice *s,
373 			   struct comedi_cmd *cmd)
374 {
375 	struct daqp_private *devpriv = dev->private;
376 	int err = 0;
377 	unsigned int arg;
378 
379 	/* Step 1 : check if triggers are trivially valid */
380 
381 	err |= comedi_check_trigger_src(&cmd->start_src, TRIG_NOW);
382 	err |= comedi_check_trigger_src(&cmd->scan_begin_src,
383 					TRIG_TIMER | TRIG_FOLLOW);
384 	err |= comedi_check_trigger_src(&cmd->convert_src,
385 					TRIG_TIMER | TRIG_NOW);
386 	err |= comedi_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
387 	err |= comedi_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
388 
389 	if (err)
390 		return 1;
391 
392 	/* Step 2a : make sure trigger sources are unique */
393 
394 	err |= comedi_check_trigger_is_unique(cmd->scan_begin_src);
395 	err |= comedi_check_trigger_is_unique(cmd->convert_src);
396 	err |= comedi_check_trigger_is_unique(cmd->stop_src);
397 
398 	/* Step 2b : and mutually compatible */
399 
400 	/* the async command requires a pacer */
401 	if (cmd->scan_begin_src != TRIG_TIMER && cmd->convert_src != TRIG_TIMER)
402 		err |= -EINVAL;
403 
404 	if (err)
405 		return 2;
406 
407 	/* Step 3: check if arguments are trivially valid */
408 
409 	err |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);
410 
411 	err |= comedi_check_trigger_arg_min(&cmd->chanlist_len, 1);
412 	err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg,
413 					   cmd->chanlist_len);
414 
415 	if (cmd->scan_begin_src == TRIG_TIMER)
416 		err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
417 						    DAQP_MAX_TIMER_SPEED);
418 
419 	if (cmd->convert_src == TRIG_TIMER) {
420 		err |= comedi_check_trigger_arg_min(&cmd->convert_arg,
421 						    DAQP_MAX_TIMER_SPEED);
422 
423 		if (cmd->scan_begin_src == TRIG_TIMER) {
424 			/*
425 			 * If both scan_begin and convert are both timer
426 			 * values, the only way that can make sense is if
427 			 * the scan time is the number of conversions times
428 			 * the convert time.
429 			 */
430 			arg = cmd->convert_arg * cmd->scan_end_arg;
431 			err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg,
432 							   arg);
433 		}
434 	}
435 
436 	if (cmd->stop_src == TRIG_COUNT)
437 		err |= comedi_check_trigger_arg_max(&cmd->stop_arg, 0x00ffffff);
438 	else	/* TRIG_NONE */
439 		err |= comedi_check_trigger_arg_is(&cmd->stop_arg, 0);
440 
441 	if (err)
442 		return 3;
443 
444 	/* step 4: fix up any arguments */
445 
446 	if (cmd->convert_src == TRIG_TIMER) {
447 		arg = cmd->convert_arg;
448 		devpriv->pacer_div = daqp_ns_to_timer(&arg, cmd->flags);
449 		err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);
450 	} else if (cmd->scan_begin_src == TRIG_TIMER) {
451 		arg = cmd->scan_begin_arg;
452 		devpriv->pacer_div = daqp_ns_to_timer(&arg, cmd->flags);
453 		err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
454 	}
455 
456 	if (err)
457 		return 4;
458 
459 	return 0;
460 }
461 
462 static int daqp_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
463 {
464 	struct daqp_private *devpriv = dev->private;
465 	struct comedi_cmd *cmd = &s->async->cmd;
466 	int scanlist_start_on_every_entry;
467 	int threshold;
468 	int ret;
469 	int i;
470 
471 	if (devpriv->stop)
472 		return -EIO;
473 
474 	outb(0, dev->iobase + DAQP_AUX_REG);
475 
476 	/* Reset scan list queue */
477 	outb(DAQP_CMD_RSTQ, dev->iobase + DAQP_CMD_REG);
478 
479 	/* Program pacer clock
480 	 *
481 	 * There's two modes we can operate in.  If convert_src is
482 	 * TRIG_TIMER, then convert_arg specifies the time between
483 	 * each conversion, so we program the pacer clock to that
484 	 * frequency and set the SCANLIST_START bit on every scanlist
485 	 * entry.  Otherwise, convert_src is TRIG_NOW, which means
486 	 * we want the fastest possible conversions, scan_begin_src
487 	 * is TRIG_TIMER, and scan_begin_arg specifies the time between
488 	 * each scan, so we program the pacer clock to this frequency
489 	 * and only set the SCANLIST_START bit on the first entry.
490 	 */
491 	daqp_set_pacer(dev, devpriv->pacer_div);
492 
493 	if (cmd->convert_src == TRIG_TIMER)
494 		scanlist_start_on_every_entry = 1;
495 	else
496 		scanlist_start_on_every_entry = 0;
497 
498 	/* Program scan list */
499 	for (i = 0; i < cmd->chanlist_len; i++) {
500 		int start = (i == 0 || scanlist_start_on_every_entry);
501 
502 		daqp_ai_set_one_scanlist_entry(dev, cmd->chanlist[i], start);
503 	}
504 
505 	/* Now it's time to program the FIFO threshold, basically the
506 	 * number of samples the card will buffer before it interrupts
507 	 * the CPU.
508 	 *
509 	 * If we don't have a stop count, then use half the size of
510 	 * the FIFO (the manufacturer's recommendation).  Consider
511 	 * that the FIFO can hold 2K samples (4K bytes).  With the
512 	 * threshold set at half the FIFO size, we have a margin of
513 	 * error of 1024 samples.  At the chip's maximum sample rate
514 	 * of 100,000 Hz, the CPU would have to delay interrupt
515 	 * service for a full 10 milliseconds in order to lose data
516 	 * here (as opposed to higher up in the kernel).  I've never
517 	 * seen it happen.  However, for slow sample rates it may
518 	 * buffer too much data and introduce too much delay for the
519 	 * user application.
520 	 *
521 	 * If we have a stop count, then things get more interesting.
522 	 * If the stop count is less than the FIFO size (actually
523 	 * three-quarters of the FIFO size - see below), we just use
524 	 * the stop count itself as the threshold, the card interrupts
525 	 * us when that many samples have been taken, and we kill the
526 	 * acquisition at that point and are done.  If the stop count
527 	 * is larger than that, then we divide it by 2 until it's less
528 	 * than three quarters of the FIFO size (we always leave the
529 	 * top quarter of the FIFO as protection against sluggish CPU
530 	 * interrupt response) and use that as the threshold.  So, if
531 	 * the stop count is 4000 samples, we divide by two twice to
532 	 * get 1000 samples, use that as the threshold, take four
533 	 * interrupts to get our 4000 samples and are done.
534 	 *
535 	 * The algorithm could be more clever.  For example, if 81000
536 	 * samples are requested, we could set the threshold to 1500
537 	 * samples and take 54 interrupts to get 81000.  But 54 isn't
538 	 * a power of two, so this algorithm won't find that option.
539 	 * Instead, it'll set the threshold at 1266 and take 64
540 	 * interrupts to get 81024 samples, of which the last 24 will
541 	 * be discarded... but we won't get the last interrupt until
542 	 * they've been collected.  To find the first option, the
543 	 * computer could look at the prime decomposition of the
544 	 * sample count (81000 = 3^4 * 5^3 * 2^3) and factor it into a
545 	 * threshold (1500 = 3 * 5^3 * 2^2) and an interrupt count (54
546 	 * = 3^3 * 2).  Hmmm... a one-line while loop or prime
547 	 * decomposition of integers... I'll leave it the way it is.
548 	 *
549 	 * I'll also note a mini-race condition before ignoring it in
550 	 * the code.  Let's say we're taking 4000 samples, as before.
551 	 * After 1000 samples, we get an interrupt.  But before that
552 	 * interrupt is completely serviced, another sample is taken
553 	 * and loaded into the FIFO.  Since the interrupt handler
554 	 * empties the FIFO before returning, it will read 1001 samples.
555 	 * If that happens four times, we'll end up taking 4004 samples,
556 	 * not 4000.  The interrupt handler will discard the extra four
557 	 * samples (by halting the acquisition with four samples still
558 	 * in the FIFO), but we will have to wait for them.
559 	 *
560 	 * In short, this code works pretty well, but for either of
561 	 * the two reasons noted, might end up waiting for a few more
562 	 * samples than actually requested.  Shouldn't make too much
563 	 * of a difference.
564 	 */
565 
566 	/* Save away the number of conversions we should perform, and
567 	 * compute the FIFO threshold (in bytes, not samples - that's
568 	 * why we multiple devpriv->count by 2 = sizeof(sample))
569 	 */
570 
571 	if (cmd->stop_src == TRIG_COUNT) {
572 		unsigned long long nsamples;
573 		unsigned long long nbytes;
574 
575 		nsamples = (unsigned long long)cmd->stop_arg *
576 			   cmd->scan_end_arg;
577 		nbytes = nsamples * comedi_bytes_per_sample(s);
578 		while (nbytes > DAQP_FIFO_SIZE * 3 / 4)
579 			nbytes /= 2;
580 		threshold = nbytes;
581 	} else {
582 		threshold = DAQP_FIFO_SIZE / 2;
583 	}
584 
585 	/* Reset data FIFO (see page 28 of DAQP User's Manual) */
586 
587 	outb(DAQP_CMD_RSTF, dev->iobase + DAQP_CMD_REG);
588 
589 	/* Set FIFO threshold.  First two bytes are near-empty
590 	 * threshold, which is unused; next two bytes are near-full
591 	 * threshold.  We computed the number of bytes we want in the
592 	 * FIFO when the interrupt is generated, what the card wants
593 	 * is actually the number of available bytes left in the FIFO
594 	 * when the interrupt is to happen.
595 	 */
596 
597 	outb(0x00, dev->iobase + DAQP_AI_FIFO_REG);
598 	outb(0x00, dev->iobase + DAQP_AI_FIFO_REG);
599 
600 	outb((DAQP_FIFO_SIZE - threshold) & 0xff,
601 	     dev->iobase + DAQP_AI_FIFO_REG);
602 	outb((DAQP_FIFO_SIZE - threshold) >> 8, dev->iobase + DAQP_AI_FIFO_REG);
603 
604 	/* Set trigger - continuous, internal */
605 	outb(DAQP_CTRL_TRIG_MODE | DAQP_CTRL_PACER_CLK_5MHZ |
606 	     DAQP_CTRL_FIFO_INT_ENA, dev->iobase + DAQP_CTRL_REG);
607 
608 	ret = daqp_clear_events(dev, 100);
609 	if (ret)
610 		return ret;
611 
612 	/* Start conversion */
613 	outb(DAQP_CMD_ARM | DAQP_CMD_FIFO_DATA, dev->iobase + DAQP_CMD_REG);
614 
615 	return 0;
616 }
617 
618 static int daqp_ao_empty(struct comedi_device *dev,
619 			 struct comedi_subdevice *s,
620 			 struct comedi_insn *insn,
621 			 unsigned long context)
622 {
623 	unsigned int status;
624 
625 	status = inb(dev->iobase + DAQP_AUX_REG);
626 	if ((status & DAQP_AUX_DA_BUFFER) == 0)
627 		return 0;
628 	return -EBUSY;
629 }
630 
631 static int daqp_ao_insn_write(struct comedi_device *dev,
632 			      struct comedi_subdevice *s,
633 			      struct comedi_insn *insn,
634 			      unsigned int *data)
635 {
636 	struct daqp_private *devpriv = dev->private;
637 	unsigned int chan = CR_CHAN(insn->chanspec);
638 	int i;
639 
640 	if (devpriv->stop)
641 		return -EIO;
642 
643 	/* Make sure D/A update mode is direct update */
644 	outb(0, dev->iobase + DAQP_AUX_REG);
645 
646 	for (i = 0; i < insn->n; i++) {
647 		unsigned int val = data[i];
648 		int ret;
649 
650 		/* D/A transfer rate is about 8ms */
651 		ret = comedi_timeout(dev, s, insn, daqp_ao_empty, 0);
652 		if (ret)
653 			return ret;
654 
655 		/* write the two's complement value to the channel */
656 		outw((chan << 12) | comedi_offset_munge(s, val),
657 		     dev->iobase + DAQP_AO_REG);
658 
659 		s->readback[chan] = val;
660 	}
661 
662 	return insn->n;
663 }
664 
665 static int daqp_di_insn_bits(struct comedi_device *dev,
666 			     struct comedi_subdevice *s,
667 			     struct comedi_insn *insn,
668 			     unsigned int *data)
669 {
670 	struct daqp_private *devpriv = dev->private;
671 
672 	if (devpriv->stop)
673 		return -EIO;
674 
675 	data[0] = inb(dev->iobase + DAQP_DI_REG);
676 
677 	return insn->n;
678 }
679 
680 static int daqp_do_insn_bits(struct comedi_device *dev,
681 			     struct comedi_subdevice *s,
682 			     struct comedi_insn *insn,
683 			     unsigned int *data)
684 {
685 	struct daqp_private *devpriv = dev->private;
686 
687 	if (devpriv->stop)
688 		return -EIO;
689 
690 	if (comedi_dio_update_state(s, data))
691 		outb(s->state, dev->iobase + DAQP_DO_REG);
692 
693 	data[1] = s->state;
694 
695 	return insn->n;
696 }
697 
698 static int daqp_auto_attach(struct comedi_device *dev,
699 			    unsigned long context)
700 {
701 	struct pcmcia_device *link = comedi_to_pcmcia_dev(dev);
702 	struct daqp_private *devpriv;
703 	struct comedi_subdevice *s;
704 	int ret;
705 
706 	devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
707 	if (!devpriv)
708 		return -ENOMEM;
709 
710 	link->config_flags |= CONF_AUTO_SET_IO | CONF_ENABLE_IRQ;
711 	ret = comedi_pcmcia_enable(dev, NULL);
712 	if (ret)
713 		return ret;
714 	dev->iobase = link->resource[0]->start;
715 
716 	link->priv = dev;
717 	ret = pcmcia_request_irq(link, daqp_interrupt);
718 	if (ret == 0)
719 		dev->irq = link->irq;
720 
721 	ret = comedi_alloc_subdevices(dev, 4);
722 	if (ret)
723 		return ret;
724 
725 	s = &dev->subdevices[0];
726 	s->type		= COMEDI_SUBD_AI;
727 	s->subdev_flags	= SDF_READABLE | SDF_GROUND | SDF_DIFF;
728 	s->n_chan	= 8;
729 	s->maxdata	= 0xffff;
730 	s->range_table	= &range_daqp_ai;
731 	s->insn_read	= daqp_ai_insn_read;
732 	if (dev->irq) {
733 		dev->read_subdev = s;
734 		s->subdev_flags	|= SDF_CMD_READ;
735 		s->len_chanlist	= 2048;
736 		s->do_cmdtest	= daqp_ai_cmdtest;
737 		s->do_cmd	= daqp_ai_cmd;
738 		s->cancel	= daqp_ai_cancel;
739 	}
740 
741 	s = &dev->subdevices[1];
742 	s->type		= COMEDI_SUBD_AO;
743 	s->subdev_flags	= SDF_WRITABLE;
744 	s->n_chan	= 2;
745 	s->maxdata	= 0x0fff;
746 	s->range_table	= &range_bipolar5;
747 	s->insn_write	= daqp_ao_insn_write;
748 
749 	ret = comedi_alloc_subdev_readback(s);
750 	if (ret)
751 		return ret;
752 
753 	/*
754 	 * Digital Input subdevice
755 	 * NOTE: The digital input lines are shared:
756 	 *
757 	 * Chan  Normal Mode        Expansion Mode
758 	 * ----  -----------------  ----------------------------
759 	 *  0    DI0, ext. trigger  Same as normal mode
760 	 *  1    DI1                External gain select, lo bit
761 	 *  2    DI2, ext. clock    Same as normal mode
762 	 *  3    DI3                External gain select, hi bit
763 	 */
764 	s = &dev->subdevices[2];
765 	s->type		= COMEDI_SUBD_DI;
766 	s->subdev_flags	= SDF_READABLE;
767 	s->n_chan	= 4;
768 	s->maxdata	= 1;
769 	s->insn_bits	= daqp_di_insn_bits;
770 
771 	/*
772 	 * Digital Output subdevice
773 	 * NOTE: The digital output lines share the same pins on the
774 	 * interface connector as the four external channel selection
775 	 * bits. If expansion mode is used the digital outputs do not
776 	 * work.
777 	 */
778 	s = &dev->subdevices[3];
779 	s->type		= COMEDI_SUBD_DO;
780 	s->subdev_flags	= SDF_WRITABLE;
781 	s->n_chan	= 4;
782 	s->maxdata	= 1;
783 	s->insn_bits	= daqp_do_insn_bits;
784 
785 	return 0;
786 }
787 
788 static struct comedi_driver driver_daqp = {
789 	.driver_name	= "quatech_daqp_cs",
790 	.module		= THIS_MODULE,
791 	.auto_attach	= daqp_auto_attach,
792 	.detach		= comedi_pcmcia_disable,
793 };
794 
795 static int daqp_cs_suspend(struct pcmcia_device *link)
796 {
797 	struct comedi_device *dev = link->priv;
798 	struct daqp_private *devpriv = dev ? dev->private : NULL;
799 
800 	/* Mark the device as stopped, to block IO until later */
801 	if (devpriv)
802 		devpriv->stop = 1;
803 
804 	return 0;
805 }
806 
807 static int daqp_cs_resume(struct pcmcia_device *link)
808 {
809 	struct comedi_device *dev = link->priv;
810 	struct daqp_private *devpriv = dev ? dev->private : NULL;
811 
812 	if (devpriv)
813 		devpriv->stop = 0;
814 
815 	return 0;
816 }
817 
818 static int daqp_cs_attach(struct pcmcia_device *link)
819 {
820 	return comedi_pcmcia_auto_config(link, &driver_daqp);
821 }
822 
823 static const struct pcmcia_device_id daqp_cs_id_table[] = {
824 	PCMCIA_DEVICE_MANF_CARD(0x0137, 0x0027),
825 	PCMCIA_DEVICE_NULL
826 };
827 MODULE_DEVICE_TABLE(pcmcia, daqp_cs_id_table);
828 
829 static struct pcmcia_driver daqp_cs_driver = {
830 	.name		= "quatech_daqp_cs",
831 	.owner		= THIS_MODULE,
832 	.id_table	= daqp_cs_id_table,
833 	.probe		= daqp_cs_attach,
834 	.remove		= comedi_pcmcia_auto_unconfig,
835 	.suspend	= daqp_cs_suspend,
836 	.resume		= daqp_cs_resume,
837 };
838 module_comedi_pcmcia_driver(driver_daqp, daqp_cs_driver);
839 
840 MODULE_DESCRIPTION("Comedi driver for Quatech DAQP PCMCIA data capture cards");
841 MODULE_AUTHOR("Brent Baccala <baccala@freesoft.org>");
842 MODULE_LICENSE("GPL");
843