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