xref: /linux/drivers/counter/104-quad-8.c (revision 662fa3d6099374c4615bf64d06895e3573b935b2)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Counter driver for the ACCES 104-QUAD-8
4  * Copyright (C) 2016 William Breathitt Gray
5  *
6  * This driver supports the ACCES 104-QUAD-8 and ACCES 104-QUAD-4.
7  */
8 #include <linux/bitops.h>
9 #include <linux/counter.h>
10 #include <linux/device.h>
11 #include <linux/errno.h>
12 #include <linux/io.h>
13 #include <linux/ioport.h>
14 #include <linux/isa.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/types.h>
19 
20 #define QUAD8_EXTENT 32
21 
22 static unsigned int base[max_num_isa_dev(QUAD8_EXTENT)];
23 static unsigned int num_quad8;
24 module_param_hw_array(base, uint, ioport, &num_quad8, 0);
25 MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
26 
27 #define QUAD8_NUM_COUNTERS 8
28 
29 /**
30  * struct quad8 - device private data structure
31  * @counter:		instance of the counter_device
32  * @fck_prescaler:	array of filter clock prescaler configurations
33  * @preset:		array of preset values
34  * @count_mode:		array of count mode configurations
35  * @quadrature_mode:	array of quadrature mode configurations
36  * @quadrature_scale:	array of quadrature mode scale configurations
37  * @ab_enable:		array of A and B inputs enable configurations
38  * @preset_enable:	array of set_to_preset_on_index attribute configurations
39  * @synchronous_mode:	array of index function synchronous mode configurations
40  * @index_polarity:	array of index function polarity configurations
41  * @cable_fault_enable:	differential encoder cable status enable configurations
42  * @base:		base port address of the device
43  */
44 struct quad8 {
45 	struct mutex lock;
46 	struct counter_device counter;
47 	unsigned int fck_prescaler[QUAD8_NUM_COUNTERS];
48 	unsigned int preset[QUAD8_NUM_COUNTERS];
49 	unsigned int count_mode[QUAD8_NUM_COUNTERS];
50 	unsigned int quadrature_mode[QUAD8_NUM_COUNTERS];
51 	unsigned int quadrature_scale[QUAD8_NUM_COUNTERS];
52 	unsigned int ab_enable[QUAD8_NUM_COUNTERS];
53 	unsigned int preset_enable[QUAD8_NUM_COUNTERS];
54 	unsigned int synchronous_mode[QUAD8_NUM_COUNTERS];
55 	unsigned int index_polarity[QUAD8_NUM_COUNTERS];
56 	unsigned int cable_fault_enable;
57 	unsigned int base;
58 };
59 
60 #define QUAD8_REG_CHAN_OP 0x11
61 #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16
62 #define QUAD8_DIFF_ENCODER_CABLE_STATUS 0x17
63 /* Borrow Toggle flip-flop */
64 #define QUAD8_FLAG_BT BIT(0)
65 /* Carry Toggle flip-flop */
66 #define QUAD8_FLAG_CT BIT(1)
67 /* Error flag */
68 #define QUAD8_FLAG_E BIT(4)
69 /* Up/Down flag */
70 #define QUAD8_FLAG_UD BIT(5)
71 /* Reset and Load Signal Decoders */
72 #define QUAD8_CTR_RLD 0x00
73 /* Counter Mode Register */
74 #define QUAD8_CTR_CMR 0x20
75 /* Input / Output Control Register */
76 #define QUAD8_CTR_IOR 0x40
77 /* Index Control Register */
78 #define QUAD8_CTR_IDR 0x60
79 /* Reset Byte Pointer (three byte data pointer) */
80 #define QUAD8_RLD_RESET_BP 0x01
81 /* Reset Counter */
82 #define QUAD8_RLD_RESET_CNTR 0x02
83 /* Reset Borrow Toggle, Carry Toggle, Compare Toggle, and Sign flags */
84 #define QUAD8_RLD_RESET_FLAGS 0x04
85 /* Reset Error flag */
86 #define QUAD8_RLD_RESET_E 0x06
87 /* Preset Register to Counter */
88 #define QUAD8_RLD_PRESET_CNTR 0x08
89 /* Transfer Counter to Output Latch */
90 #define QUAD8_RLD_CNTR_OUT 0x10
91 /* Transfer Preset Register LSB to FCK Prescaler */
92 #define QUAD8_RLD_PRESET_PSC 0x18
93 #define QUAD8_CHAN_OP_ENABLE_COUNTERS 0x00
94 #define QUAD8_CHAN_OP_RESET_COUNTERS 0x01
95 #define QUAD8_CMR_QUADRATURE_X1 0x08
96 #define QUAD8_CMR_QUADRATURE_X2 0x10
97 #define QUAD8_CMR_QUADRATURE_X4 0x18
98 
99 static int quad8_signal_read(struct counter_device *counter,
100 	struct counter_signal *signal, enum counter_signal_value *val)
101 {
102 	const struct quad8 *const priv = counter->priv;
103 	unsigned int state;
104 
105 	/* Only Index signal levels can be read */
106 	if (signal->id < 16)
107 		return -EINVAL;
108 
109 	state = inb(priv->base + QUAD8_REG_INDEX_INPUT_LEVELS)
110 		& BIT(signal->id - 16);
111 
112 	*val = (state) ? COUNTER_SIGNAL_HIGH : COUNTER_SIGNAL_LOW;
113 
114 	return 0;
115 }
116 
117 static int quad8_count_read(struct counter_device *counter,
118 	struct counter_count *count, unsigned long *val)
119 {
120 	struct quad8 *const priv = counter->priv;
121 	const int base_offset = priv->base + 2 * count->id;
122 	unsigned int flags;
123 	unsigned int borrow;
124 	unsigned int carry;
125 	int i;
126 
127 	flags = inb(base_offset + 1);
128 	borrow = flags & QUAD8_FLAG_BT;
129 	carry = !!(flags & QUAD8_FLAG_CT);
130 
131 	/* Borrow XOR Carry effectively doubles count range */
132 	*val = (unsigned long)(borrow ^ carry) << 24;
133 
134 	mutex_lock(&priv->lock);
135 
136 	/* Reset Byte Pointer; transfer Counter to Output Latch */
137 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_CNTR_OUT,
138 	     base_offset + 1);
139 
140 	for (i = 0; i < 3; i++)
141 		*val |= (unsigned long)inb(base_offset) << (8 * i);
142 
143 	mutex_unlock(&priv->lock);
144 
145 	return 0;
146 }
147 
148 static int quad8_count_write(struct counter_device *counter,
149 	struct counter_count *count, unsigned long val)
150 {
151 	struct quad8 *const priv = counter->priv;
152 	const int base_offset = priv->base + 2 * count->id;
153 	int i;
154 
155 	/* Only 24-bit values are supported */
156 	if (val > 0xFFFFFF)
157 		return -EINVAL;
158 
159 	mutex_lock(&priv->lock);
160 
161 	/* Reset Byte Pointer */
162 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
163 
164 	/* Counter can only be set via Preset Register */
165 	for (i = 0; i < 3; i++)
166 		outb(val >> (8 * i), base_offset);
167 
168 	/* Transfer Preset Register to Counter */
169 	outb(QUAD8_CTR_RLD | QUAD8_RLD_PRESET_CNTR, base_offset + 1);
170 
171 	/* Reset Byte Pointer */
172 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
173 
174 	/* Set Preset Register back to original value */
175 	val = priv->preset[count->id];
176 	for (i = 0; i < 3; i++)
177 		outb(val >> (8 * i), base_offset);
178 
179 	/* Reset Borrow, Carry, Compare, and Sign flags */
180 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_FLAGS, base_offset + 1);
181 	/* Reset Error flag */
182 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_E, base_offset + 1);
183 
184 	mutex_unlock(&priv->lock);
185 
186 	return 0;
187 }
188 
189 enum quad8_count_function {
190 	QUAD8_COUNT_FUNCTION_PULSE_DIRECTION = 0,
191 	QUAD8_COUNT_FUNCTION_QUADRATURE_X1,
192 	QUAD8_COUNT_FUNCTION_QUADRATURE_X2,
193 	QUAD8_COUNT_FUNCTION_QUADRATURE_X4
194 };
195 
196 static const enum counter_count_function quad8_count_functions_list[] = {
197 	[QUAD8_COUNT_FUNCTION_PULSE_DIRECTION] = COUNTER_COUNT_FUNCTION_PULSE_DIRECTION,
198 	[QUAD8_COUNT_FUNCTION_QUADRATURE_X1] = COUNTER_COUNT_FUNCTION_QUADRATURE_X1_A,
199 	[QUAD8_COUNT_FUNCTION_QUADRATURE_X2] = COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A,
200 	[QUAD8_COUNT_FUNCTION_QUADRATURE_X4] = COUNTER_COUNT_FUNCTION_QUADRATURE_X4
201 };
202 
203 static int quad8_function_get(struct counter_device *counter,
204 	struct counter_count *count, size_t *function)
205 {
206 	struct quad8 *const priv = counter->priv;
207 	const int id = count->id;
208 
209 	mutex_lock(&priv->lock);
210 
211 	if (priv->quadrature_mode[id])
212 		switch (priv->quadrature_scale[id]) {
213 		case 0:
214 			*function = QUAD8_COUNT_FUNCTION_QUADRATURE_X1;
215 			break;
216 		case 1:
217 			*function = QUAD8_COUNT_FUNCTION_QUADRATURE_X2;
218 			break;
219 		case 2:
220 			*function = QUAD8_COUNT_FUNCTION_QUADRATURE_X4;
221 			break;
222 		}
223 	else
224 		*function = QUAD8_COUNT_FUNCTION_PULSE_DIRECTION;
225 
226 	mutex_unlock(&priv->lock);
227 
228 	return 0;
229 }
230 
231 static int quad8_function_set(struct counter_device *counter,
232 	struct counter_count *count, size_t function)
233 {
234 	struct quad8 *const priv = counter->priv;
235 	const int id = count->id;
236 	unsigned int *const quadrature_mode = priv->quadrature_mode + id;
237 	unsigned int *const scale = priv->quadrature_scale + id;
238 	unsigned int *const synchronous_mode = priv->synchronous_mode + id;
239 	const int base_offset = priv->base + 2 * id + 1;
240 	unsigned int mode_cfg;
241 	unsigned int idr_cfg;
242 
243 	mutex_lock(&priv->lock);
244 
245 	mode_cfg = priv->count_mode[id] << 1;
246 	idr_cfg = priv->index_polarity[id] << 1;
247 
248 	if (function == QUAD8_COUNT_FUNCTION_PULSE_DIRECTION) {
249 		*quadrature_mode = 0;
250 
251 		/* Quadrature scaling only available in quadrature mode */
252 		*scale = 0;
253 
254 		/* Synchronous function not supported in non-quadrature mode */
255 		if (*synchronous_mode) {
256 			*synchronous_mode = 0;
257 			/* Disable synchronous function mode */
258 			outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
259 		}
260 	} else {
261 		*quadrature_mode = 1;
262 
263 		switch (function) {
264 		case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
265 			*scale = 0;
266 			mode_cfg |= QUAD8_CMR_QUADRATURE_X1;
267 			break;
268 		case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
269 			*scale = 1;
270 			mode_cfg |= QUAD8_CMR_QUADRATURE_X2;
271 			break;
272 		case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
273 			*scale = 2;
274 			mode_cfg |= QUAD8_CMR_QUADRATURE_X4;
275 			break;
276 		}
277 	}
278 
279 	/* Load mode configuration to Counter Mode Register */
280 	outb(QUAD8_CTR_CMR | mode_cfg, base_offset);
281 
282 	mutex_unlock(&priv->lock);
283 
284 	return 0;
285 }
286 
287 static void quad8_direction_get(struct counter_device *counter,
288 	struct counter_count *count, enum counter_count_direction *direction)
289 {
290 	const struct quad8 *const priv = counter->priv;
291 	unsigned int ud_flag;
292 	const unsigned int flag_addr = priv->base + 2 * count->id + 1;
293 
294 	/* U/D flag: nonzero = up, zero = down */
295 	ud_flag = inb(flag_addr) & QUAD8_FLAG_UD;
296 
297 	*direction = (ud_flag) ? COUNTER_COUNT_DIRECTION_FORWARD :
298 		COUNTER_COUNT_DIRECTION_BACKWARD;
299 }
300 
301 enum quad8_synapse_action {
302 	QUAD8_SYNAPSE_ACTION_NONE = 0,
303 	QUAD8_SYNAPSE_ACTION_RISING_EDGE,
304 	QUAD8_SYNAPSE_ACTION_FALLING_EDGE,
305 	QUAD8_SYNAPSE_ACTION_BOTH_EDGES
306 };
307 
308 static const enum counter_synapse_action quad8_index_actions_list[] = {
309 	[QUAD8_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE,
310 	[QUAD8_SYNAPSE_ACTION_RISING_EDGE] = COUNTER_SYNAPSE_ACTION_RISING_EDGE
311 };
312 
313 static const enum counter_synapse_action quad8_synapse_actions_list[] = {
314 	[QUAD8_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE,
315 	[QUAD8_SYNAPSE_ACTION_RISING_EDGE] = COUNTER_SYNAPSE_ACTION_RISING_EDGE,
316 	[QUAD8_SYNAPSE_ACTION_FALLING_EDGE] = COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
317 	[QUAD8_SYNAPSE_ACTION_BOTH_EDGES] = COUNTER_SYNAPSE_ACTION_BOTH_EDGES
318 };
319 
320 static int quad8_action_get(struct counter_device *counter,
321 	struct counter_count *count, struct counter_synapse *synapse,
322 	size_t *action)
323 {
324 	struct quad8 *const priv = counter->priv;
325 	int err;
326 	size_t function = 0;
327 	const size_t signal_a_id = count->synapses[0].signal->id;
328 	enum counter_count_direction direction;
329 
330 	/* Handle Index signals */
331 	if (synapse->signal->id >= 16) {
332 		if (priv->preset_enable[count->id])
333 			*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
334 		else
335 			*action = QUAD8_SYNAPSE_ACTION_NONE;
336 
337 		return 0;
338 	}
339 
340 	err = quad8_function_get(counter, count, &function);
341 	if (err)
342 		return err;
343 
344 	/* Default action mode */
345 	*action = QUAD8_SYNAPSE_ACTION_NONE;
346 
347 	/* Determine action mode based on current count function mode */
348 	switch (function) {
349 	case QUAD8_COUNT_FUNCTION_PULSE_DIRECTION:
350 		if (synapse->signal->id == signal_a_id)
351 			*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
352 		break;
353 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
354 		if (synapse->signal->id == signal_a_id) {
355 			quad8_direction_get(counter, count, &direction);
356 
357 			if (direction == COUNTER_COUNT_DIRECTION_FORWARD)
358 				*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
359 			else
360 				*action = QUAD8_SYNAPSE_ACTION_FALLING_EDGE;
361 		}
362 		break;
363 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
364 		if (synapse->signal->id == signal_a_id)
365 			*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
366 		break;
367 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
368 		*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
369 		break;
370 	}
371 
372 	return 0;
373 }
374 
375 static const struct counter_ops quad8_ops = {
376 	.signal_read = quad8_signal_read,
377 	.count_read = quad8_count_read,
378 	.count_write = quad8_count_write,
379 	.function_get = quad8_function_get,
380 	.function_set = quad8_function_set,
381 	.action_get = quad8_action_get
382 };
383 
384 static const char *const quad8_index_polarity_modes[] = {
385 	"negative",
386 	"positive"
387 };
388 
389 static int quad8_index_polarity_get(struct counter_device *counter,
390 	struct counter_signal *signal, size_t *index_polarity)
391 {
392 	const struct quad8 *const priv = counter->priv;
393 	const size_t channel_id = signal->id - 16;
394 
395 	*index_polarity = priv->index_polarity[channel_id];
396 
397 	return 0;
398 }
399 
400 static int quad8_index_polarity_set(struct counter_device *counter,
401 	struct counter_signal *signal, size_t index_polarity)
402 {
403 	struct quad8 *const priv = counter->priv;
404 	const size_t channel_id = signal->id - 16;
405 	const int base_offset = priv->base + 2 * channel_id + 1;
406 	unsigned int idr_cfg = index_polarity << 1;
407 
408 	mutex_lock(&priv->lock);
409 
410 	idr_cfg |= priv->synchronous_mode[channel_id];
411 
412 	priv->index_polarity[channel_id] = index_polarity;
413 
414 	/* Load Index Control configuration to Index Control Register */
415 	outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
416 
417 	mutex_unlock(&priv->lock);
418 
419 	return 0;
420 }
421 
422 static struct counter_signal_enum_ext quad8_index_pol_enum = {
423 	.items = quad8_index_polarity_modes,
424 	.num_items = ARRAY_SIZE(quad8_index_polarity_modes),
425 	.get = quad8_index_polarity_get,
426 	.set = quad8_index_polarity_set
427 };
428 
429 static const char *const quad8_synchronous_modes[] = {
430 	"non-synchronous",
431 	"synchronous"
432 };
433 
434 static int quad8_synchronous_mode_get(struct counter_device *counter,
435 	struct counter_signal *signal, size_t *synchronous_mode)
436 {
437 	const struct quad8 *const priv = counter->priv;
438 	const size_t channel_id = signal->id - 16;
439 
440 	*synchronous_mode = priv->synchronous_mode[channel_id];
441 
442 	return 0;
443 }
444 
445 static int quad8_synchronous_mode_set(struct counter_device *counter,
446 	struct counter_signal *signal, size_t synchronous_mode)
447 {
448 	struct quad8 *const priv = counter->priv;
449 	const size_t channel_id = signal->id - 16;
450 	const int base_offset = priv->base + 2 * channel_id + 1;
451 	unsigned int idr_cfg = synchronous_mode;
452 
453 	mutex_lock(&priv->lock);
454 
455 	idr_cfg |= priv->index_polarity[channel_id] << 1;
456 
457 	/* Index function must be non-synchronous in non-quadrature mode */
458 	if (synchronous_mode && !priv->quadrature_mode[channel_id]) {
459 		mutex_unlock(&priv->lock);
460 		return -EINVAL;
461 	}
462 
463 	priv->synchronous_mode[channel_id] = synchronous_mode;
464 
465 	/* Load Index Control configuration to Index Control Register */
466 	outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
467 
468 	mutex_unlock(&priv->lock);
469 
470 	return 0;
471 }
472 
473 static struct counter_signal_enum_ext quad8_syn_mode_enum = {
474 	.items = quad8_synchronous_modes,
475 	.num_items = ARRAY_SIZE(quad8_synchronous_modes),
476 	.get = quad8_synchronous_mode_get,
477 	.set = quad8_synchronous_mode_set
478 };
479 
480 static ssize_t quad8_count_floor_read(struct counter_device *counter,
481 	struct counter_count *count, void *private, char *buf)
482 {
483 	/* Only a floor of 0 is supported */
484 	return sprintf(buf, "0\n");
485 }
486 
487 static int quad8_count_mode_get(struct counter_device *counter,
488 	struct counter_count *count, size_t *cnt_mode)
489 {
490 	const struct quad8 *const priv = counter->priv;
491 
492 	/* Map 104-QUAD-8 count mode to Generic Counter count mode */
493 	switch (priv->count_mode[count->id]) {
494 	case 0:
495 		*cnt_mode = COUNTER_COUNT_MODE_NORMAL;
496 		break;
497 	case 1:
498 		*cnt_mode = COUNTER_COUNT_MODE_RANGE_LIMIT;
499 		break;
500 	case 2:
501 		*cnt_mode = COUNTER_COUNT_MODE_NON_RECYCLE;
502 		break;
503 	case 3:
504 		*cnt_mode = COUNTER_COUNT_MODE_MODULO_N;
505 		break;
506 	}
507 
508 	return 0;
509 }
510 
511 static int quad8_count_mode_set(struct counter_device *counter,
512 	struct counter_count *count, size_t cnt_mode)
513 {
514 	struct quad8 *const priv = counter->priv;
515 	unsigned int mode_cfg;
516 	const int base_offset = priv->base + 2 * count->id + 1;
517 
518 	/* Map Generic Counter count mode to 104-QUAD-8 count mode */
519 	switch (cnt_mode) {
520 	case COUNTER_COUNT_MODE_NORMAL:
521 		cnt_mode = 0;
522 		break;
523 	case COUNTER_COUNT_MODE_RANGE_LIMIT:
524 		cnt_mode = 1;
525 		break;
526 	case COUNTER_COUNT_MODE_NON_RECYCLE:
527 		cnt_mode = 2;
528 		break;
529 	case COUNTER_COUNT_MODE_MODULO_N:
530 		cnt_mode = 3;
531 		break;
532 	}
533 
534 	mutex_lock(&priv->lock);
535 
536 	priv->count_mode[count->id] = cnt_mode;
537 
538 	/* Set count mode configuration value */
539 	mode_cfg = cnt_mode << 1;
540 
541 	/* Add quadrature mode configuration */
542 	if (priv->quadrature_mode[count->id])
543 		mode_cfg |= (priv->quadrature_scale[count->id] + 1) << 3;
544 
545 	/* Load mode configuration to Counter Mode Register */
546 	outb(QUAD8_CTR_CMR | mode_cfg, base_offset);
547 
548 	mutex_unlock(&priv->lock);
549 
550 	return 0;
551 }
552 
553 static struct counter_count_enum_ext quad8_cnt_mode_enum = {
554 	.items = counter_count_mode_str,
555 	.num_items = ARRAY_SIZE(counter_count_mode_str),
556 	.get = quad8_count_mode_get,
557 	.set = quad8_count_mode_set
558 };
559 
560 static ssize_t quad8_count_direction_read(struct counter_device *counter,
561 	struct counter_count *count, void *priv, char *buf)
562 {
563 	enum counter_count_direction dir;
564 
565 	quad8_direction_get(counter, count, &dir);
566 
567 	return sprintf(buf, "%s\n", counter_count_direction_str[dir]);
568 }
569 
570 static ssize_t quad8_count_enable_read(struct counter_device *counter,
571 	struct counter_count *count, void *private, char *buf)
572 {
573 	const struct quad8 *const priv = counter->priv;
574 
575 	return sprintf(buf, "%u\n", priv->ab_enable[count->id]);
576 }
577 
578 static ssize_t quad8_count_enable_write(struct counter_device *counter,
579 	struct counter_count *count, void *private, const char *buf, size_t len)
580 {
581 	struct quad8 *const priv = counter->priv;
582 	const int base_offset = priv->base + 2 * count->id;
583 	int err;
584 	bool ab_enable;
585 	unsigned int ior_cfg;
586 
587 	err = kstrtobool(buf, &ab_enable);
588 	if (err)
589 		return err;
590 
591 	mutex_lock(&priv->lock);
592 
593 	priv->ab_enable[count->id] = ab_enable;
594 
595 	ior_cfg = ab_enable | priv->preset_enable[count->id] << 1;
596 
597 	/* Load I/O control configuration */
598 	outb(QUAD8_CTR_IOR | ior_cfg, base_offset + 1);
599 
600 	mutex_unlock(&priv->lock);
601 
602 	return len;
603 }
604 
605 static const char *const quad8_noise_error_states[] = {
606 	"No excessive noise is present at the count inputs",
607 	"Excessive noise is present at the count inputs"
608 };
609 
610 static int quad8_error_noise_get(struct counter_device *counter,
611 	struct counter_count *count, size_t *noise_error)
612 {
613 	const struct quad8 *const priv = counter->priv;
614 	const int base_offset = priv->base + 2 * count->id + 1;
615 
616 	*noise_error = !!(inb(base_offset) & QUAD8_FLAG_E);
617 
618 	return 0;
619 }
620 
621 static struct counter_count_enum_ext quad8_error_noise_enum = {
622 	.items = quad8_noise_error_states,
623 	.num_items = ARRAY_SIZE(quad8_noise_error_states),
624 	.get = quad8_error_noise_get
625 };
626 
627 static ssize_t quad8_count_preset_read(struct counter_device *counter,
628 	struct counter_count *count, void *private, char *buf)
629 {
630 	const struct quad8 *const priv = counter->priv;
631 
632 	return sprintf(buf, "%u\n", priv->preset[count->id]);
633 }
634 
635 static void quad8_preset_register_set(struct quad8 *const priv, const int id,
636 				      const unsigned int preset)
637 {
638 	const unsigned int base_offset = priv->base + 2 * id;
639 	int i;
640 
641 	priv->preset[id] = preset;
642 
643 	/* Reset Byte Pointer */
644 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
645 
646 	/* Set Preset Register */
647 	for (i = 0; i < 3; i++)
648 		outb(preset >> (8 * i), base_offset);
649 }
650 
651 static ssize_t quad8_count_preset_write(struct counter_device *counter,
652 	struct counter_count *count, void *private, const char *buf, size_t len)
653 {
654 	struct quad8 *const priv = counter->priv;
655 	unsigned int preset;
656 	int ret;
657 
658 	ret = kstrtouint(buf, 0, &preset);
659 	if (ret)
660 		return ret;
661 
662 	/* Only 24-bit values are supported */
663 	if (preset > 0xFFFFFF)
664 		return -EINVAL;
665 
666 	mutex_lock(&priv->lock);
667 
668 	quad8_preset_register_set(priv, count->id, preset);
669 
670 	mutex_unlock(&priv->lock);
671 
672 	return len;
673 }
674 
675 static ssize_t quad8_count_ceiling_read(struct counter_device *counter,
676 	struct counter_count *count, void *private, char *buf)
677 {
678 	struct quad8 *const priv = counter->priv;
679 
680 	mutex_lock(&priv->lock);
681 
682 	/* Range Limit and Modulo-N count modes use preset value as ceiling */
683 	switch (priv->count_mode[count->id]) {
684 	case 1:
685 	case 3:
686 		mutex_unlock(&priv->lock);
687 		return sprintf(buf, "%u\n", priv->preset[count->id]);
688 	}
689 
690 	mutex_unlock(&priv->lock);
691 
692 	/* By default 0x1FFFFFF (25 bits unsigned) is maximum count */
693 	return sprintf(buf, "33554431\n");
694 }
695 
696 static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
697 	struct counter_count *count, void *private, const char *buf, size_t len)
698 {
699 	struct quad8 *const priv = counter->priv;
700 	unsigned int ceiling;
701 	int ret;
702 
703 	ret = kstrtouint(buf, 0, &ceiling);
704 	if (ret)
705 		return ret;
706 
707 	/* Only 24-bit values are supported */
708 	if (ceiling > 0xFFFFFF)
709 		return -EINVAL;
710 
711 	mutex_lock(&priv->lock);
712 
713 	/* Range Limit and Modulo-N count modes use preset value as ceiling */
714 	switch (priv->count_mode[count->id]) {
715 	case 1:
716 	case 3:
717 		quad8_preset_register_set(priv, count->id, ceiling);
718 		break;
719 	}
720 
721 	mutex_unlock(&priv->lock);
722 
723 	return len;
724 }
725 
726 static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,
727 	struct counter_count *count, void *private, char *buf)
728 {
729 	const struct quad8 *const priv = counter->priv;
730 
731 	return sprintf(buf, "%u\n", !priv->preset_enable[count->id]);
732 }
733 
734 static ssize_t quad8_count_preset_enable_write(struct counter_device *counter,
735 	struct counter_count *count, void *private, const char *buf, size_t len)
736 {
737 	struct quad8 *const priv = counter->priv;
738 	const int base_offset = priv->base + 2 * count->id + 1;
739 	bool preset_enable;
740 	int ret;
741 	unsigned int ior_cfg;
742 
743 	ret = kstrtobool(buf, &preset_enable);
744 	if (ret)
745 		return ret;
746 
747 	/* Preset enable is active low in Input/Output Control register */
748 	preset_enable = !preset_enable;
749 
750 	mutex_lock(&priv->lock);
751 
752 	priv->preset_enable[count->id] = preset_enable;
753 
754 	ior_cfg = priv->ab_enable[count->id] | (unsigned int)preset_enable << 1;
755 
756 	/* Load I/O control configuration to Input / Output Control Register */
757 	outb(QUAD8_CTR_IOR | ior_cfg, base_offset);
758 
759 	mutex_unlock(&priv->lock);
760 
761 	return len;
762 }
763 
764 static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter,
765 					     struct counter_signal *signal,
766 					     void *private, char *buf)
767 {
768 	struct quad8 *const priv = counter->priv;
769 	const size_t channel_id = signal->id / 2;
770 	bool disabled;
771 	unsigned int status;
772 	unsigned int fault;
773 
774 	mutex_lock(&priv->lock);
775 
776 	disabled = !(priv->cable_fault_enable & BIT(channel_id));
777 
778 	if (disabled) {
779 		mutex_unlock(&priv->lock);
780 		return -EINVAL;
781 	}
782 
783 	/* Logic 0 = cable fault */
784 	status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
785 
786 	mutex_unlock(&priv->lock);
787 
788 	/* Mask respective channel and invert logic */
789 	fault = !(status & BIT(channel_id));
790 
791 	return sprintf(buf, "%u\n", fault);
792 }
793 
794 static ssize_t quad8_signal_cable_fault_enable_read(
795 	struct counter_device *counter, struct counter_signal *signal,
796 	void *private, char *buf)
797 {
798 	const struct quad8 *const priv = counter->priv;
799 	const size_t channel_id = signal->id / 2;
800 	const unsigned int enb = !!(priv->cable_fault_enable & BIT(channel_id));
801 
802 	return sprintf(buf, "%u\n", enb);
803 }
804 
805 static ssize_t quad8_signal_cable_fault_enable_write(
806 	struct counter_device *counter, struct counter_signal *signal,
807 	void *private, const char *buf, size_t len)
808 {
809 	struct quad8 *const priv = counter->priv;
810 	const size_t channel_id = signal->id / 2;
811 	bool enable;
812 	int ret;
813 	unsigned int cable_fault_enable;
814 
815 	ret = kstrtobool(buf, &enable);
816 	if (ret)
817 		return ret;
818 
819 	mutex_lock(&priv->lock);
820 
821 	if (enable)
822 		priv->cable_fault_enable |= BIT(channel_id);
823 	else
824 		priv->cable_fault_enable &= ~BIT(channel_id);
825 
826 	/* Enable is active low in Differential Encoder Cable Status register */
827 	cable_fault_enable = ~priv->cable_fault_enable;
828 
829 	outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
830 
831 	mutex_unlock(&priv->lock);
832 
833 	return len;
834 }
835 
836 static ssize_t quad8_signal_fck_prescaler_read(struct counter_device *counter,
837 	struct counter_signal *signal, void *private, char *buf)
838 {
839 	const struct quad8 *const priv = counter->priv;
840 	const size_t channel_id = signal->id / 2;
841 
842 	return sprintf(buf, "%u\n", priv->fck_prescaler[channel_id]);
843 }
844 
845 static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
846 	struct counter_signal *signal, void *private, const char *buf,
847 	size_t len)
848 {
849 	struct quad8 *const priv = counter->priv;
850 	const size_t channel_id = signal->id / 2;
851 	const int base_offset = priv->base + 2 * channel_id;
852 	u8 prescaler;
853 	int ret;
854 
855 	ret = kstrtou8(buf, 0, &prescaler);
856 	if (ret)
857 		return ret;
858 
859 	mutex_lock(&priv->lock);
860 
861 	priv->fck_prescaler[channel_id] = prescaler;
862 
863 	/* Reset Byte Pointer */
864 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
865 
866 	/* Set filter clock factor */
867 	outb(prescaler, base_offset);
868 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
869 	     base_offset + 1);
870 
871 	mutex_unlock(&priv->lock);
872 
873 	return len;
874 }
875 
876 static const struct counter_signal_ext quad8_signal_ext[] = {
877 	{
878 		.name = "cable_fault",
879 		.read = quad8_signal_cable_fault_read
880 	},
881 	{
882 		.name = "cable_fault_enable",
883 		.read = quad8_signal_cable_fault_enable_read,
884 		.write = quad8_signal_cable_fault_enable_write
885 	},
886 	{
887 		.name = "filter_clock_prescaler",
888 		.read = quad8_signal_fck_prescaler_read,
889 		.write = quad8_signal_fck_prescaler_write
890 	}
891 };
892 
893 static const struct counter_signal_ext quad8_index_ext[] = {
894 	COUNTER_SIGNAL_ENUM("index_polarity", &quad8_index_pol_enum),
895 	COUNTER_SIGNAL_ENUM_AVAILABLE("index_polarity",	&quad8_index_pol_enum),
896 	COUNTER_SIGNAL_ENUM("synchronous_mode", &quad8_syn_mode_enum),
897 	COUNTER_SIGNAL_ENUM_AVAILABLE("synchronous_mode", &quad8_syn_mode_enum)
898 };
899 
900 #define QUAD8_QUAD_SIGNAL(_id, _name) {		\
901 	.id = (_id),				\
902 	.name = (_name),			\
903 	.ext = quad8_signal_ext,		\
904 	.num_ext = ARRAY_SIZE(quad8_signal_ext)	\
905 }
906 
907 #define	QUAD8_INDEX_SIGNAL(_id, _name) {	\
908 	.id = (_id),				\
909 	.name = (_name),			\
910 	.ext = quad8_index_ext,			\
911 	.num_ext = ARRAY_SIZE(quad8_index_ext)	\
912 }
913 
914 static struct counter_signal quad8_signals[] = {
915 	QUAD8_QUAD_SIGNAL(0, "Channel 1 Quadrature A"),
916 	QUAD8_QUAD_SIGNAL(1, "Channel 1 Quadrature B"),
917 	QUAD8_QUAD_SIGNAL(2, "Channel 2 Quadrature A"),
918 	QUAD8_QUAD_SIGNAL(3, "Channel 2 Quadrature B"),
919 	QUAD8_QUAD_SIGNAL(4, "Channel 3 Quadrature A"),
920 	QUAD8_QUAD_SIGNAL(5, "Channel 3 Quadrature B"),
921 	QUAD8_QUAD_SIGNAL(6, "Channel 4 Quadrature A"),
922 	QUAD8_QUAD_SIGNAL(7, "Channel 4 Quadrature B"),
923 	QUAD8_QUAD_SIGNAL(8, "Channel 5 Quadrature A"),
924 	QUAD8_QUAD_SIGNAL(9, "Channel 5 Quadrature B"),
925 	QUAD8_QUAD_SIGNAL(10, "Channel 6 Quadrature A"),
926 	QUAD8_QUAD_SIGNAL(11, "Channel 6 Quadrature B"),
927 	QUAD8_QUAD_SIGNAL(12, "Channel 7 Quadrature A"),
928 	QUAD8_QUAD_SIGNAL(13, "Channel 7 Quadrature B"),
929 	QUAD8_QUAD_SIGNAL(14, "Channel 8 Quadrature A"),
930 	QUAD8_QUAD_SIGNAL(15, "Channel 8 Quadrature B"),
931 	QUAD8_INDEX_SIGNAL(16, "Channel 1 Index"),
932 	QUAD8_INDEX_SIGNAL(17, "Channel 2 Index"),
933 	QUAD8_INDEX_SIGNAL(18, "Channel 3 Index"),
934 	QUAD8_INDEX_SIGNAL(19, "Channel 4 Index"),
935 	QUAD8_INDEX_SIGNAL(20, "Channel 5 Index"),
936 	QUAD8_INDEX_SIGNAL(21, "Channel 6 Index"),
937 	QUAD8_INDEX_SIGNAL(22, "Channel 7 Index"),
938 	QUAD8_INDEX_SIGNAL(23, "Channel 8 Index")
939 };
940 
941 #define QUAD8_COUNT_SYNAPSES(_id) {					\
942 	{								\
943 		.actions_list = quad8_synapse_actions_list,		\
944 		.num_actions = ARRAY_SIZE(quad8_synapse_actions_list),	\
945 		.signal = quad8_signals + 2 * (_id)			\
946 	},								\
947 	{								\
948 		.actions_list = quad8_synapse_actions_list,		\
949 		.num_actions = ARRAY_SIZE(quad8_synapse_actions_list),	\
950 		.signal = quad8_signals + 2 * (_id) + 1			\
951 	},								\
952 	{								\
953 		.actions_list = quad8_index_actions_list,		\
954 		.num_actions = ARRAY_SIZE(quad8_index_actions_list),	\
955 		.signal = quad8_signals + 2 * (_id) + 16		\
956 	}								\
957 }
958 
959 static struct counter_synapse quad8_count_synapses[][3] = {
960 	QUAD8_COUNT_SYNAPSES(0), QUAD8_COUNT_SYNAPSES(1),
961 	QUAD8_COUNT_SYNAPSES(2), QUAD8_COUNT_SYNAPSES(3),
962 	QUAD8_COUNT_SYNAPSES(4), QUAD8_COUNT_SYNAPSES(5),
963 	QUAD8_COUNT_SYNAPSES(6), QUAD8_COUNT_SYNAPSES(7)
964 };
965 
966 static const struct counter_count_ext quad8_count_ext[] = {
967 	{
968 		.name = "ceiling",
969 		.read = quad8_count_ceiling_read,
970 		.write = quad8_count_ceiling_write
971 	},
972 	{
973 		.name = "floor",
974 		.read = quad8_count_floor_read
975 	},
976 	COUNTER_COUNT_ENUM("count_mode", &quad8_cnt_mode_enum),
977 	COUNTER_COUNT_ENUM_AVAILABLE("count_mode", &quad8_cnt_mode_enum),
978 	{
979 		.name = "direction",
980 		.read = quad8_count_direction_read
981 	},
982 	{
983 		.name = "enable",
984 		.read = quad8_count_enable_read,
985 		.write = quad8_count_enable_write
986 	},
987 	COUNTER_COUNT_ENUM("error_noise", &quad8_error_noise_enum),
988 	COUNTER_COUNT_ENUM_AVAILABLE("error_noise", &quad8_error_noise_enum),
989 	{
990 		.name = "preset",
991 		.read = quad8_count_preset_read,
992 		.write = quad8_count_preset_write
993 	},
994 	{
995 		.name = "preset_enable",
996 		.read = quad8_count_preset_enable_read,
997 		.write = quad8_count_preset_enable_write
998 	}
999 };
1000 
1001 #define QUAD8_COUNT(_id, _cntname) {					\
1002 	.id = (_id),							\
1003 	.name = (_cntname),						\
1004 	.functions_list = quad8_count_functions_list,			\
1005 	.num_functions = ARRAY_SIZE(quad8_count_functions_list),	\
1006 	.synapses = quad8_count_synapses[(_id)],			\
1007 	.num_synapses =	2,						\
1008 	.ext = quad8_count_ext,						\
1009 	.num_ext = ARRAY_SIZE(quad8_count_ext)				\
1010 }
1011 
1012 static struct counter_count quad8_counts[] = {
1013 	QUAD8_COUNT(0, "Channel 1 Count"),
1014 	QUAD8_COUNT(1, "Channel 2 Count"),
1015 	QUAD8_COUNT(2, "Channel 3 Count"),
1016 	QUAD8_COUNT(3, "Channel 4 Count"),
1017 	QUAD8_COUNT(4, "Channel 5 Count"),
1018 	QUAD8_COUNT(5, "Channel 6 Count"),
1019 	QUAD8_COUNT(6, "Channel 7 Count"),
1020 	QUAD8_COUNT(7, "Channel 8 Count")
1021 };
1022 
1023 static int quad8_probe(struct device *dev, unsigned int id)
1024 {
1025 	struct quad8 *priv;
1026 	int i, j;
1027 	unsigned int base_offset;
1028 
1029 	if (!devm_request_region(dev, base[id], QUAD8_EXTENT, dev_name(dev))) {
1030 		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
1031 			base[id], base[id] + QUAD8_EXTENT);
1032 		return -EBUSY;
1033 	}
1034 
1035 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
1036 	if (!priv)
1037 		return -ENOMEM;
1038 
1039 	/* Initialize Counter device and driver data */
1040 	priv->counter.name = dev_name(dev);
1041 	priv->counter.parent = dev;
1042 	priv->counter.ops = &quad8_ops;
1043 	priv->counter.counts = quad8_counts;
1044 	priv->counter.num_counts = ARRAY_SIZE(quad8_counts);
1045 	priv->counter.signals = quad8_signals;
1046 	priv->counter.num_signals = ARRAY_SIZE(quad8_signals);
1047 	priv->counter.priv = priv;
1048 	priv->base = base[id];
1049 
1050 	/* Initialize mutex */
1051 	mutex_init(&priv->lock);
1052 
1053 	/* Reset all counters and disable interrupt function */
1054 	outb(QUAD8_CHAN_OP_RESET_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
1055 	/* Set initial configuration for all counters */
1056 	for (i = 0; i < QUAD8_NUM_COUNTERS; i++) {
1057 		base_offset = base[id] + 2 * i;
1058 		/* Reset Byte Pointer */
1059 		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
1060 		/* Reset filter clock factor */
1061 		outb(0, base_offset);
1062 		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
1063 		     base_offset + 1);
1064 		/* Reset Byte Pointer */
1065 		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
1066 		/* Reset Preset Register */
1067 		for (j = 0; j < 3; j++)
1068 			outb(0x00, base_offset);
1069 		/* Reset Borrow, Carry, Compare, and Sign flags */
1070 		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_FLAGS, base_offset + 1);
1071 		/* Reset Error flag */
1072 		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_E, base_offset + 1);
1073 		/* Binary encoding; Normal count; non-quadrature mode */
1074 		outb(QUAD8_CTR_CMR, base_offset + 1);
1075 		/* Disable A and B inputs; preset on index; FLG1 as Carry */
1076 		outb(QUAD8_CTR_IOR, base_offset + 1);
1077 		/* Disable index function; negative index polarity */
1078 		outb(QUAD8_CTR_IDR, base_offset + 1);
1079 	}
1080 	/* Disable Differential Encoder Cable Status for all channels */
1081 	outb(0xFF, base[id] + QUAD8_DIFF_ENCODER_CABLE_STATUS);
1082 	/* Enable all counters */
1083 	outb(QUAD8_CHAN_OP_ENABLE_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
1084 
1085 	return devm_counter_register(dev, &priv->counter);
1086 }
1087 
1088 static struct isa_driver quad8_driver = {
1089 	.probe = quad8_probe,
1090 	.driver = {
1091 		.name = "104-quad-8"
1092 	}
1093 };
1094 
1095 module_isa_driver(quad8_driver, num_quad8);
1096 
1097 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
1098 MODULE_DESCRIPTION("ACCES 104-QUAD-8 driver");
1099 MODULE_LICENSE("GPL v2");
1100