1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * gpio-max3191x.c - GPIO driver for Maxim MAX3191x industrial serializer
4  *
5  * Copyright (C) 2017 KUNBUS GmbH
6  *
7  * The MAX3191x makes 8 digital 24V inputs available via SPI.
8  * Multiple chips can be daisy-chained, the spec does not impose
9  * a limit on the number of chips and neither does this driver.
10  *
11  * Either of two modes is selectable: In 8-bit mode, only the state
12  * of the inputs is clocked out to achieve high readout speeds;
13  * In 16-bit mode, an additional status byte is clocked out with
14  * a CRC and indicator bits for undervoltage and overtemperature.
15  * The driver returns an error instead of potentially bogus data
16  * if any of these fault conditions occur.  However it does allow
17  * readout of non-faulting chips in the same daisy-chain.
18  *
19  * MAX3191x supports four debounce settings and the driver is
20  * capable of configuring these differently for each chip in the
21  * daisy-chain.
22  *
23  * If the chips are hardwired to 8-bit mode ("modesel" pulled high),
24  * gpio-pisosr.c can be used alternatively to this driver.
25  *
26  * https://datasheets.maximintegrated.com/en/ds/MAX31910.pdf
27  * https://datasheets.maximintegrated.com/en/ds/MAX31911.pdf
28  * https://datasheets.maximintegrated.com/en/ds/MAX31912.pdf
29  * https://datasheets.maximintegrated.com/en/ds/MAX31913.pdf
30  * https://datasheets.maximintegrated.com/en/ds/MAX31953-MAX31963.pdf
31  */
32 
33 #include <linux/bitmap.h>
34 #include <linux/bitops.h>
35 #include <linux/crc8.h>
36 #include <linux/gpio/consumer.h>
37 #include <linux/gpio/driver.h>
38 #include <linux/module.h>
39 #include <linux/spi/spi.h>
40 
41 enum max3191x_mode {
42 	STATUS_BYTE_ENABLED,
43 	STATUS_BYTE_DISABLED,
44 };
45 
46 /**
47  * struct max3191x_chip - max3191x daisy-chain
48  * @gpio: GPIO controller struct
49  * @lock: protects read sequences
50  * @nchips: number of chips in the daisy-chain
51  * @mode: current mode, 0 for 16-bit, 1 for 8-bit;
52  *	for simplicity, all chips in the daisy-chain are assumed
53  *	to use the same mode
54  * @modesel_pins: GPIO pins to configure modesel of each chip
55  * @fault_pins: GPIO pins to detect fault of each chip
56  * @db0_pins: GPIO pins to configure debounce of each chip
57  * @db1_pins: GPIO pins to configure debounce of each chip
58  * @mesg: SPI message to perform a readout
59  * @xfer: SPI transfer used by @mesg
60  * @crc_error: bitmap signaling CRC error for each chip
61  * @overtemp: bitmap signaling overtemperature alarm for each chip
62  * @undervolt1: bitmap signaling undervoltage alarm for each chip
63  * @undervolt2: bitmap signaling undervoltage warning for each chip
64  * @fault: bitmap signaling assertion of @fault_pins for each chip
65  * @ignore_uv: whether to ignore undervoltage alarms;
66  *	set by a device property if the chips are powered through
67  *	5VOUT instead of VCC24V, in which case they will constantly
68  *	signal undervoltage;
69  *	for simplicity, all chips in the daisy-chain are assumed
70  *	to be powered the same way
71  */
72 struct max3191x_chip {
73 	struct gpio_chip gpio;
74 	struct mutex lock;
75 	u32 nchips;
76 	enum max3191x_mode mode;
77 	struct gpio_descs *modesel_pins;
78 	struct gpio_descs *fault_pins;
79 	struct gpio_descs *db0_pins;
80 	struct gpio_descs *db1_pins;
81 	struct spi_message mesg;
82 	struct spi_transfer xfer;
83 	unsigned long *crc_error;
84 	unsigned long *overtemp;
85 	unsigned long *undervolt1;
86 	unsigned long *undervolt2;
87 	unsigned long *fault;
88 	bool ignore_uv;
89 };
90 
91 #define MAX3191X_NGPIO 8
92 #define MAX3191X_CRC8_POLYNOMIAL 0xa8 /* (x^5) + x^4 + x^2 + x^0 */
93 
94 DECLARE_CRC8_TABLE(max3191x_crc8);
95 
max3191x_get_direction(struct gpio_chip * gpio,unsigned int offset)96 static int max3191x_get_direction(struct gpio_chip *gpio, unsigned int offset)
97 {
98 	return GPIO_LINE_DIRECTION_IN; /* always in */
99 }
100 
max3191x_direction_input(struct gpio_chip * gpio,unsigned int offset)101 static int max3191x_direction_input(struct gpio_chip *gpio, unsigned int offset)
102 {
103 	return 0;
104 }
105 
max3191x_direction_output(struct gpio_chip * gpio,unsigned int offset,int value)106 static int max3191x_direction_output(struct gpio_chip *gpio,
107 				     unsigned int offset, int value)
108 {
109 	return -EINVAL;
110 }
111 
max3191x_set(struct gpio_chip * gpio,unsigned int offset,int value)112 static void max3191x_set(struct gpio_chip *gpio, unsigned int offset, int value)
113 { }
114 
max3191x_set_multiple(struct gpio_chip * gpio,unsigned long * mask,unsigned long * bits)115 static void max3191x_set_multiple(struct gpio_chip *gpio, unsigned long *mask,
116 				  unsigned long *bits)
117 { }
118 
max3191x_wordlen(struct max3191x_chip * max3191x)119 static unsigned int max3191x_wordlen(struct max3191x_chip *max3191x)
120 {
121 	return max3191x->mode == STATUS_BYTE_ENABLED ? 2 : 1;
122 }
123 
max3191x_readout_locked(struct max3191x_chip * max3191x)124 static int max3191x_readout_locked(struct max3191x_chip *max3191x)
125 {
126 	struct device *dev = max3191x->gpio.parent;
127 	struct spi_device *spi = to_spi_device(dev);
128 	int val, i, ot = 0, uv1 = 0;
129 
130 	val = spi_sync(spi, &max3191x->mesg);
131 	if (val) {
132 		dev_err_ratelimited(dev, "SPI receive error %d\n", val);
133 		return val;
134 	}
135 
136 	for (i = 0; i < max3191x->nchips; i++) {
137 		if (max3191x->mode == STATUS_BYTE_ENABLED) {
138 			u8 in	  = ((u8 *)max3191x->xfer.rx_buf)[i * 2];
139 			u8 status = ((u8 *)max3191x->xfer.rx_buf)[i * 2 + 1];
140 
141 			val = (status & 0xf8) != crc8(max3191x_crc8, &in, 1, 0);
142 			__assign_bit(i, max3191x->crc_error, val);
143 			if (val)
144 				dev_err_ratelimited(dev,
145 					"chip %d: CRC error\n", i);
146 
147 			ot  = (status >> 1) & 1;
148 			__assign_bit(i, max3191x->overtemp, ot);
149 			if (ot)
150 				dev_err_ratelimited(dev,
151 					"chip %d: overtemperature\n", i);
152 
153 			if (!max3191x->ignore_uv) {
154 				uv1 = !((status >> 2) & 1);
155 				__assign_bit(i, max3191x->undervolt1, uv1);
156 				if (uv1)
157 					dev_err_ratelimited(dev,
158 						"chip %d: undervoltage\n", i);
159 
160 				val = !(status & 1);
161 				__assign_bit(i, max3191x->undervolt2, val);
162 				if (val && !uv1)
163 					dev_warn_ratelimited(dev,
164 						"chip %d: voltage warn\n", i);
165 			}
166 		}
167 
168 		if (max3191x->fault_pins && !max3191x->ignore_uv) {
169 			/* fault pin shared by all chips or per chip */
170 			struct gpio_desc *fault_pin =
171 				(max3191x->fault_pins->ndescs == 1)
172 					? max3191x->fault_pins->desc[0]
173 					: max3191x->fault_pins->desc[i];
174 
175 			val = gpiod_get_value_cansleep(fault_pin);
176 			if (val < 0) {
177 				dev_err_ratelimited(dev,
178 					"GPIO read error %d\n", val);
179 				return val;
180 			}
181 			__assign_bit(i, max3191x->fault, val);
182 			if (val && !uv1 && !ot)
183 				dev_err_ratelimited(dev,
184 					"chip %d: fault\n", i);
185 		}
186 	}
187 
188 	return 0;
189 }
190 
max3191x_chip_is_faulting(struct max3191x_chip * max3191x,unsigned int chipnum)191 static bool max3191x_chip_is_faulting(struct max3191x_chip *max3191x,
192 				      unsigned int chipnum)
193 {
194 	/* without status byte the only diagnostic is the fault pin */
195 	if (!max3191x->ignore_uv && test_bit(chipnum, max3191x->fault))
196 		return true;
197 
198 	if (max3191x->mode == STATUS_BYTE_DISABLED)
199 		return false;
200 
201 	return test_bit(chipnum, max3191x->crc_error) ||
202 	       test_bit(chipnum, max3191x->overtemp)  ||
203 	       (!max3191x->ignore_uv &&
204 		test_bit(chipnum, max3191x->undervolt1));
205 }
206 
max3191x_get(struct gpio_chip * gpio,unsigned int offset)207 static int max3191x_get(struct gpio_chip *gpio, unsigned int offset)
208 {
209 	struct max3191x_chip *max3191x = gpiochip_get_data(gpio);
210 	int ret, chipnum, wordlen = max3191x_wordlen(max3191x);
211 	u8 in;
212 
213 	mutex_lock(&max3191x->lock);
214 	ret = max3191x_readout_locked(max3191x);
215 	if (ret)
216 		goto out_unlock;
217 
218 	chipnum = offset / MAX3191X_NGPIO;
219 	if (max3191x_chip_is_faulting(max3191x, chipnum)) {
220 		ret = -EIO;
221 		goto out_unlock;
222 	}
223 
224 	in = ((u8 *)max3191x->xfer.rx_buf)[chipnum * wordlen];
225 	ret = (in >> (offset % MAX3191X_NGPIO)) & 1;
226 
227 out_unlock:
228 	mutex_unlock(&max3191x->lock);
229 	return ret;
230 }
231 
max3191x_get_multiple(struct gpio_chip * gpio,unsigned long * mask,unsigned long * bits)232 static int max3191x_get_multiple(struct gpio_chip *gpio, unsigned long *mask,
233 				 unsigned long *bits)
234 {
235 	struct max3191x_chip *max3191x = gpiochip_get_data(gpio);
236 	const unsigned int wordlen = max3191x_wordlen(max3191x);
237 	int ret;
238 	unsigned long bit;
239 	unsigned long gpio_mask;
240 	unsigned long in;
241 
242 	mutex_lock(&max3191x->lock);
243 	ret = max3191x_readout_locked(max3191x);
244 	if (ret)
245 		goto out_unlock;
246 
247 	bitmap_zero(bits, gpio->ngpio);
248 	for_each_set_clump8(bit, gpio_mask, mask, gpio->ngpio) {
249 		unsigned int chipnum = bit / MAX3191X_NGPIO;
250 
251 		if (max3191x_chip_is_faulting(max3191x, chipnum)) {
252 			ret = -EIO;
253 			goto out_unlock;
254 		}
255 
256 		in = ((u8 *)max3191x->xfer.rx_buf)[chipnum * wordlen];
257 		in &= gpio_mask;
258 		bitmap_set_value8(bits, in, bit);
259 	}
260 
261 out_unlock:
262 	mutex_unlock(&max3191x->lock);
263 	return ret;
264 }
265 
max3191x_set_config(struct gpio_chip * gpio,unsigned int offset,unsigned long config)266 static int max3191x_set_config(struct gpio_chip *gpio, unsigned int offset,
267 			       unsigned long config)
268 {
269 	struct max3191x_chip *max3191x = gpiochip_get_data(gpio);
270 	u32 debounce, chipnum, db0_val, db1_val;
271 
272 	if (pinconf_to_config_param(config) != PIN_CONFIG_INPUT_DEBOUNCE)
273 		return -ENOTSUPP;
274 
275 	if (!max3191x->db0_pins || !max3191x->db1_pins)
276 		return -EINVAL;
277 
278 	debounce = pinconf_to_config_argument(config);
279 	switch (debounce) {
280 	case 0:
281 		db0_val = 0;
282 		db1_val = 0;
283 		break;
284 	case 1 ... 25:
285 		db0_val = 0;
286 		db1_val = 1;
287 		break;
288 	case 26 ... 750:
289 		db0_val = 1;
290 		db1_val = 0;
291 		break;
292 	case 751 ... 3000:
293 		db0_val = 1;
294 		db1_val = 1;
295 		break;
296 	default:
297 		return -EINVAL;
298 	}
299 
300 	if (max3191x->db0_pins->ndescs == 1)
301 		chipnum = 0; /* all chips use the same pair of debounce pins */
302 	else
303 		chipnum = offset / MAX3191X_NGPIO; /* per chip debounce pins */
304 
305 	mutex_lock(&max3191x->lock);
306 	gpiod_set_value_cansleep(max3191x->db0_pins->desc[chipnum], db0_val);
307 	gpiod_set_value_cansleep(max3191x->db1_pins->desc[chipnum], db1_val);
308 	mutex_unlock(&max3191x->lock);
309 	return 0;
310 }
311 
gpiod_set_array_single_value_cansleep(unsigned int ndescs,struct gpio_desc ** desc,struct gpio_array * info,int value)312 static void gpiod_set_array_single_value_cansleep(unsigned int ndescs,
313 						  struct gpio_desc **desc,
314 						  struct gpio_array *info,
315 						  int value)
316 {
317 	unsigned long *values;
318 
319 	values = bitmap_alloc(ndescs, GFP_KERNEL);
320 	if (!values)
321 		return;
322 
323 	if (value)
324 		bitmap_fill(values, ndescs);
325 	else
326 		bitmap_zero(values, ndescs);
327 
328 	gpiod_set_array_value_cansleep(ndescs, desc, info, values);
329 	kfree(values);
330 }
331 
devm_gpiod_get_array_optional_count(struct device * dev,const char * con_id,enum gpiod_flags flags,unsigned int expected)332 static struct gpio_descs *devm_gpiod_get_array_optional_count(
333 				struct device *dev, const char *con_id,
334 				enum gpiod_flags flags, unsigned int expected)
335 {
336 	struct gpio_descs *descs;
337 	int found = gpiod_count(dev, con_id);
338 
339 	if (found == -ENOENT)
340 		return NULL;
341 
342 	if (found != expected && found != 1) {
343 		dev_err(dev, "ignoring %s-gpios: found %d, expected %u or 1\n",
344 			con_id, found, expected);
345 		return NULL;
346 	}
347 
348 	descs = devm_gpiod_get_array_optional(dev, con_id, flags);
349 
350 	if (IS_ERR(descs)) {
351 		dev_err(dev, "failed to get %s-gpios: %ld\n",
352 			con_id, PTR_ERR(descs));
353 		return NULL;
354 	}
355 
356 	return descs;
357 }
358 
max3191x_probe(struct spi_device * spi)359 static int max3191x_probe(struct spi_device *spi)
360 {
361 	struct device *dev = &spi->dev;
362 	struct max3191x_chip *max3191x;
363 	int n, ret;
364 
365 	max3191x = devm_kzalloc(dev, sizeof(*max3191x), GFP_KERNEL);
366 	if (!max3191x)
367 		return -ENOMEM;
368 	spi_set_drvdata(spi, max3191x);
369 
370 	max3191x->nchips = 1;
371 	device_property_read_u32(dev, "#daisy-chained-devices",
372 				 &max3191x->nchips);
373 
374 	n = BITS_TO_LONGS(max3191x->nchips);
375 	max3191x->crc_error   = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
376 	max3191x->undervolt1  = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
377 	max3191x->undervolt2  = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
378 	max3191x->overtemp    = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
379 	max3191x->fault       = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
380 	max3191x->xfer.rx_buf = devm_kcalloc(dev, max3191x->nchips,
381 								2, GFP_KERNEL);
382 	if (!max3191x->crc_error || !max3191x->undervolt1 ||
383 	    !max3191x->overtemp  || !max3191x->undervolt2 ||
384 	    !max3191x->fault     || !max3191x->xfer.rx_buf)
385 		return -ENOMEM;
386 
387 	max3191x->modesel_pins = devm_gpiod_get_array_optional_count(dev,
388 				 "maxim,modesel", GPIOD_ASIS, max3191x->nchips);
389 	max3191x->fault_pins   = devm_gpiod_get_array_optional_count(dev,
390 				 "maxim,fault", GPIOD_IN, max3191x->nchips);
391 	max3191x->db0_pins     = devm_gpiod_get_array_optional_count(dev,
392 				 "maxim,db0", GPIOD_OUT_LOW, max3191x->nchips);
393 	max3191x->db1_pins     = devm_gpiod_get_array_optional_count(dev,
394 				 "maxim,db1", GPIOD_OUT_LOW, max3191x->nchips);
395 
396 	max3191x->mode = device_property_read_bool(dev, "maxim,modesel-8bit")
397 				 ? STATUS_BYTE_DISABLED : STATUS_BYTE_ENABLED;
398 	if (max3191x->modesel_pins)
399 		gpiod_set_array_single_value_cansleep(
400 				 max3191x->modesel_pins->ndescs,
401 				 max3191x->modesel_pins->desc,
402 				 max3191x->modesel_pins->info, max3191x->mode);
403 
404 	max3191x->ignore_uv = device_property_read_bool(dev,
405 						  "maxim,ignore-undervoltage");
406 
407 	if (max3191x->db0_pins && max3191x->db1_pins &&
408 	    max3191x->db0_pins->ndescs != max3191x->db1_pins->ndescs) {
409 		dev_err(dev, "ignoring maxim,db*-gpios: array len mismatch\n");
410 		devm_gpiod_put_array(dev, max3191x->db0_pins);
411 		devm_gpiod_put_array(dev, max3191x->db1_pins);
412 		max3191x->db0_pins = NULL;
413 		max3191x->db1_pins = NULL;
414 	}
415 
416 	max3191x->xfer.len = max3191x->nchips * max3191x_wordlen(max3191x);
417 	spi_message_init_with_transfers(&max3191x->mesg, &max3191x->xfer, 1);
418 
419 	max3191x->gpio.label = spi->modalias;
420 	max3191x->gpio.owner = THIS_MODULE;
421 	max3191x->gpio.parent = dev;
422 	max3191x->gpio.base = -1;
423 	max3191x->gpio.ngpio = max3191x->nchips * MAX3191X_NGPIO;
424 	max3191x->gpio.can_sleep = true;
425 
426 	max3191x->gpio.get_direction = max3191x_get_direction;
427 	max3191x->gpio.direction_input = max3191x_direction_input;
428 	max3191x->gpio.direction_output = max3191x_direction_output;
429 	max3191x->gpio.set = max3191x_set;
430 	max3191x->gpio.set_multiple = max3191x_set_multiple;
431 	max3191x->gpio.get = max3191x_get;
432 	max3191x->gpio.get_multiple = max3191x_get_multiple;
433 	max3191x->gpio.set_config = max3191x_set_config;
434 
435 	mutex_init(&max3191x->lock);
436 
437 	ret = gpiochip_add_data(&max3191x->gpio, max3191x);
438 	if (ret) {
439 		mutex_destroy(&max3191x->lock);
440 		return ret;
441 	}
442 
443 	return 0;
444 }
445 
max3191x_remove(struct spi_device * spi)446 static int max3191x_remove(struct spi_device *spi)
447 {
448 	struct max3191x_chip *max3191x = spi_get_drvdata(spi);
449 
450 	gpiochip_remove(&max3191x->gpio);
451 	mutex_destroy(&max3191x->lock);
452 
453 	return 0;
454 }
455 
max3191x_register_driver(struct spi_driver * sdrv)456 static int __init max3191x_register_driver(struct spi_driver *sdrv)
457 {
458 	crc8_populate_msb(max3191x_crc8, MAX3191X_CRC8_POLYNOMIAL);
459 	return spi_register_driver(sdrv);
460 }
461 
462 #ifdef CONFIG_OF
463 static const struct of_device_id max3191x_of_id[] = {
464 	{ .compatible = "maxim,max31910" },
465 	{ .compatible = "maxim,max31911" },
466 	{ .compatible = "maxim,max31912" },
467 	{ .compatible = "maxim,max31913" },
468 	{ .compatible = "maxim,max31953" },
469 	{ .compatible = "maxim,max31963" },
470 	{ }
471 };
472 MODULE_DEVICE_TABLE(of, max3191x_of_id);
473 #endif
474 
475 static const struct spi_device_id max3191x_spi_id[] = {
476 	{ "max31910" },
477 	{ "max31911" },
478 	{ "max31912" },
479 	{ "max31913" },
480 	{ "max31953" },
481 	{ "max31963" },
482 	{ }
483 };
484 MODULE_DEVICE_TABLE(spi, max3191x_spi_id);
485 
486 static struct spi_driver max3191x_driver = {
487 	.driver = {
488 		.name		= "max3191x",
489 		.of_match_table	= of_match_ptr(max3191x_of_id),
490 	},
491 	.probe	  = max3191x_probe,
492 	.remove	  = max3191x_remove,
493 	.id_table = max3191x_spi_id,
494 };
495 module_driver(max3191x_driver, max3191x_register_driver, spi_unregister_driver);
496 
497 MODULE_AUTHOR("Lukas Wunner <lukas@wunner.de>");
498 MODULE_DESCRIPTION("GPIO driver for Maxim MAX3191x industrial serializer");
499 MODULE_LICENSE("GPL v2");
500