1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * max30100.c - Support for MAX30100 heart rate and pulse oximeter sensor
4  *
5  * Copyright (C) 2015, 2018
6  * Author: Matt Ranostay <matt.ranostay@konsulko.com>
7  *
8  * TODO: enable pulse length controls via device tree properties
9  */
10 
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/interrupt.h>
14 #include <linux/delay.h>
15 #include <linux/err.h>
16 #include <linux/irq.h>
17 #include <linux/i2c.h>
18 #include <linux/mutex.h>
19 #include <linux/property.h>
20 #include <linux/regmap.h>
21 #include <linux/iio/iio.h>
22 #include <linux/iio/buffer.h>
23 #include <linux/iio/kfifo_buf.h>
24 
25 #define MAX30100_REGMAP_NAME	"max30100_regmap"
26 #define MAX30100_DRV_NAME	"max30100"
27 
28 #define MAX30100_REG_INT_STATUS			0x00
29 #define MAX30100_REG_INT_STATUS_PWR_RDY		BIT(0)
30 #define MAX30100_REG_INT_STATUS_SPO2_RDY	BIT(4)
31 #define MAX30100_REG_INT_STATUS_HR_RDY		BIT(5)
32 #define MAX30100_REG_INT_STATUS_FIFO_RDY	BIT(7)
33 
34 #define MAX30100_REG_INT_ENABLE			0x01
35 #define MAX30100_REG_INT_ENABLE_SPO2_EN		BIT(0)
36 #define MAX30100_REG_INT_ENABLE_HR_EN		BIT(1)
37 #define MAX30100_REG_INT_ENABLE_FIFO_EN		BIT(3)
38 #define MAX30100_REG_INT_ENABLE_MASK		0xf0
39 #define MAX30100_REG_INT_ENABLE_MASK_SHIFT	4
40 
41 #define MAX30100_REG_FIFO_WR_PTR		0x02
42 #define MAX30100_REG_FIFO_OVR_CTR		0x03
43 #define MAX30100_REG_FIFO_RD_PTR		0x04
44 #define MAX30100_REG_FIFO_DATA			0x05
45 #define MAX30100_REG_FIFO_DATA_ENTRY_COUNT	16
46 #define MAX30100_REG_FIFO_DATA_ENTRY_LEN	4
47 
48 #define MAX30100_REG_MODE_CONFIG		0x06
49 #define MAX30100_REG_MODE_CONFIG_MODE_SPO2_EN	BIT(0)
50 #define MAX30100_REG_MODE_CONFIG_MODE_HR_EN	BIT(1)
51 #define MAX30100_REG_MODE_CONFIG_MODE_MASK	0x03
52 #define MAX30100_REG_MODE_CONFIG_TEMP_EN	BIT(3)
53 #define MAX30100_REG_MODE_CONFIG_PWR		BIT(7)
54 
55 #define MAX30100_REG_SPO2_CONFIG		0x07
56 #define MAX30100_REG_SPO2_CONFIG_100HZ		BIT(2)
57 #define MAX30100_REG_SPO2_CONFIG_HI_RES_EN	BIT(6)
58 #define MAX30100_REG_SPO2_CONFIG_1600US		0x3
59 
60 #define MAX30100_REG_LED_CONFIG			0x09
61 #define MAX30100_REG_LED_CONFIG_LED_MASK	0x0f
62 #define MAX30100_REG_LED_CONFIG_RED_LED_SHIFT	4
63 
64 #define MAX30100_REG_LED_CONFIG_24MA		0x07
65 #define MAX30100_REG_LED_CONFIG_50MA		0x0f
66 
67 #define MAX30100_REG_TEMP_INTEGER		0x16
68 #define MAX30100_REG_TEMP_FRACTION		0x17
69 
70 struct max30100_data {
71 	struct i2c_client *client;
72 	struct iio_dev *indio_dev;
73 	struct mutex lock;
74 	struct regmap *regmap;
75 
76 	__be16 buffer[2]; /* 2 16-bit channels */
77 };
78 
max30100_is_volatile_reg(struct device * dev,unsigned int reg)79 static bool max30100_is_volatile_reg(struct device *dev, unsigned int reg)
80 {
81 	switch (reg) {
82 	case MAX30100_REG_INT_STATUS:
83 	case MAX30100_REG_MODE_CONFIG:
84 	case MAX30100_REG_FIFO_WR_PTR:
85 	case MAX30100_REG_FIFO_OVR_CTR:
86 	case MAX30100_REG_FIFO_RD_PTR:
87 	case MAX30100_REG_FIFO_DATA:
88 	case MAX30100_REG_TEMP_INTEGER:
89 	case MAX30100_REG_TEMP_FRACTION:
90 		return true;
91 	default:
92 		return false;
93 	}
94 }
95 
96 static const struct regmap_config max30100_regmap_config = {
97 	.name = MAX30100_REGMAP_NAME,
98 
99 	.reg_bits = 8,
100 	.val_bits = 8,
101 
102 	.max_register = MAX30100_REG_TEMP_FRACTION,
103 	.cache_type = REGCACHE_FLAT,
104 
105 	.volatile_reg = max30100_is_volatile_reg,
106 };
107 
108 static const unsigned int max30100_led_current_mapping[] = {
109 	4400, 7600, 11000, 14200, 17400,
110 	20800, 24000, 27100, 30600, 33800,
111 	37000, 40200, 43600, 46800, 50000
112 };
113 
114 static const unsigned long max30100_scan_masks[] = {0x3, 0};
115 
116 static const struct iio_chan_spec max30100_channels[] = {
117 	{
118 		.type = IIO_INTENSITY,
119 		.channel2 = IIO_MOD_LIGHT_IR,
120 		.modified = 1,
121 
122 		.scan_index = 0,
123 		.scan_type = {
124 			.sign = 'u',
125 			.realbits = 16,
126 			.storagebits = 16,
127 			.endianness = IIO_BE,
128 		},
129 	},
130 	{
131 		.type = IIO_INTENSITY,
132 		.channel2 = IIO_MOD_LIGHT_RED,
133 		.modified = 1,
134 
135 		.scan_index = 1,
136 		.scan_type = {
137 			.sign = 'u',
138 			.realbits = 16,
139 			.storagebits = 16,
140 			.endianness = IIO_BE,
141 		},
142 	},
143 	{
144 		.type = IIO_TEMP,
145 		.info_mask_separate =
146 			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
147 		.scan_index = -1,
148 	},
149 };
150 
max30100_set_powermode(struct max30100_data * data,bool state)151 static int max30100_set_powermode(struct max30100_data *data, bool state)
152 {
153 	return regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
154 				  MAX30100_REG_MODE_CONFIG_PWR,
155 				  state ? 0 : MAX30100_REG_MODE_CONFIG_PWR);
156 }
157 
max30100_clear_fifo(struct max30100_data * data)158 static int max30100_clear_fifo(struct max30100_data *data)
159 {
160 	int ret;
161 
162 	ret = regmap_write(data->regmap, MAX30100_REG_FIFO_WR_PTR, 0);
163 	if (ret)
164 		return ret;
165 
166 	ret = regmap_write(data->regmap, MAX30100_REG_FIFO_OVR_CTR, 0);
167 	if (ret)
168 		return ret;
169 
170 	return regmap_write(data->regmap, MAX30100_REG_FIFO_RD_PTR, 0);
171 }
172 
max30100_buffer_postenable(struct iio_dev * indio_dev)173 static int max30100_buffer_postenable(struct iio_dev *indio_dev)
174 {
175 	struct max30100_data *data = iio_priv(indio_dev);
176 	int ret;
177 
178 	ret = max30100_set_powermode(data, true);
179 	if (ret)
180 		return ret;
181 
182 	return max30100_clear_fifo(data);
183 }
184 
max30100_buffer_predisable(struct iio_dev * indio_dev)185 static int max30100_buffer_predisable(struct iio_dev *indio_dev)
186 {
187 	struct max30100_data *data = iio_priv(indio_dev);
188 
189 	return max30100_set_powermode(data, false);
190 }
191 
192 static const struct iio_buffer_setup_ops max30100_buffer_setup_ops = {
193 	.postenable = max30100_buffer_postenable,
194 	.predisable = max30100_buffer_predisable,
195 };
196 
max30100_fifo_count(struct max30100_data * data)197 static inline int max30100_fifo_count(struct max30100_data *data)
198 {
199 	unsigned int val;
200 	int ret;
201 
202 	ret = regmap_read(data->regmap, MAX30100_REG_INT_STATUS, &val);
203 	if (ret)
204 		return ret;
205 
206 	/* FIFO is almost full */
207 	if (val & MAX30100_REG_INT_STATUS_FIFO_RDY)
208 		return MAX30100_REG_FIFO_DATA_ENTRY_COUNT - 1;
209 
210 	return 0;
211 }
212 
max30100_read_measurement(struct max30100_data * data)213 static int max30100_read_measurement(struct max30100_data *data)
214 {
215 	int ret;
216 
217 	ret = i2c_smbus_read_i2c_block_data(data->client,
218 					    MAX30100_REG_FIFO_DATA,
219 					    MAX30100_REG_FIFO_DATA_ENTRY_LEN,
220 					    (u8 *) &data->buffer);
221 
222 	return (ret == MAX30100_REG_FIFO_DATA_ENTRY_LEN) ? 0 : ret;
223 }
224 
max30100_interrupt_handler(int irq,void * private)225 static irqreturn_t max30100_interrupt_handler(int irq, void *private)
226 {
227 	struct iio_dev *indio_dev = private;
228 	struct max30100_data *data = iio_priv(indio_dev);
229 	int ret, cnt = 0;
230 
231 	mutex_lock(&data->lock);
232 
233 	while (cnt || (cnt = max30100_fifo_count(data)) > 0) {
234 		ret = max30100_read_measurement(data);
235 		if (ret)
236 			break;
237 
238 		iio_push_to_buffers(data->indio_dev, data->buffer);
239 		cnt--;
240 	}
241 
242 	mutex_unlock(&data->lock);
243 
244 	return IRQ_HANDLED;
245 }
246 
max30100_get_current_idx(unsigned int val,int * reg)247 static int max30100_get_current_idx(unsigned int val, int *reg)
248 {
249 	int idx;
250 
251 	/* LED turned off */
252 	if (val == 0) {
253 		*reg = 0;
254 		return 0;
255 	}
256 
257 	for (idx = 0; idx < ARRAY_SIZE(max30100_led_current_mapping); idx++) {
258 		if (max30100_led_current_mapping[idx] == val) {
259 			*reg = idx + 1;
260 			return 0;
261 		}
262 	}
263 
264 	return -EINVAL;
265 }
266 
max30100_led_init(struct max30100_data * data)267 static int max30100_led_init(struct max30100_data *data)
268 {
269 	struct device *dev = &data->client->dev;
270 	unsigned int val[2];
271 	int reg, ret;
272 
273 	ret = device_property_read_u32_array(dev, "maxim,led-current-microamp",
274 					(unsigned int *) &val, 2);
275 	if (ret) {
276 		/* Default to 24 mA RED LED, 50 mA IR LED */
277 		reg = (MAX30100_REG_LED_CONFIG_24MA <<
278 			MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
279 			MAX30100_REG_LED_CONFIG_50MA;
280 		dev_warn(dev, "no led-current-microamp set");
281 
282 		return regmap_write(data->regmap, MAX30100_REG_LED_CONFIG, reg);
283 	}
284 
285 	/* RED LED current */
286 	ret = max30100_get_current_idx(val[0], &reg);
287 	if (ret) {
288 		dev_err(dev, "invalid RED current setting %d", val[0]);
289 		return ret;
290 	}
291 
292 	ret = regmap_update_bits(data->regmap, MAX30100_REG_LED_CONFIG,
293 		MAX30100_REG_LED_CONFIG_LED_MASK <<
294 		MAX30100_REG_LED_CONFIG_RED_LED_SHIFT,
295 		reg << MAX30100_REG_LED_CONFIG_RED_LED_SHIFT);
296 	if (ret)
297 		return ret;
298 
299 	/* IR LED current */
300 	ret = max30100_get_current_idx(val[1], &reg);
301 	if (ret) {
302 		dev_err(dev, "invalid IR current setting %d", val[1]);
303 		return ret;
304 	}
305 
306 	return regmap_update_bits(data->regmap, MAX30100_REG_LED_CONFIG,
307 		MAX30100_REG_LED_CONFIG_LED_MASK, reg);
308 }
309 
max30100_chip_init(struct max30100_data * data)310 static int max30100_chip_init(struct max30100_data *data)
311 {
312 	int ret;
313 
314 	/* setup LED current settings */
315 	ret = max30100_led_init(data);
316 	if (ret)
317 		return ret;
318 
319 	/* enable hi-res SPO2 readings at 100Hz */
320 	ret = regmap_write(data->regmap, MAX30100_REG_SPO2_CONFIG,
321 				 MAX30100_REG_SPO2_CONFIG_HI_RES_EN |
322 				 MAX30100_REG_SPO2_CONFIG_100HZ);
323 	if (ret)
324 		return ret;
325 
326 	/* enable SPO2 mode */
327 	ret = regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
328 				 MAX30100_REG_MODE_CONFIG_MODE_MASK,
329 				 MAX30100_REG_MODE_CONFIG_MODE_HR_EN |
330 				 MAX30100_REG_MODE_CONFIG_MODE_SPO2_EN);
331 	if (ret)
332 		return ret;
333 
334 	/* enable FIFO interrupt */
335 	return regmap_update_bits(data->regmap, MAX30100_REG_INT_ENABLE,
336 				 MAX30100_REG_INT_ENABLE_MASK,
337 				 MAX30100_REG_INT_ENABLE_FIFO_EN
338 				 << MAX30100_REG_INT_ENABLE_MASK_SHIFT);
339 }
340 
max30100_read_temp(struct max30100_data * data,int * val)341 static int max30100_read_temp(struct max30100_data *data, int *val)
342 {
343 	int ret;
344 	unsigned int reg;
345 
346 	ret = regmap_read(data->regmap, MAX30100_REG_TEMP_INTEGER, &reg);
347 	if (ret < 0)
348 		return ret;
349 	*val = reg << 4;
350 
351 	ret = regmap_read(data->regmap, MAX30100_REG_TEMP_FRACTION, &reg);
352 	if (ret < 0)
353 		return ret;
354 
355 	*val |= reg & 0xf;
356 	*val = sign_extend32(*val, 11);
357 
358 	return 0;
359 }
360 
max30100_get_temp(struct max30100_data * data,int * val)361 static int max30100_get_temp(struct max30100_data *data, int *val)
362 {
363 	int ret;
364 
365 	/* start acquisition */
366 	ret = regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
367 				 MAX30100_REG_MODE_CONFIG_TEMP_EN,
368 				 MAX30100_REG_MODE_CONFIG_TEMP_EN);
369 	if (ret)
370 		return ret;
371 
372 	msleep(35);
373 
374 	return max30100_read_temp(data, val);
375 }
376 
max30100_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)377 static int max30100_read_raw(struct iio_dev *indio_dev,
378 			     struct iio_chan_spec const *chan,
379 			     int *val, int *val2, long mask)
380 {
381 	struct max30100_data *data = iio_priv(indio_dev);
382 	int ret = -EINVAL;
383 
384 	switch (mask) {
385 	case IIO_CHAN_INFO_RAW:
386 		/*
387 		 * Temperature reading can only be acquired while engine
388 		 * is running
389 		 */
390 		mutex_lock(&indio_dev->mlock);
391 
392 		if (!iio_buffer_enabled(indio_dev))
393 			ret = -EAGAIN;
394 		else {
395 			ret = max30100_get_temp(data, val);
396 			if (!ret)
397 				ret = IIO_VAL_INT;
398 
399 		}
400 
401 		mutex_unlock(&indio_dev->mlock);
402 		break;
403 	case IIO_CHAN_INFO_SCALE:
404 		*val = 1;  /* 0.0625 */
405 		*val2 = 16;
406 		ret = IIO_VAL_FRACTIONAL;
407 		break;
408 	}
409 
410 	return ret;
411 }
412 
413 static const struct iio_info max30100_info = {
414 	.read_raw = max30100_read_raw,
415 };
416 
max30100_probe(struct i2c_client * client,const struct i2c_device_id * id)417 static int max30100_probe(struct i2c_client *client,
418 			  const struct i2c_device_id *id)
419 {
420 	struct max30100_data *data;
421 	struct iio_dev *indio_dev;
422 	int ret;
423 
424 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
425 	if (!indio_dev)
426 		return -ENOMEM;
427 
428 	indio_dev->name = MAX30100_DRV_NAME;
429 	indio_dev->channels = max30100_channels;
430 	indio_dev->info = &max30100_info;
431 	indio_dev->num_channels = ARRAY_SIZE(max30100_channels);
432 	indio_dev->available_scan_masks = max30100_scan_masks;
433 	indio_dev->modes = INDIO_DIRECT_MODE;
434 
435 	ret = devm_iio_kfifo_buffer_setup(&client->dev, indio_dev,
436 					  INDIO_BUFFER_SOFTWARE,
437 					  &max30100_buffer_setup_ops);
438 	if (ret)
439 		return ret;
440 
441 	data = iio_priv(indio_dev);
442 	data->indio_dev = indio_dev;
443 	data->client = client;
444 
445 	mutex_init(&data->lock);
446 	i2c_set_clientdata(client, indio_dev);
447 
448 	data->regmap = devm_regmap_init_i2c(client, &max30100_regmap_config);
449 	if (IS_ERR(data->regmap)) {
450 		dev_err(&client->dev, "regmap initialization failed.\n");
451 		return PTR_ERR(data->regmap);
452 	}
453 	max30100_set_powermode(data, false);
454 
455 	ret = max30100_chip_init(data);
456 	if (ret)
457 		return ret;
458 
459 	if (client->irq <= 0) {
460 		dev_err(&client->dev, "no valid irq defined\n");
461 		return -EINVAL;
462 	}
463 	ret = devm_request_threaded_irq(&client->dev, client->irq,
464 					NULL, max30100_interrupt_handler,
465 					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
466 					"max30100_irq", indio_dev);
467 	if (ret) {
468 		dev_err(&client->dev, "request irq (%d) failed\n", client->irq);
469 		return ret;
470 	}
471 
472 	return iio_device_register(indio_dev);
473 }
474 
max30100_remove(struct i2c_client * client)475 static int max30100_remove(struct i2c_client *client)
476 {
477 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
478 	struct max30100_data *data = iio_priv(indio_dev);
479 
480 	iio_device_unregister(indio_dev);
481 	max30100_set_powermode(data, false);
482 
483 	return 0;
484 }
485 
486 static const struct i2c_device_id max30100_id[] = {
487 	{ "max30100", 0 },
488 	{}
489 };
490 MODULE_DEVICE_TABLE(i2c, max30100_id);
491 
492 static const struct of_device_id max30100_dt_ids[] = {
493 	{ .compatible = "maxim,max30100" },
494 	{ }
495 };
496 MODULE_DEVICE_TABLE(of, max30100_dt_ids);
497 
498 static struct i2c_driver max30100_driver = {
499 	.driver = {
500 		.name	= MAX30100_DRV_NAME,
501 		.of_match_table	= max30100_dt_ids,
502 	},
503 	.probe		= max30100_probe,
504 	.remove		= max30100_remove,
505 	.id_table	= max30100_id,
506 };
507 module_i2c_driver(max30100_driver);
508 
509 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
510 MODULE_DESCRIPTION("MAX30100 heart rate and pulse oximeter sensor");
511 MODULE_LICENSE("GPL");
512