1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * MPRLS0025PA - Honeywell MicroPressure pressure sensor series driver
4  *
5  * Copyright (c) Andreas Klinger <ak@it-klinger.de>
6  *
7  * Data sheet:
8  *  https://prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/en-us/
9  *    products/sensors/pressure-sensors/board-mount-pressure-sensors/
10  *    micropressure-mpr-series/documents/
11  *    sps-siot-mpr-series-datasheet-32332628-ciid-172626.pdf
12  *
13  * 7-bit I2C default slave address: 0x18
14  */
15 
16 #include <linux/delay.h>
17 #include <linux/device.h>
18 #include <linux/i2c.h>
19 #include <linux/math64.h>
20 #include <linux/mod_devicetable.h>
21 #include <linux/module.h>
22 #include <linux/property.h>
23 #include <linux/units.h>
24 
25 #include <linux/gpio/consumer.h>
26 
27 #include <linux/iio/buffer.h>
28 #include <linux/iio/iio.h>
29 #include <linux/iio/trigger_consumer.h>
30 #include <linux/iio/triggered_buffer.h>
31 
32 #include <linux/regulator/consumer.h>
33 
34 #include <asm/unaligned.h>
35 
36 /* bits in i2c status byte */
37 #define MPR_I2C_POWER	BIT(6)	/* device is powered */
38 #define MPR_I2C_BUSY	BIT(5)	/* device is busy */
39 #define MPR_I2C_MEMORY	BIT(2)	/* integrity test passed */
40 #define MPR_I2C_MATH	BIT(0)	/* internal math saturation */
41 
42 /*
43  * support _RAW sysfs interface:
44  *
45  * Calculation formula from the datasheet:
46  * pressure = (press_cnt - outputmin) * scale + pmin
47  * with:
48  * * pressure	- measured pressure in Pascal
49  * * press_cnt	- raw value read from sensor
50  * * pmin	- minimum pressure range value of sensor (data->pmin)
51  * * pmax	- maximum pressure range value of sensor (data->pmax)
52  * * outputmin	- minimum numerical range raw value delivered by sensor
53  *						(mpr_func_spec.output_min)
54  * * outputmax	- maximum numerical range raw value delivered by sensor
55  *						(mpr_func_spec.output_max)
56  * * scale	- (pmax - pmin) / (outputmax - outputmin)
57  *
58  * formula of the userspace:
59  * pressure = (raw + offset) * scale
60  *
61  * Values given to the userspace in sysfs interface:
62  * * raw	- press_cnt
63  * * offset	- (-1 * outputmin) - pmin / scale
64  *                note: With all sensors from the datasheet pmin = 0
65  *                which reduces the offset to (-1 * outputmin)
66  */
67 
68 /*
69  * transfer function A: 10%   to 90%   of 2^24
70  * transfer function B:  2.5% to 22.5% of 2^24
71  * transfer function C: 20%   to 80%   of 2^24
72  */
73 enum mpr_func_id {
74 	MPR_FUNCTION_A,
75 	MPR_FUNCTION_B,
76 	MPR_FUNCTION_C,
77 };
78 
79 struct mpr_func_spec {
80 	u32			output_min;
81 	u32			output_max;
82 };
83 
84 static const struct mpr_func_spec mpr_func_spec[] = {
85 	[MPR_FUNCTION_A] = {.output_min = 1677722, .output_max = 15099494},
86 	[MPR_FUNCTION_B] = {.output_min =  419430, .output_max =  3774874},
87 	[MPR_FUNCTION_C] = {.output_min = 3355443, .output_max = 13421773},
88 };
89 
90 struct mpr_chan {
91 	s32			pres;		/* pressure value */
92 	s64			ts;		/* timestamp */
93 };
94 
95 struct mpr_data {
96 	struct i2c_client	*client;
97 	struct mutex		lock;		/*
98 						 * access to device during read
99 						 */
100 	u32			pmin;		/* minimal pressure in pascal */
101 	u32			pmax;		/* maximal pressure in pascal */
102 	enum mpr_func_id	function;	/* transfer function */
103 	u32			outmin;		/*
104 						 * minimal numerical range raw
105 						 * value from sensor
106 						 */
107 	u32			outmax;		/*
108 						 * maximal numerical range raw
109 						 * value from sensor
110 						 */
111 	int                     scale;          /* int part of scale */
112 	int                     scale2;         /* nano part of scale */
113 	int                     offset;         /* int part of offset */
114 	int                     offset2;        /* nano part of offset */
115 	struct gpio_desc	*gpiod_reset;	/* reset */
116 	int			irq;		/*
117 						 * end of conversion irq;
118 						 * used to distinguish between
119 						 * irq mode and reading in a
120 						 * loop until data is ready
121 						 */
122 	struct completion	completion;	/* handshake from irq to read */
123 	struct mpr_chan		chan;		/*
124 						 * channel values for buffered
125 						 * mode
126 						 */
127 };
128 
129 static const struct iio_chan_spec mpr_channels[] = {
130 	{
131 		.type = IIO_PRESSURE,
132 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
133 					BIT(IIO_CHAN_INFO_SCALE) |
134 					BIT(IIO_CHAN_INFO_OFFSET),
135 		.scan_index = 0,
136 		.scan_type = {
137 			.sign = 's',
138 			.realbits = 32,
139 			.storagebits = 32,
140 			.endianness = IIO_CPU,
141 		},
142 	},
143 	IIO_CHAN_SOFT_TIMESTAMP(1),
144 };
145 
mpr_reset(struct mpr_data * data)146 static void mpr_reset(struct mpr_data *data)
147 {
148 	if (data->gpiod_reset) {
149 		gpiod_set_value(data->gpiod_reset, 0);
150 		udelay(10);
151 		gpiod_set_value(data->gpiod_reset, 1);
152 	}
153 }
154 
155 /**
156  * mpr_read_pressure() - Read pressure value from sensor via I2C
157  * @data: Pointer to private data struct.
158  * @press: Output value read from sensor.
159  *
160  * Reading from the sensor by sending and receiving I2C telegrams.
161  *
162  * If there is an end of conversion (EOC) interrupt registered the function
163  * waits for a maximum of one second for the interrupt.
164  *
165  * Context: The function can sleep and data->lock should be held when calling it
166  * Return:
167  * * 0		- OK, the pressure value could be read
168  * * -ETIMEDOUT	- Timeout while waiting for the EOC interrupt or busy flag is
169  *		  still set after nloops attempts of reading
170  */
mpr_read_pressure(struct mpr_data * data,s32 * press)171 static int mpr_read_pressure(struct mpr_data *data, s32 *press)
172 {
173 	struct device *dev = &data->client->dev;
174 	int ret, i;
175 	u8 wdata[] = {0xAA, 0x00, 0x00};
176 	s32 status;
177 	int nloops = 10;
178 	u8 buf[4];
179 
180 	reinit_completion(&data->completion);
181 
182 	ret = i2c_master_send(data->client, wdata, sizeof(wdata));
183 	if (ret < 0) {
184 		dev_err(dev, "error while writing ret: %d\n", ret);
185 		return ret;
186 	}
187 	if (ret != sizeof(wdata)) {
188 		dev_err(dev, "received size doesn't fit - ret: %d / %u\n", ret,
189 							(u32)sizeof(wdata));
190 		return -EIO;
191 	}
192 
193 	if (data->irq > 0) {
194 		ret = wait_for_completion_timeout(&data->completion, HZ);
195 		if (!ret) {
196 			dev_err(dev, "timeout while waiting for eoc irq\n");
197 			return -ETIMEDOUT;
198 		}
199 	} else {
200 		/* wait until status indicates data is ready */
201 		for (i = 0; i < nloops; i++) {
202 			/*
203 			 * datasheet only says to wait at least 5 ms for the
204 			 * data but leave the maximum response time open
205 			 * --> let's try it nloops (10) times which seems to be
206 			 *     quite long
207 			 */
208 			usleep_range(5000, 10000);
209 			status = i2c_smbus_read_byte(data->client);
210 			if (status < 0) {
211 				dev_err(dev,
212 					"error while reading, status: %d\n",
213 					status);
214 				return status;
215 			}
216 			if (!(status & MPR_I2C_BUSY))
217 				break;
218 		}
219 		if (i == nloops) {
220 			dev_err(dev, "timeout while reading\n");
221 			return -ETIMEDOUT;
222 		}
223 	}
224 
225 	ret = i2c_master_recv(data->client, buf, sizeof(buf));
226 	if (ret < 0) {
227 		dev_err(dev, "error in i2c_master_recv ret: %d\n", ret);
228 		return ret;
229 	}
230 	if (ret != sizeof(buf)) {
231 		dev_err(dev, "received size doesn't fit - ret: %d / %u\n", ret,
232 							(u32)sizeof(buf));
233 		return -EIO;
234 	}
235 
236 	if (buf[0] & MPR_I2C_BUSY) {
237 		/*
238 		 * it should never be the case that status still indicates
239 		 * business
240 		 */
241 		dev_err(dev, "data still not ready: %08x\n", buf[0]);
242 		return -ETIMEDOUT;
243 	}
244 
245 	*press = get_unaligned_be24(&buf[1]);
246 
247 	dev_dbg(dev, "received: %*ph cnt: %d\n", ret, buf, *press);
248 
249 	return 0;
250 }
251 
mpr_eoc_handler(int irq,void * p)252 static irqreturn_t mpr_eoc_handler(int irq, void *p)
253 {
254 	struct mpr_data *data = p;
255 
256 	complete(&data->completion);
257 
258 	return IRQ_HANDLED;
259 }
260 
mpr_trigger_handler(int irq,void * p)261 static irqreturn_t mpr_trigger_handler(int irq, void *p)
262 {
263 	int ret;
264 	struct iio_poll_func *pf = p;
265 	struct iio_dev *indio_dev = pf->indio_dev;
266 	struct mpr_data *data = iio_priv(indio_dev);
267 
268 	mutex_lock(&data->lock);
269 	ret = mpr_read_pressure(data, &data->chan.pres);
270 	if (ret < 0)
271 		goto err;
272 
273 	iio_push_to_buffers_with_timestamp(indio_dev, &data->chan,
274 						iio_get_time_ns(indio_dev));
275 
276 err:
277 	mutex_unlock(&data->lock);
278 	iio_trigger_notify_done(indio_dev->trig);
279 
280 	return IRQ_HANDLED;
281 }
282 
mpr_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)283 static int mpr_read_raw(struct iio_dev *indio_dev,
284 	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
285 {
286 	int ret;
287 	s32 pressure;
288 	struct mpr_data *data = iio_priv(indio_dev);
289 
290 	if (chan->type != IIO_PRESSURE)
291 		return -EINVAL;
292 
293 	switch (mask) {
294 	case IIO_CHAN_INFO_RAW:
295 		mutex_lock(&data->lock);
296 		ret = mpr_read_pressure(data, &pressure);
297 		mutex_unlock(&data->lock);
298 		if (ret < 0)
299 			return ret;
300 		*val = pressure;
301 		return IIO_VAL_INT;
302 	case IIO_CHAN_INFO_SCALE:
303 		*val = data->scale;
304 		*val2 = data->scale2;
305 		return IIO_VAL_INT_PLUS_NANO;
306 	case IIO_CHAN_INFO_OFFSET:
307 		*val = data->offset;
308 		*val2 = data->offset2;
309 		return IIO_VAL_INT_PLUS_NANO;
310 	default:
311 		return -EINVAL;
312 	}
313 }
314 
315 static const struct iio_info mpr_info = {
316 	.read_raw = &mpr_read_raw,
317 };
318 
mpr_probe(struct i2c_client * client)319 static int mpr_probe(struct i2c_client *client)
320 {
321 	int ret;
322 	struct mpr_data *data;
323 	struct iio_dev *indio_dev;
324 	struct device *dev = &client->dev;
325 	s64 scale, offset;
326 	u32 func;
327 
328 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE))
329 		return dev_err_probe(dev, -EOPNOTSUPP,
330 					"I2C functionality not supported\n");
331 
332 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
333 	if (!indio_dev)
334 		return dev_err_probe(dev, -ENOMEM, "couldn't get iio_dev\n");
335 
336 	data = iio_priv(indio_dev);
337 	data->client = client;
338 	data->irq = client->irq;
339 
340 	mutex_init(&data->lock);
341 	init_completion(&data->completion);
342 
343 	indio_dev->name = "mprls0025pa";
344 	indio_dev->info = &mpr_info;
345 	indio_dev->channels = mpr_channels;
346 	indio_dev->num_channels = ARRAY_SIZE(mpr_channels);
347 	indio_dev->modes = INDIO_DIRECT_MODE;
348 
349 	ret = devm_regulator_get_enable(dev, "vdd");
350 	if (ret)
351 		return dev_err_probe(dev, ret,
352 				"can't get and enable vdd supply\n");
353 
354 	if (dev_fwnode(dev)) {
355 		ret = device_property_read_u32(dev, "honeywell,pmin-pascal",
356 								&data->pmin);
357 		if (ret)
358 			return dev_err_probe(dev, ret,
359 				"honeywell,pmin-pascal could not be read\n");
360 		ret = device_property_read_u32(dev, "honeywell,pmax-pascal",
361 								&data->pmax);
362 		if (ret)
363 			return dev_err_probe(dev, ret,
364 				"honeywell,pmax-pascal could not be read\n");
365 		ret = device_property_read_u32(dev,
366 				"honeywell,transfer-function", &func);
367 		if (ret)
368 			return dev_err_probe(dev, ret,
369 				"honeywell,transfer-function could not be read\n");
370 		data->function = func - 1;
371 		if (data->function > MPR_FUNCTION_C)
372 			return dev_err_probe(dev, -EINVAL,
373 				"honeywell,transfer-function %d invalid\n",
374 								data->function);
375 	} else {
376 		/* when loaded as i2c device we need to use default values */
377 		dev_notice(dev, "firmware node not found; using defaults\n");
378 		data->pmin = 0;
379 		data->pmax = 172369; /* 25 psi */
380 		data->function = MPR_FUNCTION_A;
381 	}
382 
383 	data->outmin = mpr_func_spec[data->function].output_min;
384 	data->outmax = mpr_func_spec[data->function].output_max;
385 
386 	/* use 64 bit calculation for preserving a reasonable precision */
387 	scale = div_s64(((s64)(data->pmax - data->pmin)) * NANO,
388 						data->outmax - data->outmin);
389 	data->scale = div_s64_rem(scale, NANO, &data->scale2);
390 	/*
391 	 * multiply with NANO before dividing by scale and later divide by NANO
392 	 * again.
393 	 */
394 	offset = ((-1LL) * (s64)data->outmin) * NANO -
395 			div_s64(div_s64((s64)data->pmin * NANO, scale), NANO);
396 	data->offset = div_s64_rem(offset, NANO, &data->offset2);
397 
398 	if (data->irq > 0) {
399 		ret = devm_request_irq(dev, data->irq, mpr_eoc_handler,
400 				IRQF_TRIGGER_RISING, client->name, data);
401 		if (ret)
402 			return dev_err_probe(dev, ret,
403 				"request irq %d failed\n", data->irq);
404 	}
405 
406 	data->gpiod_reset = devm_gpiod_get_optional(dev, "reset",
407 							GPIOD_OUT_HIGH);
408 	if (IS_ERR(data->gpiod_reset))
409 		return dev_err_probe(dev, PTR_ERR(data->gpiod_reset),
410 						"request reset-gpio failed\n");
411 
412 	mpr_reset(data);
413 
414 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
415 						mpr_trigger_handler, NULL);
416 	if (ret)
417 		return dev_err_probe(dev, ret,
418 					"iio triggered buffer setup failed\n");
419 
420 	ret = devm_iio_device_register(dev, indio_dev);
421 	if (ret)
422 		return dev_err_probe(dev, ret,
423 					"unable to register iio device\n");
424 
425 	return 0;
426 }
427 
428 static const struct of_device_id mpr_matches[] = {
429 	{ .compatible = "honeywell,mprls0025pa" },
430 	{ }
431 };
432 MODULE_DEVICE_TABLE(of, mpr_matches);
433 
434 static const struct i2c_device_id mpr_id[] = {
435 	{ "mprls0025pa" },
436 	{ }
437 };
438 MODULE_DEVICE_TABLE(i2c, mpr_id);
439 
440 static struct i2c_driver mpr_driver = {
441 	.probe		= mpr_probe,
442 	.id_table	= mpr_id,
443 	.driver		= {
444 		.name		= "mprls0025pa",
445 		.of_match_table = mpr_matches,
446 	},
447 };
448 module_i2c_driver(mpr_driver);
449 
450 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
451 MODULE_DESCRIPTION("Honeywell MPRLS0025PA I2C driver");
452 MODULE_LICENSE("GPL");
453