mpl115.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * mpl115.c - Support for Freescale MPL115A pressure/temperature sensor
  4 *
  5 * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
  6 *
  7 * TODO: synchronization with system suspend
  8 */
  9
 10#include <linux/module.h>
 11#include <linux/iio/iio.h>
 12#include <linux/delay.h>
 13#include <linux/gpio/consumer.h>
 14
 15#include "mpl115.h"
 16
 17#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
 18#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
 19#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
 20#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
 21#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
 22#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
 23#define MPL115_CONVERT 0x12 /* convert temperature and pressure */
 24
 25struct mpl115_data {
 26	struct device *dev;
 27	struct mutex lock;
 28	s16 a0;
 29	s16 b1, b2;
 30	s16 c12;
 31	struct gpio_desc *shutdown;
 32	const struct mpl115_ops *ops;
 33};
 34
 35static int mpl115_request(struct mpl115_data *data)
 36{
 37	int ret = data->ops->write(data->dev, MPL115_CONVERT, 0);
 38
 39	if (ret < 0)
 40		return ret;
 41
 42	usleep_range(3000, 4000);
 43
 44	return 0;
 45}
 46
 47static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
 48{
 49	int ret;
 50	u16 padc, tadc;
 51	int a1, y1, pcomp;
 52	unsigned kpa;
 53
 54	mutex_lock(&data->lock);
 55	ret = mpl115_request(data);
 56	if (ret < 0)
 57		goto done;
 58
 59	ret = data->ops->read(data->dev, MPL115_PADC);
 60	if (ret < 0)
 61		goto done;
 62	padc = ret >> 6;
 63
 64	ret = data->ops->read(data->dev, MPL115_TADC);
 65	if (ret < 0)
 66		goto done;
 67	tadc = ret >> 6;
 68
 69	/* see Freescale AN3785 */
 70	a1 = data->b1 + ((data->c12 * tadc) >> 11);
 71	y1 = (data->a0 << 10) + a1 * padc;
 72
 73	/* compensated pressure with 4 fractional bits */
 74	pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;
 75
 76	kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
 77	*val = kpa >> 4;
 78	*val2 = (kpa & 15) * (1000000 >> 4);
 79done:
 80	mutex_unlock(&data->lock);
 81	return ret;
 82}
 83
 84static int mpl115_read_temp(struct mpl115_data *data)
 85{
 86	int ret;
 87
 88	mutex_lock(&data->lock);
 89	ret = mpl115_request(data);
 90	if (ret < 0)
 91		goto done;
 92	ret = data->ops->read(data->dev, MPL115_TADC);
 93done:
 94	mutex_unlock(&data->lock);
 95	return ret;
 96}
 97
 98static int mpl115_read_raw(struct iio_dev *indio_dev,
 99			    struct iio_chan_spec const *chan,
100			    int *val, int *val2, long mask)
101{
102	struct mpl115_data *data = iio_priv(indio_dev);
103	int ret;
104
105	switch (mask) {
106	case IIO_CHAN_INFO_PROCESSED:
107		pm_runtime_get_sync(data->dev);
108		ret = mpl115_comp_pressure(data, val, val2);
109		if (ret < 0)
110			return ret;
111		pm_runtime_put_autosuspend(data->dev);
112
113		return IIO_VAL_INT_PLUS_MICRO;
114	case IIO_CHAN_INFO_RAW:
115		pm_runtime_get_sync(data->dev);
116		/* temperature -5.35 C / LSB, 472 LSB is 25 C */
117		ret = mpl115_read_temp(data);
118		if (ret < 0)
119			return ret;
120		pm_runtime_put_autosuspend(data->dev);
121		*val = ret >> 6;
122
123		return IIO_VAL_INT;
124	case IIO_CHAN_INFO_OFFSET:
125		*val = -605;
126		*val2 = 750000;
127		return IIO_VAL_INT_PLUS_MICRO;
128	case IIO_CHAN_INFO_SCALE:
129		*val = -186;
130		*val2 = 915888;
131		return IIO_VAL_INT_PLUS_MICRO;
132	}
133	return -EINVAL;
134}
135
136static const struct iio_chan_spec mpl115_channels[] = {
137	{
138		.type = IIO_PRESSURE,
139		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
140	},
141	{
142		.type = IIO_TEMP,
143		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
144		.info_mask_shared_by_type =
145			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
146	},
147};
148
149static const struct iio_info mpl115_info = {
150	.read_raw = &mpl115_read_raw,
151};
152
153int mpl115_probe(struct device *dev, const char *name,
154			const struct mpl115_ops *ops)
155{
156	struct mpl115_data *data;
157	struct iio_dev *indio_dev;
158	int ret;
159
160	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
161	if (!indio_dev)
162		return -ENOMEM;
163
164	data = iio_priv(indio_dev);
165	data->dev = dev;
166	data->ops = ops;
167	mutex_init(&data->lock);
168
169	indio_dev->info = &mpl115_info;
170	indio_dev->name = name;
171	indio_dev->modes = INDIO_DIRECT_MODE;
172	indio_dev->channels = mpl115_channels;
173	indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
174
175	ret = data->ops->init(data->dev);
176	if (ret)
177		return ret;
178
179	dev_set_drvdata(dev, indio_dev);
180
181	ret = data->ops->read(data->dev, MPL115_A0);
182	if (ret < 0)
183		return ret;
184	data->a0 = ret;
185	ret = data->ops->read(data->dev, MPL115_B1);
186	if (ret < 0)
187		return ret;
188	data->b1 = ret;
189	ret = data->ops->read(data->dev, MPL115_B2);
190	if (ret < 0)
191		return ret;
192	data->b2 = ret;
193	ret = data->ops->read(data->dev, MPL115_C12);
194	if (ret < 0)
195		return ret;
196	data->c12 = ret;
197
198	data->shutdown = devm_gpiod_get_optional(dev, "shutdown",
199						 GPIOD_OUT_LOW);
200	if (IS_ERR(data->shutdown))
201		return dev_err_probe(dev, PTR_ERR(data->shutdown),
202				     "cannot get shutdown gpio\n");
203
204	if (data->shutdown) {
205		/* Enable runtime PM */
206		pm_runtime_get_noresume(dev);
207		pm_runtime_set_active(dev);
208		pm_runtime_enable(dev);
209
210		/*
211		 * As the device takes 3 ms to come up with a fresh
212		 * reading after power-on and 5 ms to actually power-on,
213		 * do not shut it down unnecessarily. Set autosuspend to
214		 * 2000 ms.
215		 */
216		pm_runtime_set_autosuspend_delay(dev, 2000);
217		pm_runtime_use_autosuspend(dev);
218		pm_runtime_put(dev);
219
220		dev_dbg(dev, "low-power mode enabled");
221	} else
222		dev_dbg(dev, "low-power mode disabled");
223
224	return devm_iio_device_register(dev, indio_dev);
225}
226EXPORT_SYMBOL_NS_GPL(mpl115_probe, "IIO_MPL115");
227
228static int mpl115_runtime_suspend(struct device *dev)
229{
230	struct mpl115_data *data = iio_priv(dev_get_drvdata(dev));
231
232	gpiod_set_value(data->shutdown, 1);
233
234	return 0;
235}
236
237static int mpl115_runtime_resume(struct device *dev)
238{
239	struct mpl115_data *data = iio_priv(dev_get_drvdata(dev));
240
241	gpiod_set_value(data->shutdown, 0);
242	usleep_range(5000, 6000);
243
244	return 0;
245}
246
247EXPORT_NS_RUNTIME_DEV_PM_OPS(mpl115_dev_pm_ops, mpl115_runtime_suspend,
248			  mpl115_runtime_resume, NULL, IIO_MPL115);
249
250MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
251MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
252MODULE_LICENSE("GPL");