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
25 struct 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
mpl115_request(struct mpl115_data * data)35 static 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
mpl115_comp_pressure(struct mpl115_data * data,int * val,int * val2)47 static 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);
79 done:
80 mutex_unlock(&data->lock);
81 return ret;
82 }
83
mpl115_read_temp(struct mpl115_data * data)84 static 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);
93 done:
94 mutex_unlock(&data->lock);
95 return ret;
96 }
97
mpl115_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)98 static 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
136 static 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
149 static const struct iio_info mpl115_info = {
150 .read_raw = &mpl115_read_raw,
151 };
152
mpl115_probe(struct device * dev,const char * name,const struct mpl115_ops * ops)153 int 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 }
226 EXPORT_SYMBOL_NS_GPL(mpl115_probe, "IIO_MPL115");
227
mpl115_runtime_suspend(struct device * dev)228 static 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
mpl115_runtime_resume(struct device * dev)237 static 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
247 EXPORT_NS_RUNTIME_DEV_PM_OPS(mpl115_dev_pm_ops, mpl115_runtime_suspend,
248 mpl115_runtime_resume, NULL, IIO_MPL115);
249
250 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
251 MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
252 MODULE_LICENSE("GPL");
253