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_mark_last_busy(data->dev);
112 pm_runtime_put_autosuspend(data->dev);
113
114 return IIO_VAL_INT_PLUS_MICRO;
115 case IIO_CHAN_INFO_RAW:
116 pm_runtime_get_sync(data->dev);
117 /* temperature -5.35 C / LSB, 472 LSB is 25 C */
118 ret = mpl115_read_temp(data);
119 if (ret < 0)
120 return ret;
121 pm_runtime_mark_last_busy(data->dev);
122 pm_runtime_put_autosuspend(data->dev);
123 *val = ret >> 6;
124
125 return IIO_VAL_INT;
126 case IIO_CHAN_INFO_OFFSET:
127 *val = -605;
128 *val2 = 750000;
129 return IIO_VAL_INT_PLUS_MICRO;
130 case IIO_CHAN_INFO_SCALE:
131 *val = -186;
132 *val2 = 915888;
133 return IIO_VAL_INT_PLUS_MICRO;
134 }
135 return -EINVAL;
136 }
137
138 static const struct iio_chan_spec mpl115_channels[] = {
139 {
140 .type = IIO_PRESSURE,
141 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
142 },
143 {
144 .type = IIO_TEMP,
145 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
146 .info_mask_shared_by_type =
147 BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
148 },
149 };
150
151 static const struct iio_info mpl115_info = {
152 .read_raw = &mpl115_read_raw,
153 };
154
mpl115_probe(struct device * dev,const char * name,const struct mpl115_ops * ops)155 int mpl115_probe(struct device *dev, const char *name,
156 const struct mpl115_ops *ops)
157 {
158 struct mpl115_data *data;
159 struct iio_dev *indio_dev;
160 int ret;
161
162 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
163 if (!indio_dev)
164 return -ENOMEM;
165
166 data = iio_priv(indio_dev);
167 data->dev = dev;
168 data->ops = ops;
169 mutex_init(&data->lock);
170
171 indio_dev->info = &mpl115_info;
172 indio_dev->name = name;
173 indio_dev->modes = INDIO_DIRECT_MODE;
174 indio_dev->channels = mpl115_channels;
175 indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
176
177 ret = data->ops->init(data->dev);
178 if (ret)
179 return ret;
180
181 dev_set_drvdata(dev, indio_dev);
182
183 ret = data->ops->read(data->dev, MPL115_A0);
184 if (ret < 0)
185 return ret;
186 data->a0 = ret;
187 ret = data->ops->read(data->dev, MPL115_B1);
188 if (ret < 0)
189 return ret;
190 data->b1 = ret;
191 ret = data->ops->read(data->dev, MPL115_B2);
192 if (ret < 0)
193 return ret;
194 data->b2 = ret;
195 ret = data->ops->read(data->dev, MPL115_C12);
196 if (ret < 0)
197 return ret;
198 data->c12 = ret;
199
200 data->shutdown = devm_gpiod_get_optional(dev, "shutdown",
201 GPIOD_OUT_LOW);
202 if (IS_ERR(data->shutdown))
203 return dev_err_probe(dev, PTR_ERR(data->shutdown),
204 "cannot get shutdown gpio\n");
205
206 if (data->shutdown) {
207 /* Enable runtime PM */
208 pm_runtime_get_noresume(dev);
209 pm_runtime_set_active(dev);
210 pm_runtime_enable(dev);
211
212 /*
213 * As the device takes 3 ms to come up with a fresh
214 * reading after power-on and 5 ms to actually power-on,
215 * do not shut it down unnecessarily. Set autosuspend to
216 * 2000 ms.
217 */
218 pm_runtime_set_autosuspend_delay(dev, 2000);
219 pm_runtime_use_autosuspend(dev);
220 pm_runtime_put(dev);
221
222 dev_dbg(dev, "low-power mode enabled");
223 } else
224 dev_dbg(dev, "low-power mode disabled");
225
226 return devm_iio_device_register(dev, indio_dev);
227 }
228 EXPORT_SYMBOL_NS_GPL(mpl115_probe, IIO_MPL115);
229
mpl115_runtime_suspend(struct device * dev)230 static int mpl115_runtime_suspend(struct device *dev)
231 {
232 struct mpl115_data *data = iio_priv(dev_get_drvdata(dev));
233
234 gpiod_set_value(data->shutdown, 1);
235
236 return 0;
237 }
238
mpl115_runtime_resume(struct device * dev)239 static int mpl115_runtime_resume(struct device *dev)
240 {
241 struct mpl115_data *data = iio_priv(dev_get_drvdata(dev));
242
243 gpiod_set_value(data->shutdown, 0);
244 usleep_range(5000, 6000);
245
246 return 0;
247 }
248
249 EXPORT_NS_RUNTIME_DEV_PM_OPS(mpl115_dev_pm_ops, mpl115_runtime_suspend,
250 mpl115_runtime_resume, NULL, IIO_MPL115);
251
252 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
253 MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
254 MODULE_LICENSE("GPL");
255