1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Driver for Sensirion sdp500 and sdp510 pressure sensors
4 *
5 * Datasheet: https://sensirion.com/resource/datasheet/sdp600
6 */
7
8 #include <linux/i2c.h>
9 #include <linux/crc8.h>
10 #include <linux/iio/iio.h>
11 #include <linux/mod_devicetable.h>
12 #include <linux/regulator/consumer.h>
13 #include <linux/unaligned.h>
14
15 #define SDP500_CRC8_POLYNOMIAL 0x31 /* x8+x5+x4+1 (normalized to 0x31) */
16 #define SDP500_READ_SIZE 3
17
18 #define SDP500_I2C_START_MEAS 0xF1
19
20 struct sdp500_data {
21 struct device *dev;
22 };
23
24 DECLARE_CRC8_TABLE(sdp500_crc8_table);
25
sdp500_start_measurement(struct sdp500_data * data)26 static int sdp500_start_measurement(struct sdp500_data *data)
27 {
28 struct i2c_client *client = to_i2c_client(data->dev);
29
30 return i2c_smbus_write_byte(client, SDP500_I2C_START_MEAS);
31 }
32
33 static const struct iio_chan_spec sdp500_channels[] = {
34 {
35 .type = IIO_PRESSURE,
36 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
37 BIT(IIO_CHAN_INFO_SCALE),
38 },
39 };
40
sdp500_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)41 static int sdp500_read_raw(struct iio_dev *indio_dev,
42 struct iio_chan_spec const *chan,
43 int *val, int *val2, long mask)
44 {
45 int ret;
46 u8 rxbuf[SDP500_READ_SIZE];
47 u8 received_crc, calculated_crc;
48 struct sdp500_data *data = iio_priv(indio_dev);
49 struct i2c_client *client = to_i2c_client(data->dev);
50
51 switch (mask) {
52 case IIO_CHAN_INFO_RAW:
53 ret = i2c_master_recv(client, rxbuf, SDP500_READ_SIZE);
54 if (ret < 0) {
55 dev_err(data->dev, "Failed to receive data");
56 return ret;
57 }
58 if (ret != SDP500_READ_SIZE) {
59 dev_err(data->dev, "Data is received wrongly");
60 return -EIO;
61 }
62
63 received_crc = rxbuf[2];
64 calculated_crc = crc8(sdp500_crc8_table, rxbuf,
65 sizeof(rxbuf) - 1, 0x00);
66 if (received_crc != calculated_crc) {
67 dev_err(data->dev,
68 "calculated crc = 0x%.2X, received 0x%.2X",
69 calculated_crc, received_crc);
70 return -EIO;
71 }
72
73 *val = get_unaligned_be16(rxbuf);
74 return IIO_VAL_INT;
75 case IIO_CHAN_INFO_SCALE:
76 *val = 1;
77 *val2 = 60;
78
79 return IIO_VAL_FRACTIONAL;
80 default:
81 return -EINVAL;
82 }
83 }
84
85 static const struct iio_info sdp500_info = {
86 .read_raw = &sdp500_read_raw,
87 };
88
sdp500_probe(struct i2c_client * client)89 static int sdp500_probe(struct i2c_client *client)
90 {
91 struct iio_dev *indio_dev;
92 struct sdp500_data *data;
93 struct device *dev = &client->dev;
94 int ret;
95 u8 rxbuf[SDP500_READ_SIZE];
96
97 ret = devm_regulator_get_enable(dev, "vdd");
98 if (ret)
99 return dev_err_probe(dev, ret,
100 "Failed to get and enable regulator\n");
101
102 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
103 if (!indio_dev)
104 return -ENOMEM;
105
106 /* has to be done before the first i2c communication */
107 crc8_populate_msb(sdp500_crc8_table, SDP500_CRC8_POLYNOMIAL);
108
109 data = iio_priv(indio_dev);
110 data->dev = dev;
111
112 indio_dev->name = "sdp500";
113 indio_dev->channels = sdp500_channels;
114 indio_dev->info = &sdp500_info;
115 indio_dev->modes = INDIO_DIRECT_MODE;
116 indio_dev->num_channels = ARRAY_SIZE(sdp500_channels);
117
118 ret = sdp500_start_measurement(data);
119 if (ret)
120 return dev_err_probe(dev, ret, "Failed to start measurement");
121
122 /* First measurement is not correct, read it out to get rid of it */
123 i2c_master_recv(client, rxbuf, SDP500_READ_SIZE);
124
125 ret = devm_iio_device_register(dev, indio_dev);
126 if (ret)
127 return dev_err_probe(dev, ret, "Failed to register indio_dev");
128
129 return 0;
130 }
131
132 static const struct i2c_device_id sdp500_id[] = {
133 { "sdp500" },
134 { }
135 };
136 MODULE_DEVICE_TABLE(i2c, sdp500_id);
137
138 static const struct of_device_id sdp500_of_match[] = {
139 { .compatible = "sensirion,sdp500" },
140 { }
141 };
142 MODULE_DEVICE_TABLE(of, sdp500_of_match);
143
144 static struct i2c_driver sdp500_driver = {
145 .driver = {
146 .name = "sensirion,sdp500",
147 .of_match_table = sdp500_of_match,
148 },
149 .probe = sdp500_probe,
150 .id_table = sdp500_id,
151 };
152 module_i2c_driver(sdp500_driver);
153
154 MODULE_AUTHOR("Thomas Sioutas <thomas.sioutas@prodrive-technologies.com>");
155 MODULE_DESCRIPTION("Driver for Sensirion SDP500 differential pressure sensor");
156 MODULE_LICENSE("GPL");
157