sdp500.c

  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
 20struct sdp500_data {
 21	struct device *dev;
 22};
 23
 24DECLARE_CRC8_TABLE(sdp500_crc8_table);
 25
 26static 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
 33static 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
 41static 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
 85static const struct iio_info sdp500_info = {
 86	.read_raw = &sdp500_read_raw,
 87};
 88
 89static 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
132static const struct i2c_device_id sdp500_id[] = {
133	{ "sdp500" },
134	{ }
135};
136MODULE_DEVICE_TABLE(i2c, sdp500_id);
137
138static const struct of_device_id sdp500_of_match[] = {
139	{ .compatible = "sensirion,sdp500" },
140	{ }
141};
142MODULE_DEVICE_TABLE(of, sdp500_of_match);
143
144static 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};
152module_i2c_driver(sdp500_driver);
153
154MODULE_AUTHOR("Thomas Sioutas <thomas.sioutas@prodrive-technologies.com>");
155MODULE_DESCRIPTION("Driver for Sensirion SDP500 differential pressure sensor");
156MODULE_LICENSE("GPL");