iio: pressure: add support for MS5611 pressure and temperature sensor

Add support for Measurement Specialities MS5611 pressure
and temperature sensor.

Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/pressure/ms5611_i2c.c

@@ -0,0 +1,128 @@
+/*
+ * MS5611 pressure and temperature sensor driver (I2C bus)
+ *
+ * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 7-bit I2C slave addresses:
+ *
+ * 0x77 (CSB pin low)
+ * 0x76 (CSB pin high)
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+
+#include "ms5611.h"
+
+static int ms5611_i2c_reset(struct device *dev)
+{
+	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
+
+	return i2c_smbus_write_byte(st->client, MS5611_RESET);
+}
+
+static int ms5611_i2c_read_prom_word(struct device *dev, int index, u16 *word)
+{
+	int ret;
+	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
+
+	ret = i2c_smbus_read_word_swapped(st->client,
+			MS5611_READ_PROM_WORD + (index << 1));
+	if (ret < 0)
+		return ret;
+
+	*word = ret;
+
+	return 0;
+}
+
+static int ms5611_i2c_read_adc(struct ms5611_state *st, s32 *val)
+{
+	int ret;
+	u8 buf[3];
+
+	ret = i2c_smbus_read_i2c_block_data(st->client, MS5611_READ_ADC,
+					    3, buf);
+	if (ret < 0)
+		return ret;
+
+	*val = (buf[0] << 16) | (buf[1] << 8) | buf[2];
+
+	return 0;
+}
+
+static int ms5611_i2c_read_adc_temp_and_pressure(struct device *dev,
+						 s32 *temp, s32 *pressure)
+{
+	int ret;
+	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
+
+	ret = i2c_smbus_write_byte(st->client, MS5611_START_TEMP_CONV);
+	if (ret < 0)
+		return ret;
+
+	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
+
+	ret = ms5611_i2c_read_adc(st, temp);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte(st->client, MS5611_START_PRESSURE_CONV);
+	if (ret < 0)
+		return ret;
+
+	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
+
+	return ms5611_i2c_read_adc(st, pressure);
+}
+
+static int ms5611_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct ms5611_state *st;
+	struct iio_dev *indio_dev;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_BYTE |
+				     I2C_FUNC_SMBUS_READ_WORD_DATA |
+				     I2C_FUNC_SMBUS_READ_I2C_BLOCK))
+		return -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->reset = ms5611_i2c_reset;
+	st->read_prom_word = ms5611_i2c_read_prom_word;
+	st->read_adc_temp_and_pressure = ms5611_i2c_read_adc_temp_and_pressure;
+	st->client = client;
+
+	return ms5611_probe(indio_dev, &client->dev);
+}
+
+static const struct i2c_device_id ms5611_id[] = {
+	{ "ms5611", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ms5611_id);
+
+static struct i2c_driver ms5611_driver = {
+	.driver = {
+		.name = "ms5611",
+		.owner = THIS_MODULE,
+	},
+	.id_table = ms5611_id,
+	.probe = ms5611_i2c_probe,
+};
+module_i2c_driver(ms5611_driver);
+
+MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
+MODULE_DESCRIPTION("MS5611 i2c driver");
+MODULE_LICENSE("GPL v2");