iio: pressure: ms5611: add support for MS5607 temperature and pressure sensor

MS5607 is temperature and pressure sensor which hardware is similar to MS5611.
Both sensors share command protocol and support both I2C and SPI serial
protocols. They only differ in compensation algorithms.
Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/pressure/Kconfig

@@ -56,7 +56,7 @@ config MS5611
 	tristate "Measurement Specialties MS5611 pressure sensor driver"
 	help
 	  Say Y here to build support for the Measurement Specialties
-	  MS5611 pressure and temperature sensor.
+	  MS5611, MS5607 pressure and temperature sensors.
 
 	  To compile this driver as a module, choose M here: the module will
 	  be called ms5611_core.

drivers/iio/pressure/ms5611.h

@@ -27,6 +27,18 @@
 
 #define MS5611_PROM_WORDS_NB		8
 
+enum {
+	MS5611,
+	MS5607,
+};
+
+struct ms5611_chip_info {
+	u16 prom[MS5611_PROM_WORDS_NB];
+
+	int (*temp_and_pressure_compensate)(struct ms5611_chip_info *chip_info,
+					    s32 *temp, s32 *pressure);
+};
+
 struct ms5611_state {
 	void *client;
 	struct mutex lock;
@@ -36,9 +48,9 @@ struct ms5611_state {
 	int (*read_adc_temp_and_pressure)(struct device *dev,
 					  s32 *temp, s32 *pressure);
 
-	u16 prom[MS5611_PROM_WORDS_NB];
+	struct ms5611_chip_info *chip_info;
 };
 
-int ms5611_probe(struct iio_dev *indio_dev, struct device *dev);
+int ms5611_probe(struct iio_dev *indio_dev, struct device *dev, int type);
 
 #endif /* _MS5611_H */

drivers/iio/pressure/ms5611_core.c

@@ -9,6 +9,7 @@
  *
  * Data sheet:
  *  http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
+ *  http://www.meas-spec.com/downloads/MS5607-02BA03.pdf
  *
  */
 
@@ -50,7 +51,8 @@ static int ms5611_read_prom(struct iio_dev *indio_dev)
 	struct ms5611_state *st = iio_priv(indio_dev);
 
 	for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
-		ret = st->read_prom_word(&indio_dev->dev, i, &st->prom[i]);
+		ret = st->read_prom_word(&indio_dev->dev,
+					 i, &st->chip_info->prom[i]);
 		if (ret < 0) {
 			dev_err(&indio_dev->dev,
 				"failed to read prom at %d\n", i);
@@ -58,7 +60,7 @@ static int ms5611_read_prom(struct iio_dev *indio_dev)
 		}
 	}
 
-	if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) {
+	if (!ms5611_prom_is_valid(st->chip_info->prom, MS5611_PROM_WORDS_NB)) {
 		dev_err(&indio_dev->dev, "PROM integrity check failed\n");
 		return -ENODEV;
 	}
@@ -70,22 +72,30 @@ static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
 					 s32 *temp, s32 *pressure)
 {
 	int ret;
-	s32 t, p;
-	s64 off, sens, dt;
 	struct ms5611_state *st = iio_priv(indio_dev);
 
-	ret = st->read_adc_temp_and_pressure(&indio_dev->dev, &t, &p);
+	ret = st->read_adc_temp_and_pressure(&indio_dev->dev, temp, pressure);
 	if (ret < 0) {
 		dev_err(&indio_dev->dev,
 			"failed to read temperature and pressure\n");
 		return ret;
 	}
 
-	dt = t - (st->prom[5] << 8);
-	off = ((s64)st->prom[2] << 16) + ((st->prom[4] * dt) >> 7);
-	sens = ((s64)st->prom[1] << 15) + ((st->prom[3] * dt) >> 8);
+	return st->chip_info->temp_and_pressure_compensate(st->chip_info,
+							   temp, pressure);
+}
+
+static int ms5611_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
+					       s32 *temp, s32 *pressure)
+{
+	s32 t = *temp, p = *pressure;
+	s64 off, sens, dt;
 
-	t = 2000 + ((st->prom[6] * dt) >> 23);
+	dt = t - (chip_info->prom[5] << 8);
+	off = ((s64)chip_info->prom[2] << 16) + ((chip_info->prom[4] * dt) >> 7);
+	sens = ((s64)chip_info->prom[1] << 15) + ((chip_info->prom[3] * dt) >> 8);
+
+	t = 2000 + ((chip_info->prom[6] * dt) >> 23);
 	if (t < 2000) {
 		s64 off2, sens2, t2;
 
@@ -111,6 +121,42 @@ static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
 	return 0;
 }
 
+static int ms5607_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
+					       s32 *temp, s32 *pressure)
+{
+	s32 t = *temp, p = *pressure;
+	s64 off, sens, dt;
+
+	dt = t - (chip_info->prom[5] << 8);
+	off = ((s64)chip_info->prom[2] << 17) + ((chip_info->prom[4] * dt) >> 6);
+	sens = ((s64)chip_info->prom[1] << 16) + ((chip_info->prom[3] * dt) >> 7);
+
+	t = 2000 + ((chip_info->prom[6] * dt) >> 23);
+	if (t < 2000) {
+		s64 off2, sens2, t2;
+
+		t2 = (dt * dt) >> 31;
+		off2 = (61 * (t - 2000) * (t - 2000)) >> 4;
+		sens2 = off2 << 1;
+
+		if (t < -1500) {
+			s64 tmp = (t + 1500) * (t + 1500);
+
+			off2 += 15 * tmp;
+			sens2 += (8 * tmp);
+		}
+
+		t -= t2;
+		off -= off2;
+		sens -= sens2;
+	}
+
+	*temp = t;
+	*pressure = (((p * sens) >> 21) - off) >> 15;
+
+	return 0;
+}
+
 static int ms5611_reset(struct iio_dev *indio_dev)
 {
 	int ret;
@@ -160,6 +206,15 @@ static int ms5611_read_raw(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
+static struct ms5611_chip_info chip_info_tbl[] = {
+	[MS5611] = {
+		.temp_and_pressure_compensate = ms5611_temp_and_pressure_compensate,
+	},
+	[MS5607] = {
+		.temp_and_pressure_compensate = ms5607_temp_and_pressure_compensate,
+	}
+};
+
 static const struct iio_chan_spec ms5611_channels[] = {
 	{
 		.type = IIO_PRESSURE,
@@ -187,12 +242,13 @@ static int ms5611_init(struct iio_dev *indio_dev)
 	return ms5611_read_prom(indio_dev);
 }
 
-int ms5611_probe(struct iio_dev *indio_dev, struct device *dev)
+int ms5611_probe(struct iio_dev *indio_dev, struct device *dev, int type)
 {
 	int ret;
 	struct ms5611_state *st = iio_priv(indio_dev);
 
 	mutex_init(&st->lock);
+	st->chip_info = &chip_info_tbl[type];
 	indio_dev->dev.parent = dev;
 	indio_dev->name = dev->driver->name;
 	indio_dev->info = &ms5611_info;

drivers/iio/pressure/ms5611_i2c.c

@@ -104,11 +104,12 @@ static int ms5611_i2c_probe(struct i2c_client *client,
 	st->read_adc_temp_and_pressure = ms5611_i2c_read_adc_temp_and_pressure;
 	st->client = client;
 
-	return ms5611_probe(indio_dev, &client->dev);
+	return ms5611_probe(indio_dev, &client->dev, id->driver_data);
 }
 
 static const struct i2c_device_id ms5611_id[] = {
-	{ "ms5611", 0 },
+	{ "ms5611", MS5611 },
+	{ "ms5607", MS5607 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ms5611_id);

drivers/iio/pressure/ms5611_spi.c

@@ -103,11 +103,13 @@ static int ms5611_spi_probe(struct spi_device *spi)
 	st->read_adc_temp_and_pressure = ms5611_spi_read_adc_temp_and_pressure;
 	st->client = spi;
 
-	return ms5611_probe(indio_dev, &spi->dev);
+	return ms5611_probe(indio_dev, &spi->dev,
+			    spi_get_device_id(spi)->driver_data);
 }
 
 static const struct spi_device_id ms5611_id[] = {
-	{ "ms5611", 0 },
+	{ "ms5611", MS5611 },
+	{ "ms5607", MS5607 },
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, ms5611_id);