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/Kconfig

@@ -52,6 +52,33 @@ config MPL3115
           To compile this driver as a module, choose M here: the module
           will be called mpl3115.
 
+config MS5611
+	tristate "Measurement Specialities MS5611 pressure sensor driver"
+	help
+	  Say Y here to build support for the Measurement Specialities
+	  MS5611 pressure and temperature sensor.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called ms5611_core.
+
+config MS5611_I2C
+	tristate "support I2C bus connection"
+	depends on I2C && MS5611
+	help
+	  Say Y here to build I2C bus support for MS5611.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called ms5611_i2c.
+
+config MS5611_SPI
+	tristate "support SPI bus connection"
+	depends on SPI_MASTER && MS5611
+	help
+	  Say Y here to build SPI bus support for MS5611.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called ms5611_spi.
+
 config IIO_ST_PRESS
 	tristate "STMicroelectronics pressure sensor Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS

drivers/iio/pressure/Makefile

@@ -7,6 +7,9 @@ obj-$(CONFIG_BMP280) += bmp280.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_MPL115) += mpl115.o
 obj-$(CONFIG_MPL3115) += mpl3115.o
+obj-$(CONFIG_MS5611) += ms5611_core.o
+obj-$(CONFIG_MS5611_I2C) += ms5611_i2c.o
+obj-$(CONFIG_MS5611_SPI) += ms5611_spi.o
 obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o
 st_pressure-y := st_pressure_core.o
 st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o

drivers/iio/pressure/ms5611.h

@@ -0,0 +1,44 @@
+/*
+ * MS5611 pressure and temperature sensor driver
+ *
+ * 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.
+ *
+ */
+
+#ifndef _MS5611_H
+#define _MS5611_H
+
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/mutex.h>
+
+#define MS5611_RESET			0x1e
+#define MS5611_READ_ADC			0x00
+#define MS5611_READ_PROM_WORD		0xA0
+#define MS5611_START_TEMP_CONV		0x58
+#define MS5611_START_PRESSURE_CONV	0x48
+
+#define MS5611_CONV_TIME_MIN		9040
+#define MS5611_CONV_TIME_MAX		10000
+
+#define MS5611_PROM_WORDS_NB		8
+
+struct ms5611_state {
+	void *client;
+	struct mutex lock;
+
+	int (*reset)(struct device *dev);
+	int (*read_prom_word)(struct device *dev, int index, u16 *word);
+	int (*read_adc_temp_and_pressure)(struct device *dev,
+					  s32 *temp, s32 *pressure);
+
+	u16 prom[MS5611_PROM_WORDS_NB];
+};
+
+int ms5611_probe(struct iio_dev *indio_dev, struct device *dev);
+
+#endif /* _MS5611_H */

drivers/iio/pressure/ms5611_core.c

@@ -0,0 +1,215 @@
+/*
+ * MS5611 pressure and temperature sensor driver
+ *
+ * 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.
+ *
+ * Data sheet:
+ *  http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/delay.h>
+
+#include "ms5611.h"
+
+static bool ms5611_prom_is_valid(u16 *prom, size_t len)
+{
+	int i, j;
+	uint16_t crc = 0, crc_orig = prom[7] & 0x000F;
+
+	prom[7] &= 0xFF00;
+
+	for (i = 0; i < len * 2; i++) {
+		if (i % 2 == 1)
+			crc ^= prom[i >> 1] & 0x00FF;
+		else
+			crc ^= prom[i >> 1] >> 8;
+
+		for (j = 0; j < 8; j++) {
+			if (crc & 0x8000)
+				crc = (crc << 1) ^ 0x3000;
+			else
+				crc <<= 1;
+		}
+	}
+
+	crc = (crc >> 12) & 0x000F;
+
+	return crc_orig != 0x0000 && crc == crc_orig;
+}
+
+static int ms5611_read_prom(struct iio_dev *indio_dev)
+{
+	int ret, i;
+	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]);
+		if (ret < 0) {
+			dev_err(&indio_dev->dev,
+				"failed to read prom at %d\n", i);
+			return ret;
+		}
+	}
+
+	if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) {
+		dev_err(&indio_dev->dev, "PROM integrity check failed\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+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);
+	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);
+
+	t = 2000 + ((st->prom[6] * dt) >> 23);
+	if (t < 2000) {
+		s64 off2, sens2, t2;
+
+		t2 = (dt * dt) >> 31;
+		off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
+		sens2 = off2 >> 1;
+
+		if (t < -1500) {
+			s64 tmp = (t + 1500) * (t + 1500);
+
+			off2 += 7 * tmp;
+			sens2 += (11 * tmp) >> 1;
+		}
+
+		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;
+	struct ms5611_state *st = iio_priv(indio_dev);
+
+	ret = st->reset(&indio_dev->dev);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "failed to reset device\n");
+		return ret;
+	}
+
+	usleep_range(3000, 4000);
+
+	return 0;
+}
+
+static int ms5611_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	int ret;
+	s32 temp, pressure;
+	struct ms5611_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		mutex_lock(&st->lock);
+		ret = ms5611_read_temp_and_pressure(indio_dev,
+						    &temp, &pressure);
+		mutex_unlock(&st->lock);
+		if (ret < 0)
+			return ret;
+
+		switch (chan->type) {
+		case IIO_TEMP:
+			*val = temp * 10;
+			return IIO_VAL_INT;
+		case IIO_PRESSURE:
+			*val = pressure / 1000;
+			*val2 = (pressure % 1000) * 1000;
+			return IIO_VAL_INT_PLUS_MICRO;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_chan_spec ms5611_channels[] = {
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+			BIT(IIO_CHAN_INFO_SCALE)
+	},
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+			BIT(IIO_CHAN_INFO_SCALE)
+	}
+};
+
+static const struct iio_info ms5611_info = {
+	.read_raw = &ms5611_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int ms5611_init(struct iio_dev *indio_dev)
+{
+	int ret;
+
+	ret = ms5611_reset(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	return ms5611_read_prom(indio_dev);
+}
+
+int ms5611_probe(struct iio_dev *indio_dev, struct device *dev)
+{
+	int ret;
+	struct ms5611_state *st = iio_priv(indio_dev);
+
+	mutex_init(&st->lock);
+	indio_dev->dev.parent = dev;
+	indio_dev->name = dev->driver->name;
+	indio_dev->info = &ms5611_info;
+	indio_dev->channels = ms5611_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = ms5611_init(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+EXPORT_SYMBOL(ms5611_probe);
+
+MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
+MODULE_DESCRIPTION("MS5611 core driver");
+MODULE_LICENSE("GPL v2");