[PATCH] iio: (ms5637) Add Measurement Specialties MS5637 support

[Markezana, William]

Signed-off-by: Ludovic <ludovic.tancerel@xxxxxxxxxxxxxxxxx>
---
 drivers/iio/pressure/Kconfig                      |   10 +
 drivers/iio/pressure/Makefile                     |    1 +
 drivers/iio/pressure/ms5637.c                     |  488 +++++++++++++++++++++
 drivers/staging/iio/Documentation/pressure/ms5637 |   25 ++
 4 files changed, 524 insertions(+)
 create mode 100644 drivers/iio/pressure/ms5637.c
 create mode 100644 drivers/staging/iio/Documentation/pressure/ms5637

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index ffac8ac..4ba9bd5 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -41,6 +41,16 @@ config MPL3115
           To compile this driver as a module, choose M here: the module
           will be called mpl3115.
 
+config MS5637
+        tristate "MS5637 pressure & temperature sensor"
+        depends on I2C
+        help
+          If you say yes here you get support for the Measurement Specialties
+          MS5637 pressure and temperature sensor.
+
+          This driver can also be built as a module. If so, the module will
+          be called ms5637.
+
 config IIO_ST_PRESS
 	tristate "STMicroelectronics pressure sensor Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS
diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
index c53d250..50fe66e 100644
--- a/drivers/iio/pressure/Makefile
+++ b/drivers/iio/pressure/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_MPL115) += mpl115.o
 obj-$(CONFIG_MPL3115) += mpl3115.o
+obj-$(CONFIG_MS5637) += ms5637.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
diff --git a/drivers/iio/pressure/ms5637.c b/drivers/iio/pressure/ms5637.c
new file mode 100644
index 0000000..ea74636
--- /dev/null
+++ b/drivers/iio/pressure/ms5637.c
@@ -0,0 +1,488 @@
+/*
+ * ms5637.c - Support for Measurement Specialties MS5637 temperature sensor
+ *
+ * Copyright (c) 2014 Measurement Specialties
+ *
+ * Licensed under the GPL-2.
+ *
+ * (7-bit I2C slave address 0x77)
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/stat.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+
+/* MS5637 Commands */
+#define MS5637_RESET				(0x1E)
+#define MS5637_TEMPERATURE_CONVERSION_START	(0x50)
+#define MS5637_PRESSURE_CONVERSION_START	(0x40)
+#define MS5637_ADC_READ				(0x00)
+#define MS5637_PROM_READ			(0xA0)
+#define MS5637_PROM_ELEMENTS_NB                 (7)
+
+#define ATTR_RESET				0
+#define ATTR_RESOLUTION				1
+
+static const u16 conversion_time[] = { 1000, 2000, 3000, 5000, 9000, 17000 };
+
+struct ms5637_dev {
+	struct i2c_client *client;
+	struct mutex lock; /* mutex protecting this data structure */
+	u16 calibration_coeffs[MS5637_PROM_ELEMENTS_NB];
+	bool got_calibration_words;
+	unsigned long last_update;
+	bool valid;
+	int temperature;
+	unsigned int pressure;
+	u8 resolution_index;
+};
+
+static int ms5637_get_calibration_coeffs(struct ms5637_dev *dev_data,
+					 unsigned char index, u16 *word)
+{
+	int ret = 0;
+
+	ret = i2c_smbus_read_word_swapped(dev_data->client,
+					  MS5637_PROM_READ + (index << 1));
+	if (ret < 0)
+		return ret;
+	*word = (u16) ret & 0xFFFF;
+	return 0;
+}
+
+static bool ms5637_crc_check(u16 *n_prom, u8 crc)
+{
+	u8 cnt, n_bit;
+	u16 n_rem, crc_read;
+
+	n_rem = 0x00;
+	crc_read = n_prom[0];
+	n_prom[MS5637_PROM_ELEMENTS_NB] = 0;
+	n_prom[0] = (0x0FFF & (n_prom[0]));	/* Clear the CRC byte */
+
+	for (cnt = 0; cnt < (MS5637_PROM_ELEMENTS_NB + 1) * 2; cnt++) {
+		if (cnt % 2 == 1)
+			n_rem ^= n_prom[cnt >> 1] & 0x00FF;
+		else
+			n_rem ^= n_prom[cnt >> 1] >> 8;
+
+		for (n_bit = 8; n_bit > 0; n_bit--) {
+			if (n_rem & 0x8000)
+				n_rem = (n_rem << 1) ^ 0x3000;
+			else
+				n_rem <<= 1;
+		}
+	}
+	n_rem >>= 12;
+	n_prom[0] = crc_read;
+	return (n_rem == crc);
+}
+
+static int ms5637_fill_calibration_coeffs(struct ms5637_dev *dev_data)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < MS5637_PROM_ELEMENTS_NB; i++) {
+		ret = ms5637_get_calibration_coeffs(dev_data, i,
+				&dev_data->calibration_coeffs
+				[i]);
+
+		dev_dbg(&dev_data->client->dev, "Coeff %d : %d", i,
+			dev_data->calibration_coeffs[i]);
+
+		if (ret < 0) {
+			dev_err(&dev_data->client->dev,
+				"unable to get calibration coefficients at address %d\n",
+				i + 1);
+			return ret;
+		}
+	}
+
+	if (!ms5637_crc_check(dev_data->calibration_coeffs,
+			      (dev_data->
+			       calibration_coeffs[0] & 0xF000) >> 12)) {
+		dev_err(&dev_data->client->dev,
+			"Calibration coefficients crc check error\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int ms5637_read_adc_value(struct ms5637_dev *dev_data, u32 *adc_value)
+{
+	int ret = 0;
+	u8 buf[3];
+
+	ret =
+	    i2c_smbus_read_i2c_block_data(dev_data->client, MS5637_ADC_READ, 3,
+					  buf);
+	if (ret < 0)
+		return ret;
+	dev_dbg(&dev_data->client->dev, "ADC raw value : %x %x %x\n", buf[0],
+		buf[1], buf[2]);
+	*adc_value = (buf[0] << 16) + (buf[1] << 8) + buf[0];
+	return 0;
+}
+
+static int ms5637_conversion_and_read_adc(struct ms5637_dev *dev_data,
+					  u32 *t_adc, u32 *p_adc)
+{
+	int ret;
+
+	/* Trigger Temperature conversion */
+	ret = i2c_smbus_write_byte(dev_data->client,
+				   MS5637_TEMPERATURE_CONVERSION_START
+				   + dev_data->resolution_index * 2);
+	if (ret < 0)
+		return ret;
+	usleep_range(conversion_time[dev_data->resolution_index],
+		     conversion_time[dev_data->resolution_index]+3000);
+	/* Retrieve ADC value */
+	ret = ms5637_read_adc_value(dev_data, t_adc);
+
+	/* Trigger Pressure conversion */
+	ret = i2c_smbus_write_byte(dev_data->client,
+				   MS5637_PRESSURE_CONVERSION_START
+				   + dev_data->resolution_index * 2);
+	if (ret < 0)
+		return ret;
+	usleep_range(conversion_time[dev_data->resolution_index],
+		     conversion_time[dev_data->resolution_index]+3000);
+	/* Retrieve ADC value */
+	ret = ms5637_read_adc_value(dev_data, p_adc);
+
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static int ms5637_read_temperature_and_pressure(struct ms5637_dev *dev_data)
+{
+	int ret = 0;
+	u32 t_adc, p_adc;
+	s32 dt, temp;
+	s64 off, sens, t2, off2, sens2;
+
+	mutex_lock(&dev_data->lock);
+
+	if (time_after(jiffies, dev_data->last_update + HZ / 2) ||
+	    !dev_data->valid) {
+		if (!dev_data->got_calibration_words) {
+			ret = ms5637_fill_calibration_coeffs(dev_data);
+			if (ret < 0)
+				goto out;
+
+			dev_data->got_calibration_words = true;
+		}
+
+		ret = ms5637_conversion_and_read_adc(dev_data, &t_adc, &p_adc);
+
+		if (ret < 0) {
+			dev_data->got_calibration_words = false;
+			dev_err(&dev_data->client->dev,
+				"unable to make sensor adc conversion\n");
+			goto out;
+		}
+
+		dt = (s32) t_adc - (dev_data->calibration_coeffs[5] << 8);
+
+		/* Actual temperature = 2000 + dT * TEMPSENS */
+		temp =
+		    2000 + (((s64) dt * dev_data->calibration_coeffs[6]) >> 23);
+
+		/* Second order temperature compensation */
+		if (temp < 2000) {
+			s64 tmp = (s64) temp - 2000;
+
+			t2 = (3 * ((s64) dt * (s64) dt)) >> 33;
+			off2 = (61 * tmp * tmp) >> 4;
+			sens2 = (29 * tmp * tmp) >> 4;
+
+			if (temp < -1500) {
+				s64 tmp = (s64) temp + 1500;
+
+				off2 += 17 * tmp * tmp;
+				sens2 += 9 * tmp * tmp;
+			}
+		} else {
+			t2 = (5 * ((s64) dt * (s64) dt)) >> 38;
+			off2 = 0;
+			sens2 = 0;
+		}
+
+		/* OFF = OFF_T1 + TCO * dT */
+		off = (((s64) dev_data->calibration_coeffs[2]) << 17)
+		    +
+		    ((((s64) dev_data->calibration_coeffs[4]) * (s64) dt) >> 6);
+		off -= off2;
+
+		/* Sensitivity at actual temperature = SENS_T1 + TCS * dT */
+		sens = (((s64) dev_data->calibration_coeffs[1]) << 16)
+		    + (((s64) dev_data->calibration_coeffs[3] * dt) >> 7);
+		sens -= sens2;
+
+		/* Temperature compensated pressure = D1 * SENS - OFF */
+		dev_data->temperature = (temp - t2) * 10;
+		dev_data->pressure = (u32) (((((s64) p_adc * sens) >> 21)
+					     - off) >> 15) / 100;
+
+		dev_data->last_update = jiffies;
+		dev_data->valid = true;
+	}
+ out:
+	mutex_unlock(&dev_data->lock);
+
+	return ret >= 0 ? 0 : ret;
+}
+
+static int ms5637_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *channel, int *val,
+			   int *val2, long mask)
+{
+	int ret;
+	struct ms5637_dev *dev_data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (channel->type) {
+		case IIO_TEMP:	/* in 0.001 °C */
+			ret = ms5637_read_temperature_and_pressure(dev_data);
+			if (ret)
+				goto t_err;
+			*val = dev_data->temperature;
+			break;
+		case IIO_PRESSURE:	/* in mB */
+			ret = ms5637_read_temperature_and_pressure(dev_data);
+			if (ret)
+				goto p_err;
+			*val = dev_data->pressure;
+			break;
+		default:
+			return -EINVAL;
+		}
+		ret = IIO_VAL_INT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+ t_err:
+	dev_err(&indio_dev->dev, "Temperature read error\n");
+	return ret;
+ p_err:
+	dev_err(&indio_dev->dev, "Pressure read error\n");
+	return ret;
+}
+
+static const struct iio_chan_spec ms5637_channels[] = {
+	{
+	 .type = IIO_TEMP,
+	 .output = 1,
+	 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+	 .scan_index = 0,
+	 },
+	{
+	 .type = IIO_PRESSURE,
+	 .output = 1,
+	 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+	 .scan_index = 0,
+	 }
+};
+
+static ssize_t ms5637_read_attr(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ms5637_dev *dev_data = iio_priv(indio_dev);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	int ret = 0;
+
+	switch (this_attr->address) {
+	case ATTR_RESET:
+		ret = sprintf(buf, "0\n");
+		break;
+	case ATTR_RESOLUTION:
+		ret = sprintf(buf, "%d\n", dev_data->resolution_index + 8);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static ssize_t ms5637_write_attr(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ms5637_dev *dev_data = iio_priv(indio_dev);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	u8 val;
+	int ret;
+
+	ret = kstrtou8(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev_data->lock);
+	switch (this_attr->address) {
+	case ATTR_RESET:
+		if (val != 1)
+			goto einval;
+
+		ret = i2c_smbus_write_byte(dev_data->client, MS5637_RESET);
+		if (ret < 0)
+			goto out;
+		usleep_range(3000, 6000);
+
+		break;
+	case ATTR_RESOLUTION:
+		if ((val < 8) || (val > 13))
+			goto einval;
+		dev_data->resolution_index = val - 8;
+		break;
+	default:
+		goto einval;
+	}
+
+	dev_data->valid = false;
+	goto out;
+ einval:
+	ret = -EINVAL;
+ out:
+	mutex_unlock(&dev_data->lock);
+
+	return ret ? ret : len;
+}
+
+static IIO_DEVICE_ATTR(in_reset,
+		       S_IRUGO | S_IWUSR,
+		       ms5637_read_attr, ms5637_write_attr, ATTR_RESET);
+static IIO_DEVICE_ATTR(in_resolution,
+		       S_IRUGO | S_IWUSR,
+		       ms5637_read_attr, ms5637_write_attr, ATTR_RESOLUTION);
+static IIO_CONST_ATTR(resolution_available, "8 9 10 11 12 13");
+
+static struct attribute *ms5637_attributes[] = {
+	&iio_dev_attr_in_reset.dev_attr.attr,
+	&iio_dev_attr_in_resolution.dev_attr.attr,
+	&iio_const_attr_resolution_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ms5637_attribute_group = {
+	.attrs = ms5637_attributes,
+};
+
+static const struct iio_info ms5637_info = {
+	.read_raw = ms5637_read_raw,
+	.attrs = &ms5637_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+static int ms5637_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct ms5637_dev *dev_data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
+		dev_err(&client->dev,
+			"adapter does not support SMBus read word transactions\n");
+		return -ENODEV;
+	}
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_BYTE)) {
+		dev_err(&client->dev,
+			"adapter does not support SMBus write byte transactions\n");
+		return -ENODEV;
+	}
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+		dev_err(&client->dev,
+			"adapter does not support SMBus read block transactions\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev_data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	dev_data = iio_priv(indio_dev);
+	dev_data->client = client;
+	mutex_init(&dev_data->lock);
+
+	indio_dev->info = &ms5637_info;
+	indio_dev->name = id->name;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ms5637_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ms5637_channels);
+
+	i2c_set_clientdata(client, indio_dev);
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte(client, MS5637_RESET);
+	if (ret < 0)
+		return ret;
+	usleep_range(3000, 6000);
+
+	ret = ms5637_fill_calibration_coeffs(dev_data);
+	if (ret == 0)
+		dev_data->got_calibration_words = true;
+
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&client->dev, "Driver initialization done");
+	return 0;
+}
+
+static int ms5637_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id ms5637_id[] = {
+	{"ms5637", 0},
+	{}
+};
+
+static struct i2c_driver ms5637_driver = {
+	.probe = ms5637_probe,
+	.remove = ms5637_remove,
+	.id_table = ms5637_id,
+	.driver = {
+		   .name = "ms5637",
+		   .owner = THIS_MODULE,
+		   },
+};
+
+module_i2c_driver(ms5637_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Measurement Specialties MS5637 temperature driver");
+MODULE_AUTHOR("William Markezana <william.markezana@xxxxxxxxxxxxx>");
+MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@xxxxxxxxxxxxxxxxx>");
diff --git a/drivers/staging/iio/Documentation/pressure/ms5637 b/drivers/staging/iio/Documentation/pressure/ms5637
new file mode 100644
index 0000000..d0d64f3
--- /dev/null
+++ b/drivers/staging/iio/Documentation/pressure/ms5637
@@ -0,0 +1,25 @@
+Kernel driver ms5637
+====================
+
+Supported chips:
+  * Measurement Specialties MS5637
+    Prefix: 'ms5637'
+    Addresses scanned: I2C 0x76
+    Datasheet: Available for download on meas-spec.com
+
+Authors:
+    William Markezana (Meas-Spec) <william.markezana@xxxxxxxxxxxxx>
+    Ludovic Tancerel <ludovic.tancerel@xxxxxxxxxxxxxxxxx>
+
+Description
+-----------
+
+The MS5637 is a single chip pressure & temperature sensor.
+The driver returns a milli-bar pressure value and a milli-degre celius value using the iio framework
+
+Via the iio sysfs interface, there are several attributes available.
+in_reset - Reset ms5637 device by writing a 1 in it.
+in_resolution - Set the number of bits for ADC resolution.
+out_pressure_input - Current pressure from ms5637 sensor (milli-bar)
+out_temp_input - Current temperature from htu21 sensor (milli-°C value)
+resolution_available - List of resolutions supported
-- 
1.7.9.5

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