iio: Add Freescale MPL115A2 pressure / temperature sensor driver

I2C-controlled sensor with 10-bit pressure and temperature measurement

datasheet: http://cache.freescale.com/files/sensors/doc/data_sheet/MPL3115A2.pdf

v2:
* use devm_iio_device_register()

Signed-off-by: Peter Meerwald <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/pressure/Kconfig

···
           To compile this driver as a module, choose M here: the module
           will be called hid-sensor-press.
 
+config MPL115
+	tristate "Freescale MPL115A2 pressure sensor driver"
+	depends on I2C
+	help
+	  Say yes here to build support for the Freescale MPL115A2
+	  pressure sensor connected via I2C.
+
+          To compile this driver as a module, choose M here: the module
+          will be called mpl115.
+
 config MPL3115
 	tristate "Freescale MPL3115A2 pressure sensor driver"
 	depends on I2C

drivers/iio/pressure/Makefile

···
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
+obj-$(CONFIG_MPL115) += mpl115.o
 obj-$(CONFIG_MPL3115) += mpl3115.o
 obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o
 st_pressure-y := st_pressure_core.o

drivers/iio/pressure/mpl115.c

···
+/*
+ * mpl115.c - Support for Freescale MPL115A2 pressure/temperature sensor
+ *
+ * Copyright (c) 2014 Peter Meerwald <[e-mail]>
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * (7-bit I2C slave address 0x60)
+ *
+ * TODO: shutdown pin
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/delay.h>
+
+#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
+#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
+#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
+#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
+#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
+#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
+#define MPL115_CONVERT 0x12 /* convert temperature and pressure */
+
+struct mpl115_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	s16 a0;
+	s16 b1, b2;
+	s16 c12;
+};
+
+static int mpl115_request(struct mpl115_data *data)
+{
+	int ret = i2c_smbus_write_byte_data(data->client, MPL115_CONVERT, 0);
+	if (ret < 0)
+		return ret;
+
+	usleep_range(3000, 4000);
+
+	return 0;
+}
+
+static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
+{
+	int ret;
+	u16 padc, tadc;
+	int a1, y1, pcomp;
+	unsigned kpa;
+
+	mutex_lock(&data->lock);
+	ret = mpl115_request(data);
+	if (ret < 0)
+		goto done;
+
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_PADC);
+	if (ret < 0)
+		goto done;
+	padc = ret >> 6;
+
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_TADC);
+	if (ret < 0)
+		goto done;
+	tadc = ret >> 6;
+
+	/* see Freescale AN3785 */
+	a1 = data->b1 + ((data->c12 * tadc) >> 11);
+	y1 = (data->a0 << 10) + a1 * padc;
+
+	/* compensated pressure with 4 fractional bits */
+	pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;
+
+	kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
+	*val = kpa >> 4;
+	*val2 = (kpa & 15) * (1000000 >> 4);
+done:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int mpl115_read_temp(struct mpl115_data *data)
+{
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = mpl115_request(data);
+	if (ret < 0)
+		goto done;
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_TADC);
+done:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int mpl115_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct mpl115_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = mpl115_comp_pressure(data, val, val2);
+		if (ret < 0)
+			return ret;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_RAW:
+		/* temperature -5.35 C / LSB, 472 LSB is 25 C */
+		ret = mpl115_read_temp(data);
+		if (ret < 0)
+			return ret;
+		*val = ret >> 6;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = 605;
+		*val2 = 750000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SCALE:
+		*val = -186;
+		*val2 = 915888;
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+	return -EINVAL;
+}
+
+static const struct iio_chan_spec mpl115_channels[] = {
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+	},
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static const struct iio_info mpl115_info = {
+	.read_raw = &mpl115_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int mpl115_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct mpl115_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+
+	i2c_set_clientdata(client, indio_dev);
+	indio_dev->info = &mpl115_info;
+	indio_dev->name = id->name;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mpl115_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
+
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_A0);
+	if (ret < 0)
+		return ret;
+	data->a0 = ret;
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_B1);
+	if (ret < 0)
+		return ret;
+	data->b1 = ret;
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_B2);
+	if (ret < 0)
+		return ret;
+	data->b2 = ret;
+	ret = i2c_smbus_read_word_swapped(data->client, MPL115_C12);
+	if (ret < 0)
+		return ret;
+	data->c12 = ret;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id mpl115_id[] = {
+	{ "mpl115", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mpl115_id);
+
+static struct i2c_driver mpl115_driver = {
+	.driver = {
+		.name	= "mpl115",
+	},
+	.probe = mpl115_probe,
+	.id_table = mpl115_id,
+};
+module_i2c_driver(mpl115_driver);
+
+MODULE_AUTHOR("Peter Meerwald <[e-mail]>");
+MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
+MODULE_LICENSE("GPL");