iio: Add tmp006 IR temperature sensor

the TI TMP006 is a non-contact temperature sensor with I2C interface;
it measures the surface temperature of a distance object using a
thermopile to absorb IR energy emitted from the object

the sensor has two channels: IR sensor voltage (16-bit) and reference
temperature of the chip (14-bit); datasheet is here:
http://www.ti.com/lit/ds/symlink/tmp006.pdf

v2 (thanks to Grygorii Strashko, Lars-Peter Clausen, Jonathan Cameron
for review comments):
* power down device on driver remove
* use sign_extend32()
* style cleanup
* add comments what channel raw LSBs mean
* spelling of thermopile
Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: LM Sensors <lm-sensors@lm-sensors.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/Kconfig

@@ -73,5 +73,6 @@ if IIO_TRIGGER
    source "drivers/iio/trigger/Kconfig"
 endif #IIO_TRIGGER
 source "drivers/iio/pressure/Kconfig"
+source "drivers/iio/temperature/Kconfig"
 
 endif # IIO

drivers/iio/Makefile

@@ -21,5 +21,6 @@ obj-y += frequency/
 obj-y += imu/
 obj-y += light/
 obj-y += magnetometer/
+obj-y += temperature/
 obj-y += trigger/
 obj-y += pressure/

drivers/iio/temperature/Kconfig

+#
+# Temperature sensor drivers
+#
+menu "Temperature sensors"
+
+config TMP006
+	tristate "TMP006 infrared thermopile sensor"
+	depends on I2C
+	help
+	  If you say yes here you get support for the Texas Instruments
+	  TMP006 infrared thermopile sensor.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called tmp006.
+
+endmenu

drivers/iio/temperature/Makefile

+#
+# Makefile for industrial I/O temperature drivers
+#
+
+obj-$(CONFIG_TMP006) += tmp006.o

drivers/iio/temperature/tmp006.c

+/*
+ * tmp006.c - Support for TI TMP006 IR thermopile sensor
+ *
+ * Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>
+ *
+ * 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.
+ *
+ * Driver for the Texas Instruments I2C 16-bit IR thermopile sensor
+ *
+ * (7-bit I2C slave address 0x40, changeable via ADR pins)
+ *
+ * TODO: data ready irq
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/bitops.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define TMP006_VOBJECT 0x00
+#define TMP006_TAMBIENT 0x01
+#define TMP006_CONFIG 0x02
+#define TMP006_MANUFACTURER_ID 0xfe
+#define TMP006_DEVICE_ID 0xff
+
+#define TMP006_TAMBIENT_SHIFT 2
+
+#define TMP006_CONFIG_RESET BIT(15)
+#define TMP006_CONFIG_DRDY_EN BIT(8)
+#define TMP006_CONFIG_DRDY BIT(7)
+
+#define TMP006_CONFIG_MOD_MASK 0x7000
+
+#define TMP006_CONFIG_CR_MASK 0x0e00
+#define TMP006_CONFIG_CR_SHIFT 9
+
+#define MANUFACTURER_MAGIC 0x5449
+#define DEVICE_MAGIC 0x0067
+
+struct tmp006_data {
+	struct i2c_client *client;
+	u16 config;
+};
+
+static int tmp006_read_measurement(struct tmp006_data *data, u8 reg)
+{
+	s32 ret;
+	int tries = 50;
+
+	while (tries-- > 0) {
+		ret = i2c_smbus_read_word_swapped(data->client,
+			TMP006_CONFIG);
+		if (ret < 0)
+			return ret;
+		if (ret & TMP006_CONFIG_DRDY)
+			break;
+		msleep(100);
+	}
+
+	if (tries < 0)
+		return -EIO;
+
+	return i2c_smbus_read_word_swapped(data->client, reg);
+}
+
+static int tmp006_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel, int *val,
+			    int *val2, long mask)
+{
+	struct tmp006_data *data = iio_priv(indio_dev);
+	s32 ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (channel->type == IIO_VOLTAGE) {
+			/* LSB is 156.25 nV */
+			ret = tmp006_read_measurement(data, TMP006_VOBJECT);
+			if (ret < 0)
+				return ret;
+			*val = sign_extend32(ret, 15);
+		} else if (channel->type == IIO_TEMP) {
+			/* LSB is 0.03125 degrees Celsius */
+			ret = tmp006_read_measurement(data, TMP006_TAMBIENT);
+			if (ret < 0)
+				return ret;
+			*val = sign_extend32(ret, 15) >> TMP006_TAMBIENT_SHIFT;
+		} else {
+			break;
+		}
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (channel->type == IIO_VOLTAGE) {
+			*val = 0;
+			*val2 = 156250;
+		} else if (channel->type == IIO_TEMP) {
+			*val = 31;
+			*val2 = 250000;
+		} else {
+			break;
+		}
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static const char * const tmp006_freqs[] = { "4", "2", "1", "0.5", "0.25" };
+
+static ssize_t tmp006_show_freq(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct tmp006_data *data = iio_priv(dev_to_iio_dev(dev));
+	int cr = (data->config & TMP006_CONFIG_CR_MASK)
+		>> TMP006_CONFIG_CR_SHIFT;
+	return sprintf(buf, "%s\n", tmp006_freqs[cr]);
+}
+
+static ssize_t tmp006_store_freq(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct tmp006_data *data = iio_priv(indio_dev);
+	int i;
+	bool found = false;
+
+	for (i = 0; i < ARRAY_SIZE(tmp006_freqs); i++)
+		if (sysfs_streq(buf, tmp006_freqs[i])) {
+			found = true;
+			break;
+		}
+	if (!found)
+		return -EINVAL;
+
+	data->config &= ~TMP006_CONFIG_CR_MASK;
+	data->config |= i << TMP006_CONFIG_CR_SHIFT;
+
+	return i2c_smbus_write_word_swapped(data->client, TMP006_CONFIG,
+		data->config);
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ(S_IRUGO | S_IWUSR,
+			tmp006_show_freq, tmp006_store_freq);
+
+static IIO_CONST_ATTR(sampling_frequency_available, "4 2 1 0.5 0.25");
+
+static struct attribute *tmp006_attributes[] = {
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group tmp006_attribute_group = {
+	.attrs = tmp006_attributes,
+};
+
+static const struct iio_chan_spec tmp006_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
+	}
+};
+
+static const struct iio_info tmp006_info = {
+	.read_raw = tmp006_read_raw,
+	.attrs = &tmp006_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+static bool tmp006_check_identification(struct i2c_client *client)
+{
+	int mid, did;
+
+	mid = i2c_smbus_read_word_swapped(client, TMP006_MANUFACTURER_ID);
+	if (mid < 0)
+		return false;
+
+	did = i2c_smbus_read_word_swapped(client, TMP006_DEVICE_ID);
+	if (did < 0)
+		return false;
+
+	return mid == MANUFACTURER_MAGIC && did == DEVICE_MAGIC;
+}
+
+static int tmp006_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct tmp006_data *data;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	if (!tmp006_check_identification(client)) {
+		dev_err(&client->dev, "no TMP006 sensor\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->name = dev_name(&client->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &tmp006_info;
+
+	indio_dev->channels = tmp006_channels;
+	indio_dev->num_channels = ARRAY_SIZE(tmp006_channels);
+
+	ret = i2c_smbus_read_word_swapped(data->client, TMP006_CONFIG);
+	if (ret < 0)
+		return ret;
+	data->config = ret;
+
+	return iio_device_register(indio_dev);
+}
+
+static int tmp006_powerdown(struct tmp006_data *data)
+{
+	return i2c_smbus_write_word_swapped(data->client, TMP006_CONFIG,
+		data->config & ~TMP006_CONFIG_MOD_MASK);
+}
+
+static int tmp006_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+	tmp006_powerdown(iio_priv(indio_dev));
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int tmp006_suspend(struct device *dev)
+{
+	return tmp006_powerdown(iio_priv(dev_to_iio_dev(dev)));
+}
+
+static int tmp006_resume(struct device *dev)
+{
+	struct tmp006_data *data = iio_priv(dev_to_iio_dev(dev));
+	return i2c_smbus_write_word_swapped(data->client, TMP006_CONFIG,
+		data->config | TMP006_CONFIG_MOD_MASK);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(tmp006_pm_ops, tmp006_suspend, tmp006_resume);
+
+static const struct i2c_device_id tmp006_id[] = {
+	{ "tmp006", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tmp006_id);
+
+static struct i2c_driver tmp006_driver = {
+	.driver = {
+		.name	= "tmp006",
+		.pm	= &tmp006_pm_ops,
+		.owner	= THIS_MODULE,
+	},
+	.probe = tmp006_probe,
+	.remove = tmp006_remove,
+	.id_table = tmp006_id,
+};
+module_i2c_driver(tmp006_driver);
+
+MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
+MODULE_DESCRIPTION("TI TMP006 IR thermopile sensor driver");
+MODULE_LICENSE("GPL");