iio: st_sensors: add devicetree probing support

The I2C devices that make up the STMicroelectronics MEMS sensors
may be sneakily enabled by cleverly giving the device node the same
name as a string match from the platform device ID table. However
the right method is to use the compatible string.

On detection, the ST sensors use the ID string to probe and
instatiate the right sensor driver, so pass the kernel-internal ID
string in the .data field of the OF match table, and set the I2C
client name to this name when a compatible match is used.

This avoids having misc Linux-specific strings floating around in
the device tree.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Denis CIOCCA <denis.ciocca@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/gyro/st_gyro_i2c.c

@@ -18,6 +18,43 @@
 #include <linux/iio/common/st_sensors_i2c.h>
 #include "st_gyro.h"
 
+#ifdef CONFIG_OF
+static const struct of_device_id st_gyro_of_match[] = {
+	{
+		.compatible = "st,l3g4200d-gyro",
+		.data = L3G4200D_GYRO_DEV_NAME,
+	},
+	{
+		.compatible = "st,lsm330d-gyro",
+		.data = LSM330D_GYRO_DEV_NAME,
+	},
+	{
+		.compatible = "st,lsm330dl-gyro",
+		.data = LSM330DL_GYRO_DEV_NAME,
+	},
+	{
+		.compatible = "st,lsm330dlc-gyro",
+		.data = LSM330DLC_GYRO_DEV_NAME,
+	},
+	{
+		.compatible = "st,l3gd20-gyro",
+		.data = L3GD20_GYRO_DEV_NAME,
+	},
+	{
+		.compatible = "st,l3g4is-gyro",
+		.data = L3G4IS_GYRO_DEV_NAME,
+	},
+	{
+		.compatible = "st,lsm330-gyro",
+		.data = LSM330_GYRO_DEV_NAME,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, st_gyro_of_match);
+#else
+#define st_gyro_of_match NULL
+#endif
+
 static int st_gyro_i2c_probe(struct i2c_client *client,
 						const struct i2c_device_id *id)
 {
@@ -31,6 +68,7 @@ static int st_gyro_i2c_probe(struct i2c_client *client,
 
 	gdata = iio_priv(indio_dev);
 	gdata->dev = &client->dev;
+	st_sensors_of_i2c_probe(client, st_gyro_of_match);
 
 	st_sensors_i2c_configure(indio_dev, client, gdata);
 
@@ -65,6 +103,7 @@ static struct i2c_driver st_gyro_driver = {
 	.driver = {
 		.owner = THIS_MODULE,
 		.name = "st-gyro-i2c",
+		.of_match_table = of_match_ptr(st_gyro_of_match),
 	},
 	.probe = st_gyro_i2c_probe,
 	.remove = st_gyro_i2c_remove,