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>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/iio/common/st_sensors/st_sensors_i2c.c b/drivers/iio/common/st_sensors/st_sensors_i2c.c
index 38af9440c10..bb6f3085f57 100644
--- a/drivers/iio/common/st_sensors/st_sensors_i2c.c
+++ b/drivers/iio/common/st_sensors/st_sensors_i2c.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/iio/iio.h>
+#include <linux/of_device.h>
 
 #include <linux/iio/common/st_sensors_i2c.h>
 
@@ -76,6 +77,35 @@ void st_sensors_i2c_configure(struct iio_dev *indio_dev,
 }
 EXPORT_SYMBOL(st_sensors_i2c_configure);
 
+#ifdef CONFIG_OF
+/**
+ * st_sensors_of_i2c_probe() - device tree probe for ST I2C sensors
+ * @client: the I2C client device for the sensor
+ * @match: the OF match table for the device, containing compatible strings
+ *	but also a .data field with the corresponding internal kernel name
+ *	used by this sensor.
+ *
+ * In effect this function matches a compatible string to an internal kernel
+ * name for a certain sensor device, so that the rest of the autodetection can
+ * rely on that name from this point on. I2C client devices will be renamed
+ * to match the internal kernel convention.
+ */
+void st_sensors_of_i2c_probe(struct i2c_client *client,
+			     const struct of_device_id *match)
+{
+	const struct of_device_id *of_id;
+
+	of_id = of_match_device(match, &client->dev);
+	if (!of_id)
+		return;
+
+	/* The name from the OF match takes precedence if present */
+	strncpy(client->name, of_id->data, sizeof(client->name));
+	client->name[sizeof(client->name) - 1] = '\0';
+}
+EXPORT_SYMBOL(st_sensors_of_i2c_probe);
+#endif
+
 MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
 MODULE_DESCRIPTION("STMicroelectronics ST-sensors i2c driver");
 MODULE_LICENSE("GPL v2");