[PATCH v2] iio: dac: dac5571: Fix chip id detection for OF devices

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

From: Jose Cazarin <joseespiriki@gmail.com>

When matching an OF device, the match mechanism tries all components of
the compatible property. This can result with a device matched with a
compatible string that isn't the first in the compatible list. For
instance, with a compatible property set to

    compatible = "ti,dac081c081", "ti,dac5571";

the driver will match the second compatible string, as the first one
isn't listed in the of_device_id table. The device will however be named
"dac081c081" by the I2C core.

This causes an issue when identifying the chip. The probe function
receives a i2c_device_id that comes from the module's I2C device ID
table. There is no entry in that table for "dac081c081", which results
in a NULL pointer passed to the probe function.

To fix this, add chip_id information in the data field of the OF device
ID table, and retrieve it with of_device_get_match_data() for OF
devices.

Signed-off-by: Jose Cazarin <joseespiriki@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
Changes since v1:

- Use device_get_match_data()
---
 drivers/iio/dac/ti-dac5571.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/dac/ti-dac5571.c b/drivers/iio/dac/ti-dac5571.c
index 4a3b8d875518..4f50e31dffb0 100644
--- a/drivers/iio/dac/ti-dac5571.c
+++ b/drivers/iio/dac/ti-dac5571.c
@@ -19,6 +19,7 @@
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
+#include <linux/property.h>
 #include <linux/regulator/consumer.h>
 
 enum chip_id {
@@ -311,6 +312,7 @@ static int dac5571_probe(struct i2c_client *client,
 	const struct dac5571_spec *spec;
 	struct dac5571_data *data;
 	struct iio_dev *indio_dev;
+	enum chip_id chip_id;
 	int ret, i;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
@@ -326,7 +328,13 @@ static int dac5571_probe(struct i2c_client *client,
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = dac5571_channels;
 
-	spec = &dac5571_spec[id->driver_data];
+	if (dev->of_node)
+		chip_id = (uintptr_t)device_get_match_data(dev);
+	else
+		chip_id = id->driver_data;
+
+	spec = &dac5571_spec[chip_id];
+
 	indio_dev->num_channels = spec->num_channels;
 	data->spec = spec;
 
@@ -385,15 +393,15 @@ static int dac5571_remove(struct i2c_client *i2c)
 }
 
 static const struct of_device_id dac5571_of_id[] = {
-	{.compatible = "ti,dac5571"},
-	{.compatible = "ti,dac6571"},
-	{.compatible = "ti,dac7571"},
-	{.compatible = "ti,dac5574"},
-	{.compatible = "ti,dac6574"},
-	{.compatible = "ti,dac7574"},
-	{.compatible = "ti,dac5573"},
-	{.compatible = "ti,dac6573"},
-	{.compatible = "ti,dac7573"},
+	{.compatible = "ti,dac5571", .data = (void *)single_8bit},
+	{.compatible = "ti,dac6571", .data = (void *)single_10bit},
+	{.compatible = "ti,dac7571", .data = (void *)single_12bit},
+	{.compatible = "ti,dac5574", .data = (void *)quad_8bit},
+	{.compatible = "ti,dac6574", .data = (void *)quad_10bit},
+	{.compatible = "ti,dac7574", .data = (void *)quad_12bit},
+	{.compatible = "ti,dac5573", .data = (void *)quad_8bit},
+	{.compatible = "ti,dac6573", .data = (void *)quad_10bit},
+	{.compatible = "ti,dac7573", .data = (void *)quad_12bit},
 	{}
 };
 MODULE_DEVICE_TABLE(of, dac5571_of_id);
-- 
Regards,

Laurent Pinchart