[PATCH v3 1/2] power: supply: ltc2941-battery-gauge: Add OF device ID table

[Javier Martinez Canillas <javier@osg.samsung.com>]

The driver doesn't have a struct of_device_id table but supported devices
are registered via Device Trees. This is working on the assumption that a
I2C device registered via OF will always match a legacy I2C device ID and
that the MODALIAS reported will always be of the form i2c:<device>.

But this could change in the future so the correct approach is to have an
OF device ID table if the devices are registered via OF.

The compatible strings don't have a vendor prefix because that's how it's
used currently, and changing this will be a Device Tree ABI break.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>

---

Changes in v3:
- Don't use of_match_ptr() to avoid build warning when CONFIG_OF is disabled.

Changes in v2:
 Fix build warning reported by kbuild test robot.
- Fix wrong compatible strings due a copy & paste error.

 drivers/power/supply/ltc2941-battery-gauge.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/ltc2941-battery-gauge.c b/drivers/power/supply/ltc2941-battery-gauge.c
index 4adf2ba021ce..d3052be1bead 100644
--- a/drivers/power/supply/ltc2941-battery-gauge.c
+++ b/drivers/power/supply/ltc2941-battery-gauge.c
@@ -9,6 +9,7 @@
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of_device.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/swab.h>
@@ -61,7 +62,7 @@ struct ltc294x_info {
 	struct power_supply *supply;	/* Supply pointer */
 	struct power_supply_desc supply_desc;	/* Supply description */
 	struct delayed_work work;	/* Work scheduler */
-	int num_regs;	/* Number of registers (chip type) */
+	unsigned long num_regs;	/* Number of registers (chip type) */
 	int charge;	/* Last charge register content */
 	int r_sense;	/* mOhm */
 	int Qlsb;	/* nAh */
@@ -387,7 +388,7 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 
 	np = of_node_get(client->dev.of_node);
 
-	info->num_regs = id->driver_data;
+	info->num_regs = (unsigned long)of_device_get_match_data(&client->dev);
 	info->supply_desc.name = np->name;
 
 	/* r_sense can be negative, when sense+ is connected to the battery
@@ -497,9 +498,23 @@ static const struct i2c_device_id ltc294x_i2c_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
 
+static const struct of_device_id ltc294x_i2c_of_match[] = {
+	{
+		.compatible = "ltc2941",
+		.data = (void *)LTC2941_NUM_REGS
+	},
+	{
+		.compatible = "ltc2943",
+		.data = (void *)LTC2943_NUM_REGS
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
+
 static struct i2c_driver ltc294x_driver = {
 	.driver = {
 		.name	= "LTC2941",
+		.of_match_table = ltc294x_i2c_of_match,
 		.pm	= LTC294X_PM_OPS,
 	},
 	.probe		= ltc294x_i2c_probe,
-- 
2.9.3