iio: imu: mpu6050: Fix name/chip_id when using ACPI

When using ACPI, id is NULL and the current code automatically
defaults name to NULL and chip id to 0. We should instead use
the data provided in the ACPI device table.

Fixes: c816d9e7 ("iio: imu: mpu6050: fix possible NULL dereferences")
Signed-off-by: NDaniel Baluta <daniel.baluta@intel.com>
Reviewed-By: NMatt Ranostay <matt.ranostay@intel.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c

@@ -104,6 +104,19 @@ static int inv_mpu6050_deselect_bypass(struct i2c_adapter *adap,
 	return 0;
 }
 
+static const char *inv_mpu_match_acpi_device(struct device *dev, int *chip_id)
+{
+	const struct acpi_device_id *id;
+
+	id = acpi_match_device(dev->driver->acpi_match_table, dev);
+	if (!id)
+		return NULL;
+
+	*chip_id = (int)id->driver_data;
+
+	return dev_name(dev);
+}
+
 /**
  *  inv_mpu_probe() - probe function.
  *  @client:          i2c client.
@@ -115,15 +128,25 @@ static int inv_mpu_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct inv_mpu6050_state *st;
-	int result;
-	const char *name = id ? id->name : NULL;
-	const int chip_type = id ? id->driver_data : 0;
+	int result, chip_type;
 	struct regmap *regmap;
+	const char *name;
 
 	if (!i2c_check_functionality(client->adapter,
 				     I2C_FUNC_SMBUS_I2C_BLOCK))
 		return -EOPNOTSUPP;
 
+	if (id) {
+		chip_type = (int)id->driver_data;
+		name = id->name;
+	} else if (ACPI_HANDLE(&client->dev)) {
+		name = inv_mpu_match_acpi_device(&client->dev, &chip_type);
+		if (!name)
+			return -ENODEV;
+	} else {
+		return -ENOSYS;
+	}
+
 	regmap = devm_regmap_init_i2c(client, &inv_mpu_regmap_config);
 	if (IS_ERR(regmap)) {
 		dev_err(&client->dev, "Failed to register i2c regmap %d\n",