iio: imu: mpu6050: add level shifter flag

Some boards fail in magnetometer probe if level shifter flag is not set,
definition was found in the vendor Linux kernel v3.0.
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
Link: https://lore.kernel.org/r/20230927173245.2151083-3-andreas@kemnade.infoSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c

@@ -71,6 +71,19 @@ int inv_mpu_aux_init(const struct inv_mpu6050_state *st)
 	unsigned int val;
 	int ret;
 
+	/*
+	 * Code based on the vendor Linux kernel v3.0,
+	 * the exact meaning is unknown.
+	 */
+	if (st->chip_type == INV_MPU9150) {
+		unsigned int mask = BIT(7);
+
+		val = st->level_shifter ? mask : 0;
+		ret = regmap_update_bits(st->map, 0x1, mask, val);
+		if (ret)
+			return ret;
+	}
+
 	/* configure i2c master */
 	val = INV_MPU6050_BITS_I2C_MST_CLK_400KHZ |
 			INV_MPU6050_BIT_WAIT_FOR_ES;

drivers/iio/imu/inv_mpu6050/inv_mpu_core.c

@@ -17,6 +17,7 @@
 #include <linux/regulator/consumer.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
+#include <linux/property.h>
 
 #include <linux/iio/common/inv_sensors_timestamp.h>
 #include <linux/iio/iio.h>
@@ -1495,6 +1496,8 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 	st->irq = irq;
 	st->map = regmap;
 
+	st->level_shifter = device_property_read_bool(dev,
+						      "invensense,level-shifter");
 	pdata = dev_get_platdata(dev);
 	if (!pdata) {
 		result = iio_read_mount_matrix(dev, &st->orientation);

drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h

@@ -203,6 +203,7 @@ struct inv_mpu6050_state {
 	s32 magn_raw_to_gauss[3];
 	struct iio_mount_matrix magn_orient;
 	unsigned int suspended_sensors;
+	bool level_shifter;
 	u8 *data;
 };