iio: gyro: mpu3050: fix chip ID reading

commit 409a51e0a4a5f908763191fae2c29008632eb712 upstream.

According to the datasheet, the last bit of CHIP_ID register controls
I2C bus, and the first one is unused. Handle this correctly.

Note that there are chips out there that have a value such that
the id check currently fails.
Signed-off-by: NSergey Larin <cerg2010cerg2010@mail.ru>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/iio/gyro/mpu3050-core.c

@@ -29,7 +29,8 @@
 
 #include "mpu3050.h"
 
-#define MPU3050_CHIP_ID		0x69
+#define MPU3050_CHIP_ID		0x68
+#define MPU3050_CHIP_ID_MASK	0x7E
 
 /*
  * Register map: anything suffixed *_H is a big-endian high byte and always
@@ -1176,8 +1177,9 @@ int mpu3050_common_probe(struct device *dev,
 		goto err_power_down;
 	}
 
-	if (val != MPU3050_CHIP_ID) {
-		dev_err(dev, "unsupported chip id %02x\n", (u8)val);
+	if ((val & MPU3050_CHIP_ID_MASK) != MPU3050_CHIP_ID) {
+		dev_err(dev, "unsupported chip id %02x\n",
+				(u8)(val & MPU3050_CHIP_ID_MASK));
 		ret = -ENODEV;
 		goto err_power_down;
 	}