+/* AK8963 mag sensor on the I2C bus */
+
+#define MPU9250_MAG_ADDR 0x0c
+
+#define MPU9250_MAG_WIA 0x00
+#define MPU9250_MAG_WIA_VALUE 0x48
+
+#define MPU9250_MAG_INFO 0x01
+#define MPU9250_MAG_ST1 0x02
+#define MPU9250_MAG_ST1_DOR 1
+#define MPU9250_MAG_ST1_DRDY 0
+
+#define MPU9250_MAG_HXL 0x03
+#define MPU9250_MAG_HXH 0x04
+#define MPU9250_MAG_HYL 0x05
+#define MPU9250_MAG_HYH 0x06
+#define MPU9250_MAG_HZL 0x07
+#define MPU9250_MAG_HZH 0x08
+#define MPU9250_MAG_ST2 0x09
+#define MPU9250_MAG_ST2_BITM 4
+#define MPU9250_MAG_ST2_HOFL 3
+
+#define MPU9250_MAG_CNTL1 0x0a
+#define MPU9250_MAG_CNTL1_MODE 0
+#define MPU9250_MAG_CNTL1_MODE_POWER_DOWN 0x0
+#define MPU9250_MAG_CNTL1_MODE_SINGLE 0x1
+#define MPU9250_MAG_CNTL1_MODE_CONT_1 0x2 /* 8Hz */
+#define MPU9250_MAG_CNTL1_MODE_CONT_2 0x6 /* 100Hz */
+#define MPU9250_MAG_CNTL1_MODE_EXTERNAL 0x4
+#define MPU9250_MAG_CNTL1_MODE_SELF_TEST 0x8
+#define MPU9250_MAG_CNTL1_MODE_FUSE_ACCESS 0xf
+
+#define MPU9250_MAG_CNTL1_BIT 4
+#define MPU9250_MAG_CNTL1_BIT_14 0
+#define MPU9250_MAG_CNTL1_BIT_16 1
+
+#define MPU9250_MAG_CNTL2 0x0b
+#define MPU9250_MAG_CNTL2_SRST 0
+
+#define MPU9250_MAG_ASTC 0x0c
+#define MPU9250_MAG_ASTC_SELF 6
+
+#define MPU9250_MAG_TS1 0x0d
+#define MPU9250_MAG_TS2 0x0e
+#define MPU9250_MAG_I2CDIS 0x0f
+#define MPU9250_MAG_I2CDIS_VALUE 0x1d
+
+#define MPU9250_MAG_ASAX 0x10
+#define MPU9250_MAG_ASAY 0x11
+#define MPU9250_MAG_ASAZ 0x12
+