Kernel driver mpu
=====================

Supported chips:
  * InvenSense IMU3050
    Prefix: 'mpu3050'
    Datasheet:
        PS-MPU-3000A-00.2.4b.pdf

Author: InvenSense <http://invensense.com>

Description
-----------
The mpu is a motion processor unit that controls the mpu3050 gyroscope, a slave
accelerometer, a compass and a pressure sensor.  This document describes how to
install the driver into a Linux kernel.

Sysfs entries
-------------
/dev/mpu
/dev/mpuirq
/dev/accelirq
/dev/compassirq
/dev/pressureirq

General Remarks MPU3050
-----------------------
* Valid addresses for the MPU3050 is 0x68.
* Accelerometer must be on the secondary I2C bus for MPU3050, the
  magnetometer must be on the primary bus and pressure sensor must
  be on the primary bus.

Programming the chip using /dev/mpu
----------------------------------
Programming of MPU3050 is done by first opening the /dev/mpu file and
then performing a series of IOCTLS on the handle returned.  The IOCTL codes can
be found in mpu.h.  Typically this is done by the mllite library in user
space.

Board and Platform Data
-----------------------

In order for the driver to work, board and platform data specific to the device
needs to be added to the board file.  A mpu_platform_data structure must
be created and populated and set in the i2c_board_info_structure.  For details
of each structure member see mpu.h.  All values below are simply an example and
should be modified for your platform.

#include <linux/mpu.h>

static struct mpu_platform_data mpu3050_data = {
	.int_config  = 0x10,
	.orientation = {  -1,  0,  0,
			   0,  1,  0,
			   0,  0, -1 },
};

/* accel */
static struct ext_slave_platform_data inv_mpu_kxtf9_data = {
	.bus         = EXT_SLAVE_BUS_SECONDARY,
	.orientation = {  -1,  0,  0,
			  0,  1,  0,
			  0,  0, -1 },
};
/* compass */
static struct ext_slave_platform_data inv_mpu_ak8975_data = {
	.bus         = EXT_SLAVE_BUS_PRIMARY,
	.orientation = { 1, 0, 0,
			 0, 1, 0,
			 0, 0, 1 },
};

static struct i2c_board_info __initdata panda_inv_mpu_i2c4_boardinfo[] = {
	{
		I2C_BOARD_INFO("mpu3050", 0x68),
		.irq = (IH_GPIO_BASE + MPUIRQ_GPIO),
		.platform_data = &mpu3050_data,
	},
	{
		I2C_BOARD_INFO("kxtf9", 0x0F),
		.irq = (IH_GPIO_BASE + ACCEL_IRQ_GPIO),
		.platform_data = &inv_mpu_kxtf9_data
	},
	{
		I2C_BOARD_INFO("ak8975", 0x0E),
		.irq = (IH_GPIO_BASE + COMPASS_IRQ_GPIO),
		.platform_data = &inv_mpu_ak8975_data,
	},
};

Typically the IRQ is a GPIO input pin and needs to be configured properly.  If
in the above example GPIO 168 corresponds to IRQ 299, the following should be
done as well:

#define MPU_GPIO_IRQ 168

    gpio_request(MPU_GPIO_IRQ,"MPUIRQ");
    gpio_direction_input(MPU_GPIO_IRQ)

Dynamic Debug
=============

The mpu3050 makes use of dynamic debug.  For details on how to use this
refer to Documentation/dynamic-debug-howto.txt