ams-i2c.c

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/*
 * Apple Motion Sensor driver (I2C variant)
 *
 * Copyright (C) 2005 Stelian Pop ([email protected])
 * Copyright (C) 2006 Michael Hanselmann ([email protected])
 *
 * Clean room implementation based on the reverse engineered Mac OS X driver by
 * Johannes Berg <[email protected]>, documentation available at
 * http://johannes.sipsolutions.net/PowerBook/Apple_Motion_Sensor_Specification
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/delay.h>

#include "ams.h"

/* AMS registers */
#define AMS_COMMAND 0x00    /* command register */
#define AMS_STATUS  0x01    /* status register */
#define AMS_CTRL1   0x02    /* read control 1 (number of values) */
#define AMS_CTRL2   0x03    /* read control 2 (offset?) */
#define AMS_CTRL3   0x04    /* read control 3 (size of each value?) */
#define AMS_DATA1   0x05    /* read data 1 */
#define AMS_DATA2   0x06    /* read data 2 */
#define AMS_DATA3   0x07    /* read data 3 */
#define AMS_DATA4   0x08    /* read data 4 */
#define AMS_DATAX   0x20    /* data X */
#define AMS_DATAY   0x21    /* data Y */
#define AMS_DATAZ   0x22    /* data Z */
#define AMS_FREEFALL    0x24    /* freefall int control */
#define AMS_SHOCK   0x25    /* shock int control */
#define AMS_SENSLOW 0x26    /* sensitivity low limit */
#define AMS_SENSHIGH    0x27    /* sensitivity high limit */
#define AMS_CTRLX   0x28    /* control X */
#define AMS_CTRLY   0x29    /* control Y */
#define AMS_CTRLZ   0x2A    /* control Z */
#define AMS_UNKNOWN1    0x2B    /* unknown 1 */
#define AMS_UNKNOWN2    0x2C    /* unknown 2 */
#define AMS_UNKNOWN3    0x2D    /* unknown 3 */
#define AMS_VENDOR  0x2E    /* vendor */

/* AMS commands - use with the AMS_COMMAND register */
enum ams_i2c_cmd {
    AMS_CMD_NOOP = 0,
    AMS_CMD_VERSION,
    AMS_CMD_READMEM,
    AMS_CMD_WRITEMEM,
    AMS_CMD_ERASEMEM,
    AMS_CMD_READEE,
    AMS_CMD_WRITEEE,
    AMS_CMD_RESET,
    AMS_CMD_START,
};

static int ams_i2c_probe(struct i2c_client *client,
             const struct i2c_device_id *id);
static int ams_i2c_remove(struct i2c_client *client);

static const struct i2c_device_id ams_id[] = {
    { "MAC,accelerometer_1", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, ams_id);

static struct i2c_driver ams_i2c_driver = {
    .driver = {
        .name   = "ams",
        .owner  = THIS_MODULE,
    },
    .probe          = ams_i2c_probe,
    .remove         = ams_i2c_remove,
    .id_table       = ams_id,
};

static s32 ams_i2c_read(u8 reg)
{
    return i2c_smbus_read_byte_data(ams_info.i2c_client, reg);
}

static int ams_i2c_write(u8 reg, u8 value)
{
    return i2c_smbus_write_byte_data(ams_info.i2c_client, reg, value);
}

static int ams_i2c_cmd(enum ams_i2c_cmd cmd)
{
    s32 result;
    int count = 3;

    ams_i2c_write(AMS_COMMAND, cmd);
    msleep(5);

    while (count--) {
        result = ams_i2c_read(AMS_COMMAND);
        if (result == 0 || result & 0x80)
            return 0;

        schedule_timeout_uninterruptible(HZ / 20);
    }

    return -1;
}

static void ams_i2c_set_irq(enum ams_irq reg, char enable)
{
    if (reg & AMS_IRQ_FREEFALL) {
        u8 val = ams_i2c_read(AMS_CTRLX);
        if (enable)
            val |= 0x80;
        else
            val &= ~0x80;
        ams_i2c_write(AMS_CTRLX, val);
    }

    if (reg & AMS_IRQ_SHOCK) {
        u8 val = ams_i2c_read(AMS_CTRLY);
        if (enable)
            val |= 0x80;
        else
            val &= ~0x80;
        ams_i2c_write(AMS_CTRLY, val);
    }

    if (reg & AMS_IRQ_GLOBAL) {
        u8 val = ams_i2c_read(AMS_CTRLZ);
        if (enable)
            val |= 0x80;
        else
            val &= ~0x80;
        ams_i2c_write(AMS_CTRLZ, val);
    }
}

static void ams_i2c_clear_irq(enum ams_irq reg)
{
    if (reg & AMS_IRQ_FREEFALL)
        ams_i2c_write(AMS_FREEFALL, 0);

    if (reg & AMS_IRQ_SHOCK)
        ams_i2c_write(AMS_SHOCK, 0);
}

static u8 ams_i2c_get_vendor(void)
{
    return ams_i2c_read(AMS_VENDOR);
}

static void ams_i2c_get_xyz(s8 *x, s8 *y, s8 *z)
{
    *x = ams_i2c_read(AMS_DATAX);
    *y = ams_i2c_read(AMS_DATAY);
    *z = ams_i2c_read(AMS_DATAZ);
}

static int ams_i2c_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    int vmaj, vmin;
    int result;

    /* There can be only one */
    if (unlikely(ams_info.has_device))
        return -ENODEV;

    ams_info.i2c_client = client;

    if (ams_i2c_cmd(AMS_CMD_RESET)) {
        printk(KERN_INFO "ams: Failed to reset the device\n");
        return -ENODEV;
    }

    if (ams_i2c_cmd(AMS_CMD_START)) {
        printk(KERN_INFO "ams: Failed to start the device\n");
        return -ENODEV;
    }

    /* get version/vendor information */
    ams_i2c_write(AMS_CTRL1, 0x02);
    ams_i2c_write(AMS_CTRL2, 0x85);
    ams_i2c_write(AMS_CTRL3, 0x01);

    ams_i2c_cmd(AMS_CMD_READMEM);

    vmaj = ams_i2c_read(AMS_DATA1);
    vmin = ams_i2c_read(AMS_DATA2);
    if (vmaj != 1 || vmin != 52) {
        printk(KERN_INFO "ams: Incorrect device version (%d.%d)\n",
            vmaj, vmin);
        return -ENODEV;
    }

    ams_i2c_cmd(AMS_CMD_VERSION);

    vmaj = ams_i2c_read(AMS_DATA1);
    vmin = ams_i2c_read(AMS_DATA2);
    if (vmaj != 0 || vmin != 1) {
        printk(KERN_INFO "ams: Incorrect firmware version (%d.%d)\n",
            vmaj, vmin);
        return -ENODEV;
    }

    /* Disable interrupts */
    ams_i2c_set_irq(AMS_IRQ_ALL, 0);

    result = ams_sensor_attach();
    if (result < 0)
        return result;

    /* Set default values */
    ams_i2c_write(AMS_SENSLOW, 0x15);
    ams_i2c_write(AMS_SENSHIGH, 0x60);
    ams_i2c_write(AMS_CTRLX, 0x08);
    ams_i2c_write(AMS_CTRLY, 0x0F);
    ams_i2c_write(AMS_CTRLZ, 0x4F);
    ams_i2c_write(AMS_UNKNOWN1, 0x14);

    /* Clear interrupts */
    ams_i2c_clear_irq(AMS_IRQ_ALL);

    ams_info.has_device = 1;

    /* Enable interrupts */
    ams_i2c_set_irq(AMS_IRQ_ALL, 1);

    printk(KERN_INFO "ams: Found I2C based motion sensor\n");

    return 0;
}

static int ams_i2c_remove(struct i2c_client *client)
{
    if (ams_info.has_device) {
        ams_sensor_detach();

        /* Disable interrupts */
        ams_i2c_set_irq(AMS_IRQ_ALL, 0);

        /* Clear interrupts */
        ams_i2c_clear_irq(AMS_IRQ_ALL);

        printk(KERN_INFO "ams: Unloading\n");

        ams_info.has_device = 0;
    }

    return 0;
}

static void ams_i2c_exit(void)
{
    i2c_del_driver(&ams_i2c_driver);
}

int __init ams_i2c_init(struct device_node *np)
{
    int result;

    /* Set implementation stuff */
    ams_info.of_node = np;
    ams_info.exit = ams_i2c_exit;
    ams_info.get_vendor = ams_i2c_get_vendor;
    ams_info.get_xyz = ams_i2c_get_xyz;
    ams_info.clear_irq = ams_i2c_clear_irq;
    ams_info.bustype = BUS_I2C;

    result = i2c_add_driver(&ams_i2c_driver);

    return result;
}