/*
 * Apple Motion Sensor driver (I2C variant)
 *
 * Copyright (C) 2005 Stelian Pop (stelian@popies.net)
 * Copyright (C) 2006 Michael Hanselmann (linux-kernel@hansmi.ch)
 *
 * Clean room implementation based on the reverse engineered Mac OS X driver by
 * Johannes Berg <johannes@sipsolutions.net>, 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",
        },
        .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;
}