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ams-i2c.c

/*
 * 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_attach(struct i2c_adapter *adapter);
static int ams_i2c_detach(struct i2c_adapter *adapter);

static struct i2c_driver ams_i2c_driver = {
      .driver = {
            .name   = "ams",
            .owner  = THIS_MODULE,
      },
      .attach_adapter = ams_i2c_attach,
      .detach_adapter = ams_i2c_detach,
};

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_attach(struct i2c_adapter *adapter)
{
      unsigned long bus;
      int vmaj, vmin;
      int result;

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

      if (strncmp(adapter->name, "uni-n", 5))
            return -ENODEV;

      bus = simple_strtoul(adapter->name + 6, NULL, 10);
      if (bus != ams_info.i2c_bus)
            return -ENODEV;

      ams_info.i2c_client.addr = ams_info.i2c_address;
      ams_info.i2c_client.adapter = adapter;
      ams_info.i2c_client.driver = &ams_i2c_driver;
      strcpy(ams_info.i2c_client.name, "Apple Motion Sensor");

      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_detach(struct i2c_adapter *adapter)
{
      if (ams_info.has_device) {
            /* 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)
{
      char *tmp_bus;
      int result;
      const u32 *prop;

      mutex_lock(&ams_info.lock);

      /* 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;

      /* look for bus either using "reg" or by path */
      prop = of_get_property(ams_info.of_node, "reg", NULL);
      if (!prop) {
            result = -ENODEV;

            goto exit;
      }

      tmp_bus = strstr(ams_info.of_node->full_name, "/i2c-bus@");
      if (tmp_bus)
            ams_info.i2c_bus = *(tmp_bus + 9) - '0';
      else
            ams_info.i2c_bus = ((*prop) >> 8) & 0x0f;
      ams_info.i2c_address = ((*prop) & 0xff) >> 1;

      result = i2c_add_driver(&ams_i2c_driver);

exit:
      mutex_unlock(&ams_info.lock);

      return result;
}

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