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sbshc.c

/*
 * SMBus driver for ACPI Embedded Controller (v0.1)
 *
 * Copyright (c) 2007 Alexey Starikovskiy
 *
 * 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 version 2.
 */

#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <acpi/actypes.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include "sbshc.h"

#define ACPI_SMB_HC_CLASS     "smbus_host_controller"
#define ACPI_SMB_HC_DEVICE_NAME     "ACPI SMBus HC"

struct acpi_smb_hc {
      struct acpi_ec *ec;
      struct mutex lock;
      wait_queue_head_t wait;
      u8 offset;
      u8 query_bit;
      smbus_alarm_callback callback;
      void *context;
};

static int acpi_smbus_hc_add(struct acpi_device *device);
static int acpi_smbus_hc_remove(struct acpi_device *device, int type);

static const struct acpi_device_id sbs_device_ids[] = {
      {"ACPI0001", 0},
      {"ACPI0005", 0},
      {"", 0},
};

MODULE_DEVICE_TABLE(acpi, sbs_device_ids);

static struct acpi_driver acpi_smb_hc_driver = {
      .name = "smbus_hc",
      .class = ACPI_SMB_HC_CLASS,
      .ids = sbs_device_ids,
      .ops = {
            .add = acpi_smbus_hc_add,
            .remove = acpi_smbus_hc_remove,
            },
};

union acpi_smb_status {
      u8 raw;
      struct {
            u8 status:5;
            u8 reserved:1;
            u8 alarm:1;
            u8 done:1;
      } fields;
};

enum acpi_smb_status_codes {
      SMBUS_OK = 0,
      SMBUS_UNKNOWN_FAILURE = 0x07,
      SMBUS_DEVICE_ADDRESS_NACK = 0x10,
      SMBUS_DEVICE_ERROR = 0x11,
      SMBUS_DEVICE_COMMAND_ACCESS_DENIED = 0x12,
      SMBUS_UNKNOWN_ERROR = 0x13,
      SMBUS_DEVICE_ACCESS_DENIED = 0x17,
      SMBUS_TIMEOUT = 0x18,
      SMBUS_HOST_UNSUPPORTED_PROTOCOL = 0x19,
      SMBUS_BUSY = 0x1a,
      SMBUS_PEC_ERROR = 0x1f,
};

enum acpi_smb_offset {
      ACPI_SMB_PROTOCOL = 0,  /* protocol, PEC */
      ACPI_SMB_STATUS = 1,    /* status */
      ACPI_SMB_ADDRESS = 2,   /* address */
      ACPI_SMB_COMMAND = 3,   /* command */
      ACPI_SMB_DATA = 4,      /* 32 data registers */
      ACPI_SMB_BLOCK_COUNT = 0x24,  /* number of data bytes */
      ACPI_SMB_ALARM_ADDRESS = 0x25,      /* alarm address */
      ACPI_SMB_ALARM_DATA = 0x26,   /* 2 bytes alarm data */
};

static inline int smb_hc_read(struct acpi_smb_hc *hc, u8 address, u8 *data)
{
      return ec_read(hc->offset + address, data);
}

static inline int smb_hc_write(struct acpi_smb_hc *hc, u8 address, u8 data)
{
      return ec_write(hc->offset + address, data);
}

static inline int smb_check_done(struct acpi_smb_hc *hc)
{
      union acpi_smb_status status = {.raw = 0};
      smb_hc_read(hc, ACPI_SMB_STATUS, &status.raw);
      return status.fields.done && (status.fields.status == SMBUS_OK);
}

static int wait_transaction_complete(struct acpi_smb_hc *hc, int timeout)
{
      if (wait_event_timeout(hc->wait, smb_check_done(hc),
                         msecs_to_jiffies(timeout)))
            return 0;
      else
            return -ETIME;
}

int acpi_smbus_transaction(struct acpi_smb_hc *hc, u8 protocol, u8 address,
                u8 command, u8 *data, u8 length)
{
      int ret = -EFAULT, i;
      u8 temp, sz = 0;

      mutex_lock(&hc->lock);
      if (smb_hc_read(hc, ACPI_SMB_PROTOCOL, &temp))
            goto end;
      if (temp) {
            ret = -EBUSY;
            goto end;
      }
      smb_hc_write(hc, ACPI_SMB_COMMAND, command);
      smb_hc_write(hc, ACPI_SMB_COMMAND, command);
      if (!(protocol & 0x01)) {
            smb_hc_write(hc, ACPI_SMB_BLOCK_COUNT, length);
            for (i = 0; i < length; ++i)
                  smb_hc_write(hc, ACPI_SMB_DATA + i, data[i]);
      }
      smb_hc_write(hc, ACPI_SMB_ADDRESS, address << 1);
      smb_hc_write(hc, ACPI_SMB_PROTOCOL, protocol);
      /*
       * Wait for completion. Save the status code, data size,
       * and data into the return package (if required by the protocol).
       */
      ret = wait_transaction_complete(hc, 1000);
      if (ret || !(protocol & 0x01))
            goto end;
      switch (protocol) {
      case SMBUS_RECEIVE_BYTE:
      case SMBUS_READ_BYTE:
            sz = 1;
            break;
      case SMBUS_READ_WORD:
            sz = 2;
            break;
      case SMBUS_READ_BLOCK:
            if (smb_hc_read(hc, ACPI_SMB_BLOCK_COUNT, &sz)) {
                  ret = -EFAULT;
                  goto end;
            }
            sz &= 0x1f;
            break;
      }
      for (i = 0; i < sz; ++i)
            smb_hc_read(hc, ACPI_SMB_DATA + i, &data[i]);
      end:
      mutex_unlock(&hc->lock);
      return ret;
}

int acpi_smbus_read(struct acpi_smb_hc *hc, u8 protocol, u8 address,
                u8 command, u8 *data)
{
      return acpi_smbus_transaction(hc, protocol, address, command, data, 0);
}

EXPORT_SYMBOL_GPL(acpi_smbus_read);

int acpi_smbus_write(struct acpi_smb_hc *hc, u8 protocol, u8 address,
                 u8 command, u8 *data, u8 length)
{
      return acpi_smbus_transaction(hc, protocol, address, command, data, length);
}

EXPORT_SYMBOL_GPL(acpi_smbus_write);

int acpi_smbus_register_callback(struct acpi_smb_hc *hc,
                           smbus_alarm_callback callback, void *context)
{
      mutex_lock(&hc->lock);
      hc->callback = callback;
      hc->context = context;
      mutex_unlock(&hc->lock);
      return 0;
}

EXPORT_SYMBOL_GPL(acpi_smbus_register_callback);

int acpi_smbus_unregister_callback(struct acpi_smb_hc *hc)
{
      mutex_lock(&hc->lock);
      hc->callback = NULL;
      hc->context = NULL;
      mutex_unlock(&hc->lock);
      return 0;
}

EXPORT_SYMBOL_GPL(acpi_smbus_unregister_callback);

static inline void acpi_smbus_callback(void *context)
{
      struct acpi_smb_hc *hc = context;
      if (hc->callback)
            hc->callback(hc->context);
}

static int smbus_alarm(void *context)
{
      struct acpi_smb_hc *hc = context;
      union acpi_smb_status status;
      u8 address;
      if (smb_hc_read(hc, ACPI_SMB_STATUS, &status.raw))
            return 0;
      /* Check if it is only a completion notify */
      if (status.fields.done)
            wake_up(&hc->wait);
      if (!status.fields.alarm)
            return 0;
      mutex_lock(&hc->lock);
      smb_hc_read(hc, ACPI_SMB_ALARM_ADDRESS, &address);
      status.fields.alarm = 0;
      smb_hc_write(hc, ACPI_SMB_STATUS, status.raw);
      /* We are only interested in events coming from known devices */
      switch (address >> 1) {
            case ACPI_SBS_CHARGER:
            case ACPI_SBS_MANAGER:
            case ACPI_SBS_BATTERY:
                  acpi_os_execute(OSL_GPE_HANDLER,
                              acpi_smbus_callback, hc);
            default:;
      }
      mutex_unlock(&hc->lock);
      return 0;
}

typedef int (*acpi_ec_query_func) (void *data);

extern int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
                        acpi_handle handle, acpi_ec_query_func func,
                        void *data);

static int acpi_smbus_hc_add(struct acpi_device *device)
{
      int status;
      unsigned long val;
      struct acpi_smb_hc *hc;

      if (!device)
            return -EINVAL;

      status = acpi_evaluate_integer(device->handle, "_EC", NULL, &val);
      if (ACPI_FAILURE(status)) {
            printk(KERN_ERR PREFIX "error obtaining _EC.\n");
            return -EIO;
      }

      strcpy(acpi_device_name(device), ACPI_SMB_HC_DEVICE_NAME);
      strcpy(acpi_device_class(device), ACPI_SMB_HC_CLASS);

      hc = kzalloc(sizeof(struct acpi_smb_hc), GFP_KERNEL);
      if (!hc)
            return -ENOMEM;
      mutex_init(&hc->lock);
      init_waitqueue_head(&hc->wait);

      hc->ec = acpi_driver_data(device->parent);
      hc->offset = (val >> 8) & 0xff;
      hc->query_bit = val & 0xff;
      acpi_driver_data(device) = hc;

      acpi_ec_add_query_handler(hc->ec, hc->query_bit, NULL, smbus_alarm, hc);
      printk(KERN_INFO PREFIX "SBS HC: EC = 0x%p, offset = 0x%0x, query_bit = 0x%0x\n",
            hc->ec, hc->offset, hc->query_bit);

      return 0;
}

extern void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit);

static int acpi_smbus_hc_remove(struct acpi_device *device, int type)
{
      struct acpi_smb_hc *hc;

      if (!device)
            return -EINVAL;

      hc = acpi_driver_data(device);
      acpi_ec_remove_query_handler(hc->ec, hc->query_bit);
      kfree(hc);
      return 0;
}

static int __init acpi_smb_hc_init(void)
{
      int result;

      result = acpi_bus_register_driver(&acpi_smb_hc_driver);
      if (result < 0)
            return -ENODEV;
      return 0;
}

static void __exit acpi_smb_hc_exit(void)
{
      acpi_bus_unregister_driver(&acpi_smb_hc_driver);
}

module_init(acpi_smb_hc_init);
module_exit(acpi_smb_hc_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexey Starikovskiy");
MODULE_DESCRIPTION("ACPI SMBus HC driver");

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