LXR linux/drivers/acpi/acpi_cmos

   1/*
   2 * ACPI support for CMOS RTC Address Space access
   3 *
   4 * Copyright (C) 2013, Intel Corporation
   5 * Authors: Lan Tianyu <tianyu.lan@intel.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#include <linux/acpi.h>
  13#include <linux/device.h>
  14#include <linux/err.h>
  15#include <linux/kernel.h>
  16#include <linux/module.h>
  17#include <linux/mc146818rtc.h>
  18
  19#include "internal.h"
  20
  21ACPI_MODULE_NAME("cmos rtc");
  22
  23static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
  24        { "PNP0B00" },
  25        { "PNP0B01" },
  26        { "PNP0B02" },
  27        {}
  28};
  29
  30static acpi_status
  31acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address,
  32                      u32 bits, u64 *value64,
  33                      void *handler_context, void *region_context)
  34{
  35        int i;
  36        u8 *value = (u8 *)value64;
  37
  38        if (address > 0xff || !value64)
  39                return AE_BAD_PARAMETER;
  40
  41        if (function != ACPI_WRITE && function != ACPI_READ)
  42                return AE_BAD_PARAMETER;
  43
  44        spin_lock_irq(&rtc_lock);
  45
  46        for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
  47                if (function == ACPI_READ)
  48                        *value = CMOS_READ(address);
  49                else
  50                        CMOS_WRITE(*value, address);
  51
  52        spin_unlock_irq(&rtc_lock);
  53
  54        return AE_OK;
  55}
  56
  57static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
  58                const struct acpi_device_id *id)
  59{
  60        acpi_status status;
  61
  62        status = acpi_install_address_space_handler(adev->handle,
  63                        ACPI_ADR_SPACE_CMOS,
  64                        &acpi_cmos_rtc_space_handler,
  65                        NULL, NULL);
  66        if (ACPI_FAILURE(status)) {
  67                pr_err(PREFIX "Error installing CMOS-RTC region handler\n");
  68                return -ENODEV;
  69        }
  70
  71        return 1;
  72}
  73
  74static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
  75{
  76        if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle,
  77                        ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
  78                pr_err(PREFIX "Error removing CMOS-RTC region handler\n");
  79}
  80
  81static struct acpi_scan_handler cmos_rtc_handler = {
  82        .ids = acpi_cmos_rtc_ids,
  83        .attach = acpi_install_cmos_rtc_space_handler,
  84        .detach = acpi_remove_cmos_rtc_space_handler,
  85};
  86
  87void __init acpi_cmos_rtc_init(void)
  88{
  89        acpi_scan_add_handler(&cmos_rtc_handler);
  90}
  91