linux/drivers/acpi/acpi_cmos_rtc.c
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   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 <asm-generic/rtc.h>
  18
  19#include "internal.h"
  20
  21#define PREFIX "ACPI: "
  22
  23ACPI_MODULE_NAME("cmos rtc");
  24
  25static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
  26        { "PNP0B00" },
  27        { "PNP0B01" },
  28        { "PNP0B02" },
  29        {}
  30};
  31
  32static acpi_status
  33acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address,
  34                      u32 bits, u64 *value64,
  35                      void *handler_context, void *region_context)
  36{
  37        int i;
  38        u8 *value = (u8 *)&value64;
  39
  40        if (address > 0xff || !value64)
  41                return AE_BAD_PARAMETER;
  42
  43        if (function != ACPI_WRITE && function != ACPI_READ)
  44                return AE_BAD_PARAMETER;
  45
  46        spin_lock_irq(&rtc_lock);
  47
  48        for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
  49                if (function == ACPI_READ)
  50                        *value = CMOS_READ(address);
  51                else
  52                        CMOS_WRITE(*value, address);
  53
  54        spin_unlock_irq(&rtc_lock);
  55
  56        return AE_OK;
  57}
  58
  59static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
  60                const struct acpi_device_id *id)
  61{
  62        acpi_status status;
  63
  64        status = acpi_install_address_space_handler(adev->handle,
  65                        ACPI_ADR_SPACE_CMOS,
  66                        &acpi_cmos_rtc_space_handler,
  67                        NULL, NULL);
  68        if (ACPI_FAILURE(status)) {
  69                pr_err(PREFIX "Error installing CMOS-RTC region handler\n");
  70                return -ENODEV;
  71        }
  72
  73        return 0;
  74}
  75
  76static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
  77{
  78        if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle,
  79                        ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
  80                pr_err(PREFIX "Error removing CMOS-RTC region handler\n");
  81}
  82
  83static struct acpi_scan_handler cmos_rtc_handler = {
  84        .ids = acpi_cmos_rtc_ids,
  85        .attach = acpi_install_cmos_rtc_space_handler,
  86        .detach = acpi_remove_cmos_rtc_space_handler,
  87};
  88
  89void __init acpi_cmos_rtc_init(void)
  90{
  91        acpi_scan_add_handler(&cmos_rtc_handler);
  92}
  93
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