drivers/acpi/acpi_cmos_rtc.c

   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 ACPI_MODULE_NAME("cmos rtc");
  22
  23 static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
  24         { "PNP0B00" },
  25         { "PNP0B01" },
  26         { "PNP0B02" },
  27         {}
  28 };
  29
  30 static acpi_status
  31 acpi_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
  57 static 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
  74 static 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
  81 static 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
  87 void __init acpi_cmos_rtc_init(void)
  88 {
  89         acpi_scan_add_handler(&cmos_rtc_handler);
  90 }