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 #define PREFIX "ACPI: "
  22
  23 ACPI_MODULE_NAME("cmos rtc");
  24
  25 static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
  26         { "PNP0B00" },
  27         { "PNP0B01" },
  28         { "PNP0B02" },
  29         {}
  30 };
  31
  32 static acpi_status
  33 acpi_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
  59 static 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
  76 static 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
  83 static 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
  89 void __init acpi_cmos_rtc_init(void)
  90 {
  91         acpi_scan_add_handler(&cmos_rtc_handler);
  92 }