drivers/acpi/acpi_cmos_rtc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ACPI support for CMOS RTC Address Space access
   4  *
   5  * Copyright (C) 2013, Intel Corporation
   6  * Authors: Lan Tianyu <tianyu.lan@intel.com>
   7  */
   8
   9 #define pr_fmt(fmt) "ACPI: " fmt
  10
  11 #include <linux/acpi.h>
  12 #include <linux/device.h>
  13 #include <linux/err.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/mc146818rtc.h>
  17
  18 #include "internal.h"
  19
  20 static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
  21         { "PNP0B00" },
  22         { "PNP0B01" },
  23         { "PNP0B02" },
  24         {}
  25 };
  26
  27 static acpi_status
  28 acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address,
  29                       u32 bits, u64 *value64,
  30                       void *handler_context, void *region_context)
  31 {
  32         int i;
  33         u8 *value = (u8 *)value64;
  34
  35         if (address > 0xff || !value64)
  36                 return AE_BAD_PARAMETER;
  37
  38         if (function != ACPI_WRITE && function != ACPI_READ)
  39                 return AE_BAD_PARAMETER;
  40
  41         spin_lock_irq(&rtc_lock);
  42
  43         for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
  44                 if (function == ACPI_READ)
  45                         *value = CMOS_READ(address);
  46                 else
  47                         CMOS_WRITE(*value, address);
  48
  49         spin_unlock_irq(&rtc_lock);
  50
  51         return AE_OK;
  52 }
  53
  54 static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
  55                 const struct acpi_device_id *id)
  56 {
  57         acpi_status status;
  58
  59         status = acpi_install_address_space_handler(adev->handle,
  60                         ACPI_ADR_SPACE_CMOS,
  61                         &acpi_cmos_rtc_space_handler,
  62                         NULL, NULL);
  63         if (ACPI_FAILURE(status)) {
  64                 pr_err("Error installing CMOS-RTC region handler\n");
  65                 return -ENODEV;
  66         }
  67
  68         return 1;
  69 }
  70
  71 static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
  72 {
  73         if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle,
  74                         ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
  75                 pr_err("Error removing CMOS-RTC region handler\n");
  76 }
  77
  78 static struct acpi_scan_handler cmos_rtc_handler = {
  79         .ids = acpi_cmos_rtc_ids,
  80         .attach = acpi_install_cmos_rtc_space_handler,
  81         .detach = acpi_remove_cmos_rtc_space_handler,
  82 };
  83
  84 void __init acpi_cmos_rtc_init(void)
  85 {
  86         acpi_scan_add_handler(&cmos_rtc_handler);
  87 }