LXR linux/drivers/acpi/acpi_cmos

   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
  20static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
  21        { "PNP0B00" },
  22        { "PNP0B01" },
  23        { "PNP0B02" },
  24        {}
  25};
  26
  27static acpi_status
  28acpi_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
  54static 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
  71static 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
  78static 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
  84void __init acpi_cmos_rtc_init(void)
  85{
  86        acpi_scan_add_handler(&cmos_rtc_handler);
  87}
  88