cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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acpi_cmos_rtc.c (2021B)

      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}