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