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}