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 { .id: "PNP0B01" },
23 { .id: "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(lock: &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(lock: &rtc_lock);
50
51 return AE_OK;
52}
53
54int acpi_install_cmos_rtc_space_handler(acpi_handle handle)
55{
56 acpi_status status;
57
58 status = acpi_install_address_space_handler(device: handle,
59 ACPI_ADR_SPACE_CMOS,
60 handler: &acpi_cmos_rtc_space_handler,
61 NULL, NULL);
62 if (ACPI_FAILURE(status)) {
63 pr_err("Error installing CMOS-RTC region handler\n");
64 return -ENODEV;
65 }
66
67 return 1;
68}
69EXPORT_SYMBOL_GPL(acpi_install_cmos_rtc_space_handler);
70
71void acpi_remove_cmos_rtc_space_handler(acpi_handle handle)
72{
73 if (ACPI_FAILURE(acpi_remove_address_space_handler(handle,
74 ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
75 pr_err("Error removing CMOS-RTC region handler\n");
76}
77EXPORT_SYMBOL_GPL(acpi_remove_cmos_rtc_space_handler);
78
79static int acpi_cmos_rtc_attach_handler(struct acpi_device *adev, const struct acpi_device_id *id)
80{
81 return acpi_install_cmos_rtc_space_handler(adev->handle);
82}
83
84static void acpi_cmos_rtc_detach_handler(struct acpi_device *adev)
85{
86 acpi_remove_cmos_rtc_space_handler(adev->handle);
87}
88
89static struct acpi_scan_handler cmos_rtc_handler = {
90 .ids = acpi_cmos_rtc_ids,
91 .attach = acpi_cmos_rtc_attach_handler,
92 .detach = acpi_cmos_rtc_detach_handler,
93};
94
95void __init acpi_cmos_rtc_init(void)
96{
97 acpi_scan_add_handler(handler: &cmos_rtc_handler);
98}
99