1/*
2 * ACPI support for CMOS RTC Address Space access
3 *
4 * Copyright (C) 2013, Intel Corporation
5 * Authors: Lan Tianyu <tianyu.lan@intel.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/acpi.h>
13#include <linux/device.h>
14#include <linux/err.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/mc146818rtc.h>
18
19#include "internal.h"
20
21ACPI_MODULE_NAME("cmos rtc");
22
23static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
24 { "PNP0B00" },
25 { "PNP0B01" },
26 { "PNP0B02" },
27 {}
28};
29
30static acpi_status
31acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address,
32 u32 bits, u64 *value64,
33 void *handler_context, void *region_context)
34{
35 int i;
36 u8 *value = (u8 *)value64;
37
38 if (address > 0xff || !value64)
39 return AE_BAD_PARAMETER;
40
41 if (function != ACPI_WRITE && function != ACPI_READ)
42 return AE_BAD_PARAMETER;
43
44 spin_lock_irq(&rtc_lock);
45
46 for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
47 if (function == ACPI_READ)
48 *value = CMOS_READ(address);
49 else
50 CMOS_WRITE(*value, address);
51
52 spin_unlock_irq(&rtc_lock);
53
54 return AE_OK;
55}
56
57static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
58 const struct acpi_device_id *id)
59{
60 acpi_status status;
61
62 status = acpi_install_address_space_handler(adev->handle,
63 ACPI_ADR_SPACE_CMOS,
64 &acpi_cmos_rtc_space_handler,
65 NULL, NULL);
66 if (ACPI_FAILURE(status)) {
67 pr_err(PREFIX "Error installing CMOS-RTC region handler\n");
68 return -ENODEV;
69 }
70
71 return 1;
72}
73
74static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
75{
76 if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle,
77 ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
78 pr_err(PREFIX "Error removing CMOS-RTC region handler\n");
79}
80
81static struct acpi_scan_handler cmos_rtc_handler = {
82 .ids = acpi_cmos_rtc_ids,
83 .attach = acpi_install_cmos_rtc_space_handler,
84 .detach = acpi_remove_cmos_rtc_space_handler,
85};
86
87void __init acpi_cmos_rtc_init(void)
88{
89 acpi_scan_add_handler(&cmos_rtc_handler);
90}
91