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
20 static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
21 { "PNP0B00" },
22 { "PNP0B01" },
23 { "PNP0B02" },
24 {}
25 };
26
27 static acpi_status
acpi_cmos_rtc_space_handler(u32 function,acpi_physical_address address,u32 bits,u64 * value64,void * handler_context,void * region_context)28 acpi_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
acpi_install_cmos_rtc_space_handler(acpi_handle handle)54 int acpi_install_cmos_rtc_space_handler(acpi_handle handle)
55 {
56 acpi_status status;
57
58 status = acpi_install_address_space_handler(handle,
59 ACPI_ADR_SPACE_CMOS,
60 &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 }
69 EXPORT_SYMBOL_GPL(acpi_install_cmos_rtc_space_handler);
70
acpi_remove_cmos_rtc_space_handler(acpi_handle handle)71 void 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 }
77 EXPORT_SYMBOL_GPL(acpi_remove_cmos_rtc_space_handler);
78
acpi_cmos_rtc_attach_handler(struct acpi_device * adev,const struct acpi_device_id * id)79 static 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
acpi_cmos_rtc_detach_handler(struct acpi_device * adev)84 static void acpi_cmos_rtc_detach_handler(struct acpi_device *adev)
85 {
86 acpi_remove_cmos_rtc_space_handler(adev->handle);
87 }
88
89 static 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
acpi_cmos_rtc_init(void)95 void __init acpi_cmos_rtc_init(void)
96 {
97 acpi_scan_add_handler(&cmos_rtc_handler);
98 }
99