xref: /openbmc/linux/drivers/acpi/acpi_cmos_rtc.c (revision 596ca52a)
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