xref: /openbmc/linux/drivers/acpi/acpi_cmos_rtc.c (revision 293d5b43)
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 
21 ACPI_MODULE_NAME("cmos rtc");
22 
23 static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
24 	{ "PNP0B00" },
25 	{ "PNP0B01" },
26 	{ "PNP0B02" },
27 	{}
28 };
29 
30 static acpi_status
31 acpi_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 
57 static 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 
74 static 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 
81 static 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 
87 void __init acpi_cmos_rtc_init(void)
88 {
89 	acpi_scan_add_handler(&cmos_rtc_handler);
90 }
91