xref: /openbmc/linux/drivers/acpi/acpi_cmos_rtc.c (revision e23feb16)
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 <asm-generic/rtc.h>
18 
19 #include "internal.h"
20 
21 #define PREFIX "ACPI: "
22 
23 ACPI_MODULE_NAME("cmos rtc");
24 
25 static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
26 	{ "PNP0B00" },
27 	{ "PNP0B01" },
28 	{ "PNP0B02" },
29 	{}
30 };
31 
32 static acpi_status
33 acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address,
34 		      u32 bits, u64 *value64,
35 		      void *handler_context, void *region_context)
36 {
37 	int i;
38 	u8 *value = (u8 *)&value64;
39 
40 	if (address > 0xff || !value64)
41 		return AE_BAD_PARAMETER;
42 
43 	if (function != ACPI_WRITE && function != ACPI_READ)
44 		return AE_BAD_PARAMETER;
45 
46 	spin_lock_irq(&rtc_lock);
47 
48 	for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
49 		if (function == ACPI_READ)
50 			*value = CMOS_READ(address);
51 		else
52 			CMOS_WRITE(*value, address);
53 
54 	spin_unlock_irq(&rtc_lock);
55 
56 	return AE_OK;
57 }
58 
59 static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
60 		const struct acpi_device_id *id)
61 {
62 	acpi_status status;
63 
64 	status = acpi_install_address_space_handler(adev->handle,
65 			ACPI_ADR_SPACE_CMOS,
66 			&acpi_cmos_rtc_space_handler,
67 			NULL, NULL);
68 	if (ACPI_FAILURE(status)) {
69 		pr_err(PREFIX "Error installing CMOS-RTC region handler\n");
70 		return -ENODEV;
71 	}
72 
73 	return 0;
74 }
75 
76 static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
77 {
78 	if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle,
79 			ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
80 		pr_err(PREFIX "Error removing CMOS-RTC region handler\n");
81 }
82 
83 static struct acpi_scan_handler cmos_rtc_handler = {
84 	.ids = acpi_cmos_rtc_ids,
85 	.attach = acpi_install_cmos_rtc_space_handler,
86 	.detach = acpi_remove_cmos_rtc_space_handler,
87 };
88 
89 void __init acpi_cmos_rtc_init(void)
90 {
91 	acpi_scan_add_handler(&cmos_rtc_handler);
92 }
93