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(struct acpi_device * adev,const struct acpi_device_id * id)54 static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
55 		const struct acpi_device_id *id)
56 {
57 	acpi_status status;
58 
59 	status = acpi_install_address_space_handler(adev->handle,
60 			ACPI_ADR_SPACE_CMOS,
61 			&acpi_cmos_rtc_space_handler,
62 			NULL, NULL);
63 	if (ACPI_FAILURE(status)) {
64 		pr_err("Error installing CMOS-RTC region handler\n");
65 		return -ENODEV;
66 	}
67 
68 	return 1;
69 }
70 
acpi_remove_cmos_rtc_space_handler(struct acpi_device * adev)71 static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
72 {
73 	if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle,
74 			ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
75 		pr_err("Error removing CMOS-RTC region handler\n");
76 }
77 
78 static struct acpi_scan_handler cmos_rtc_handler = {
79 	.ids = acpi_cmos_rtc_ids,
80 	.attach = acpi_install_cmos_rtc_space_handler,
81 	.detach = acpi_remove_cmos_rtc_space_handler,
82 };
83 
acpi_cmos_rtc_init(void)84 void __init acpi_cmos_rtc_init(void)
85 {
86 	acpi_scan_add_handler(&cmos_rtc_handler);
87 }
88