1/*
2 * rtc-efi: RTC Class Driver for EFI-based systems
3 *
4 * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
5 *
6 * Author: dann frazier <dannf@hp.com>
7 * Based on efirtc.c by Stephane Eranian
8 *
9 *  This program is free software; you can redistribute  it and/or modify it
10 *  under  the terms of  the GNU General  Public License as published by the
11 *  Free Software Foundation;  either version 2 of the  License, or (at your
12 *  option) any later version.
13 *
14 */
15
16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17
18#include <linux/kernel.h>
19#include <linux/module.h>
20#include <linux/stringify.h>
21#include <linux/time.h>
22#include <linux/platform_device.h>
23#include <linux/rtc.h>
24#include <linux/efi.h>
25
26#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
27/*
28 * EFI Epoch is 1/1/1998
29 */
30#define EFI_RTC_EPOCH		1998
31
32/*
33 * returns day of the year [0-365]
34 */
35static inline int
36compute_yday(efi_time_t *eft)
37{
38	/* efi_time_t.month is in the [1-12] so, we need -1 */
39	return rtc_year_days(eft->day, eft->month - 1, eft->year);
40}
41/*
42 * returns day of the week [0-6] 0=Sunday
43 *
44 * Don't try to provide a year that's before 1998, please !
45 */
46static int
47compute_wday(efi_time_t *eft)
48{
49	int y;
50	int ndays = 0;
51
52	if (eft->year < EFI_RTC_EPOCH) {
53		pr_err("EFI year < " __stringify(EFI_RTC_EPOCH) ", invalid date\n");
54		return -1;
55	}
56
57	for (y = EFI_RTC_EPOCH; y < eft->year; y++)
58		ndays += 365 + (is_leap_year(y) ? 1 : 0);
59
60	ndays += compute_yday(eft);
61
62	/*
63	 * 4=1/1/1998 was a Thursday
64	 */
65	return (ndays + 4) % 7;
66}
67
68static void
69convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
70{
71	eft->year	= wtime->tm_year + 1900;
72	eft->month	= wtime->tm_mon + 1;
73	eft->day	= wtime->tm_mday;
74	eft->hour	= wtime->tm_hour;
75	eft->minute	= wtime->tm_min;
76	eft->second	= wtime->tm_sec;
77	eft->nanosecond = 0;
78	eft->daylight	= wtime->tm_isdst ? EFI_ISDST : 0;
79	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
80}
81
82static bool
83convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
84{
85	memset(wtime, 0, sizeof(*wtime));
86
87	if (eft->second >= 60)
88		return false;
89	wtime->tm_sec  = eft->second;
90
91	if (eft->minute >= 60)
92		return false;
93	wtime->tm_min  = eft->minute;
94
95	if (eft->hour >= 24)
96		return false;
97	wtime->tm_hour = eft->hour;
98
99	if (!eft->day || eft->day > 31)
100		return false;
101	wtime->tm_mday = eft->day;
102
103	if (!eft->month || eft->month > 12)
104		return false;
105	wtime->tm_mon  = eft->month - 1;
106	wtime->tm_year = eft->year - 1900;
107
108	/* day of the week [0-6], Sunday=0 */
109	wtime->tm_wday = compute_wday(eft);
110	if (wtime->tm_wday < 0)
111		return false;
112
113	/* day in the year [1-365]*/
114	wtime->tm_yday = compute_yday(eft);
115
116
117	switch (eft->daylight & EFI_ISDST) {
118	case EFI_ISDST:
119		wtime->tm_isdst = 1;
120		break;
121	case EFI_TIME_ADJUST_DAYLIGHT:
122		wtime->tm_isdst = 0;
123		break;
124	default:
125		wtime->tm_isdst = -1;
126	}
127
128	return true;
129}
130
131static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
132{
133	efi_time_t eft;
134	efi_status_t status;
135
136	/*
137	 * As of EFI v1.10, this call always returns an unsupported status
138	 */
139	status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
140				     (efi_bool_t *)&wkalrm->pending, &eft);
141
142	if (status != EFI_SUCCESS)
143		return -EINVAL;
144
145	if (!convert_from_efi_time(&eft, &wkalrm->time))
146		return -EIO;
147
148	return rtc_valid_tm(&wkalrm->time);
149}
150
151static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
152{
153	efi_time_t eft;
154	efi_status_t status;
155
156	convert_to_efi_time(&wkalrm->time, &eft);
157
158	/*
159	 * XXX Fixme:
160	 * As of EFI 0.92 with the firmware I have on my
161	 * machine this call does not seem to work quite
162	 * right
163	 *
164	 * As of v1.10, this call always returns an unsupported status
165	 */
166	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
167
168	dev_warn(dev, "write status is %d\n", (int)status);
169
170	return status == EFI_SUCCESS ? 0 : -EINVAL;
171}
172
173static int efi_read_time(struct device *dev, struct rtc_time *tm)
174{
175	efi_status_t status;
176	efi_time_t eft;
177	efi_time_cap_t cap;
178
179	status = efi.get_time(&eft, &cap);
180
181	if (status != EFI_SUCCESS) {
182		/* should never happen */
183		dev_err(dev, "can't read time\n");
184		return -EINVAL;
185	}
186
187	if (!convert_from_efi_time(&eft, tm))
188		return -EIO;
189
190	return rtc_valid_tm(tm);
191}
192
193static int efi_set_time(struct device *dev, struct rtc_time *tm)
194{
195	efi_status_t status;
196	efi_time_t eft;
197
198	convert_to_efi_time(tm, &eft);
199
200	status = efi.set_time(&eft);
201
202	return status == EFI_SUCCESS ? 0 : -EINVAL;
203}
204
205static const struct rtc_class_ops efi_rtc_ops = {
206	.read_time = efi_read_time,
207	.set_time = efi_set_time,
208	.read_alarm = efi_read_alarm,
209	.set_alarm = efi_set_alarm,
210};
211
212static int __init efi_rtc_probe(struct platform_device *dev)
213{
214	struct rtc_device *rtc;
215
216	rtc = devm_rtc_device_register(&dev->dev, "rtc-efi", &efi_rtc_ops,
217					THIS_MODULE);
218	if (IS_ERR(rtc))
219		return PTR_ERR(rtc);
220
221	platform_set_drvdata(dev, rtc);
222
223	return 0;
224}
225
226static struct platform_driver efi_rtc_driver = {
227	.driver = {
228		.name = "rtc-efi",
229		.owner = THIS_MODULE,
230	},
231};
232
233module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
234
235MODULE_ALIAS("platform:rtc-efi");
236MODULE_AUTHOR("dann frazier <dannf@hp.com>");
237MODULE_LICENSE("GPL");
238MODULE_DESCRIPTION("EFI RTC driver");
239MODULE_ALIAS("platform:rtc-efi");
240