1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * RTC interface for Wilco Embedded Controller with R/W abilities |
4 | * |
5 | * Copyright 2018 Google LLC |
6 | * |
7 | * The corresponding platform device is typically registered in |
8 | * drivers/platform/chrome/wilco_ec/core.c |
9 | */ |
10 | |
11 | #include <linux/bcd.h> |
12 | #include <linux/err.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/module.h> |
15 | #include <linux/platform_device.h> |
16 | #include <linux/platform_data/wilco-ec.h> |
17 | #include <linux/rtc.h> |
18 | #include <linux/timekeeping.h> |
19 | |
20 | #define EC_COMMAND_CMOS 0x7c |
21 | #define EC_CMOS_TOD_WRITE 0x02 |
22 | #define EC_CMOS_TOD_READ 0x08 |
23 | |
24 | /* Message sent to the EC to request the current time. */ |
25 | struct ec_rtc_read_request { |
26 | u8 command; |
27 | u8 reserved; |
28 | u8 param; |
29 | } __packed; |
30 | static struct ec_rtc_read_request read_rq = { |
31 | .command = EC_COMMAND_CMOS, |
32 | .param = EC_CMOS_TOD_READ, |
33 | }; |
34 | |
35 | /** |
36 | * struct ec_rtc_read_response - Format of RTC returned by EC. |
37 | * @reserved: Unused byte |
38 | * @second: Second value (0..59) |
39 | * @minute: Minute value (0..59) |
40 | * @hour: Hour value (0..23) |
41 | * @day: Day value (1..31) |
42 | * @month: Month value (1..12) |
43 | * @year: Year value (full year % 100) |
44 | * @century: Century value (full year / 100) |
45 | * |
46 | * All values are presented in binary (not BCD). |
47 | */ |
48 | struct ec_rtc_read_response { |
49 | u8 reserved; |
50 | u8 second; |
51 | u8 minute; |
52 | u8 hour; |
53 | u8 day; |
54 | u8 month; |
55 | u8 year; |
56 | u8 century; |
57 | } __packed; |
58 | |
59 | /** |
60 | * struct ec_rtc_write_request - Format of RTC sent to the EC. |
61 | * @command: Always EC_COMMAND_CMOS |
62 | * @reserved: Unused byte |
63 | * @param: Always EC_CMOS_TOD_WRITE |
64 | * @century: Century value (full year / 100) |
65 | * @year: Year value (full year % 100) |
66 | * @month: Month value (1..12) |
67 | * @day: Day value (1..31) |
68 | * @hour: Hour value (0..23) |
69 | * @minute: Minute value (0..59) |
70 | * @second: Second value (0..59) |
71 | * @weekday: Day of the week (0=Saturday) |
72 | * |
73 | * All values are presented in BCD. |
74 | */ |
75 | struct ec_rtc_write_request { |
76 | u8 command; |
77 | u8 reserved; |
78 | u8 param; |
79 | u8 century; |
80 | u8 year; |
81 | u8 month; |
82 | u8 day; |
83 | u8 hour; |
84 | u8 minute; |
85 | u8 second; |
86 | u8 weekday; |
87 | } __packed; |
88 | |
89 | static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) |
90 | { |
91 | struct wilco_ec_device *ec = dev_get_drvdata(dev: dev->parent); |
92 | struct ec_rtc_read_response rtc; |
93 | struct wilco_ec_message msg; |
94 | int ret; |
95 | |
96 | memset(&msg, 0, sizeof(msg)); |
97 | msg.type = WILCO_EC_MSG_LEGACY; |
98 | msg.request_data = &read_rq; |
99 | msg.request_size = sizeof(read_rq); |
100 | msg.response_data = &rtc; |
101 | msg.response_size = sizeof(rtc); |
102 | |
103 | ret = wilco_ec_mailbox(ec, msg: &msg); |
104 | if (ret < 0) |
105 | return ret; |
106 | |
107 | tm->tm_sec = rtc.second; |
108 | tm->tm_min = rtc.minute; |
109 | tm->tm_hour = rtc.hour; |
110 | tm->tm_mday = rtc.day; |
111 | tm->tm_mon = rtc.month - 1; |
112 | tm->tm_year = rtc.year + (rtc.century * 100) - 1900; |
113 | /* Ignore other tm fields, man rtc says userspace shouldn't use them. */ |
114 | |
115 | if (rtc_valid_tm(tm)) { |
116 | dev_err(dev, "Time from RTC is invalid: %ptRr\n" , tm); |
117 | return -EIO; |
118 | } |
119 | |
120 | return 0; |
121 | } |
122 | |
123 | static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm) |
124 | { |
125 | struct wilco_ec_device *ec = dev_get_drvdata(dev: dev->parent); |
126 | struct ec_rtc_write_request rtc; |
127 | struct wilco_ec_message msg; |
128 | int year = tm->tm_year + 1900; |
129 | /* |
130 | * Convert from 0=Sunday to 0=Saturday for the EC |
131 | * We DO need to set weekday because the EC controls battery charging |
132 | * schedules that depend on the day of the week. |
133 | */ |
134 | int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1; |
135 | int ret; |
136 | |
137 | rtc.command = EC_COMMAND_CMOS; |
138 | rtc.param = EC_CMOS_TOD_WRITE; |
139 | rtc.century = bin2bcd(year / 100); |
140 | rtc.year = bin2bcd(year % 100); |
141 | rtc.month = bin2bcd(tm->tm_mon + 1); |
142 | rtc.day = bin2bcd(tm->tm_mday); |
143 | rtc.hour = bin2bcd(tm->tm_hour); |
144 | rtc.minute = bin2bcd(tm->tm_min); |
145 | rtc.second = bin2bcd(tm->tm_sec); |
146 | rtc.weekday = bin2bcd(wday); |
147 | |
148 | memset(&msg, 0, sizeof(msg)); |
149 | msg.type = WILCO_EC_MSG_LEGACY; |
150 | msg.request_data = &rtc; |
151 | msg.request_size = sizeof(rtc); |
152 | |
153 | ret = wilco_ec_mailbox(ec, msg: &msg); |
154 | if (ret < 0) |
155 | return ret; |
156 | |
157 | return 0; |
158 | } |
159 | |
160 | static const struct rtc_class_ops wilco_ec_rtc_ops = { |
161 | .read_time = wilco_ec_rtc_read, |
162 | .set_time = wilco_ec_rtc_write, |
163 | }; |
164 | |
165 | static int wilco_ec_rtc_probe(struct platform_device *pdev) |
166 | { |
167 | struct rtc_device *rtc; |
168 | |
169 | rtc = devm_rtc_allocate_device(dev: &pdev->dev); |
170 | if (IS_ERR(ptr: rtc)) |
171 | return PTR_ERR(ptr: rtc); |
172 | |
173 | rtc->ops = &wilco_ec_rtc_ops; |
174 | /* EC only supports this century */ |
175 | rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; |
176 | rtc->range_max = RTC_TIMESTAMP_END_2099; |
177 | rtc->owner = THIS_MODULE; |
178 | |
179 | return devm_rtc_register_device(rtc); |
180 | } |
181 | |
182 | static struct platform_driver wilco_ec_rtc_driver = { |
183 | .driver = { |
184 | .name = "rtc-wilco-ec" , |
185 | }, |
186 | .probe = wilco_ec_rtc_probe, |
187 | }; |
188 | |
189 | module_platform_driver(wilco_ec_rtc_driver); |
190 | |
191 | MODULE_ALIAS("platform:rtc-wilco-ec" ); |
192 | MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>" ); |
193 | MODULE_LICENSE("GPL v2" ); |
194 | MODULE_DESCRIPTION("Wilco EC RTC driver" ); |
195 | |