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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 | ||
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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 | ||
0d2f2a3d | 35 | /** |
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36 | * struct ec_rtc_read_response - Format of RTC returned by EC. |
37 | * @reserved: Unused byte | |
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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 | */ | |
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48 | struct ec_rtc_read_response { |
49 | u8 reserved; | |
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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 | /** | |
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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 | |
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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 | */ | |
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75 | struct ec_rtc_write_request { |
76 | u8 command; | |
77 | u8 reserved; | |
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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->parent); | |
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92 | struct ec_rtc_read_response rtc; |
93 | struct wilco_ec_message msg; | |
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94 | int ret; |
95 | ||
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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 | ||
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103 | ret = wilco_ec_mailbox(ec, &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; | |
9aa0d0be | 113 | /* Ignore other tm fields, man rtc says userspace shouldn't use them. */ |
0d2f2a3d | 114 | |
9aa0d0be NC |
115 | if (rtc_valid_tm(tm)) { |
116 | dev_err(dev, "Time from RTC is invalid: %ptRr\n", tm); | |
117 | return -EIO; | |
118 | } | |
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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->parent); | |
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126 | struct ec_rtc_write_request rtc; |
127 | struct wilco_ec_message msg; | |
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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 | ||
14e14aaf | 137 | rtc.command = EC_COMMAND_CMOS; |
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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 | ||
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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 | ||
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153 | ret = wilco_ec_mailbox(ec, &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(&pdev->dev); | |
170 | if (IS_ERR(rtc)) | |
171 | return PTR_ERR(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 | ||
fdcfd854 | 179 | return devm_rtc_register_device(rtc); |
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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"); |