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 /** 25 * struct ec_rtc_read - Format of RTC returned by EC. 26 * @second: Second value (0..59) 27 * @minute: Minute value (0..59) 28 * @hour: Hour value (0..23) 29 * @day: Day value (1..31) 30 * @month: Month value (1..12) 31 * @year: Year value (full year % 100) 32 * @century: Century value (full year / 100) 33 * 34 * All values are presented in binary (not BCD). 35 */ 36 struct ec_rtc_read { 37 u8 second; 38 u8 minute; 39 u8 hour; 40 u8 day; 41 u8 month; 42 u8 year; 43 u8 century; 44 } __packed; 45 46 /** 47 * struct ec_rtc_write - Format of RTC sent to the EC. 48 * @param: EC_CMOS_TOD_WRITE 49 * @century: Century value (full year / 100) 50 * @year: Year value (full year % 100) 51 * @month: Month value (1..12) 52 * @day: Day value (1..31) 53 * @hour: Hour value (0..23) 54 * @minute: Minute value (0..59) 55 * @second: Second value (0..59) 56 * @weekday: Day of the week (0=Saturday) 57 * 58 * All values are presented in BCD. 59 */ 60 struct ec_rtc_write { 61 u8 param; 62 u8 century; 63 u8 year; 64 u8 month; 65 u8 day; 66 u8 hour; 67 u8 minute; 68 u8 second; 69 u8 weekday; 70 } __packed; 71 72 static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) 73 { 74 struct wilco_ec_device *ec = dev_get_drvdata(dev->parent); 75 u8 param = EC_CMOS_TOD_READ; 76 struct ec_rtc_read rtc; 77 struct wilco_ec_message msg = { 78 .type = WILCO_EC_MSG_LEGACY, 79 .flags = WILCO_EC_FLAG_RAW_RESPONSE, 80 .command = EC_COMMAND_CMOS, 81 .request_data = ¶m, 82 .request_size = sizeof(param), 83 .response_data = &rtc, 84 .response_size = sizeof(rtc), 85 }; 86 int ret; 87 88 ret = wilco_ec_mailbox(ec, &msg); 89 if (ret < 0) 90 return ret; 91 92 tm->tm_sec = rtc.second; 93 tm->tm_min = rtc.minute; 94 tm->tm_hour = rtc.hour; 95 tm->tm_mday = rtc.day; 96 tm->tm_mon = rtc.month - 1; 97 tm->tm_year = rtc.year + (rtc.century * 100) - 1900; 98 tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year); 99 100 /* Don't compute day of week, we don't need it. */ 101 tm->tm_wday = -1; 102 103 return 0; 104 } 105 106 static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm) 107 { 108 struct wilco_ec_device *ec = dev_get_drvdata(dev->parent); 109 struct ec_rtc_write rtc; 110 struct wilco_ec_message msg = { 111 .type = WILCO_EC_MSG_LEGACY, 112 .flags = WILCO_EC_FLAG_RAW_RESPONSE, 113 .command = EC_COMMAND_CMOS, 114 .request_data = &rtc, 115 .request_size = sizeof(rtc), 116 }; 117 int year = tm->tm_year + 1900; 118 /* 119 * Convert from 0=Sunday to 0=Saturday for the EC 120 * We DO need to set weekday because the EC controls battery charging 121 * schedules that depend on the day of the week. 122 */ 123 int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1; 124 int ret; 125 126 rtc.param = EC_CMOS_TOD_WRITE; 127 rtc.century = bin2bcd(year / 100); 128 rtc.year = bin2bcd(year % 100); 129 rtc.month = bin2bcd(tm->tm_mon + 1); 130 rtc.day = bin2bcd(tm->tm_mday); 131 rtc.hour = bin2bcd(tm->tm_hour); 132 rtc.minute = bin2bcd(tm->tm_min); 133 rtc.second = bin2bcd(tm->tm_sec); 134 rtc.weekday = bin2bcd(wday); 135 136 ret = wilco_ec_mailbox(ec, &msg); 137 if (ret < 0) 138 return ret; 139 140 return 0; 141 } 142 143 static const struct rtc_class_ops wilco_ec_rtc_ops = { 144 .read_time = wilco_ec_rtc_read, 145 .set_time = wilco_ec_rtc_write, 146 }; 147 148 static int wilco_ec_rtc_probe(struct platform_device *pdev) 149 { 150 struct rtc_device *rtc; 151 152 rtc = devm_rtc_allocate_device(&pdev->dev); 153 if (IS_ERR(rtc)) 154 return PTR_ERR(rtc); 155 156 rtc->ops = &wilco_ec_rtc_ops; 157 /* EC only supports this century */ 158 rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; 159 rtc->range_max = RTC_TIMESTAMP_END_2099; 160 rtc->owner = THIS_MODULE; 161 162 return rtc_register_device(rtc); 163 } 164 165 static struct platform_driver wilco_ec_rtc_driver = { 166 .driver = { 167 .name = "rtc-wilco-ec", 168 }, 169 .probe = wilco_ec_rtc_probe, 170 }; 171 172 module_platform_driver(wilco_ec_rtc_driver); 173 174 MODULE_ALIAS("platform:rtc-wilco-ec"); 175 MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>"); 176 MODULE_LICENSE("GPL v2"); 177 MODULE_DESCRIPTION("Wilco EC RTC driver"); 178