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1// SPDX-License-Identifier: GPL-2.02/*3 * RTC interface for Wilco Embedded Controller with R/W abilities4 *5 * Copyright 2018 Google LLC6 *7 * The corresponding platform device is typically registered in8 * drivers/platform/chrome/wilco_ec/core.c9 */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 0x7c21#define EC_CMOS_TOD_WRITE 0x0222#define EC_CMOS_TOD_READ 0x0823 24/* Message sent to the EC to request the current time. */25struct ec_rtc_read_request {26 u8 command;27 u8 reserved;28 u8 param;29} __packed;30static 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 byte38 * @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 */48struct 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_CMOS62 * @reserved: Unused byte63 * @param: Always EC_CMOS_TOD_WRITE64 * @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 */75struct 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 89static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm)90{91 struct wilco_ec_device *ec = dev_get_drvdata(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);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 123static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)124{125 struct wilco_ec_device *ec = dev_get_drvdata(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 EC131 * We DO need to set weekday because the EC controls battery charging132 * 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);154 if (ret < 0)155 return ret;156 157 return 0;158}159 160static 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 165static 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;178 179 return devm_rtc_register_device(rtc);180}181 182static struct platform_driver wilco_ec_rtc_driver = {183 .driver = {184 .name = "rtc-wilco-ec",185 },186 .probe = wilco_ec_rtc_probe,187};188 189module_platform_driver(wilco_ec_rtc_driver);190 191MODULE_ALIAS("platform:rtc-wilco-ec");192MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");193MODULE_LICENSE("GPL v2");194MODULE_DESCRIPTION("Wilco EC RTC driver");195