// SPDX-License-Identifier: GPL-2.0 /* * RTC interface for Wilco Embedded Controller with R/W abilities * * Copyright 2018 Google LLC * * The corresponding platform device is typically registered in * drivers/platform/chrome/wilco_ec/core.c */ #include <linux/bcd.h> #include <linux/err.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/platform_data/wilco-ec.h> #include <linux/rtc.h> #include <linux/timekeeping.h> #define EC_COMMAND_CMOS 0x7c #define EC_CMOS_TOD_WRITE 0x02 #define EC_CMOS_TOD_READ 0x08 /* Message sent to the EC to request the current time. */ struct ec_rtc_read_request { u8 command; u8 reserved; u8 param; } __packed; static struct ec_rtc_read_request read_rq = { .command = EC_COMMAND_CMOS, .param = EC_CMOS_TOD_READ, }; /** * struct ec_rtc_read_response - Format of RTC returned by EC. * @reserved: Unused byte * @second: Second value (0..59) * @minute: Minute value (0..59) * @hour: Hour value (0..23) * @day: Day value (1..31) * @month: Month value (1..12) * @year: Year value (full year % 100) * @century: Century value (full year / 100) * * All values are presented in binary (not BCD). */ struct ec_rtc_read_response { u8 reserved; u8 second; u8 minute; u8 hour; u8 day; u8 month; u8 year; u8 century; } __packed; /** * struct ec_rtc_write_request - Format of RTC sent to the EC. * @command: Always EC_COMMAND_CMOS * @reserved: Unused byte * @param: Always EC_CMOS_TOD_WRITE * @century: Century value (full year / 100) * @year: Year value (full year % 100) * @month: Month value (1..12) * @day: Day value (1..31) * @hour: Hour value (0..23) * @minute: Minute value (0..59) * @second: Second value (0..59) * @weekday: Day of the week (0=Saturday) * * All values are presented in BCD. */ struct ec_rtc_write_request { u8 command; u8 reserved; u8 param; u8 century; u8 year; u8 month; u8 day; u8 hour; u8 minute; u8 second; u8 weekday; } __packed; static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm) { struct wilco_ec_device *ec = dev_get_drvdata(dev->parent); struct ec_rtc_read_response rtc; struct wilco_ec_message msg; int ret; memset(&msg, 0, sizeof(msg)); msg.type = WILCO_EC_MSG_LEGACY; msg.request_data = &read_rq; msg.request_size = sizeof(read_rq); msg.response_data = &rtc; msg.response_size = sizeof(rtc); ret = wilco_ec_mailbox(ec, &msg); if (ret < 0) return ret; tm->tm_sec = rtc.second; tm->tm_min = rtc.minute; tm->tm_hour = rtc.hour; tm->tm_mday = rtc.day; tm->tm_mon = rtc.month - 1; tm->tm_year = rtc.year + (rtc.century * 100) - 1900; /* Ignore other tm fields, man rtc says userspace shouldn't use them. */ if (rtc_valid_tm(tm)) { dev_err(dev, "Time from RTC is invalid: %ptRr\n", tm); return -EIO; } return 0; } static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm) { struct wilco_ec_device *ec = dev_get_drvdata(dev->parent); struct ec_rtc_write_request rtc; struct wilco_ec_message msg; int year = tm->tm_year + 1900; /* * Convert from 0=Sunday to 0=Saturday for the EC * We DO need to set weekday because the EC controls battery charging * schedules that depend on the day of the week. */ int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1; int ret; rtc.command = EC_COMMAND_CMOS; rtc.param = EC_CMOS_TOD_WRITE; rtc.century = bin2bcd(year / 100); rtc.year = bin2bcd(year % 100); rtc.month = bin2bcd(tm->tm_mon + 1); rtc.day = bin2bcd(tm->tm_mday); rtc.hour = bin2bcd(tm->tm_hour); rtc.minute = bin2bcd(tm->tm_min); rtc.second = bin2bcd(tm->tm_sec); rtc.weekday = bin2bcd(wday); memset(&msg, 0, sizeof(msg)); msg.type = WILCO_EC_MSG_LEGACY; msg.request_data = &rtc; msg.request_size = sizeof(rtc); ret = wilco_ec_mailbox(ec, &msg); if (ret < 0) return ret; return 0; } static const struct rtc_class_ops wilco_ec_rtc_ops = { .read_time = wilco_ec_rtc_read, .set_time = wilco_ec_rtc_write, }; static int wilco_ec_rtc_probe(struct platform_device *pdev) { struct rtc_device *rtc; rtc = devm_rtc_allocate_device(&pdev->dev); if (IS_ERR(rtc)) return PTR_ERR(rtc); rtc->ops = &wilco_ec_rtc_ops; /* EC only supports this century */ rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; rtc->range_max = RTC_TIMESTAMP_END_2099; rtc->owner = THIS_MODULE; return devm_rtc_register_device(rtc); } static struct platform_driver wilco_ec_rtc_driver = { .driver = { .name = "rtc-wilco-ec", }, .probe = wilco_ec_rtc_probe, }; module_platform_driver(wilco_ec_rtc_driver); MODULE_ALIAS("platform:rtc-wilco-ec"); MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>"); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("Wilco EC RTC driver");