| // 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 |
| |
| /** |
| * struct ec_rtc_read - Format of RTC returned by EC. |
| * @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 { |
| u8 second; |
| u8 minute; |
| u8 hour; |
| u8 day; |
| u8 month; |
| u8 year; |
| u8 century; |
| } __packed; |
| |
| /** |
| * struct ec_rtc_write - Format of RTC sent to the EC. |
| * @param: 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 { |
| 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); |
| u8 param = EC_CMOS_TOD_READ; |
| struct ec_rtc_read rtc; |
| struct wilco_ec_message msg = { |
| .type = WILCO_EC_MSG_LEGACY, |
| .flags = WILCO_EC_FLAG_RAW_RESPONSE, |
| .command = EC_COMMAND_CMOS, |
| .request_data = ¶m, |
| .request_size = sizeof(param), |
| .response_data = &rtc, |
| .response_size = sizeof(rtc), |
| }; |
| int ret; |
| |
| 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; |
| tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year); |
| |
| /* Don't compute day of week, we don't need it. */ |
| tm->tm_wday = -1; |
| |
| 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 rtc; |
| struct wilco_ec_message msg = { |
| .type = WILCO_EC_MSG_LEGACY, |
| .flags = WILCO_EC_FLAG_RAW_RESPONSE, |
| .command = EC_COMMAND_CMOS, |
| .request_data = &rtc, |
| .request_size = sizeof(rtc), |
| }; |
| 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.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); |
| |
| 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 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"); |