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