linux/drivers/rtc/rtc-wilco-ec.c

// 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 …
#define EC_CMOS_TOD_WRITE …
#define EC_CMOS_TOD_READ …

/* Message sent to the EC to request the current time. */
struct ec_rtc_read_request { … } __packed;
static struct ec_rtc_read_request read_rq = …;

/**
 * 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 { … } __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 { … } __packed;

static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm)
{ … }

static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)
{ … }

static const struct rtc_class_ops wilco_ec_rtc_ops = …;

static int wilco_ec_rtc_probe(struct platform_device *pdev)
{ … }

static struct platform_driver wilco_ec_rtc_driver = …;

module_platform_driver(…) …;

MODULE_ALIAS(…) …;
MODULE_AUTHOR(…) …;
MODULE_LICENSE(…) …;
MODULE_DESCRIPTION(…) …;