rtc-wm8350.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Real Time Clock driver for Wolfson Microelectronics WM8350
 *
 *	Copyright (C) 2007, 2008 Wolfson Microelectronics PLC.
 *
 *  Author: Liam Girdwood
 *          linux@wolfsonmicro.com
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/interrupt.h>
#include <linux/ioctl.h>
#include <linux/completion.h>
#include <linux/mfd/wm8350/rtc.h>
#include <linux/mfd/wm8350/core.h>
#include <linux/delay.h>
#include <linux/platform_device.h>

#define WM8350_SET_ALM_RETRIES	5
#define WM8350_SET_TIME_RETRIES	5
#define WM8350_GET_TIME_RETRIES	5

/*
 * Read current time and date in RTC
 */
static int wm8350_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);
	u16 time1[4], time2[4];
	int retries = WM8350_GET_TIME_RETRIES, ret;

	/*
	 * Read the time twice and compare.
	 * If time1 == time2, then time is valid else retry.
	 */
	do {
		ret = wm8350_block_read(wm8350, WM8350_RTC_SECONDS_MINUTES,
					4, time1);
		if (ret < 0)
			return ret;
		ret = wm8350_block_read(wm8350, WM8350_RTC_SECONDS_MINUTES,
					4, time2);
		if (ret < 0)
			return ret;

		if (memcmp(time1, time2, sizeof(time1)) == 0) {
			tm->tm_sec = time1[0] & WM8350_RTC_SECS_MASK;

			tm->tm_min = (time1[0] & WM8350_RTC_MINS_MASK)
			    >> WM8350_RTC_MINS_SHIFT;

			tm->tm_hour = time1[1] & WM8350_RTC_HRS_MASK;

			tm->tm_wday = ((time1[1] >> WM8350_RTC_DAY_SHIFT)
				       & 0x7) - 1;

			tm->tm_mon = ((time1[2] & WM8350_RTC_MTH_MASK)
				      >> WM8350_RTC_MTH_SHIFT) - 1;

			tm->tm_mday = (time1[2] & WM8350_RTC_DATE_MASK);

			tm->tm_year = ((time1[3] & WM8350_RTC_YHUNDREDS_MASK)
				       >> WM8350_RTC_YHUNDREDS_SHIFT) * 100;
			tm->tm_year += time1[3] & WM8350_RTC_YUNITS_MASK;

			tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon,
						    tm->tm_year);
			tm->tm_year -= 1900;

			dev_dbg(dev, "Read (%d left): %04x %04x %04x %04x\n",
				retries,
				time1[0], time1[1], time1[2], time1[3]);

			return 0;
		}
	} while (retries--);

	dev_err(dev, "timed out reading RTC time\n");
	return -EIO;
}

/*
 * Set current time and date in RTC
 */
static int wm8350_rtc_settime(struct device *dev, struct rtc_time *tm)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);
	u16 time[4];
	u16 rtc_ctrl;
	int ret, retries = WM8350_SET_TIME_RETRIES;

	time[0] = tm->tm_sec;
	time[0] |= tm->tm_min << WM8350_RTC_MINS_SHIFT;
	time[1] = tm->tm_hour;
	time[1] |= (tm->tm_wday + 1) << WM8350_RTC_DAY_SHIFT;
	time[2] = tm->tm_mday;
	time[2] |= (tm->tm_mon + 1) << WM8350_RTC_MTH_SHIFT;
	time[3] = ((tm->tm_year + 1900) / 100) << WM8350_RTC_YHUNDREDS_SHIFT;
	time[3] |= (tm->tm_year + 1900) % 100;

	dev_dbg(dev, "Setting: %04x %04x %04x %04x\n",
		time[0], time[1], time[2], time[3]);

	/* Set RTC_SET to stop the clock */
	ret = wm8350_set_bits(wm8350, WM8350_RTC_TIME_CONTROL, WM8350_RTC_SET);
	if (ret < 0)
		return ret;

	/* Wait until confirmation of stopping */
	do {
		rtc_ctrl = wm8350_reg_read(wm8350, WM8350_RTC_TIME_CONTROL);
		schedule_timeout_uninterruptible(msecs_to_jiffies(1));
	} while (--retries && !(rtc_ctrl & WM8350_RTC_STS));

	if (!retries) {
		dev_err(dev, "timed out on set confirmation\n");
		return -EIO;
	}

	/* Write time to RTC */
	ret = wm8350_block_write(wm8350, WM8350_RTC_SECONDS_MINUTES, 4, time);
	if (ret < 0)
		return ret;

	/* Clear RTC_SET to start the clock */
	ret = wm8350_clear_bits(wm8350, WM8350_RTC_TIME_CONTROL,
				WM8350_RTC_SET);
	return ret;
}

/*
 * Read alarm time and date in RTC
 */
static int wm8350_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);
	struct rtc_time *tm = &alrm->time;
	u16 time[4];
	int ret;

	ret = wm8350_block_read(wm8350, WM8350_ALARM_SECONDS_MINUTES, 4, time);
	if (ret < 0)
		return ret;

	tm->tm_sec = time[0] & WM8350_RTC_ALMSECS_MASK;
	if (tm->tm_sec == WM8350_RTC_ALMSECS_MASK)
		tm->tm_sec = -1;

	tm->tm_min = time[0] & WM8350_RTC_ALMMINS_MASK;
	if (tm->tm_min == WM8350_RTC_ALMMINS_MASK)
		tm->tm_min = -1;
	else
		tm->tm_min >>= WM8350_RTC_ALMMINS_SHIFT;

	tm->tm_hour = time[1] & WM8350_RTC_ALMHRS_MASK;
	if (tm->tm_hour == WM8350_RTC_ALMHRS_MASK)
		tm->tm_hour = -1;

	tm->tm_wday = ((time[1] >> WM8350_RTC_ALMDAY_SHIFT) & 0x7) - 1;
	if (tm->tm_wday > 7)
		tm->tm_wday = -1;

	tm->tm_mon = time[2] & WM8350_RTC_ALMMTH_MASK;
	if (tm->tm_mon == WM8350_RTC_ALMMTH_MASK)
		tm->tm_mon = -1;
	else
		tm->tm_mon = (tm->tm_mon >> WM8350_RTC_ALMMTH_SHIFT) - 1;

	tm->tm_mday = (time[2] & WM8350_RTC_ALMDATE_MASK);
	if (tm->tm_mday == WM8350_RTC_ALMDATE_MASK)
		tm->tm_mday = -1;

	tm->tm_year = -1;

	alrm->enabled = !(time[3] & WM8350_RTC_ALMSTS);

	return 0;
}

static int wm8350_rtc_stop_alarm(struct wm8350 *wm8350)
{
	int retries = WM8350_SET_ALM_RETRIES;
	u16 rtc_ctrl;
	int ret;

	/* Set RTC_SET to stop the clock */
	ret = wm8350_set_bits(wm8350, WM8350_RTC_TIME_CONTROL,
			      WM8350_RTC_ALMSET);
	if (ret < 0)
		return ret;

	/* Wait until confirmation of stopping */
	do {
		rtc_ctrl = wm8350_reg_read(wm8350, WM8350_RTC_TIME_CONTROL);
		schedule_timeout_uninterruptible(msecs_to_jiffies(1));
	} while (retries-- && !(rtc_ctrl & WM8350_RTC_ALMSTS));

	if (!(rtc_ctrl & WM8350_RTC_ALMSTS))
		return -ETIMEDOUT;

	return 0;
}

static int wm8350_rtc_start_alarm(struct wm8350 *wm8350)
{
	int ret;
	int retries = WM8350_SET_ALM_RETRIES;
	u16 rtc_ctrl;

	ret = wm8350_clear_bits(wm8350, WM8350_RTC_TIME_CONTROL,
				WM8350_RTC_ALMSET);
	if (ret < 0)
		return ret;

	/* Wait until confirmation */
	do {
		rtc_ctrl = wm8350_reg_read(wm8350, WM8350_RTC_TIME_CONTROL);
		schedule_timeout_uninterruptible(msecs_to_jiffies(1));
	} while (retries-- && rtc_ctrl & WM8350_RTC_ALMSTS);

	if (rtc_ctrl & WM8350_RTC_ALMSTS)
		return -ETIMEDOUT;

	return 0;
}

static int wm8350_rtc_alarm_irq_enable(struct device *dev,
				       unsigned int enabled)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);

	if (enabled)
		return wm8350_rtc_start_alarm(wm8350);
	else
		return wm8350_rtc_stop_alarm(wm8350);
}

static int wm8350_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);
	struct rtc_time *tm = &alrm->time;
	u16 time[3];
	int ret;

	memset(time, 0, sizeof(time));

	if (tm->tm_sec != -1)
		time[0] |= tm->tm_sec;
	else
		time[0] |= WM8350_RTC_ALMSECS_MASK;

	if (tm->tm_min != -1)
		time[0] |= tm->tm_min << WM8350_RTC_ALMMINS_SHIFT;
	else
		time[0] |= WM8350_RTC_ALMMINS_MASK;

	if (tm->tm_hour != -1)
		time[1] |= tm->tm_hour;
	else
		time[1] |= WM8350_RTC_ALMHRS_MASK;

	if (tm->tm_wday != -1)
		time[1] |= (tm->tm_wday + 1) << WM8350_RTC_ALMDAY_SHIFT;
	else
		time[1] |= WM8350_RTC_ALMDAY_MASK;

	if (tm->tm_mday != -1)
		time[2] |= tm->tm_mday;
	else
		time[2] |= WM8350_RTC_ALMDATE_MASK;

	if (tm->tm_mon != -1)
		time[2] |= (tm->tm_mon + 1) << WM8350_RTC_ALMMTH_SHIFT;
	else
		time[2] |= WM8350_RTC_ALMMTH_MASK;

	ret = wm8350_rtc_stop_alarm(wm8350);
	if (ret < 0)
		return ret;

	/* Write time to RTC */
	ret = wm8350_block_write(wm8350, WM8350_ALARM_SECONDS_MINUTES,
				 3, time);
	if (ret < 0)
		return ret;

	if (alrm->enabled)
		ret = wm8350_rtc_start_alarm(wm8350);

	return ret;
}

static irqreturn_t wm8350_rtc_alarm_handler(int irq, void *data)
{
	struct wm8350 *wm8350 = data;
	struct rtc_device *rtc = wm8350->rtc.rtc;
	int ret;

	rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);

	/* Make it one shot */
	ret = wm8350_set_bits(wm8350, WM8350_RTC_TIME_CONTROL,
			      WM8350_RTC_ALMSET);
	if (ret != 0) {
		dev_err(&(wm8350->rtc.pdev->dev),
			"Failed to disable alarm: %d\n", ret);
	}

	return IRQ_HANDLED;
}

static irqreturn_t wm8350_rtc_update_handler(int irq, void *data)
{
	struct wm8350 *wm8350 = data;
	struct rtc_device *rtc = wm8350->rtc.rtc;

	rtc_update_irq(rtc, 1, RTC_IRQF | RTC_UF);

	return IRQ_HANDLED;
}

static const struct rtc_class_ops wm8350_rtc_ops = {
	.read_time = wm8350_rtc_readtime,
	.set_time = wm8350_rtc_settime,
	.read_alarm = wm8350_rtc_readalarm,
	.set_alarm = wm8350_rtc_setalarm,
	.alarm_irq_enable = wm8350_rtc_alarm_irq_enable,
};

#ifdef CONFIG_PM_SLEEP
static int wm8350_rtc_suspend(struct device *dev)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);
	int ret = 0;
	u16 reg;

	reg = wm8350_reg_read(wm8350, WM8350_RTC_TIME_CONTROL);

	if (device_may_wakeup(&wm8350->rtc.pdev->dev) &&
	    reg & WM8350_RTC_ALMSTS) {
		ret = wm8350_rtc_stop_alarm(wm8350);
		if (ret != 0)
			dev_err(dev, "Failed to stop RTC alarm: %d\n", ret);
	}

	return ret;
}

static int wm8350_rtc_resume(struct device *dev)
{
	struct wm8350 *wm8350 = dev_get_drvdata(dev);
	int ret;

	if (wm8350->rtc.alarm_enabled) {
		ret = wm8350_rtc_start_alarm(wm8350);
		if (ret != 0)
			dev_err(dev, "Failed to restart RTC alarm: %d\n", ret);
	}

	return 0;
}
#endif

static int wm8350_rtc_probe(struct platform_device *pdev)
{
	struct wm8350 *wm8350 = platform_get_drvdata(pdev);
	struct wm8350_rtc *wm_rtc = &wm8350->rtc;
	int ret = 0;
	u16 timectl, power5;

	timectl = wm8350_reg_read(wm8350, WM8350_RTC_TIME_CONTROL);
	if (timectl & WM8350_RTC_BCD) {
		dev_err(&pdev->dev, "RTC BCD mode not supported\n");
		return -EINVAL;
	}
	if (timectl & WM8350_RTC_12HR) {
		dev_err(&pdev->dev, "RTC 12 hour mode not supported\n");
		return -EINVAL;
	}

	/* enable the RTC if it's not already enabled */
	power5 = wm8350_reg_read(wm8350, WM8350_POWER_MGMT_5);
	if (!(power5 &  WM8350_RTC_TICK_ENA)) {
		dev_info(wm8350->dev, "Starting RTC\n");

		wm8350_reg_unlock(wm8350);

		ret = wm8350_set_bits(wm8350, WM8350_POWER_MGMT_5,
				      WM8350_RTC_TICK_ENA);
		if (ret < 0) {
			dev_err(&pdev->dev, "failed to enable RTC: %d\n", ret);
			return ret;
		}

		wm8350_reg_lock(wm8350);
	}

	if (timectl & WM8350_RTC_STS) {
		int retries;

		ret = wm8350_clear_bits(wm8350, WM8350_RTC_TIME_CONTROL,
					WM8350_RTC_SET);
		if (ret < 0) {
			dev_err(&pdev->dev, "failed to start: %d\n", ret);
			return ret;
		}

		retries = WM8350_SET_TIME_RETRIES;
		do {
			timectl = wm8350_reg_read(wm8350,
						  WM8350_RTC_TIME_CONTROL);
		} while (timectl & WM8350_RTC_STS && --retries);

		if (retries == 0) {
			dev_err(&pdev->dev, "failed to start: timeout\n");
			return -ENODEV;
		}
	}

	device_init_wakeup(&pdev->dev, 1);

	wm_rtc->rtc = devm_rtc_device_register(&pdev->dev, "wm8350",
					&wm8350_rtc_ops, THIS_MODULE);
	if (IS_ERR(wm_rtc->rtc)) {
		ret = PTR_ERR(wm_rtc->rtc);
		dev_err(&pdev->dev, "failed to register RTC: %d\n", ret);
		return ret;
	}

	ret = wm8350_register_irq(wm8350, WM8350_IRQ_RTC_SEC,
			    wm8350_rtc_update_handler, 0,
			    "RTC Seconds", wm8350);
	if (ret)
		return ret;

	wm8350_mask_irq(wm8350, WM8350_IRQ_RTC_SEC);

	ret = wm8350_register_irq(wm8350, WM8350_IRQ_RTC_ALM,
			    wm8350_rtc_alarm_handler, 0,
			    "RTC Alarm", wm8350);
	if (ret) {
		wm8350_free_irq(wm8350, WM8350_IRQ_RTC_SEC, wm8350);
		return ret;
	}

	return 0;
}

static int wm8350_rtc_remove(struct platform_device *pdev)
{
	struct wm8350 *wm8350 = platform_get_drvdata(pdev);

	wm8350_free_irq(wm8350, WM8350_IRQ_RTC_SEC, wm8350);
	wm8350_free_irq(wm8350, WM8350_IRQ_RTC_ALM, wm8350);

	return 0;
}

static SIMPLE_DEV_PM_OPS(wm8350_rtc_pm_ops, wm8350_rtc_suspend,
			wm8350_rtc_resume);

static struct platform_driver wm8350_rtc_driver = {
	.probe = wm8350_rtc_probe,
	.remove = wm8350_rtc_remove,
	.driver = {
		.name = "wm8350-rtc",
		.pm = &wm8350_rtc_pm_ops,
	},
};

module_platform_driver(wm8350_rtc_driver);

MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
MODULE_DESCRIPTION("RTC driver for the WM8350");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm8350-rtc");