[PATCH 4/7] rtc: rzn1: Add alarm support

[Miquel Raynal <miquel.raynal@bootlin.com>]

The RZN1 RTC can trigger an interrupt when reaching a particular date up
to 7 days ahead. Bring support for this alarm.

One drawback though, the granularity is about a minute.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/rtc/rtc-rzn1.c | 108 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/drivers/rtc/rtc-rzn1.c b/drivers/rtc/rtc-rzn1.c
index 15c533333930..85c5a68944a0 100644
--- a/drivers/rtc/rtc-rzn1.c
+++ b/drivers/rtc/rtc-rzn1.c
@@ -154,14 +154,110 @@ static int rzn1_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	return ret;
 }
 
+static irqreturn_t rzn1_rtc_alarm_irq(int irq, void *dev_id)
+{
+	struct rzn1_rtc *rtc = dev_id;
+
+	rtc_update_irq(rtc->rtcdev, 1, RTC_AF | RTC_IRQF);
+
+	return IRQ_HANDLED;
+}
+
+static int rzn1_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
+	u32 ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
+
+	if (enable)
+		ctl1 |= RZN1_RTC_CTL1_ALME;
+	else
+		ctl1 &= ~RZN1_RTC_CTL1_ALME;
+
+	writel(ctl1, rtc->base + RZN1_RTC_CTL1);
+
+	return 0;
+}
+
+static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
+	struct rtc_time *tm = &alrm->time;
+	unsigned int min, hour, wday, delta_days;
+	u32 ctl1;
+	int ret;
+
+	ret = rzn1_rtc_read_time(dev, tm);
+	if (ret)
+		return ret;
+
+	min = readl(rtc->base + RZN1_RTC_ALM);
+	hour = readl(rtc->base + RZN1_RTC_ALH);
+	wday = readl(rtc->base + RZN1_RTC_ALW);
+
+	tm->tm_sec = 0;
+	tm->tm_min = bcd2bin(min);
+	tm->tm_hour = bcd2bin(hour);
+	delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
+	tm->tm_wday = fls(wday) - 1;
+	tm->tm_mday += delta_days;
+	if (delta_days > rtc_month_days(tm->tm_mon, tm->tm_year)) {
+		tm->tm_mday %= rtc_month_days(tm->tm_mon, tm->tm_year);
+		tm->tm_mon++;
+	}
+	if (tm->tm_mon > 12) {
+		tm->tm_mon %= 12;
+		tm->tm_year++;
+	}
+
+	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
+	alrm->enabled = !!(ctl1 & RZN1_RTC_CTL1_ALME);
+
+	return 0;
+}
+
+static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
+	struct rtc_time *tm = &alrm->time, tm_now;
+	unsigned long alarm, farest;
+	unsigned int days_ahead, wday;
+	int ret;
+
+	ret = rzn1_rtc_read_time(dev, &tm_now);
+	if (ret)
+		return ret;
+
+	/* We cannot set alarms more than one week ahead */
+	farest = rtc_tm_to_time64(&tm_now) + (7 * 86400);
+	alarm = rtc_tm_to_time64(tm);
+	if (time_after(alarm, farest))
+		return -EOPNOTSUPP;
+
+	/* Convert alarm day into week day */
+	days_ahead = tm->tm_mday - tm_now.tm_mday;
+	wday = (tm_now.tm_wday + days_ahead) % 7;
+
+	writel(bin2bcd(tm->tm_min), rtc->base + RZN1_RTC_ALM);
+	writel(bin2bcd(tm->tm_hour), rtc->base + RZN1_RTC_ALH);
+	writel(BIT(wday), rtc->base + RZN1_RTC_ALW);
+
+	rzn1_rtc_alarm_irq_enable(dev, alrm->enabled);
+
+	return 0;
+}
+
 static const struct rtc_class_ops rzn1_rtc_ops = {
 	.read_time = rzn1_rtc_read_time,
 	.set_time = rzn1_rtc_set_time,
+	.read_alarm = rzn1_rtc_read_alarm,
+	.set_alarm = rzn1_rtc_set_alarm,
+	.alarm_irq_enable = rzn1_rtc_alarm_irq_enable,
 };
 
 static int rzn1_rtc_probe(struct platform_device *pdev)
 {
 	struct rzn1_rtc *rtc;
+	int alarm_irq;
 	int ret;
 
 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
@@ -178,12 +274,17 @@ static int rzn1_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(rtc->base))
 		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->base), "Missing reg\n");
 
+	alarm_irq = platform_get_irq(pdev, 0);
+	if (alarm_irq < 0)
+		return dev_err_probe(&pdev->dev, alarm_irq, "Missing timer IRQ\n");
+
 	rtc->rtcdev = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(rtc->rtcdev))
 		return PTR_ERR(rtc);
 
 	rtc->rtcdev->range_max = 3178591199UL; /* 100 years */
 	rtc->rtcdev->ops = &rzn1_rtc_ops;
+	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtcdev->features);
 
 	ret = r9a06g032_sysctrl_enable_rtc(true);
 	if (ret)
@@ -206,6 +307,13 @@ static int rzn1_rtc_probe(struct platform_device *pdev)
 	/* Enable counter operation */
 	writel(0, rtc->base + RZN1_RTC_CTL2);
 
+	ret = devm_request_irq(&pdev->dev, alarm_irq, rzn1_rtc_alarm_irq, 0,
+			       dev_name(&pdev->dev), rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "RTC timer interrupt not available\n");
+		goto disable_clk;
+	}
+
 	ret = devm_rtc_register_device(rtc->rtcdev);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to register RTC\n");
-- 
2.27.0