rtc: pcf2127: add alarm support

Add alarm support for the pcf2127 RTC chip family.
Tested on pca2129.
Signed-off-by: Liam Beguin <lvb@xiphos.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Link: https://lore.kernel.org/r/20200630024211.12782-3-liambeguin@gmail.com

drivers/rtc/rtc-pcf2127.c

@@ -20,6 +20,7 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_irq.h>
 #include <linux/regmap.h>
 #include <linux/watchdog.h>
 
@@ -28,7 +29,9 @@
 #define PCF2127_BIT_CTRL1_TSF1			BIT(4)
 /* Control register 2 */
 #define PCF2127_REG_CTRL2		0x01
+#define PCF2127_BIT_CTRL2_AIE			BIT(1)
 #define PCF2127_BIT_CTRL2_TSIE			BIT(2)
+#define PCF2127_BIT_CTRL2_AF			BIT(4)
 #define PCF2127_BIT_CTRL2_TSF2			BIT(5)
 /* Control register 3 */
 #define PCF2127_REG_CTRL3		0x02
@@ -46,6 +49,12 @@
 #define PCF2127_REG_DW			0x07
 #define PCF2127_REG_MO			0x08
 #define PCF2127_REG_YR			0x09
+/* Alarm registers */
+#define PCF2127_REG_ALARM_SC		0x0A
+#define PCF2127_REG_ALARM_MN		0x0B
+#define PCF2127_REG_ALARM_HR		0x0C
+#define PCF2127_REG_ALARM_DM		0x0D
+#define PCF2127_REG_ALARM_DW		0x0E
 /* Watchdog registers */
 #define PCF2127_REG_WD_CTL		0x10
 #define PCF2127_BIT_WD_CTL_TF0			BIT(0)
@@ -324,6 +333,114 @@ static const struct watchdog_ops pcf2127_watchdog_ops = {
 	.set_timeout = pcf2127_wdt_set_timeout,
 };
 
+/* Alarm */
+static int pcf2127_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
+	unsigned int buf[5], ctrl2;
+	int ret;
+
+	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL2, &ctrl2);
+	if (ret)
+		return ret;
+
+	ret = pcf2127_wdt_active_ping(&pcf2127->wdd);
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_ALARM_SC, buf,
+			       sizeof(buf));
+	if (ret)
+		return ret;
+
+	alrm->enabled = ctrl2 & PCF2127_BIT_CTRL2_AIE;
+	alrm->pending = ctrl2 & PCF2127_BIT_CTRL2_AF;
+
+	alrm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
+	alrm->time.tm_min = bcd2bin(buf[1] & 0x7F);
+	alrm->time.tm_hour = bcd2bin(buf[2] & 0x3F);
+	alrm->time.tm_mday = bcd2bin(buf[3] & 0x3F);
+	alrm->time.tm_wday = buf[4] & 0x07;
+
+	return 0;
+}
+
+static int pcf2127_rtc_alarm_irq_enable(struct device *dev, u32 enable)
+{
+	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL2,
+				 PCF2127_BIT_CTRL2_AIE,
+				 enable ? PCF2127_BIT_CTRL2_AIE : 0);
+	if (ret)
+		return ret;
+
+	return pcf2127_wdt_active_ping(&pcf2127->wdd);
+}
+
+static int pcf2127_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
+	uint8_t buf[5];
+	int ret;
+
+	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL2,
+				 PCF2127_BIT_CTRL2_AF, 0);
+	if (ret)
+		return ret;
+
+	ret = pcf2127_wdt_active_ping(&pcf2127->wdd);
+	if (ret)
+		return ret;
+
+	buf[0] = bin2bcd(alrm->time.tm_sec);
+	buf[1] = bin2bcd(alrm->time.tm_min);
+	buf[2] = bin2bcd(alrm->time.tm_hour);
+	buf[3] = bin2bcd(alrm->time.tm_mday);
+	buf[4] = (alrm->time.tm_wday & 0x07);
+
+	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_ALARM_SC, buf,
+				sizeof(buf));
+	if (ret)
+		return ret;
+
+	return pcf2127_rtc_alarm_irq_enable(dev, alrm->enabled);
+}
+
+static irqreturn_t pcf2127_rtc_irq(int irq, void *dev)
+{
+	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
+	unsigned int ctrl2 = 0;
+	int ret = 0;
+
+	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL2, &ctrl2);
+	if (ret)
+		return IRQ_NONE;
+
+	if (ctrl2 & PCF2127_BIT_CTRL2_AF) {
+		regmap_write(pcf2127->regmap, PCF2127_REG_CTRL2,
+			     ctrl2 & ~PCF2127_BIT_CTRL2_AF);
+
+		rtc_update_irq(pcf2127->rtc, 1, RTC_IRQF | RTC_AF);
+	}
+
+	ret = pcf2127_wdt_active_ping(&pcf2127->wdd);
+	if (ret)
+		return IRQ_NONE;
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops pcf2127_rtc_alrm_ops = {
+	.ioctl            = pcf2127_rtc_ioctl,
+	.read_time        = pcf2127_rtc_read_time,
+	.set_time         = pcf2127_rtc_set_time,
+	.read_alarm       = pcf2127_rtc_read_alarm,
+	.set_alarm        = pcf2127_rtc_set_alarm,
+	.alarm_irq_enable = pcf2127_rtc_alarm_irq_enable,
+};
+
 /* sysfs interface */
 
 static ssize_t timestamp0_store(struct device *dev,
@@ -419,6 +536,7 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 			const char *name, bool has_nvmem)
 {
 	struct pcf2127 *pcf2127;
+	int alarm_irq = 0;
 	u32 wdd_timeout;
 	int ret = 0;
 
@@ -441,6 +559,22 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 	pcf2127->rtc->range_max = RTC_TIMESTAMP_END_2099;
 	pcf2127->rtc->set_start_time = true; /* Sets actual start to 1970 */
 
+	alarm_irq = of_irq_get_byname(dev->of_node, "alarm");
+	if (alarm_irq >= 0) {
+		ret = devm_request_irq(dev, alarm_irq, pcf2127_rtc_irq,
+				       IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+				       dev_name(dev), dev);
+		if (ret) {
+			dev_err(dev, "failed to request alarm irq\n");
+			return ret;
+		}
+	}
+
+	if (alarm_irq >= 0 || device_property_read_bool(dev, "wakeup-source")) {
+		device_init_wakeup(dev, true);
+		pcf2127->rtc->ops = &pcf2127_rtc_alrm_ops;
+	}
+
 	pcf2127->wdd.parent = dev;
 	pcf2127->wdd.info = &pcf2127_wdt_info;
 	pcf2127->wdd.ops = &pcf2127_watchdog_ops;