[PATCH] drivers/rtc/rtc-ds1307.c: Support optional wakeup interrupt source

[Nishanth Menon <nm@ti.com>]

With the recent pinctrl-single changes, SoCs such as Texas
Instrument's OMAP processors can treat wake-up events from deeper idle
states as interrupts.

Let's add support for the optional second interrupt for wake-up
events. And then SoC can wakeup and handle the event using it's
regular handler.

Finally, to pass the wake-up interrupt in the dts file,
interrupts-extended property needs to be passed.

This is similar in approach to commit 2a0b965cfb6e ("serial: omap: Add
support for optional wake-up")

Signed-off-by: Nishanth Menon <nm@ti.com>
---
 drivers/rtc/rtc-ds1307.c |   57 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index f03d5ba..5feedfc 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -15,6 +15,8 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
 #include <linux/string.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
@@ -115,6 +117,7 @@ struct ds1307 {
 	struct i2c_client	*client;
 	struct rtc_device	*rtc;
 	struct work_struct	work;
+	int			wakeirq;
 	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
 			       u8 length, u8 *values);
 	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
@@ -835,6 +838,34 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
 
 /*----------------------------------------------------------------------*/
 
+static int ds1307_i2c_suspend(struct i2c_client *client,  pm_message_t mesg)
+{
+	struct ds1307 *ds1307 = i2c_get_clientdata(client);
+	struct device *dev = &client->dev;
+
+	if (!ds1307->wakeirq)
+		return 0;
+
+	if (device_may_wakeup(dev))
+		enable_irq(ds1307->wakeirq);
+
+	return 0;
+}
+
+static int ds1307_i2c_resume(struct i2c_client *client)
+{
+	struct ds1307 *ds1307 = i2c_get_clientdata(client);
+	struct device *dev = &client->dev;
+
+	if (!ds1307->wakeirq)
+		return 0;
+
+	if (device_may_wakeup(dev))
+		disable_irq_nosync(ds1307->wakeirq);
+
+	return 0;
+}
+
 static int ds1307_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -1116,6 +1147,8 @@ read_rtc:
 	}
 
 	if (want_irq) {
+		struct device_node *node = client->dev.of_node;
+
 		err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
 			  ds1307->rtc->name, client);
 		if (err) {
@@ -1125,6 +1158,28 @@ read_rtc:
 
 			set_bit(HAS_ALARM, &ds1307->flags);
 			dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
+			if (node)
+				ds1307->wakeirq = irq_of_parse_and_map(node, 1);
+
+			if (ds1307->wakeirq <= 0)
+				ds1307->wakeirq = 0;
+			else
+				err = devm_request_irq(&client->dev,
+						       ds1307->wakeirq,
+						       ds1307_irq,
+						       IRQF_ONESHOT,
+						       ds1307->rtc->name,
+						       client);
+			if (err) {
+				dev_err(&client->dev, "unable to get wakeIRQ %d\n",
+					err);
+				free_irq(client->irq, client);
+				goto exit;
+			}
+
+			/* We enable the interrupt only during suspend path */
+			if (ds1307->wakeirq)
+				disable_irq_nosync(ds1307->wakeirq);
 		}
 	}
 
@@ -1189,6 +1244,8 @@ static struct i2c_driver ds1307_driver = {
 	},
 	.probe		= ds1307_probe,
 	.remove		= ds1307_remove,
+	.suspend	= ds1307_i2c_suspend,
+	.resume		= ds1307_i2c_resume,
 	.id_table	= ds1307_id,
 };
 
-- 
1.7.9.5