[PATCH 2/2] rtc: rs5c372: let the alarm to be used as wakeup source

["Daniel González Cabanelas" <dgcbueu@gmail.com>]

Currently there is no use for the interrupts on the rs5c372 RTC and the
wakealarm isn't enabled. There are some devices like NAS which use this
RTC to wake up from the power off state when the INTR pin is activated by
the alarm clock.

Enable the alarm and let to be used as a wakeup source. Tested on a Buffalo
LS421DE NAS.

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
---
 drivers/rtc/rtc-rs5c372.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
index 94b778c6e..76775d66e 100644
--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -654,6 +654,7 @@ static int rs5c372_probe(struct i2c_client *client,
 	int err = 0;
 	int smbus_mode = 0;
 	struct rs5c372 *rs5c372;
+	bool rs5c372_can_wakeup_device = false;
 
 	dev_dbg(&client->dev, "%s\n", __func__);
 
@@ -689,6 +690,12 @@ static int rs5c372_probe(struct i2c_client *client,
 	else
 		rs5c372->type = id->driver_data;
 
+#ifdef CONFIG_OF
+	if(of_property_read_bool(client->dev.of_node,
+					      "wakeup-source"))
+		rs5c372_can_wakeup_device = true;
+#endif
+
 	/* we read registers 0x0f then 0x00-0x0f; skip the first one */
 	rs5c372->regs = &rs5c372->buf[1];
 	rs5c372->smbus = smbus_mode;
@@ -722,6 +729,8 @@ static int rs5c372_probe(struct i2c_client *client,
 		goto exit;
 	}
 
+	rs5c372->has_irq = 1;
+
 	/* if the oscillator lost power and no other software (like
 	 * the bootloader) set it up, do it here.
 	 *
@@ -748,6 +757,10 @@ static int rs5c372_probe(struct i2c_client *client,
 			);
 
 	/* REVISIT use client->irq to register alarm irq ... */
+	if (rs5c372_can_wakeup_device) {
+		device_init_wakeup(&client->dev, true);
+	}
+
 	rs5c372->rtc = devm_rtc_device_register(&client->dev,
 					rs5c372_driver.driver.name,
 					&rs5c372_rtc_ops, THIS_MODULE);
@@ -761,6 +774,9 @@ static int rs5c372_probe(struct i2c_client *client,
 	if (err)
 		goto exit;
 
+	/* the rs5c372 alarm only supports a minute accuracy */
+	rs5c372->rtc->uie_unsupported = 1;
+
 	return 0;
 
 exit:
-- 
2.29.2