linux-kernel - [PATCH 02/13] RTC: ds1307: Disable square wave and timers as default

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Date:	Tue, 14 Jun 2016 22:59:28 -0700
From:	Andrey Smirnov <andrew.smirnov@...il.com>
To:	rtc-linux@...glegroups.com
Cc:	Alessandro Zummo <a.zummo@...ertech.it>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	linux-kernel@...r.kernel.org,
	Andrey Smirnov <andrew.smirnov@...il.com>
Subject: [PATCH 02/13] RTC: ds1307: Disable square wave and timers as default

Disable square wave and timers as default for DS1337/39/41 and
DS3231. The rationale being that configuring a chip this way puts it
into a known state with lower power consumption. While it is not very
likely it is still possible that the code controlling RTCs that ran
before this driver configured it to produce square wave and left it in
such a state.

Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
---
 drivers/rtc/rtc-ds1307.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 7e65e2e..c618c22 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -1320,19 +1320,17 @@ static int ds1307_probe(struct i2c_client *client,
 			ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 
 		/*
-		 * Using IRQ or defined as wakeup-source?
 		 * Disable the square wave and both alarms.
 		 * For some variants, be sure alarms can trigger when we're
 		 * running on Vbackup (BBSQI/BBSQW)
 		 */
-		if (chip->alarm && (ds1307->client->irq > 0 ||
-						ds1307_can_wakeup_device)) {
-			ds1307->regs[0] |= DS1337_BIT_INTCN
-					| bbsqi_bitpos[ds1307->type];
-			ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
+		ds1307->regs[0] |= DS1337_BIT_INTCN
+			| bbsqi_bitpos[ds1307->type];
+		ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
 
+		if (chip->alarm && (ds1307->client->irq > 0 ||
+				    ds1307_can_wakeup_device))
 			want_irq = true;
-		}
 
 		i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
 							ds1307->regs[0]);
-- 
2.5.5