linux-kernel - [PATCH] rtc: OMAP: Add external 32k clock feature

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Date:	Tue, 3 Mar 2015 15:12:02 +0530
From:	Keerthy <j-keerthy@...com>
To:	<a.zummo@...ertech.it>
CC:	<rtc-linux@...glegroups.com>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <j-keerthy@...com>
Subject: [PATCH] rtc: OMAP: Add external 32k clock feature

Add external 32k clock feature. The internal clock will be gated during suspend.
Hence make use of the external 32k clock so that rtc is functional accross
suspend/resume.

Signed-off-by: Keerthy <j-keerthy@...com>
---

Tested on DRA7-EVM.

 drivers/rtc/rtc-omap.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 8e5851a..4f803ca 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -107,6 +107,8 @@
 
 /* OMAP_RTC_OSC_REG bit fields: */
 #define OMAP_RTC_OSC_32KCLK_EN		BIT(6)
+#define OMAP_RTC_OSC_OSC32K_GZ		BIT(4)
+#define OMAP_RTC_OSC_EXT_32K		BIT(3)
 
 /* OMAP_RTC_IRQWAKEEN bit fields: */
 #define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN	BIT(1)
@@ -120,6 +122,7 @@
 
 struct omap_rtc_device_type {
 	bool has_32kclk_en;
+	bool has_osc_ext_32k;
 	bool has_kicker;
 	bool has_irqwakeen;
 	bool has_pmic_mode;
@@ -446,6 +449,7 @@ static const struct omap_rtc_device_type omap_rtc_default_type = {
 
 static const struct omap_rtc_device_type omap_rtc_am3352_type = {
 	.has_32kclk_en	= true,
+	.has_osc_ext_32k = true,
 	.has_kicker	= true,
 	.has_irqwakeen	= true,
 	.has_pmic_mode	= true,
@@ -543,7 +547,16 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
 	if (rtc->type->has_32kclk_en) {
 		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
 		rtc_writel(rtc, OMAP_RTC_OSC_REG,
-				reg | OMAP_RTC_OSC_32KCLK_EN);
+			   reg | OMAP_RTC_OSC_32KCLK_EN);
+	}
+
+	/* Enable External clock as the source */
+
+	if (rtc->type->has_osc_ext_32k) {
+		rtc_writel(rtc, OMAP_RTC_OSC_REG,
+			   (OMAP_RTC_OSC_EXT_32K |
+			   rtc_read(rtc, OMAP_RTC_OSC_REG)) &
+			   (~OMAP_RTC_OSC_OSC32K_GZ));
 	}
 
 	/* clear old status */
-- 
1.9.1

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