linux-kernel - [PATCH 07/12] rtc: omap: silence bogus power-up reset message at probe

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Date:	Thu,  9 Oct 2014 21:06:29 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Alessandro Zummo <a.zummo@...ertech.it>,
	Tony Lindgren <tony@...mide.com>,
	Benoît Cousson <bcousson@...libre.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Felipe Balbi <balbi@...com>, Lokesh Vutla <lokeshvutla@...com>,
	Guenter Roeck <linux@...ck-us.net>,
	Colin Foe-Parker <colin.foeparker@...icpd.com>,
	AnilKumar Ch <anilkumar@...com>, nsekhar@...com,
	t-kristo@...com, j-keerthy@...com, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
	Johan Hovold <johan@...nel.org>
Subject: [PATCH 07/12] rtc: omap: silence bogus power-up reset message at probe

Some legacy RTC IP revisions has a power-up reset flag in the status
register that later revisions lack.

As this flag is always read back as set on later revisions (or is
overloaded with a different flag), make sure to only clear the flag and
print the info message on legacy platforms.

Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/rtc/rtc-omap.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 1c58920b0c88..0ef016553a97 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -118,6 +118,12 @@
  */
 #define OMAP_RTC_HAS_32KCLK_EN		BIT(2)
 
+/*
+ * Some legacy RTC IP revisions has a power-up reset flag which later
+ * revisions lack.
+ */
+#define OMAP_RTC_HAS_POWER_UP_RESET	BIT(3)
+
 static void __iomem	*rtc_base;
 
 #define rtc_read(addr)		readb(rtc_base + (addr))
@@ -347,6 +353,7 @@ static int omap_rtc_timer;
 static struct platform_device_id omap_rtc_devtype[] = {
 	{
 		.name	= DRIVER_NAME,
+		.driver_data = OMAP_RTC_HAS_POWER_UP_RESET,
 	},
 	[OMAP_RTC_DATA_AM3352_IDX] = {
 		.name	= "am3352-rtc",
@@ -376,7 +383,7 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
 {
 	struct resource		*res;
 	struct rtc_device	*rtc;
-	u8			reg, new_ctrl;
+	u8			reg, mask, new_ctrl;
 	const struct platform_device_id *id_entry;
 	const struct of_device_id *of_id;
 
@@ -429,12 +436,16 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
 
 	/* clear old status */
 	reg = rtc_read(OMAP_RTC_STATUS_REG);
-	if (reg & (u8) OMAP_RTC_STATUS_POWER_UP) {
-		dev_info(&pdev->dev, "RTC power up reset detected\n");
-		rtc_write(OMAP_RTC_STATUS_POWER_UP, OMAP_RTC_STATUS_REG);
+
+	mask = OMAP_RTC_STATUS_ALARM;
+	if (id_entry->driver_data & OMAP_RTC_HAS_POWER_UP_RESET) {
+		mask |= OMAP_RTC_STATUS_POWER_UP;
+		if (reg & OMAP_RTC_STATUS_POWER_UP)
+			dev_info(&pdev->dev, "RTC power up reset detected\n");
 	}
-	if (reg & (u8) OMAP_RTC_STATUS_ALARM)
-		rtc_write(OMAP_RTC_STATUS_ALARM, OMAP_RTC_STATUS_REG);
+
+	if (reg & mask)
+		rtc_write(reg & mask, OMAP_RTC_STATUS_REG);
 
 	/* handle periodic and alarm irqs */
 	if (devm_request_irq(&pdev->dev, omap_rtc_timer, rtc_irq, 0,
-- 
2.0.4

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