linux-kernel - [ 105/117] drivers/rtc/rtc-pl031.c: configure correct wday for 2000-01-01

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Message-Id: <20120528031217.341260477@decadent.org.uk>
Date:	Mon, 28 May 2012 04:13:47 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Rajkumar Kasirajan <rajkumar.kasirajan@...ricsson.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Mattias Wallin <mattias.wallin@...ricsson.com>,
	Alessandro Zummo <a.zummo@...ertech.it>
Subject: [ 105/117] drivers/rtc/rtc-pl031.c: configure correct wday for 2000-01-01

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rajkumar Kasirajan <rajkumar.kasirajan@...ricsson.com>

commit c0a5f4a05af588a0f9951f8d24e2564b09501918 upstream.

The reset date of the ST Micro version of PL031 is 2000-01-01.  The
correct weekday for 2000-01-01 is saturday, but pl031 is initialized to
sunday.  This may lead to alarm malfunction, so configure the correct
wday if RTC_DR indicates reset.

Signed-off-by: Rajkumar Kasirajan <rajkumar.kasirajan@...ricsson.com>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Cc: Mattias Wallin <mattias.wallin@...ricsson.com>
Cc: Alessandro Zummo <a.zummo@...ertech.it>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/rtc/rtc-pl031.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/rtc/rtc-pl031.c b/drivers/rtc/rtc-pl031.c
index 684ef4b..f027c06 100644
--- a/drivers/rtc/rtc-pl031.c
+++ b/drivers/rtc/rtc-pl031.c
@@ -312,6 +312,7 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 	int ret;
 	struct pl031_local *ldata;
 	struct rtc_class_ops *ops = id->data;
+	unsigned long time;
 
 	ret = amba_request_regions(adev, NULL);
 	if (ret)
@@ -343,6 +344,23 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 		writel(readl(ldata->base + RTC_CR) | RTC_CR_CWEN,
 		       ldata->base + RTC_CR);
 
+	/*
+	 * On ST PL031 variants, the RTC reset value does not provide correct
+	 * weekday for 2000-01-01. Correct the erroneous sunday to saturday.
+	 */
+	if (ldata->hw_designer == AMBA_VENDOR_ST) {
+		if (readl(ldata->base + RTC_YDR) == 0x2000) {
+			time = readl(ldata->base + RTC_DR);
+			if ((time &
+			     (RTC_MON_MASK | RTC_MDAY_MASK | RTC_WDAY_MASK))
+			    == 0x02120000) {
+				time = time | (0x7 << RTC_WDAY_SHIFT);
+				writel(0x2000, ldata->base + RTC_YLR);
+				writel(time, ldata->base + RTC_LR);
+			}
+		}
+	}
+
 	ldata->rtc = rtc_device_register("pl031", &adev->dev, ops,
 					THIS_MODULE);
 	if (IS_ERR(ldata->rtc)) {


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