[ 3.5.y.z extended stable ] Patch "drivers/rtc/rtc-pl031.c: fix the missing operation on enable" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    drivers/rtc/rtc-pl031.c: fix the missing operation on enable

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From b8dd9bacb8f5ec533cee7234c629f69ceaaa8aa5 Mon Sep 17 00:00:00 2001
From: Haojian Zhuang <haojian.zhuang at linaro.org>
Date: Mon, 4 Feb 2013 14:28:54 -0800
Subject: [PATCH] drivers/rtc/rtc-pl031.c: fix the missing operation on enable

commit e7e034e18a0ab6bafb2425c3242cac311164f4d6 upstream.

The RTC control register should be enabled in the process of
initializing.

Without this patch, I failed to enable RTC in Hisilicon Hi3620 SoC.  The
register mapping section in RTC is always read as zero.  So I doubt that
ST guys may already enable this register in bootloader.  So they won't
meet this issue.

Signed-off-by: Haojian Zhuang <haojian.zhuang at linaro.org>
Cc: Srinidhi Kasagar <srinidhi.kasagar at stericsson.com>
Cc: Linus Walleij <linus.walleij at linaro.org>
Cc: Alessandro Zummo <a.zummo at towertech.it>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
[ herton: adjust context ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/rtc/rtc-pl031.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-pl031.c b/drivers/rtc/rtc-pl031.c
index cc05339..c42054b 100644
--- a/drivers/rtc/rtc-pl031.c
+++ b/drivers/rtc/rtc-pl031.c
@@ -44,6 +44,7 @@
 #define RTC_YMR		0x34	/* Year match register */
 #define RTC_YLR		0x38	/* Year data load register */

+#define RTC_CR_EN	(1 << 0)	/* counter enable bit */
 #define RTC_CR_CWEN	(1 << 26)	/* Clockwatch enable bit */

 #define RTC_TCR_EN	(1 << 1) /* Periodic timer enable bit */
@@ -304,7 +305,7 @@ 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;
+	unsigned long time, data;

 	ret = amba_request_regions(adev, NULL);
 	if (ret)
@@ -331,10 +332,11 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 	dev_dbg(&adev->dev, "designer ID = 0x%02x\n", ldata->hw_designer);
 	dev_dbg(&adev->dev, "revision = 0x%01x\n", ldata->hw_revision);

+	data = readl(ldata->base + RTC_CR);
 	/* Enable the clockwatch on ST Variants */
 	if (ldata->hw_designer == AMBA_VENDOR_ST)
-		writel(readl(ldata->base + RTC_CR) | RTC_CR_CWEN,
-		       ldata->base + RTC_CR);
+		data |= RTC_CR_CWEN;
+	writel(data | RTC_CR_EN, ldata->base + RTC_CR);

 	/*
 	 * On ST PL031 variants, the RTC reset value does not provide correct
--
1.7.9.5