drivers/rtc/rtc-pl031.c: fix the missing operation on enable
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@linaro.org>
Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-pl031.c b/drivers/rtc/rtc-pl031.c
index 08378e3..10c1a34 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 */
@@ -320,7 +321,7 @@
struct pl031_local *ldata;
struct pl031_vendor_data *vendor = id->data;
struct rtc_class_ops *ops = &vendor->ops;
- unsigned long time;
+ unsigned long time, data;
ret = amba_request_regions(adev, NULL);
if (ret)
@@ -345,10 +346,11 @@
dev_dbg(&adev->dev, "designer ID = 0x%02x\n", amba_manf(adev));
dev_dbg(&adev->dev, "revision = 0x%01x\n", amba_rev(adev));
+ data = readl(ldata->base + RTC_CR);
/* Enable the clockwatch on ST Variants */
if (vendor->clockwatch)
- 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