linux-kernel - [PATCH v2 09/17] rtc: mt6397: replace a poll with regmap_read_poll

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Date:   Wed, 25 Apr 2018 17:32:35 +0800
From:   <sean.wang@...iatek.com>
To:     <robh+dt@...nel.org>, <mark.rutland@....com>, <sre@...nel.org>,
        <lee.jones@...aro.org>, <a.zummo@...ertech.it>,
        <alexandre.belloni@...e-electrons.com>, <matthias.bgg@...il.com>,
        <eddie.huang@...iatek.com>
CC:     <devicetree@...r.kernel.org>, <linux-rtc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Sean Wang <sean.wang@...iatek.com>
Subject: [PATCH v2 09/17] rtc: mt6397: replace a poll with regmap_read_poll_timeout

From: Sean Wang <sean.wang@...iatek.com>

Reuse the helper regmap_read_poll_timeout instead of an open-coding
handling to simpify the logic.

Furthermore, the time for a wait in each iteration changed from cpu_relax
to 20us is for matching the usage of the helper, but it wouldn't acctually
break any the existent functionality according to a good test on MT6323
PMIC.

Signed-off-by: Sean Wang <sean.wang@...iatek.com>
---
 drivers/rtc/rtc-mt6397.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c
index 0df7ccd..efb9370 100644
--- a/drivers/rtc/rtc-mt6397.c
+++ b/drivers/rtc/rtc-mt6397.c
@@ -18,6 +18,7 @@
 #include <linux/regmap.h>
 #include <linux/rtc.h>
 #include <linux/irqdomain.h>
+#include <linux/jiffies.h>
 #include <linux/platform_device.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
@@ -63,6 +64,9 @@
 #define RTC_NUM_YEARS		128
 #define RTC_MIN_YEAR_OFFSET	(RTC_MIN_YEAR - RTC_BASE_YEAR)
 
+#define MTK_RTC_POLL_DELAY_US	10
+#define MTK_RTC_POLL_TIMEOUT	(jiffies_to_usecs(HZ))
+
 struct mt6397_rtc {
 	struct device		*dev;
 	struct rtc_device	*rtc_dev;
@@ -74,7 +78,6 @@ struct mt6397_rtc {
 
 static int mtk_rtc_write_trigger(struct mt6397_rtc *rtc)
 {
-	unsigned long timeout = jiffies + HZ;
 	int ret;
 	u32 data;
 
@@ -82,19 +85,13 @@ static int mtk_rtc_write_trigger(struct mt6397_rtc *rtc)
 	if (ret < 0)
 		return ret;
 
-	while (1) {
-		ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_BBPU,
-				  &data);
-		if (ret < 0)
-			break;
-		if (!(data & RTC_BBPU_CBUSY))
-			break;
-		if (time_after(jiffies, timeout)) {
-			ret = -ETIMEDOUT;
-			break;
-		}
-		cpu_relax();
-	}
+	ret = regmap_read_poll_timeout(rtc->regmap,
+				       rtc->addr_base + RTC_BBPU, data,
+				       !(data & RTC_BBPU_CBUSY),
+				       MTK_RTC_POLL_DELAY_US,
+				       MTK_RTC_POLL_TIMEOUT);
+	if (ret < 0)
+		dev_err(rtc->dev, "failed to write WRTGE: %d\n", ret);
 
 	return ret;
 }
-- 
2.7.4