linux-kernel - [PATCH] rtc: pcf2127: clear the flag TSF1 before enabling interrupt generation

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Date:   Tue,  1 Dec 2020 16:47:46 +0800
From:   Biwen Li <biwen.li@....nxp.com>
To:     leoyang.li@....com, alexandre.belloni@...tlin.com,
        anson.huang@....com, aisheng.dong@....com
Cc:     linux-kernel@...r.kernel.org, jiafei.pan@....com,
        linux-rtc@...r.kernel.org, Biwen Li <biwen.li@....com>
Subject: [PATCH] rtc: pcf2127: clear the flag TSF1 before enabling interrupt generation

From: Biwen Li <biwen.li@....com>

- clear the flag TSF1 before enabling interrupt generation
- properly set flag WD_CD for rtc chips(pcf2129, pca2129)

Signed-off-by: Biwen Li <biwen.li@....com>
---
 drivers/rtc/rtc-pcf2127.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index 07a5630ec841..0a45e2512258 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -601,6 +601,10 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 	 * Watchdog timer enabled and reset pin /RST activated when timed out.
 	 * Select 1Hz clock source for watchdog timer.
 	 * Note: Countdown timer disabled and not available.
+	 * For pca2129, pcf2129, only bit[7] is for Symbol WD_CD
+	 * of register watchdg_tim_ctl. The bit[6] is labeled
+	 * as T. Bits labeled as T must always be written with
+	 * logic 0.
 	 */
 	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_WD_CTL,
 				 PCF2127_BIT_WD_CTL_CD1 |
@@ -608,7 +612,7 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 				 PCF2127_BIT_WD_CTL_TF1 |
 				 PCF2127_BIT_WD_CTL_TF0,
 				 PCF2127_BIT_WD_CTL_CD1 |
-				 PCF2127_BIT_WD_CTL_CD0 |
+				 has_nvmem ? (PCF2127_BIT_WD_CTL_CD0) : (0) |
 				 PCF2127_BIT_WD_CTL_TF1);
 	if (ret) {
 		dev_err(dev, "%s: watchdog config (wd_ctl) failed\n", __func__);
@@ -659,6 +663,21 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 		return ret;
 	}
 
+	/*
+	 * Clear TSF1 field of ctrl1 register to clear interrupt
+	 * before enabling interrupt generation when
+	 * timestamp flag set. Unless the flag TSF1 won't
+	 * be cleared and the interrupt(INT pin) is
+	 * triggered continueously.
+	 */
+	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
+				 PCF2127_BIT_CTRL1_TSF1,
+				 0);
+	if (ret) {
+		dev_err(dev, "%s:  control and status register 1 (ctrl1) failed, ret = 0x%x\n",
+			__func__, ret);
+		return ret;
+	}
 	/*
 	 * Enable interrupt generation when TSF1 or TSF2 timestamp flags
 	 * are set. Interrupt signal is an open-drain output and can be
-- 
2.17.1