linux-kernel - [PATCH] [v5] clocksource/drivers/npcm: fix GENMASK and timer operation

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Date:   Mon, 29 Jul 2019 20:03:54 +0300
From:   Avi Fishman <avifishman70@...il.com>
To:     tmaimon77@...il.com, tali.perry1@...il.com, venture@...gle.com,
        yuenn@...gle.com, benjaminfair@...gle.com,
        daniel.lezcano@...aro.org, tglx@...utronix.de,
        avifishman70@...il.com
Cc:     openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH] [v5] clocksource/drivers/npcm: fix GENMASK and timer operation

NPCM7XX_Tx_OPER GENMASK bits where wrong,
Since NPCM7XX_REG_TICR0 register reset value of those bits was 0,
it did not cause an issue.
in npcm7xx_timer_oneshot() the original NPCM7XX_REG_TCSR0 register was
read again after masking it with ~NPCM7XX_Tx_OPER so the masking didn't
take effect.

npcm7xx_timer_periodic() was not wrong but it wrote to NPCM7XX_REG_TICR0
in a middle of read modify write to NPCM7XX_REG_TCSR0 which is
confusing.
npcm7xx_timer_oneshot() did wrong calculation

Signed-off-by: Avi Fishman <avifishman70@...il.com>
---
 drivers/clocksource/timer-npcm7xx.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/clocksource/timer-npcm7xx.c b/drivers/clocksource/timer-npcm7xx.c
index 8a30da7f083b..9780ffd8010e 100644
--- a/drivers/clocksource/timer-npcm7xx.c
+++ b/drivers/clocksource/timer-npcm7xx.c
@@ -32,7 +32,7 @@
 #define NPCM7XX_Tx_INTEN		BIT(29)
 #define NPCM7XX_Tx_COUNTEN		BIT(30)
 #define NPCM7XX_Tx_ONESHOT		0x0
-#define NPCM7XX_Tx_OPER			GENMASK(27, 3)
+#define NPCM7XX_Tx_OPER			GENMASK(28, 27)
 #define NPCM7XX_Tx_MIN_PRESCALE		0x1
 #define NPCM7XX_Tx_TDR_MASK_BITS	24
 #define NPCM7XX_Tx_MAX_CNT		0xFFFFFF
@@ -84,8 +84,6 @@ static int npcm7xx_timer_oneshot(struct clock_event_device *evt)
 
 	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
 	val &= ~NPCM7XX_Tx_OPER;
-
-	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
 	val |= NPCM7XX_START_ONESHOT_Tx;
 	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
 
@@ -97,12 +95,11 @@ static int npcm7xx_timer_periodic(struct clock_event_device *evt)
 	struct timer_of *to = to_timer_of(evt);
 	u32 val;
 
+	writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
+
 	val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
 	val &= ~NPCM7XX_Tx_OPER;
-
-	writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
 	val |= NPCM7XX_START_PERIODIC_Tx;
-
 	writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
 
 	return 0;
-- 
2.18.0