linux-kernel - [PATCH] [v4] clocksource/drivers/npcm: fix GENMASK and timer operation

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Message-ID: <CAKKbWA6=9rBhR7iTfH27FZXPtuin9FengQh77T6Qgb3XDuZaYA@mail.gmail.com>
Date:   Mon, 29 Jul 2019 19:50:17 +0300
From:   Avi Fishman <avifishman70@...il.com>
To:     Tomer Maimon <tmaimon77@...il.com>,
        Tali Perry <tali.perry1@...il.com>,
        Patrick Venture <venture@...gle.com>,
        Nancy Yuen <yuenn@...gle.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Avi Fishman <avifishman70@...il.com>
Cc:     OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] [v4] 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