Messages in this thread Patch in this message | | | From | Kars de Jong <> | Subject | [PATCH] rtc: msm6242: Remove unneeded msm6242_set()/msm6242_clear() functions | Date | Sat, 16 Nov 2019 12:46:20 +0100 |
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The msm6242_set()/msm6242_clear() functions are used when writing to Control Register D to set or clear the HOLD bit when reading the current time from the RTC.
Doing this with a read-modify-write cycle will potentially clear an interrupt condition which occurs between the read and the write.
The datasheet states the following about this:
When writing the HOLD or 30 second adjust bits of register D, it is necessary to write the IRQ FLAG bit to a "1".
Since the only other bits in the register are the 30 second adjust bit (which is not used) and the BUSY bit (which is read-only), the read-modify-write cycle can be replaced by a simple write with the IRQ FLAG bit set to 1 and the other bits (except HOLD) set to 0.
Cc: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Kars de Jong <jongk@linux-m68k.org> Signed-off-by: Kars de Jong <jongk@linux-m68k.org> --- drivers/rtc/rtc-msm6242.c | 20 ++++---------------- 1 file changed, 4 insertions(+), 16 deletions(-)
diff --git a/drivers/rtc/rtc-msm6242.c b/drivers/rtc/rtc-msm6242.c index b1f2bedee77e..80e364baac53 100644 --- a/drivers/rtc/rtc-msm6242.c +++ b/drivers/rtc/rtc-msm6242.c @@ -88,28 +88,16 @@ static inline void msm6242_write(struct msm6242_priv *priv, unsigned int val, __raw_writel(val, &priv->regs[reg]); } -static inline void msm6242_set(struct msm6242_priv *priv, unsigned int val, - unsigned int reg) -{ - msm6242_write(priv, msm6242_read(priv, reg) | val, reg); -} - -static inline void msm6242_clear(struct msm6242_priv *priv, unsigned int val, - unsigned int reg) -{ - msm6242_write(priv, msm6242_read(priv, reg) & ~val, reg); -} - static void msm6242_lock(struct msm6242_priv *priv) { int cnt = 5; - msm6242_set(priv, MSM6242_CD_HOLD, MSM6242_CD); + msm6242_write(priv, MSM6242_CD_HOLD|MSM6242_CD_IRQ_FLAG, MSM6242_CD); while ((msm6242_read(priv, MSM6242_CD) & MSM6242_CD_BUSY) && cnt) { - msm6242_clear(priv, MSM6242_CD_HOLD, MSM6242_CD); + msm6242_write(priv, MSM6242_CD_IRQ_FLAG, MSM6242_CD); udelay(70); - msm6242_set(priv, MSM6242_CD_HOLD, MSM6242_CD); + msm6242_write(priv, MSM6242_CD_HOLD|MSM6242_CD_IRQ_FLAG, MSM6242_CD); cnt--; } @@ -120,7 +108,7 @@ static void msm6242_lock(struct msm6242_priv *priv) static void msm6242_unlock(struct msm6242_priv *priv) { - msm6242_clear(priv, MSM6242_CD_HOLD, MSM6242_CD); + msm6242_write(priv, MSM6242_CD_IRQ_FLAG, MSM6242_CD); } static int msm6242_read_time(struct device *dev, struct rtc_time *tm) -- 2.17.1
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