diff options
| author | Kars de Jong <jongk@linux-m68k.org> | 2019-11-16 12:46:20 +0100 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2019-11-18 15:23:54 +0100 |
| commit | 32c4d9e8a4eb286674dc1a3b93d51d791c7f645e (patch) | |
| tree | 50570b50f40b17d5669058401b70bce0a5bc36c4 /drivers/rtc | |
| parent | e34494c8df0cd96fc432efae121db3212c46ae48 (diff) | |
rtc: msm6242: Remove unneeded msm6242_set()/msm6242_clear() functions
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.
Tested-by: Kars de Jong <jongk@linux-m68k.org>
Signed-off-by: Kars de Jong <jongk@linux-m68k.org>
Link: https://lore.kernel.org/r/20191116114620.9193-1-jongk@linux-m68k.org
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-msm6242.c | 20 |
1 files 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) |