rtc: msm6242: Remove unneeded msm6242_set()/msm6242_clear() functions (32c4d9e8) · Commits · 戴 / test

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>

drivers/rtc/rtc-msm6242.c

+4 −16

Original line number	Diff line number	Diff line
		@@ -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)

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