The patch titled
Subject: drivers/rtc/rtc-m41t93.c: don't let get_time() reset error state
has been added to the -mm tree. Its filename is
drivers-rtc-rtc-m41t93c-dont-let-get_time-reset-error-state.patch
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From: Nikolaus Voss <n.voss@xxxxxxxxxxx>
Subject: drivers/rtc/rtc-m41t93.c: don't let get_time() reset error state
If the rtc reports the time might be invalid due to oscillator failure,
the M41T93_FLAG_ST flag must not be reset by get_time() as the read
operation doesn't make the time valid.
Instead, the M41T93_FLAG_ST flag is reset in set_time() when a valid time
is to be written.
Signed-off-by: Nikolaus Voss <n.voss@xxxxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-m41t93.c | 46 +++++++++++++++++++++----------------
1 file changed, 27 insertions(+), 19 deletions(-)
diff -puN drivers/rtc/rtc-m41t93.c~drivers-rtc-rtc-m41t93c-dont-let-get_time-reset-error-state drivers/rtc/rtc-m41t93.c
--- a/drivers/rtc/rtc-m41t93.c~drivers-rtc-rtc-m41t93c-dont-let-get_time-reset-error-state
+++ a/drivers/rtc/rtc-m41t93.c
@@ -48,6 +48,7 @@ static inline int m41t93_set_reg(struct
static int m41t93_set_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
+ int tmp;
u8 buf[9] = {0x80}; /* write cmd + 8 data bytes */
u8 * const data = &buf[1]; /* ptr to first data byte */
@@ -62,6 +63,30 @@ static int m41t93_set_time(struct device
return -EINVAL;
}
+ tmp = spi_w8r8(spi, M41T93_REG_FLAGS);
+ if (tmp < 0)
+ return tmp;
+
+ if (tmp & M41T93_FLAG_OF) {
+ dev_warn(&spi->dev, "OF bit is set, resetting.\n");
+ m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF);
+
+ tmp = spi_w8r8(spi, M41T93_REG_FLAGS);
+ if (tmp < 0) {
+ return tmp;
+ } else if (tmp & M41T93_FLAG_OF) {
+ /* OF cannot be immediately reset: oscillator has to be
+ * restarted. */
+ u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST;
+
+ dev_warn(&spi->dev,
+ "OF bit is still set, kickstarting clock.\n");
+ m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc);
+ reset_osc &= ~M41T93_FLAG_ST;
+ m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc);
+ }
+ }
+
data[M41T93_REG_SSEC] = 0;
data[M41T93_REG_ST_SEC] = bin2bcd(tm->tm_sec);
data[M41T93_REG_MIN] = bin2bcd(tm->tm_min);
@@ -89,10 +114,7 @@ static int m41t93_get_time(struct device
1. halt bit (HT) is set: the clock is running but update of readout
registers has been disabled due to power failure. This is normal
case after poweron. Time is valid after resetting HT bit.
- 2. oscillator fail bit (OF) is set. Oscillator has be stopped and
- time is invalid:
- a) OF can be immeditely reset.
- b) OF cannot be immediately reset: oscillator has to be restarted.
+ 2. oscillator fail bit (OF) is set: time is invalid.
*/
tmp = spi_w8r8(spi, M41T93_REG_ALM_HOUR_HT);
if (tmp < 0)
@@ -110,21 +132,7 @@ static int m41t93_get_time(struct device
if (tmp & M41T93_FLAG_OF) {
ret = -EINVAL;
- dev_warn(&spi->dev, "OF bit is set, resetting.\n");
- m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF);
-
- tmp = spi_w8r8(spi, M41T93_REG_FLAGS);
- if (tmp < 0)
- return tmp;
- else if (tmp & M41T93_FLAG_OF) {
- u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST;
-
- dev_warn(&spi->dev,
- "OF bit is still set, kickstarting clock.\n");
- m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc);
- reset_osc &= ~M41T93_FLAG_ST;
- m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc);
- }
+ dev_warn(&spi->dev, "OF bit is set, write time to restart.\n");
}
if (tmp & M41T93_FLAG_BL)
_
Subject: Subject: drivers/rtc/rtc-m41t93.c: don't let get_time() reset error state
Patches currently in -mm which might be from n.voss@xxxxxxxxxxx are
drivers-rtc-rtc-m41t93c-dont-let-get_time-reset-error-state.patch
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