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rtc: pcf8563: fix write of invalid bits to ST2 reg

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The NXP datasheet says:
 "Bits labeled as N should always be written with logic 0."

At least one of those bits is sometime read as a 1, therfore violating
this rule.  To fix this we mask away those bits.

Signed-off-by: Jan Kardell <jan.kardell@telliq.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Vincent Donnefort <vdonnefort@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Kardell 2014-12-10 15:53:34 -08:00 committed by Linus Torvalds
parent 17a1e5e830
commit 45ef0458fb
1 changed files with 2 additions and 1 deletions
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3
drivers/rtc/rtc-pcf8563.c
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@ -28,6 +28,7 @@
#define PCF8563_REG_ST2 0x01
#define PCF8563_BIT_AIE (1 << 1)
#define PCF8563_BIT_AF (1 << 3)
#define PCF8563_BITS_ST2_N (7 << 5)
#define PCF8563_REG_SC 0x02 /* datetime */
#define PCF8563_REG_MN 0x03
@ -130,7 +131,7 @@ static int pcf8563_set_alarm_mode(struct i2c_client *client, bool on)
else
buf &= ~PCF8563_BIT_AIE;
buf &= ~PCF8563_BIT_AF;
buf &= ~(PCF8563_BIT_AF | PCF8563_BITS_ST2_N);
err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
if (err < 0) {