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rtc: pcf8523: Fix oscillator stop bit handling

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See: https://github.com/raspberrypi/firmware/issues/1065

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
This commit is contained in:
Phil Elwell
2018-10-29 14:45:45 +00:00
committed by Dom Cobley
parent 7686a1a09d
commit 57bf8601a6
1 changed files with 28 additions and 0 deletions
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28
drivers/rtc/rtc-pcf8523.c
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@@ -100,6 +100,7 @@ static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
u8 regs[10];
u32 value;
int err;
err = regmap_bulk_read(pcf8523->regmap, PCF8523_REG_CONTROL1, regs,
@@ -110,6 +111,33 @@ static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
if ((regs[0] & PCF8523_CONTROL1_STOP) || (regs[3] & PCF8523_SECONDS_OS))
return -EINVAL;
if (regs[0] & PCF8523_SECONDS_OS) {
/*
* If the oscillator was stopped, try to clear the flag. Upon
* power-up the flag is always set, but if we cannot clear it
* the oscillator isn't running properly for some reason. The
* sensible thing therefore is to return an error, signalling
* that the clock cannot be assumed to be correct.
*/
regs[0] &= ~PCF8523_SECONDS_OS;
err = regmap_write(pcf8523->regmap, PCF8523_REG_SECONDS,
regs[0]);
if (err < 0)
return err;
err = regmap_read(pcf8523->regmap, PCF8523_REG_SECONDS,
&value);
if (err < 0)
return err;
if (value & PCF8523_SECONDS_OS)
return -EAGAIN;
regs[0] = value;
}
tm->tm_sec = bcd2bin(regs[3] & 0x7f);
tm->tm_min = bcd2bin(regs[4] & 0x7f);
tm->tm_hour = bcd2bin(regs[5] & 0x3f);