diff options
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-cmos.c | 8 | ||||
| -rw-r--r-- | drivers/rtc/rtc-mc146818-lib.c | 7 |
2 files changed, 15 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index 51e80bc70d42..a701dae653c4 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -805,6 +805,14 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq) spin_lock_irq(&rtc_lock); + /* Ensure that the RTC is accessible. Bit 6 must be 0! */ + if ((CMOS_READ(RTC_VALID) & 0x40) != 0) { + spin_unlock_irq(&rtc_lock); + dev_warn(dev, "not accessible\n"); + retval = -ENXIO; + goto cleanup1; + } + if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) { /* force periodic irq to CMOS reset default of 1024Hz; * diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index 972a5b9a629d..dcfaf09946ee 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -21,6 +21,13 @@ unsigned int mc146818_get_time(struct rtc_time *time) again: spin_lock_irqsave(&rtc_lock, flags); + /* Ensure that the RTC is accessible. Bit 6 must be 0! */ + if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x40) != 0)) { + spin_unlock_irqrestore(&rtc_lock, flags); + memset(time, 0xff, sizeof(*time)); + return 0; + } + /* * Check whether there is an update in progress during which the * readout is unspecified. The maximum update time is ~2ms. Poll |