lkml.org 
[lkml]   [2021]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[GIT pull] timers/urgent for v5.11-rc6
Linus,

please pull the latest timers/urgent branch from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-urgent-2021-01-31

up to: 211e5db19d15: rtc: mc146818: Detect and handle broken RTCs


A fix for handling advertised, but non-existent 146818 RTCs correctly. With
the recent UIP handling changes the time readout of non-existent RTCs hangs
forever as the read returns always 0xFF which means the UIP bit is
set. Sanity check the RTC before registering by checking the RTC_VALID
register for correctness.

Thanks,

tglx

------------------>
Thomas Gleixner (1):
rtc: mc146818: Detect and handle broken RTCs


drivers/rtc/rtc-cmos.c | 8 ++++++++
drivers/rtc/rtc-mc146818-lib.c | 7 +++++++
2 files changed, 15 insertions(+)

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index 51e80bc70d42..68a9ac6f2fe1 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 0-6 must be 0! */
+ if ((CMOS_READ(RTC_VALID) & 0x7f) != 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..f83c13818af3 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 0-6 must be 0! */
+ if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x7f) != 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
\
 
 \ /
  Last update: 2021-01-31 15:08    [W:0.031 / U:7.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site