diff options
| author | Michael Kelley <mikelley@microsoft.com> | 2018-11-04 03:48:54 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-21 09:27:42 +0100 |
| commit | 989e44d6d2688a9bb162589a719410d6e7898502 (patch) | |
| tree | 1f7649c2596724da08825920b93d9367839b1d1b | |
| parent | f02c3c34bda23e96df909d23625073539db19e3d (diff) | |
| download | linux-stable-989e44d6d2688a9bb162589a719410d6e7898502.tar.gz linux-stable-989e44d6d2688a9bb162589a719410d6e7898502.tar.bz2 linux-stable-989e44d6d2688a9bb162589a719410d6e7898502.zip | |
clockevents/drivers/i8253: Add support for PIT shutdown quirk
commit 35b69a420bfb56b7b74cb635ea903db05e357bec upstream.
Add support for platforms where pit_shutdown() doesn't work because of a
quirk in the PIT emulation. On these platforms setting the counter register
to zero causes the PIT to start running again, negating the shutdown.
Provide a global variable that controls whether the counter register is
zero'ed, which platform specific code can override.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "virtualization@lists.linux-foundation.org" <virtualization@lists.linux-foundation.org>
Cc: "jgross@suse.com" <jgross@suse.com>
Cc: "akataria@vmware.com" <akataria@vmware.com>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: vkuznets <vkuznets@redhat.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1541303219-11142-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/clocksource/i8253.c | 14 | ||||
| -rw-r--r-- | include/linux/i8253.h | 1 |
2 files changed, 13 insertions, 2 deletions
diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c index 0efd36e483ab..60c8a9bd562d 100644 --- a/drivers/clocksource/i8253.c +++ b/drivers/clocksource/i8253.c @@ -19,6 +19,13 @@ DEFINE_RAW_SPINLOCK(i8253_lock); EXPORT_SYMBOL(i8253_lock); +/* + * Handle PIT quirk in pit_shutdown() where zeroing the counter register + * restarts the PIT, negating the shutdown. On platforms with the quirk, + * platform specific code can set this to false. + */ +bool i8253_clear_counter_on_shutdown = true; + #ifdef CONFIG_CLKSRC_I8253 /* * Since the PIT overflows every tick, its not very useful @@ -108,8 +115,11 @@ static int pit_shutdown(struct clock_event_device *evt) raw_spin_lock(&i8253_lock); outb_p(0x30, PIT_MODE); - outb_p(0, PIT_CH0); - outb_p(0, PIT_CH0); + + if (i8253_clear_counter_on_shutdown) { + outb_p(0, PIT_CH0); + outb_p(0, PIT_CH0); + } raw_spin_unlock(&i8253_lock); return 0; diff --git a/include/linux/i8253.h b/include/linux/i8253.h index e6bb36a97519..8336b2f6f834 100644 --- a/include/linux/i8253.h +++ b/include/linux/i8253.h @@ -21,6 +21,7 @@ #define PIT_LATCH ((PIT_TICK_RATE + HZ/2) / HZ) extern raw_spinlock_t i8253_lock; +extern bool i8253_clear_counter_on_shutdown; extern struct clock_event_device i8253_clockevent; extern void clockevent_i8253_init(bool oneshot); |