linux/include/linux/i8253.h
Michael Kelley 35b69a420b clockevents/drivers/i8253: Add support for PIT shutdown quirk
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
2018-11-04 11:04:46 +01:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Machine specific IO port address definition for generic.
* Written by Osamu Tomita <tomita@cinet.co.jp>
*/
#ifndef __LINUX_I8253_H
#define __LINUX_I8253_H
#include <linux/param.h>
#include <linux/spinlock.h>
#include <linux/timex.h>
/* i8253A PIT registers */
#define PIT_MODE 0x43
#define PIT_CH0 0x40
#define PIT_CH2 0x42
#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);
extern void setup_pit_timer(void);
#endif /* __LINUX_I8253_H */