![Rafael J. Wysocki](/assets/img/avatar_default.png)
Some clock event devices, for example such that belong to PM domains, need to be handled in a spcial way during the timekeeping suspend and resume (which takes place in the system core, or "syscore", stages of system power transitions) in analogy with clock sources. Introduce .suspend() and .resume() callbacks for clock event devices that will be executed by timekeeping_suspend/_resume(), respectively, next the the clock sources' .suspend() and .resume() callbacks. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
465 lines
12 KiB
C
465 lines
12 KiB
C
/*
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* linux/kernel/time/clockevents.c
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*
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* This file contains functions which manage clock event devices.
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*
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* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
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*
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* This code is licenced under the GPL version 2. For details see
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* kernel-base/COPYING.
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*/
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#include <linux/clockchips.h>
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#include <linux/hrtimer.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/smp.h>
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#include "tick-internal.h"
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/* The registered clock event devices */
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static LIST_HEAD(clockevent_devices);
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static LIST_HEAD(clockevents_released);
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/* Notification for clock events */
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static RAW_NOTIFIER_HEAD(clockevents_chain);
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/* Protection for the above */
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static DEFINE_RAW_SPINLOCK(clockevents_lock);
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/**
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* clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
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* @latch: value to convert
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* @evt: pointer to clock event device descriptor
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*
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* Math helper, returns latch value converted to nanoseconds (bound checked)
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*/
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u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
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{
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u64 clc = (u64) latch << evt->shift;
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if (unlikely(!evt->mult)) {
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evt->mult = 1;
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WARN_ON(1);
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}
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do_div(clc, evt->mult);
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if (clc < 1000)
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clc = 1000;
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if (clc > KTIME_MAX)
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clc = KTIME_MAX;
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return clc;
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}
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EXPORT_SYMBOL_GPL(clockevent_delta2ns);
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/**
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* clockevents_set_mode - set the operating mode of a clock event device
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* @dev: device to modify
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* @mode: new mode
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*
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* Must be called with interrupts disabled !
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*/
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void clockevents_set_mode(struct clock_event_device *dev,
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enum clock_event_mode mode)
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{
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if (dev->mode != mode) {
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dev->set_mode(mode, dev);
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dev->mode = mode;
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/*
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* A nsec2cyc multiplicator of 0 is invalid and we'd crash
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* on it, so fix it up and emit a warning:
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*/
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if (mode == CLOCK_EVT_MODE_ONESHOT) {
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if (unlikely(!dev->mult)) {
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dev->mult = 1;
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WARN_ON(1);
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}
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}
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}
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}
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/**
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* clockevents_shutdown - shutdown the device and clear next_event
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* @dev: device to shutdown
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*/
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void clockevents_shutdown(struct clock_event_device *dev)
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{
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clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
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dev->next_event.tv64 = KTIME_MAX;
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}
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#ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST
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/* Limit min_delta to a jiffie */
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#define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ)
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/**
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* clockevents_increase_min_delta - raise minimum delta of a clock event device
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* @dev: device to increase the minimum delta
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*
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* Returns 0 on success, -ETIME when the minimum delta reached the limit.
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*/
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static int clockevents_increase_min_delta(struct clock_event_device *dev)
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{
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/* Nothing to do if we already reached the limit */
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if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
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printk(KERN_WARNING "CE: Reprogramming failure. Giving up\n");
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dev->next_event.tv64 = KTIME_MAX;
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return -ETIME;
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}
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if (dev->min_delta_ns < 5000)
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dev->min_delta_ns = 5000;
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else
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dev->min_delta_ns += dev->min_delta_ns >> 1;
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if (dev->min_delta_ns > MIN_DELTA_LIMIT)
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dev->min_delta_ns = MIN_DELTA_LIMIT;
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printk(KERN_WARNING "CE: %s increased min_delta_ns to %llu nsec\n",
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dev->name ? dev->name : "?",
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(unsigned long long) dev->min_delta_ns);
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return 0;
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}
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/**
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* clockevents_program_min_delta - Set clock event device to the minimum delay.
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* @dev: device to program
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*
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* Returns 0 on success, -ETIME when the retry loop failed.
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*/
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static int clockevents_program_min_delta(struct clock_event_device *dev)
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{
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unsigned long long clc;
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int64_t delta;
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int i;
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for (i = 0;;) {
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delta = dev->min_delta_ns;
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dev->next_event = ktime_add_ns(ktime_get(), delta);
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if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
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return 0;
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dev->retries++;
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clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
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if (dev->set_next_event((unsigned long) clc, dev) == 0)
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return 0;
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if (++i > 2) {
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/*
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* We tried 3 times to program the device with the
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* given min_delta_ns. Try to increase the minimum
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* delta, if that fails as well get out of here.
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*/
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if (clockevents_increase_min_delta(dev))
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return -ETIME;
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i = 0;
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}
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}
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}
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#else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
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/**
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* clockevents_program_min_delta - Set clock event device to the minimum delay.
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* @dev: device to program
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*
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* Returns 0 on success, -ETIME when the retry loop failed.
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*/
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static int clockevents_program_min_delta(struct clock_event_device *dev)
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{
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unsigned long long clc;
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int64_t delta;
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delta = dev->min_delta_ns;
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dev->next_event = ktime_add_ns(ktime_get(), delta);
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if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
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return 0;
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dev->retries++;
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clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
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return dev->set_next_event((unsigned long) clc, dev);
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}
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#endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
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/**
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* clockevents_program_event - Reprogram the clock event device.
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* @dev: device to program
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* @expires: absolute expiry time (monotonic clock)
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* @force: program minimum delay if expires can not be set
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*
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* Returns 0 on success, -ETIME when the event is in the past.
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*/
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int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
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bool force)
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{
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unsigned long long clc;
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int64_t delta;
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int rc;
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if (unlikely(expires.tv64 < 0)) {
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WARN_ON_ONCE(1);
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return -ETIME;
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}
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dev->next_event = expires;
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if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
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return 0;
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/* Shortcut for clockevent devices that can deal with ktime. */
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if (dev->features & CLOCK_EVT_FEAT_KTIME)
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return dev->set_next_ktime(expires, dev);
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delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
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if (delta <= 0)
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return force ? clockevents_program_min_delta(dev) : -ETIME;
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delta = min(delta, (int64_t) dev->max_delta_ns);
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delta = max(delta, (int64_t) dev->min_delta_ns);
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clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
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rc = dev->set_next_event((unsigned long) clc, dev);
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return (rc && force) ? clockevents_program_min_delta(dev) : rc;
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}
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/**
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* clockevents_register_notifier - register a clock events change listener
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*/
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int clockevents_register_notifier(struct notifier_block *nb)
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{
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unsigned long flags;
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int ret;
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raw_spin_lock_irqsave(&clockevents_lock, flags);
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ret = raw_notifier_chain_register(&clockevents_chain, nb);
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raw_spin_unlock_irqrestore(&clockevents_lock, flags);
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return ret;
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}
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/*
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* Notify about a clock event change. Called with clockevents_lock
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* held.
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*/
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static void clockevents_do_notify(unsigned long reason, void *dev)
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{
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raw_notifier_call_chain(&clockevents_chain, reason, dev);
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}
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/*
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* Called after a notify add to make devices available which were
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* released from the notifier call.
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*/
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static void clockevents_notify_released(void)
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{
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struct clock_event_device *dev;
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while (!list_empty(&clockevents_released)) {
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dev = list_entry(clockevents_released.next,
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struct clock_event_device, list);
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list_del(&dev->list);
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list_add(&dev->list, &clockevent_devices);
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clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
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}
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}
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/**
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* clockevents_register_device - register a clock event device
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* @dev: device to register
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*/
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void clockevents_register_device(struct clock_event_device *dev)
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{
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unsigned long flags;
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BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
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if (!dev->cpumask) {
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WARN_ON(num_possible_cpus() > 1);
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dev->cpumask = cpumask_of(smp_processor_id());
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}
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raw_spin_lock_irqsave(&clockevents_lock, flags);
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list_add(&dev->list, &clockevent_devices);
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clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
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clockevents_notify_released();
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raw_spin_unlock_irqrestore(&clockevents_lock, flags);
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}
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EXPORT_SYMBOL_GPL(clockevents_register_device);
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void clockevents_config(struct clock_event_device *dev, u32 freq)
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{
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u64 sec;
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if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
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return;
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/*
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* Calculate the maximum number of seconds we can sleep. Limit
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* to 10 minutes for hardware which can program more than
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* 32bit ticks so we still get reasonable conversion values.
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*/
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sec = dev->max_delta_ticks;
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do_div(sec, freq);
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if (!sec)
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sec = 1;
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else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
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sec = 600;
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clockevents_calc_mult_shift(dev, freq, sec);
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dev->min_delta_ns = clockevent_delta2ns(dev->min_delta_ticks, dev);
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dev->max_delta_ns = clockevent_delta2ns(dev->max_delta_ticks, dev);
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}
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/**
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* clockevents_config_and_register - Configure and register a clock event device
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* @dev: device to register
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* @freq: The clock frequency
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* @min_delta: The minimum clock ticks to program in oneshot mode
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* @max_delta: The maximum clock ticks to program in oneshot mode
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*
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* min/max_delta can be 0 for devices which do not support oneshot mode.
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*/
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void clockevents_config_and_register(struct clock_event_device *dev,
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u32 freq, unsigned long min_delta,
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unsigned long max_delta)
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{
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dev->min_delta_ticks = min_delta;
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dev->max_delta_ticks = max_delta;
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clockevents_config(dev, freq);
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clockevents_register_device(dev);
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}
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/**
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* clockevents_update_freq - Update frequency and reprogram a clock event device.
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* @dev: device to modify
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* @freq: new device frequency
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*
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* Reconfigure and reprogram a clock event device in oneshot
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* mode. Must be called on the cpu for which the device delivers per
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* cpu timer events with interrupts disabled! Returns 0 on success,
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* -ETIME when the event is in the past.
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*/
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int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
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{
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clockevents_config(dev, freq);
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if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
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return 0;
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return clockevents_program_event(dev, dev->next_event, false);
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}
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/*
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* Noop handler when we shut down an event device
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*/
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void clockevents_handle_noop(struct clock_event_device *dev)
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{
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}
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/**
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* clockevents_exchange_device - release and request clock devices
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* @old: device to release (can be NULL)
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* @new: device to request (can be NULL)
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*
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* Called from the notifier chain. clockevents_lock is held already
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*/
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void clockevents_exchange_device(struct clock_event_device *old,
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struct clock_event_device *new)
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{
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unsigned long flags;
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local_irq_save(flags);
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/*
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* Caller releases a clock event device. We queue it into the
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* released list and do a notify add later.
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*/
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if (old) {
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clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
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list_del(&old->list);
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list_add(&old->list, &clockevents_released);
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}
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if (new) {
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BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
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clockevents_shutdown(new);
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}
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local_irq_restore(flags);
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}
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/**
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* clockevents_suspend - suspend clock devices
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*/
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void clockevents_suspend(void)
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{
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struct clock_event_device *dev;
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list_for_each_entry_reverse(dev, &clockevent_devices, list)
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if (dev->suspend)
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dev->suspend(dev);
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}
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/**
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* clockevents_resume - resume clock devices
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*/
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void clockevents_resume(void)
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{
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struct clock_event_device *dev;
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list_for_each_entry(dev, &clockevent_devices, list)
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if (dev->resume)
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dev->resume(dev);
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}
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#ifdef CONFIG_GENERIC_CLOCKEVENTS
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/**
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* clockevents_notify - notification about relevant events
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*/
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void clockevents_notify(unsigned long reason, void *arg)
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{
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struct clock_event_device *dev, *tmp;
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unsigned long flags;
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int cpu;
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raw_spin_lock_irqsave(&clockevents_lock, flags);
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clockevents_do_notify(reason, arg);
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switch (reason) {
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case CLOCK_EVT_NOTIFY_CPU_DEAD:
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/*
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* Unregister the clock event devices which were
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* released from the users in the notify chain.
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*/
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list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
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list_del(&dev->list);
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/*
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* Now check whether the CPU has left unused per cpu devices
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*/
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cpu = *((int *)arg);
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list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
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if (cpumask_test_cpu(cpu, dev->cpumask) &&
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cpumask_weight(dev->cpumask) == 1 &&
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!tick_is_broadcast_device(dev)) {
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BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
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list_del(&dev->list);
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}
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}
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break;
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default:
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break;
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}
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raw_spin_unlock_irqrestore(&clockevents_lock, flags);
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}
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EXPORT_SYMBOL_GPL(clockevents_notify);
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#endif
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