// SPDX-License-Identifier: GPL-2.0
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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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#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/smp.h>
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#include <linux/device.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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/* Protection for the above */
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static DEFINE_RAW_SPINLOCK(clockevents_lock);
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/* Protection for unbind operations */
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static DEFINE_MUTEX(clockevents_mutex);
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struct ce_unbind {
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struct clock_event_device *ce;
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int res;
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};
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static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
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bool ismax)
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{
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u64 clc = (u64) latch << evt->shift;
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u64 rnd;
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if (WARN_ON(!evt->mult))
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evt->mult = 1;
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rnd = (u64) evt->mult - 1;
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/*
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* Upper bound sanity check. If the backwards conversion is
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* not equal latch, we know that the above shift overflowed.
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*/
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if ((clc >> evt->shift) != (u64)latch)
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clc = ~0ULL;
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/*
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* Scaled math oddities:
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*
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* For mult <= (1 << shift) we can safely add mult - 1 to
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* prevent integer rounding loss. So the backwards conversion
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* from nsec to device ticks will be correct.
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*
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* For mult > (1 << shift), i.e. device frequency is > 1GHz we
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* need to be careful. Adding mult - 1 will result in a value
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* which when converted back to device ticks can be larger
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* than latch by up to (mult - 1) >> shift. For the min_delta
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* calculation we still want to apply this in order to stay
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* above the minimum device ticks limit. For the upper limit
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* we would end up with a latch value larger than the upper
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* limit of the device, so we omit the add to stay below the
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* device upper boundary.
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*
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* Also omit the add if it would overflow the u64 boundary.
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*/
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if ((~0ULL - clc > rnd) &&
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(!ismax || evt->mult <= (1ULL << evt->shift)))
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clc += rnd;
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do_div(clc, evt->mult);
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/* Deltas less than 1usec are pointless noise */
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return clc > 1000 ? clc : 1000;
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}
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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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return cev_delta2ns(latch, evt, false);
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}
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EXPORT_SYMBOL_GPL(clockevent_delta2ns);
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static int __clockevents_switch_state(struct clock_event_device *dev,
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enum clock_event_state state)
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{
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if (dev->features & CLOCK_EVT_FEAT_DUMMY)
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return 0;
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/* Transition with new state-specific callbacks */
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switch (state) {
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case CLOCK_EVT_STATE_DETACHED:
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/* The clockevent device is getting replaced. Shut it down. */
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case CLOCK_EVT_STATE_SHUTDOWN:
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if (dev->set_state_shutdown)
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return dev->set_state_shutdown(dev);
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return 0;
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case CLOCK_EVT_STATE_PERIODIC:
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/* Core internal bug */
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if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
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return -ENOSYS;
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if (dev->set_state_periodic)
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return dev->set_state_periodic(dev);
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return 0;
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case CLOCK_EVT_STATE_ONESHOT:
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/* Core internal bug */
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if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
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return -ENOSYS;
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if (dev->set_state_oneshot)
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return dev->set_state_oneshot(dev);
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return 0;
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case CLOCK_EVT_STATE_ONESHOT_STOPPED:
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/* Core internal bug */
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if (WARN_ONCE(!clockevent_state_oneshot(dev),
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"Current state: %d\n",
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clockevent_get_state(dev)))
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return -EINVAL;
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if (dev->set_state_oneshot_stopped)
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return dev->set_state_oneshot_stopped(dev);
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else
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return -ENOSYS;
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default:
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return -ENOSYS;
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}
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}
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/**
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* clockevents_switch_state - set the operating state of a clock event device
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* @dev: device to modify
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* @state: new state
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*
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* Must be called with interrupts disabled !
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*/
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void clockevents_switch_state(struct clock_event_device *dev,
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enum clock_event_state state)
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{
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if (clockevent_get_state(dev) != state) {
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if (__clockevents_switch_state(dev, state))
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return;
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clockevent_set_state(dev, state);
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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 (clockevent_state_oneshot(dev)) {
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if (WARN_ON(!dev->mult))
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dev->mult = 1;
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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_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
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dev->next_event = KTIME_MAX;
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}
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/**
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* clockevents_tick_resume - Resume the tick device before using it again
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* @dev: device to resume
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*/
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int clockevents_tick_resume(struct clock_event_device *dev)
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{
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int ret = 0;
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if (dev->tick_resume)
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ret = dev->tick_resume(dev);
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return ret;
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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_deferred(KERN_WARNING
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"CE: Reprogramming failure. Giving up\n");
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dev->next_event = 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_deferred(KERN_WARNING
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"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 (clockevent_state_shutdown(dev))
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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 = 0;
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int i;
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for (i = 0; i < 10; i++) {
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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 (clockevent_state_shutdown(dev))
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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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}
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return -ETIME;
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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 (WARN_ON_ONCE(expires < 0))
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return -ETIME;
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dev->next_event = expires;
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if (clockevent_state_shutdown(dev))
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return 0;
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/* We must be in ONESHOT state here */
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WARN_ONCE(!clockevent_state_oneshot(dev), "Current state: %d\n",
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clockevent_get_state(dev));
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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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* 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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tick_check_new_device(dev);
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}
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}
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/*
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* Try to install a replacement clock event device
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*/
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static int clockevents_replace(struct clock_event_device *ced)
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{
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struct clock_event_device *dev, *newdev = NULL;
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list_for_each_entry(dev, &clockevent_devices, list) {
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if (dev == ced || !clockevent_state_detached(dev))
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continue;
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if (!tick_check_replacement(newdev, dev))
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continue;
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if (!try_module_get(dev->owner))
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continue;
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if (newdev)
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module_put(newdev->owner);
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newdev = dev;
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}
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if (newdev) {
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tick_install_replacement(newdev);
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list_del_init(&ced->list);
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}
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return newdev ? 0 : -EBUSY;
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}
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/*
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* Called with clockevents_mutex and clockevents_lock held
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*/
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static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
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{
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/* Fast track. Device is unused */
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if (clockevent_state_detached(ced)) {
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list_del_init(&ced->list);
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return 0;
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}
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return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
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}
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/*
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* SMP function call to unbind a device
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*/
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static void __clockevents_unbind(void *arg)
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{
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struct ce_unbind *cu = arg;
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int res;
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raw_spin_lock(&clockevents_lock);
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res = __clockevents_try_unbind(cu->ce, smp_processor_id());
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if (res == -EAGAIN)
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res = clockevents_replace(cu->ce);
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cu->res = res;
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raw_spin_unlock(&clockevents_lock);
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}
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/*
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* Issues smp function call to unbind a per cpu device. Called with
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* clockevents_mutex held.
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*/
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static int clockevents_unbind(struct clock_event_device *ced, int cpu)
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{
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struct ce_unbind cu = { .ce = ced, .res = -ENODEV };
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smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
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return cu.res;
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}
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/*
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* Unbind a clockevents device.
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*/
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int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
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{
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int ret;
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mutex_lock(&clockevents_mutex);
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ret = clockevents_unbind(ced, cpu);
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mutex_unlock(&clockevents_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(clockevents_unbind_device);
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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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/* Initialize state to DETACHED */
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clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
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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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if (dev->cpumask == cpu_all_mask) {
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WARN(1, "%s cpumask == cpu_all_mask, using cpu_possible_mask instead\n",
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dev->name);
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dev->cpumask = cpu_possible_mask;
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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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tick_check_new_device(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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static 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 = cev_delta2ns(dev->min_delta_ticks, dev, false);
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dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
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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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* min/max_delta can be 0 for devices which do not support oneshot mode.
|
*/
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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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EXPORT_SYMBOL_GPL(clockevents_config_and_register);
|
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int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
|
{
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clockevents_config(dev, freq);
|
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if (clockevent_state_oneshot(dev))
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return clockevents_program_event(dev, dev->next_event, false);
|
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if (clockevent_state_periodic(dev))
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return __clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);
|
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return 0;
|
}
|
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/**
|
* clockevents_update_freq - Update frequency and reprogram a clock event device.
|
* @dev: device to modify
|
* @freq: new device frequency
|
*
|
* Reconfigure and reprogram a clock event device in oneshot
|
* mode. Must be called on the cpu for which the device delivers per
|
* cpu timer events. If called for the broadcast device the core takes
|
* care of serialization.
|
*
|
* Returns 0 on success, -ETIME when the event is in the past.
|
*/
|
int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
|
{
|
unsigned long flags;
|
int ret;
|
|
local_irq_save(flags);
|
ret = tick_broadcast_update_freq(dev, freq);
|
if (ret == -ENODEV)
|
ret = __clockevents_update_freq(dev, freq);
|
local_irq_restore(flags);
|
return ret;
|
}
|
|
/*
|
* Noop handler when we shut down an event device
|
*/
|
void clockevents_handle_noop(struct clock_event_device *dev)
|
{
|
}
|
|
/**
|
* clockevents_exchange_device - release and request clock devices
|
* @old: device to release (can be NULL)
|
* @new: device to request (can be NULL)
|
*
|
* Called from various tick functions with clockevents_lock held and
|
* interrupts disabled.
|
*/
|
void clockevents_exchange_device(struct clock_event_device *old,
|
struct clock_event_device *new)
|
{
|
/*
|
* Caller releases a clock event device. We queue it into the
|
* released list and do a notify add later.
|
*/
|
if (old) {
|
module_put(old->owner);
|
clockevents_switch_state(old, CLOCK_EVT_STATE_DETACHED);
|
list_del(&old->list);
|
list_add(&old->list, &clockevents_released);
|
}
|
|
if (new) {
|
BUG_ON(!clockevent_state_detached(new));
|
clockevents_shutdown(new);
|
}
|
}
|
|
/**
|
* clockevents_suspend - suspend clock devices
|
*/
|
void clockevents_suspend(void)
|
{
|
struct clock_event_device *dev;
|
|
list_for_each_entry_reverse(dev, &clockevent_devices, list)
|
if (dev->suspend && !clockevent_state_detached(dev))
|
dev->suspend(dev);
|
}
|
|
/**
|
* clockevents_resume - resume clock devices
|
*/
|
void clockevents_resume(void)
|
{
|
struct clock_event_device *dev;
|
|
list_for_each_entry(dev, &clockevent_devices, list)
|
if (dev->resume && !clockevent_state_detached(dev))
|
dev->resume(dev);
|
}
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
# ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
|
/**
|
* tick_offline_cpu - Take CPU out of the broadcast mechanism
|
* @cpu: The outgoing CPU
|
*
|
* Called on the outgoing CPU after it took itself offline.
|
*/
|
void tick_offline_cpu(unsigned int cpu)
|
{
|
raw_spin_lock(&clockevents_lock);
|
tick_broadcast_offline(cpu);
|
raw_spin_unlock(&clockevents_lock);
|
}
|
# endif
|
|
/**
|
* tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
|
*/
|
void tick_cleanup_dead_cpu(int cpu)
|
{
|
struct clock_event_device *dev, *tmp;
|
unsigned long flags;
|
|
raw_spin_lock_irqsave(&clockevents_lock, flags);
|
|
tick_shutdown(cpu);
|
/*
|
* Unregister the clock event devices which were
|
* released from the users in the notify chain.
|
*/
|
list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
|
list_del(&dev->list);
|
/*
|
* Now check whether the CPU has left unused per cpu devices
|
*/
|
list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
|
if (cpumask_test_cpu(cpu, dev->cpumask) &&
|
cpumask_weight(dev->cpumask) == 1 &&
|
!tick_is_broadcast_device(dev)) {
|
BUG_ON(!clockevent_state_detached(dev));
|
list_del(&dev->list);
|
}
|
}
|
raw_spin_unlock_irqrestore(&clockevents_lock, flags);
|
}
|
#endif
|
|
#ifdef CONFIG_SYSFS
|
static struct bus_type clockevents_subsys = {
|
.name = "clockevents",
|
.dev_name = "clockevent",
|
};
|
|
static DEFINE_PER_CPU(struct device, tick_percpu_dev);
|
static struct tick_device *tick_get_tick_dev(struct device *dev);
|
|
static ssize_t sysfs_show_current_tick_dev(struct device *dev,
|
struct device_attribute *attr,
|
char *buf)
|
{
|
struct tick_device *td;
|
ssize_t count = 0;
|
|
raw_spin_lock_irq(&clockevents_lock);
|
td = tick_get_tick_dev(dev);
|
if (td && td->evtdev)
|
count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
|
raw_spin_unlock_irq(&clockevents_lock);
|
return count;
|
}
|
static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL);
|
|
/* We don't support the abomination of removable broadcast devices */
|
static ssize_t sysfs_unbind_tick_dev(struct device *dev,
|
struct device_attribute *attr,
|
const char *buf, size_t count)
|
{
|
char name[CS_NAME_LEN];
|
ssize_t ret = sysfs_get_uname(buf, name, count);
|
struct clock_event_device *ce;
|
|
if (ret < 0)
|
return ret;
|
|
ret = -ENODEV;
|
mutex_lock(&clockevents_mutex);
|
raw_spin_lock_irq(&clockevents_lock);
|
list_for_each_entry(ce, &clockevent_devices, list) {
|
if (!strcmp(ce->name, name)) {
|
ret = __clockevents_try_unbind(ce, dev->id);
|
break;
|
}
|
}
|
raw_spin_unlock_irq(&clockevents_lock);
|
/*
|
* We hold clockevents_mutex, so ce can't go away
|
*/
|
if (ret == -EAGAIN)
|
ret = clockevents_unbind(ce, dev->id);
|
mutex_unlock(&clockevents_mutex);
|
return ret ? ret : count;
|
}
|
static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev);
|
|
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
|
static struct device tick_bc_dev = {
|
.init_name = "broadcast",
|
.id = 0,
|
.bus = &clockevents_subsys,
|
};
|
|
static struct tick_device *tick_get_tick_dev(struct device *dev)
|
{
|
return dev == &tick_bc_dev ? tick_get_broadcast_device() :
|
&per_cpu(tick_cpu_device, dev->id);
|
}
|
|
static __init int tick_broadcast_init_sysfs(void)
|
{
|
int err = device_register(&tick_bc_dev);
|
|
if (!err)
|
err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
|
return err;
|
}
|
#else
|
static struct tick_device *tick_get_tick_dev(struct device *dev)
|
{
|
return &per_cpu(tick_cpu_device, dev->id);
|
}
|
static inline int tick_broadcast_init_sysfs(void) { return 0; }
|
#endif
|
|
static int __init tick_init_sysfs(void)
|
{
|
int cpu;
|
|
for_each_possible_cpu(cpu) {
|
struct device *dev = &per_cpu(tick_percpu_dev, cpu);
|
int err;
|
|
dev->id = cpu;
|
dev->bus = &clockevents_subsys;
|
err = device_register(dev);
|
if (!err)
|
err = device_create_file(dev, &dev_attr_current_device);
|
if (!err)
|
err = device_create_file(dev, &dev_attr_unbind_device);
|
if (err)
|
return err;
|
}
|
return tick_broadcast_init_sysfs();
|
}
|
|
static int __init clockevents_init_sysfs(void)
|
{
|
int err = subsys_system_register(&clockevents_subsys, NULL);
|
|
if (!err)
|
err = tick_init_sysfs();
|
return err;
|
}
|
device_initcall(clockevents_init_sysfs);
|
#endif /* SYSFS */
|
