poll_state.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * poll_state.c - Polling idle state
 4 */
 5
 6#include <linux/cpuidle.h>
 7#include <linux/export.h>
 8#include <linux/irqflags.h>
 9#include <linux/sched.h>
10#include <linux/sched/clock.h>
11#include <linux/sched/idle.h>
12#include <linux/sprintf.h>
13#include <linux/types.h>
14
15#define POLL_IDLE_RELAX_COUNT	200
16
17static int __cpuidle poll_idle(struct cpuidle_device *dev,
18			       struct cpuidle_driver *drv, int index)
19{
20	u64 time_start;
21
22	time_start = local_clock_noinstr();
23
24	dev->poll_time_limit = false;
25
26	raw_local_irq_enable();
27	if (!current_set_polling_and_test()) {
28		unsigned int loop_count = 0;
29		u64 limit;
30
31		limit = cpuidle_poll_time(drv, dev);
32
33		while (!need_resched()) {
34			cpu_relax();
35			if (loop_count++ < POLL_IDLE_RELAX_COUNT)
36				continue;
37
38			loop_count = 0;
39			if (local_clock_noinstr() - time_start > limit) {
40				dev->poll_time_limit = true;
41				break;
42			}
43		}
44	}
45	raw_local_irq_disable();
46
47	current_clr_polling();
48
49	return index;
50}
51
52void cpuidle_poll_state_init(struct cpuidle_driver *drv)
53{
54	struct cpuidle_state *state = &drv->states[0];
55
56	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
57	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
58	state->exit_latency = 0;
59	state->target_residency = 0;
60	state->exit_latency_ns = 0;
61	state->target_residency_ns = 0;
62	state->power_usage = -1;
63	state->enter = poll_idle;
64	state->flags = CPUIDLE_FLAG_POLLING;
65}
66EXPORT_SYMBOL_GPL(cpuidle_poll_state_init);