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