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 = local_clock();
17 
18 	dev->poll_time_limit = false;
19 
20 	local_irq_enable();
21 	if (!current_set_polling_and_test()) {
22 		unsigned int loop_count = 0;
23 		u64 limit;
24 
25 		limit = cpuidle_poll_time(drv, dev);
26 
27 		while (!need_resched()) {
28 			cpu_relax();
29 			if (loop_count++ < POLL_IDLE_RELAX_COUNT)
30 				continue;
31 
32 			loop_count = 0;
33 			if (local_clock() - time_start > limit) {
34 				dev->poll_time_limit = true;
35 				break;
36 			}
37 		}
38 	}
39 	current_clr_polling();
40 
41 	return index;
42 }
43 
cpuidle_poll_state_init(struct cpuidle_driver * drv)44 void cpuidle_poll_state_init(struct cpuidle_driver *drv)
45 {
46 	struct cpuidle_state *state = &drv->states[0];
47 
48 	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
49 	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
50 	state->exit_latency = 0;
51 	state->target_residency = 0;
52 	state->exit_latency_ns = 0;
53 	state->target_residency_ns = 0;
54 	state->power_usage = -1;
55 	state->enter = poll_idle;
56 	state->flags = CPUIDLE_FLAG_POLLING;
57 }
58 EXPORT_SYMBOL_GPL(cpuidle_poll_state_init);
59