1 /* 2 * poll_state.c - Polling idle state 3 * 4 * This file is released under the GPLv2. 5 */ 6 7 #include <linux/cpuidle.h> 8 #include <linux/sched.h> 9 #include <linux/sched/clock.h> 10 #include <linux/sched/idle.h> 11 12 #define POLL_IDLE_TIME_LIMIT (TICK_NSEC / 16) 13 #define POLL_IDLE_RELAX_COUNT 200 14 poll_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)15static int __cpuidle poll_idle(struct cpuidle_device *dev, 16 struct cpuidle_driver *drv, int index) 17 { 18 u64 time_start = local_clock(); 19 20 dev->poll_time_limit = false; 21 22 local_irq_enable(); 23 if (!current_set_polling_and_test()) { 24 unsigned int loop_count = 0; 25 26 while (!need_resched()) { 27 cpu_relax(); 28 if (loop_count++ < POLL_IDLE_RELAX_COUNT) 29 continue; 30 31 loop_count = 0; 32 if (local_clock() - time_start > POLL_IDLE_TIME_LIMIT) { 33 dev->poll_time_limit = true; 34 break; 35 } 36 } 37 } 38 current_clr_polling(); 39 40 return index; 41 } 42 cpuidle_poll_state_init(struct cpuidle_driver * drv)43void cpuidle_poll_state_init(struct cpuidle_driver *drv) 44 { 45 struct cpuidle_state *state = &drv->states[0]; 46 47 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); 48 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 49 state->exit_latency = 0; 50 state->target_residency = 0; 51 state->power_usage = -1; 52 state->enter = poll_idle; 53 state->disabled = false; 54 state->flags = CPUIDLE_FLAG_POLLING; 55 } 56 EXPORT_SYMBOL_GPL(cpuidle_poll_state_init); 57