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_RELAX_COUNT 200 13 14 static int __cpuidle poll_idle(struct cpuidle_device *dev, 15 struct cpuidle_driver *drv, int index) 16 { 17 u64 time_start = local_clock(); 18 19 dev->poll_time_limit = false; 20 21 local_irq_enable(); 22 if (!current_set_polling_and_test()) { 23 unsigned int loop_count = 0; 24 u64 limit = TICK_NSEC; 25 int i; 26 27 for (i = 1; i < drv->state_count; i++) { 28 if (drv->states[i].disabled || dev->states_usage[i].disable) 29 continue; 30 31 limit = (u64)drv->states[i].target_residency * NSEC_PER_USEC; 32 break; 33 } 34 35 while (!need_resched()) { 36 cpu_relax(); 37 if (loop_count++ < POLL_IDLE_RELAX_COUNT) 38 continue; 39 40 loop_count = 0; 41 if (local_clock() - time_start > limit) { 42 dev->poll_time_limit = true; 43 break; 44 } 45 } 46 } 47 current_clr_polling(); 48 49 return index; 50 } 51 52 void 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->power_usage = -1; 61 state->enter = poll_idle; 62 state->disabled = false; 63 state->flags = CPUIDLE_FLAG_POLLING; 64 } 65 EXPORT_SYMBOL_GPL(cpuidle_poll_state_init); 66