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 15 static int __cpuidle poll_idle(struct cpuidle_device *dev, 16 struct cpuidle_driver *drv, int index) 17 { 18 u64 time_start = local_clock(); 19 20 local_irq_enable(); 21 if (!current_set_polling_and_test()) { 22 unsigned int loop_count = 0; 23 24 while (!need_resched()) { 25 cpu_relax(); 26 if (loop_count++ < POLL_IDLE_RELAX_COUNT) 27 continue; 28 29 loop_count = 0; 30 if (local_clock() - time_start > POLL_IDLE_TIME_LIMIT) 31 break; 32 } 33 } 34 current_clr_polling(); 35 36 return index; 37 } 38 39 void cpuidle_poll_state_init(struct cpuidle_driver *drv) 40 { 41 struct cpuidle_state *state = &drv->states[0]; 42 43 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); 44 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 45 state->exit_latency = 0; 46 state->target_residency = 0; 47 state->power_usage = -1; 48 state->enter = poll_idle; 49 state->disabled = false; 50 state->flags = CPUIDLE_FLAG_POLLING; 51 } 52 EXPORT_SYMBOL_GPL(cpuidle_poll_state_init); 53