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 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 = TICK_NSEC; 24 int i; 25 26 for (i = 1; i < drv->state_count; i++) { 27 if (drv->states[i].disabled || dev->states_usage[i].disable) 28 continue; 29 30 limit = (u64)drv->states[i].target_residency * NSEC_PER_USEC; 31 break; 32 } 33 34 while (!need_resched()) { 35 cpu_relax(); 36 if (loop_count++ < POLL_IDLE_RELAX_COUNT) 37 continue; 38 39 loop_count = 0; 40 if (local_clock() - time_start > limit) { 41 dev->poll_time_limit = true; 42 break; 43 } 44 } 45 } 46 current_clr_polling(); 47 48 return index; 49 } 50 51 void cpuidle_poll_state_init(struct cpuidle_driver *drv) 52 { 53 struct cpuidle_state *state = &drv->states[0]; 54 55 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); 56 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 57 state->exit_latency = 0; 58 state->target_residency = 0; 59 state->power_usage = -1; 60 state->enter = poll_idle; 61 state->disabled = false; 62 state->flags = CPUIDLE_FLAG_POLLING; 63 } 64 EXPORT_SYMBOL_GPL(cpuidle_poll_state_init); 65