drivers/cpuidle/poll_state.c

   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;
  17
  18         time_start = local_clock_noinstr();
  19
  20         dev->poll_time_limit = false;
  21
  22         raw_local_irq_enable();
  23         if (!current_set_polling_and_test()) {
  24                 unsigned int loop_count = 0;
  25                 u64 limit;
  26
  27                 limit = cpuidle_poll_time(drv, dev);
  28
  29                 while (!need_resched()) {
  30                         cpu_relax();
  31                         if (loop_count++ < POLL_IDLE_RELAX_COUNT)
  32                                 continue;
  33
  34                         loop_count = 0;
  35                         if (local_clock_noinstr() - time_start > limit) {
  36                                 dev->poll_time_limit = true;
  37                                 break;
  38                         }
  39                 }
  40         }
  41         raw_local_irq_disable();
  42
  43         current_clr_polling();
  44
  45         return index;
  46 }
  47
  48 void cpuidle_poll_state_init(struct cpuidle_driver *drv)
  49 {
  50         struct cpuidle_state *state = &drv->states[0];
  51
  52         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
  53         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
  54         state->exit_latency = 0;
  55         state->target_residency = 0;
  56         state->exit_latency_ns = 0;
  57         state->target_residency_ns = 0;
  58         state->power_usage = -1;
  59         state->enter = poll_idle;
  60         state->flags = CPUIDLE_FLAG_POLLING;
  61 }
  62 EXPORT_SYMBOL_GPL(cpuidle_poll_state_init);