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