LXR linux/drivers/cpuidle/poll

   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
  13static 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
  44void 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}
  58EXPORT_SYMBOL_GPL(cpuidle_poll_state_init);
  59