LXR linux/drivers/cpuidle/cpuidle-zynq.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2012-2013 Xilinx
   4 *
   5 * CPU idle support for Xilinx Zynq
   6 *
   7 * based on arch/arm/mach-at91/cpuidle.c
   8 *
   9 * The cpu idle uses wait-for-interrupt and RAM self refresh in order
  10 * to implement two idle states -
  11 * #1 wait-for-interrupt
  12 * #2 wait-for-interrupt and RAM self refresh
  13 *
  14 * Maintainer: Michal Simek <michal.simek@xilinx.com>
  15 */
  16
  17#include <linux/init.h>
  18#include <linux/cpuidle.h>
  19#include <linux/platform_device.h>
  20#include <asm/cpuidle.h>
  21
  22#define ZYNQ_MAX_STATES         2
  23
  24/* Actual code that puts the SoC in different idle states */
  25static int zynq_enter_idle(struct cpuidle_device *dev,
  26                           struct cpuidle_driver *drv, int index)
  27{
  28        /* Add code for DDR self refresh start */
  29        cpu_do_idle();
  30
  31        return index;
  32}
  33
  34static struct cpuidle_driver zynq_idle_driver = {
  35        .name = "zynq_idle",
  36        .owner = THIS_MODULE,
  37        .states = {
  38                ARM_CPUIDLE_WFI_STATE,
  39                {
  40                        .enter                  = zynq_enter_idle,
  41                        .exit_latency           = 10,
  42                        .target_residency       = 10000,
  43                        .name                   = "RAM_SR",
  44                        .desc                   = "WFI and RAM Self Refresh",
  45                },
  46        },
  47        .safe_state_index = 0,
  48        .state_count = ZYNQ_MAX_STATES,
  49};
  50
  51/* Initialize CPU idle by registering the idle states */
  52static int zynq_cpuidle_probe(struct platform_device *pdev)
  53{
  54        pr_info("Xilinx Zynq CpuIdle Driver started\n");
  55
  56        return cpuidle_register(&zynq_idle_driver, NULL);
  57}
  58
  59static struct platform_driver zynq_cpuidle_driver = {
  60        .driver = {
  61                .name = "cpuidle-zynq",
  62        },
  63        .probe = zynq_cpuidle_probe,
  64};
  65builtin_platform_driver(zynq_cpuidle_driver);
  66