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 */
  25 static 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
  34 static 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 */
  52 static 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
  59 static struct platform_driver zynq_cpuidle_driver = {
  60         .driver = {
  61                 .name = "cpuidle-zynq",
  62         },
  63         .probe = zynq_cpuidle_probe,
  64 };
  65 builtin_platform_driver(zynq_cpuidle_driver);