drivers/cpuidle/cpuidle-zynq.c

   1 /*
   2  * Copyright (C) 2012-2013 Xilinx
   3  *
   4  * CPU idle support for Xilinx Zynq
   5  *
   6  * based on arch/arm/mach-at91/cpuidle.c
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms and conditions of the GNU General Public License,
  10  * version 2, as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along with
  18  * this program.  If not, see <http://www.gnu.org/licenses/>.
  19  *
  20  * The cpu idle uses wait-for-interrupt and RAM self refresh in order
  21  * to implement two idle states -
  22  * #1 wait-for-interrupt
  23  * #2 wait-for-interrupt and RAM self refresh
  24  *
  25  * Maintainer: Michal Simek <michal.simek@xilinx.com>
  26  */
  27
  28 #include <linux/init.h>
  29 #include <linux/cpuidle.h>
  30 #include <linux/platform_device.h>
  31 #include <asm/cpuidle.h>
  32
  33 #define ZYNQ_MAX_STATES         2
  34
  35 /* Actual code that puts the SoC in different idle states */
  36 static int zynq_enter_idle(struct cpuidle_device *dev,
  37                            struct cpuidle_driver *drv, int index)
  38 {
  39         /* Add code for DDR self refresh start */
  40         cpu_do_idle();
  41
  42         return index;
  43 }
  44
  45 static struct cpuidle_driver zynq_idle_driver = {
  46         .name = "zynq_idle",
  47         .owner = THIS_MODULE,
  48         .states = {
  49                 ARM_CPUIDLE_WFI_STATE,
  50                 {
  51                         .enter                  = zynq_enter_idle,
  52                         .exit_latency           = 10,
  53                         .target_residency       = 10000,
  54                         .name                   = "RAM_SR",
  55                         .desc                   = "WFI and RAM Self Refresh",
  56                 },
  57         },
  58         .safe_state_index = 0,
  59         .state_count = ZYNQ_MAX_STATES,
  60 };
  61
  62 /* Initialize CPU idle by registering the idle states */
  63 static int zynq_cpuidle_probe(struct platform_device *pdev)
  64 {
  65         pr_info("Xilinx Zynq CpuIdle Driver started\n");
  66
  67         return cpuidle_register(&zynq_idle_driver, NULL);
  68 }
  69
  70 static struct platform_driver zynq_cpuidle_driver = {
  71         .driver = {
  72                 .name = "cpuidle-zynq",
  73         },
  74         .probe = zynq_cpuidle_probe,
  75 };
  76 builtin_platform_driver(zynq_cpuidle_driver);