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Linux/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/cpu_pm.h>
 30 #include <linux/cpuidle.h>
 31 #include <linux/platform_device.h>
 32 #include <asm/proc-fns.h>
 33 #include <asm/cpuidle.h>
 34 
 35 #define ZYNQ_MAX_STATES         2
 36 
 37 /* Actual code that puts the SoC in different idle states */
 38 static int zynq_enter_idle(struct cpuidle_device *dev,
 39                            struct cpuidle_driver *drv, int index)
 40 {
 41         /* Devices must be stopped here */
 42         cpu_pm_enter();
 43 
 44         /* Add code for DDR self refresh start */
 45         cpu_do_idle();
 46 
 47         /* Add code for DDR self refresh stop */
 48         cpu_pm_exit();
 49 
 50         return index;
 51 }
 52 
 53 static struct cpuidle_driver zynq_idle_driver = {
 54         .name = "zynq_idle",
 55         .owner = THIS_MODULE,
 56         .states = {
 57                 ARM_CPUIDLE_WFI_STATE,
 58                 {
 59                         .enter                  = zynq_enter_idle,
 60                         .exit_latency           = 10,
 61                         .target_residency       = 10000,
 62                         .flags                  = CPUIDLE_FLAG_TIME_VALID |
 63                                                   CPUIDLE_FLAG_TIMER_STOP,
 64                         .name                   = "RAM_SR",
 65                         .desc                   = "WFI and RAM Self Refresh",
 66                 },
 67         },
 68         .safe_state_index = 0,
 69         .state_count = ZYNQ_MAX_STATES,
 70 };
 71 
 72 /* Initialize CPU idle by registering the idle states */
 73 static int zynq_cpuidle_probe(struct platform_device *pdev)
 74 {
 75         pr_info("Xilinx Zynq CpuIdle Driver started\n");
 76 
 77         return cpuidle_register(&zynq_idle_driver, NULL);
 78 }
 79 
 80 static struct platform_driver zynq_cpuidle_driver = {
 81         .driver = {
 82                 .name = "cpuidle-zynq",
 83                 .owner = THIS_MODULE,
 84         },
 85         .probe = zynq_cpuidle_probe,
 86 };
 87 
 88 module_platform_driver(zynq_cpuidle_driver);
 89 

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