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/*
* Copyright (C) 2012-2013 Xilinx
*
* CPU idle support for Xilinx Zynq
*
* based on arch/arm/mach-at91/cpuidle.c
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*
* The cpu idle uses wait-for-interrupt and RAM self refresh in order
* to implement two idle states -
* #1 wait-for-interrupt
* #2 wait-for-interrupt and RAM self refresh
*
* Maintainer: Michal Simek <michal.simek@xilinx.com>
*/
#include <linux/init.h>
#include <linux/cpu_pm.h>
#include <linux/cpuidle.h>
#include <linux/of.h>
#include <asm/proc-fns.h>
#include <asm/cpuidle.h>
#define ZYNQ_MAX_STATES 2
/* Actual code that puts the SoC in different idle states */
static int zynq_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
/* Devices must be stopped here */
cpu_pm_enter();
/* Add code for DDR self refresh start */
cpu_do_idle();
/* Add code for DDR self refresh stop */
cpu_pm_exit();
return index;
}
static struct cpuidle_driver zynq_idle_driver = {
.name = "zynq_idle",
.owner = THIS_MODULE,
.states = {
ARM_CPUIDLE_WFI_STATE,
{
.enter = zynq_enter_idle,
.exit_latency = 10,
.target_residency = 10000,
.flags = CPUIDLE_FLAG_TIME_VALID |
CPUIDLE_FLAG_TIMER_STOP,
.name = "RAM_SR",
.desc = "WFI and RAM Self Refresh",
},
},
.safe_state_index = 0,
.state_count = ZYNQ_MAX_STATES,
};
/* Initialize CPU idle by registering the idle states */
static int __init zynq_cpuidle_init(void)
{
if (!of_machine_is_compatible("xlnx,zynq-7000"))
return -ENODEV;
pr_info("Xilinx Zynq CpuIdle Driver started\n");
return cpuidle_register(&zynq_idle_driver, NULL);
}
device_initcall(zynq_cpuidle_init);
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