drivers/cpuidle/cpuidle-zynq.c

/*
 * 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);