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linux-next/arch/arm/mach-imx/cpuidle-imx6sl.c
Anson Huang 751f7e999a ARM: imx: add cpuidle support for i.mx6sl
Add cpuidle support for i.MX6SL, currently only support
two cpuidle levels(ARM wfi and WAIT mode), and add software
workaround for WAIT mode errata as below:

ERR005311 CCM: After exit from WAIT mode, unwanted interrupt(s) taken
          during WAIT mode entry process could cause cache memory
          corruption.

Software workaround:
    To prevent this issue from occurring, software should ensure that
the ARM to IPG clock ratio is less than 12:5 (that is < 2.4x), before
entering WAIT mode.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
2014-03-05 10:35:01 +08:00

58 lines
1.2 KiB
C

/*
* Copyright (C) 2014 Freescale Semiconductor, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/cpuidle.h>
#include <linux/module.h>
#include <asm/cpuidle.h>
#include <asm/proc-fns.h>
#include "common.h"
#include "cpuidle.h"
static int imx6sl_enter_wait(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
imx6q_set_lpm(WAIT_UNCLOCKED);
/*
* Software workaround for ERR005311, see function
* description for details.
*/
imx6sl_set_wait_clk(true);
cpu_do_idle();
imx6sl_set_wait_clk(false);
imx6q_set_lpm(WAIT_CLOCKED);
return index;
}
static struct cpuidle_driver imx6sl_cpuidle_driver = {
.name = "imx6sl_cpuidle",
.owner = THIS_MODULE,
.states = {
/* WFI */
ARM_CPUIDLE_WFI_STATE,
/* WAIT */
{
.exit_latency = 50,
.target_residency = 75,
.flags = CPUIDLE_FLAG_TIME_VALID |
CPUIDLE_FLAG_TIMER_STOP,
.enter = imx6sl_enter_wait,
.name = "WAIT",
.desc = "Clock off",
},
},
.state_count = 2,
.safe_state_index = 0,
};
int __init imx6sl_cpuidle_init(void)
{
return cpuidle_register(&imx6sl_cpuidle_driver, NULL);
}