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Commit 751f7e99 authored by Anson Huang's avatar Anson Huang Committed by Shawn Guo
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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: default avatarAnson Huang <b20788@freescale.com>
Signed-off-by: default avatarShawn Guo <shawn.guo@linaro.org>
parent 848db4a0

arch/arm/mach-imx/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o 
ifeq ($(CONFIG_CPU_IDLE),y)

obj-$(CONFIG_SOC_IMX5) += cpuidle-imx5.o

obj-$(CONFIG_SOC_IMX6Q) += cpuidle-imx6q.o

obj-$(CONFIG_SOC_IMX6SL) += cpuidle-imx6sl.o

endif



ifdef CONFIG_SND_IMX_SOC

arch/arm/mach-imx/clk-imx6sl.c

+26 −0
Original line number Diff line number Diff line
@@ -66,6 +66,32 @@ static struct clk_div_table video_div_table[] = { 
static struct clk *clks[IMX6SL_CLK_END];

static struct clk_onecell_data clk_data;



/*

 * 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.

 *

 * This function will set the ARM clk to max value within the 12:5 limit.

 */

void imx6sl_set_wait_clk(bool enter)

{

	static unsigned long saved_arm_rate;



	if (enter) {

		unsigned long ipg_rate = clk_get_rate(clks[IMX6SL_CLK_IPG]);

		unsigned long max_arm_wait_rate = (12 * ipg_rate) / 5;

		saved_arm_rate = clk_get_rate(clks[IMX6SL_CLK_ARM]);

		clk_set_rate(clks[IMX6SL_CLK_ARM], max_arm_wait_rate);

	} else {

		clk_set_rate(clks[IMX6SL_CLK_ARM], saved_arm_rate);

	}

}



static void __init imx6sl_clocks_init(struct device_node *ccm_node)

{

	struct device_node *np;

arch/arm/mach-imx/common.h

+1 −0
Original line number Diff line number Diff line
@@ -140,6 +140,7 @@ void imx_anatop_pre_suspend(void); 
void imx_anatop_post_resume(void);

int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode);

void imx6q_set_int_mem_clk_lpm(void);

void imx6sl_set_wait_clk(bool enter);



void imx_cpu_die(unsigned int cpu);

int imx_cpu_kill(unsigned int cpu);

arch/arm/mach-imx/cpuidle-imx6sl.c

0 → 100644
+57 −0
Original line number Diff line number Diff line 
/*

 * 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);

}

arch/arm/mach-imx/cpuidle.h

+5 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#ifdef CONFIG_CPU_IDLE

extern int imx5_cpuidle_init(void);

extern int imx6q_cpuidle_init(void);

extern int imx6sl_cpuidle_init(void);

#else

static inline int imx5_cpuidle_init(void)

{
@@ -22,4 +23,8 @@ static inline int imx6q_cpuidle_init(void) 
{

	return 0;

}

static inline int imx6sl_cpuidle_init(void)

{

	return 0;

}

#endif