arch/arm/mach-imx/cpuidle-imx6sx.c

Source file repositories/reference/linux-study-clean/arch/arm/mach-imx/cpuidle-imx6sx.c

File Facts

System
Linux kernel
Corpus path
arch/arm/mach-imx/cpuidle-imx6sx.c
Extension
.c
Size
2644 bytes
Lines
119
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2014 Freescale Semiconductor, Inc.
 */

#include <linux/cpuidle.h>
#include <linux/cpu_pm.h>
#include <linux/module.h>
#include <asm/cacheflush.h>
#include <asm/cpuidle.h>
#include <asm/suspend.h>

#include "common.h"
#include "cpuidle.h"
#include "hardware.h"

static int imx6sx_idle_finish(unsigned long val)
{
	/*
	 * for Cortex-A7 which has an internal L2
	 * cache, need to flush it before powering
	 * down ARM platform, since flushing L1 cache
	 * here again has very small overhead, compared
	 * to adding conditional code for L2 cache type,
	 * just call flush_cache_all() is fine.
	 */
	flush_cache_all();
	cpu_do_idle();

	return 0;
}

static __cpuidle int imx6sx_enter_wait(struct cpuidle_device *dev,
				       struct cpuidle_driver *drv, int index)
{
	imx6_set_lpm(WAIT_UNCLOCKED);

	switch (index) {
	case 1:
		cpu_do_idle();
		break;
	case 2:
		imx6_enable_rbc(true);
		imx_gpc_set_arm_power_in_lpm(true);
		imx_set_cpu_jump(0, v7_cpu_resume);
		/* Need to notify there is a cpu pm operation. */
		cpu_pm_enter();
		cpu_cluster_pm_enter();

		ct_cpuidle_enter();
		cpu_suspend(0, imx6sx_idle_finish);
		ct_cpuidle_exit();

		cpu_cluster_pm_exit();
		cpu_pm_exit();
		imx_gpc_set_arm_power_in_lpm(false);
		imx6_enable_rbc(false);
		break;
	default:
		break;
	}

	imx6_set_lpm(WAIT_CLOCKED);

	return index;
}

static struct cpuidle_driver imx6sx_cpuidle_driver = {
	.name = "imx6sx_cpuidle",
	.owner = THIS_MODULE,
	.states = {
		/* WFI */
		ARM_CPUIDLE_WFI_STATE,
		/* WAIT */
		{
			.exit_latency = 50,
			.target_residency = 75,
			.flags = CPUIDLE_FLAG_TIMER_STOP,
			.enter = imx6sx_enter_wait,
			.name = "WAIT",
			.desc = "Clock off",
		},
		/* WAIT + ARM power off  */
		{
			/*
			 * ARM gating 31us * 5 + RBC clear 65us
			 * and some margin for SW execution, here set it
			 * to 300us.
			 */
			.exit_latency = 300,

Annotation

Implementation Notes