arch/arm/mach-imx/cpuidle-imx6q.c

Source file repositories/reference/linux-study-clean/arch/arm/mach-imx/cpuidle-imx6q.c

File Facts

System
Linux kernel
Corpus path
arch/arm/mach-imx/cpuidle-imx6q.c
Extension
.c
Size
2063 bytes
Lines
85
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration 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) 2012 Freescale Semiconductor, Inc.
 */

#include <linux/context_tracking.h>
#include <linux/cpuidle.h>
#include <linux/module.h>
#include <asm/cpuidle.h>

#include <soc/imx/cpuidle.h>

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

static int num_idle_cpus = 0;
static DEFINE_RAW_SPINLOCK(cpuidle_lock);

static __cpuidle int imx6q_enter_wait(struct cpuidle_device *dev,
				      struct cpuidle_driver *drv, int index)
{
	raw_spin_lock(&cpuidle_lock);
	if (++num_idle_cpus == num_online_cpus())
		imx6_set_lpm(WAIT_UNCLOCKED);
	raw_spin_unlock(&cpuidle_lock);

	ct_cpuidle_enter();
	cpu_do_idle();
	ct_cpuidle_exit();

	raw_spin_lock(&cpuidle_lock);
	if (num_idle_cpus-- == num_online_cpus())
		imx6_set_lpm(WAIT_CLOCKED);
	raw_spin_unlock(&cpuidle_lock);

	return index;
}

static struct cpuidle_driver imx6q_cpuidle_driver = {
	.name = "imx6q_cpuidle",
	.owner = THIS_MODULE,
	.states = {
		/* WFI */
		ARM_CPUIDLE_WFI_STATE,
		/* WAIT */
		{
			.exit_latency = 50,
			.target_residency = 75,
			.flags = CPUIDLE_FLAG_TIMER_STOP | CPUIDLE_FLAG_RCU_IDLE,
			.enter = imx6q_enter_wait,
			.name = "WAIT",
			.desc = "Clock off",
		},
	},
	.state_count = 2,
	.safe_state_index = 0,
};

/*
 * i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the
 * CPUs when they are in wait(unclocked) state. As the hardware workaround isn't
 * applicable to all boards, disable the deeper idle state when the workaround
 * isn't present and the FEC is in use.
 */
void imx6q_cpuidle_fec_irqs_used(void)
{
	cpuidle_driver_state_disabled(&imx6q_cpuidle_driver, 1, true);
}
EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used);

void imx6q_cpuidle_fec_irqs_unused(void)
{
	cpuidle_driver_state_disabled(&imx6q_cpuidle_driver, 1, false);
}
EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused);

int __init imx6q_cpuidle_init(void)
{
	/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
	imx6_set_int_mem_clk_lpm(true);

	return cpuidle_register(&imx6q_cpuidle_driver, NULL);
}

Annotation

Implementation Notes