123 lines
3.0 KiB
C
123 lines
3.0 KiB
C
/*
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* ARM64 generic CPU idle driver.
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*
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* Copyright (C) 2014 ARM Ltd.
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* Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) "CPUidle arm64: " fmt
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#include <linux/cpuidle.h>
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#include <linux/cpumask.h>
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#include <linux/cpu_pm.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <asm/cpuidle.h>
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#include "dt_idle_states.h"
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/*
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* arm64_enter_idle_state - Programs CPU to enter the specified state
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*
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* dev: cpuidle device
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* drv: cpuidle driver
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* idx: state index
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*
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* Called from the CPUidle framework to program the device to the
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* specified target state selected by the governor.
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*/
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static int arm64_enter_idle_state(struct cpuidle_device *dev,
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struct cpuidle_driver *drv, int idx)
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{
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int ret;
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if (!idx) {
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cpu_do_idle();
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return idx;
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}
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ret = cpu_pm_enter();
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if (!ret) {
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/*
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* Pass idle state index to cpu_suspend which in turn will
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* call the CPU ops suspend protocol with idle index as a
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* parameter.
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*/
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ret = cpu_suspend(idx);
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cpu_pm_exit();
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}
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return ret ? -1 : idx;
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}
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static struct cpuidle_driver arm64_idle_driver = {
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.name = "arm64_idle",
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.owner = THIS_MODULE,
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/*
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* State at index 0 is standby wfi and considered standard
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* on all ARM platforms. If in some platforms simple wfi
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* can't be used as "state 0", DT bindings must be implemented
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* to work around this issue and allow installing a special
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* handler for idle state index 0.
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*/
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.states[0] = {
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.enter = arm64_enter_idle_state,
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.exit_latency = 1,
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.target_residency = 1,
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.power_usage = UINT_MAX,
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.name = "WFI",
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.desc = "ARM64 WFI",
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}
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};
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static const struct of_device_id arm64_idle_state_match[] __initconst = {
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{ .compatible = "arm,idle-state",
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.data = arm64_enter_idle_state },
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{ },
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};
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/*
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* arm64_idle_init
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*
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* Registers the arm64 specific cpuidle driver with the cpuidle
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* framework. It relies on core code to parse the idle states
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* and initialize them using driver data structures accordingly.
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*/
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static int __init arm64_idle_init(void)
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{
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int cpu, ret;
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struct cpuidle_driver *drv = &arm64_idle_driver;
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/*
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* Initialize idle states data, starting at index 1.
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* This driver is DT only, if no DT idle states are detected (ret == 0)
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* let the driver initialization fail accordingly since there is no
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* reason to initialize the idle driver if only wfi is supported.
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*/
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ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
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if (ret <= 0)
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return ret ? : -ENODEV;
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/*
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* Call arch CPU operations in order to initialize
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* idle states suspend back-end specific data
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*/
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for_each_possible_cpu(cpu) {
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ret = cpu_init_idle(cpu);
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if (ret) {
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pr_err("CPU %d failed to init idle CPU ops\n", cpu);
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return ret;
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}
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}
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return cpuidle_register(drv, NULL);
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}
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device_initcall(arm64_idle_init);
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