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![Daniel Lezcano](/assets/img/avatar_default.png)
If the cpuidle init cpu operation returns -ENXIO, therefore reporting HW failure or misconfiguration, the CPUidle driver skips the respective cpuidle device initialization because the associated platform back-end HW is not operational. That prevents the system to crash and allows to handle the error gracefully. For example, on Qcom's platform, each core has a SPM. The device associated with this SPM is initialized before the cpuidle framework. If there is an error in the initialization (eg. error in the DT), the system continues to boot but in degraded mode as some SPM may not be correctly initialized. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
163 lines
3.8 KiB
C
163 lines
3.8 KiB
C
/*
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* ARM/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 arm: " 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 <linux/slab.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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* arm_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 arm_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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arm_cpuidle_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 arm_idle_driver = {
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.name = "arm_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 = arm_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 = "ARM WFI",
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}
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};
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static const struct of_device_id arm_idle_state_match[] __initconst = {
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{ .compatible = "arm,idle-state",
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.data = arm_enter_idle_state },
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{ },
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};
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/*
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* arm_idle_init
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*
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* Registers the arm 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 arm_idle_init(void)
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{
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int cpu, ret;
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struct cpuidle_driver *drv = &arm_idle_driver;
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struct cpuidle_device *dev;
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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, arm_idle_state_match, 1);
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if (ret <= 0)
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return ret ? : -ENODEV;
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ret = cpuidle_register_driver(drv);
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if (ret) {
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pr_err("Failed to register cpuidle driver\n");
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return ret;
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}
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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 = arm_cpuidle_init(cpu);
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/*
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* Skip the cpuidle device initialization if the reported
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* failure is a HW misconfiguration/breakage (-ENXIO).
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*/
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if (ret == -ENXIO)
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continue;
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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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goto out_fail;
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}
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dev = kzalloc(sizeof(*dev), GFP_KERNEL);
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if (!dev) {
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pr_err("Failed to allocate cpuidle device\n");
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goto out_fail;
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}
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dev->cpu = cpu;
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ret = cpuidle_register_device(dev);
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if (ret) {
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pr_err("Failed to register cpuidle device for CPU %d\n",
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cpu);
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kfree(dev);
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goto out_fail;
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}
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}
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return 0;
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out_fail:
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while (--cpu >= 0) {
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dev = per_cpu(cpuidle_devices, cpu);
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cpuidle_unregister_device(dev);
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kfree(dev);
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}
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cpuidle_unregister_driver(drv);
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return ret;
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}
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device_initcall(arm_idle_init);
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