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172 lines
3.9 KiB
172 lines
3.9 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* ledtrig-cpu.c - LED trigger based on CPU activity |
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* |
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* This LED trigger will be registered for first 8 CPUs and named |
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* as cpu0..cpu7. There's additional trigger called cpu that |
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* is on when any CPU is active. |
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* |
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* If you want support for arbitrary number of CPUs, make it one trigger, |
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* with additional sysfs file selecting which CPU to watch. |
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* |
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* It can be bound to any LED just like other triggers using either a |
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* board file or via sysfs interface. |
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* |
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* An API named ledtrig_cpu is exported for any user, who want to add CPU |
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* activity indication in their code. |
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* |
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* Copyright 2011 Linus Walleij <[email protected]> |
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* Copyright 2011 - 2012 Bryan Wu <[email protected]> |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/percpu.h> |
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#include <linux/syscore_ops.h> |
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#include <linux/rwsem.h> |
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#include <linux/cpu.h> |
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#include "../leds.h" |
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#define MAX_NAME_LEN 8 |
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struct led_trigger_cpu { |
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bool is_active; |
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char name[MAX_NAME_LEN]; |
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struct led_trigger *_trig; |
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}; |
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static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig); |
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static struct led_trigger *trig_cpu_all; |
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static atomic_t num_active_cpus = ATOMIC_INIT(0); |
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/** |
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* ledtrig_cpu - emit a CPU event as a trigger |
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* @evt: CPU event to be emitted |
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* |
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* Emit a CPU event on a CPU core, which will trigger a |
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* bound LED to turn on or turn off. |
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*/ |
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void ledtrig_cpu(enum cpu_led_event ledevt) |
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{ |
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struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig); |
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bool is_active = trig->is_active; |
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/* Locate the correct CPU LED */ |
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switch (ledevt) { |
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case CPU_LED_IDLE_END: |
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case CPU_LED_START: |
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/* Will turn the LED on, max brightness */ |
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is_active = true; |
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break; |
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case CPU_LED_IDLE_START: |
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case CPU_LED_STOP: |
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case CPU_LED_HALTED: |
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/* Will turn the LED off */ |
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is_active = false; |
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break; |
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default: |
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/* Will leave the LED as it is */ |
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break; |
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} |
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if (is_active != trig->is_active) { |
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unsigned int active_cpus; |
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unsigned int total_cpus; |
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/* Update trigger state */ |
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trig->is_active = is_active; |
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atomic_add(is_active ? 1 : -1, &num_active_cpus); |
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active_cpus = atomic_read(&num_active_cpus); |
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total_cpus = num_present_cpus(); |
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led_trigger_event(trig->_trig, |
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is_active ? LED_FULL : LED_OFF); |
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led_trigger_event(trig_cpu_all, |
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DIV_ROUND_UP(LED_FULL * active_cpus, total_cpus)); |
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} |
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} |
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EXPORT_SYMBOL(ledtrig_cpu); |
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static int ledtrig_cpu_syscore_suspend(void) |
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{ |
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ledtrig_cpu(CPU_LED_STOP); |
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return 0; |
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} |
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static void ledtrig_cpu_syscore_resume(void) |
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{ |
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ledtrig_cpu(CPU_LED_START); |
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} |
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static void ledtrig_cpu_syscore_shutdown(void) |
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{ |
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ledtrig_cpu(CPU_LED_HALTED); |
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} |
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static struct syscore_ops ledtrig_cpu_syscore_ops = { |
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.shutdown = ledtrig_cpu_syscore_shutdown, |
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.suspend = ledtrig_cpu_syscore_suspend, |
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.resume = ledtrig_cpu_syscore_resume, |
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}; |
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static int ledtrig_online_cpu(unsigned int cpu) |
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{ |
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ledtrig_cpu(CPU_LED_START); |
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return 0; |
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} |
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static int ledtrig_prepare_down_cpu(unsigned int cpu) |
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{ |
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ledtrig_cpu(CPU_LED_STOP); |
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return 0; |
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} |
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static int __init ledtrig_cpu_init(void) |
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{ |
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int cpu; |
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int ret; |
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/* Supports up to 9999 cpu cores */ |
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BUILD_BUG_ON(CONFIG_NR_CPUS > 9999); |
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/* |
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* Registering a trigger for all CPUs. |
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*/ |
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led_trigger_register_simple("cpu", &trig_cpu_all); |
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/* |
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* Registering CPU led trigger for each CPU core here |
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* ignores CPU hotplug, but after this CPU hotplug works |
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* fine with this trigger. |
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*/ |
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for_each_possible_cpu(cpu) { |
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struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu); |
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if (cpu >= 8) |
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continue; |
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snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu); |
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led_trigger_register_simple(trig->name, &trig->_trig); |
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} |
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register_syscore_ops(&ledtrig_cpu_syscore_ops); |
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ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting", |
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ledtrig_online_cpu, ledtrig_prepare_down_cpu); |
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if (ret < 0) |
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pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n", |
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ret); |
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pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n"); |
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return 0; |
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} |
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device_initcall(ledtrig_cpu_init);
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