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Diffstat (limited to 'drivers/leds/trigger/ledtrig-cpu.c')
| -rw-r--r-- | drivers/leds/trigger/ledtrig-cpu.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/ledtrig-cpu.c new file mode 100644 index 000000000..f19baed61 --- /dev/null +++ b/drivers/leds/trigger/ledtrig-cpu.c @@ -0,0 +1,172 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ledtrig-cpu.c - LED trigger based on CPU activity + * + * This LED trigger will be registered for first 8 CPUs and named + * as cpu0..cpu7. There's additional trigger called cpu that + * is on when any CPU is active. + * + * If you want support for arbitrary number of CPUs, make it one trigger, + * with additional sysfs file selecting which CPU to watch. + * + * It can be bound to any LED just like other triggers using either a + * board file or via sysfs interface. + * + * An API named ledtrig_cpu is exported for any user, who want to add CPU + * activity indication in their code. + * + * Copyright 2011 Linus Walleij <linus.walleij@linaro.org> + * Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com> + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/percpu.h> +#include <linux/syscore_ops.h> +#include <linux/rwsem.h> +#include <linux/cpu.h> +#include "../leds.h" + +#define MAX_NAME_LEN 8 + +struct led_trigger_cpu { + bool is_active; + char name[MAX_NAME_LEN]; + struct led_trigger *_trig; +}; + +static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig); + +static struct led_trigger *trig_cpu_all; +static atomic_t num_active_cpus = ATOMIC_INIT(0); + +/** + * ledtrig_cpu - emit a CPU event as a trigger + * @evt: CPU event to be emitted + * + * Emit a CPU event on a CPU core, which will trigger a + * bound LED to turn on or turn off. + */ +void ledtrig_cpu(enum cpu_led_event ledevt) +{ + struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig); + bool is_active = trig->is_active; + + /* Locate the correct CPU LED */ + switch (ledevt) { + case CPU_LED_IDLE_END: + case CPU_LED_START: + /* Will turn the LED on, max brightness */ + is_active = true; + break; + + case CPU_LED_IDLE_START: + case CPU_LED_STOP: + case CPU_LED_HALTED: + /* Will turn the LED off */ + is_active = false; + break; + + default: + /* Will leave the LED as it is */ + break; + } + + if (is_active != trig->is_active) { + unsigned int active_cpus; + unsigned int total_cpus; + + /* Update trigger state */ + trig->is_active = is_active; + atomic_add(is_active ? 1 : -1, &num_active_cpus); + active_cpus = atomic_read(&num_active_cpus); + total_cpus = num_present_cpus(); + + led_trigger_event(trig->_trig, + is_active ? LED_FULL : LED_OFF); + + + led_trigger_event(trig_cpu_all, + DIV_ROUND_UP(LED_FULL * active_cpus, total_cpus)); + + } +} +EXPORT_SYMBOL(ledtrig_cpu); + +static int ledtrig_cpu_syscore_suspend(void) +{ + ledtrig_cpu(CPU_LED_STOP); + return 0; +} + +static void ledtrig_cpu_syscore_resume(void) +{ + ledtrig_cpu(CPU_LED_START); +} + +static void ledtrig_cpu_syscore_shutdown(void) +{ + ledtrig_cpu(CPU_LED_HALTED); +} + +static struct syscore_ops ledtrig_cpu_syscore_ops = { + .shutdown = ledtrig_cpu_syscore_shutdown, + .suspend = ledtrig_cpu_syscore_suspend, + .resume = ledtrig_cpu_syscore_resume, +}; + +static int ledtrig_online_cpu(unsigned int cpu) +{ + ledtrig_cpu(CPU_LED_START); + return 0; +} + +static int ledtrig_prepare_down_cpu(unsigned int cpu) +{ + ledtrig_cpu(CPU_LED_STOP); + return 0; +} + +static int __init ledtrig_cpu_init(void) +{ + unsigned int cpu; + int ret; + + /* Supports up to 9999 cpu cores */ + BUILD_BUG_ON(CONFIG_NR_CPUS > 9999); + + /* + * Registering a trigger for all CPUs. + */ + led_trigger_register_simple("cpu", &trig_cpu_all); + + /* + * Registering CPU led trigger for each CPU core here + * ignores CPU hotplug, but after this CPU hotplug works + * fine with this trigger. + */ + for_each_possible_cpu(cpu) { + struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu); + + if (cpu >= 8) + continue; + + snprintf(trig->name, MAX_NAME_LEN, "cpu%u", cpu); + + led_trigger_register_simple(trig->name, &trig->_trig); + } + + register_syscore_ops(&ledtrig_cpu_syscore_ops); + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting", + ledtrig_online_cpu, ledtrig_prepare_down_cpu); + if (ret < 0) + pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n", + ret); + + pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n"); + + return 0; +} +device_initcall(ledtrig_cpu_init); |