Hi Paulo,
Thanks for the patch,
Pavel - thanks for the review.
Patch applied to the for-4.12 branch of linux-leds.git.
Best regards,
Jacek Anaszewski
On 02/10/2017 12:07 AM, Paulo Costa wrote:
> Currently there is one CPU led trigger per cpu ('cpu0', 'cpu1', ...)
>
> This patch adds a new trigger, 'cpu', with brightness proportional to
> the number of active CPUs.
>
> If multiple brightness levels aren't supported on the LED,
> it effectively indicates if there is any CPU active.
>
> This is particularly useful on tiny linux boards with more CPU cores than LED pins.
>
> Signed-off-by: Paulo Costa <me@xxxxxxxxxxxxxxxxxx>
> CC: Pavel Machek <pavel@xxxxxx>
> ---
> v2:
> * Fix concurrency issues during initialization
> * Round up the division
> ---
> drivers/leds/trigger/ledtrig-cpu.c | 33 +++++++++++++++++++++++++++++++--
> 1 file changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/ledtrig-cpu.c
> index 22f0634..06ec733 100644
> --- a/drivers/leds/trigger/ledtrig-cpu.c
> +++ b/drivers/leds/trigger/ledtrig-cpu.c
> @@ -31,12 +31,16 @@
> #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
> @@ -47,26 +51,46 @@ static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
> 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 */
> - led_trigger_event(trig->_trig, LED_FULL);
> + is_active = true;
> break;
>
> case CPU_LED_IDLE_START:
> case CPU_LED_STOP:
> case CPU_LED_HALTED:
> /* Will turn the LED off */
> - led_trigger_event(trig->_trig, 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);
>
> @@ -113,6 +137,11 @@ static int __init ledtrig_cpu_init(void)
> 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.
>
