On Thu, Oct 03, 2019 at 12:13:01AM +0900, Akinobu Mita wrote: > Reading /sys/class/leds/<led>/trigger returns all available LED triggers. > However, this violates the "one value per file" rule of sysfs. > > This provides /sys/class/leds/<led>/current-trigger which is almost > identical to /sys/class/leds/<led>/trigger. The only difference is that > 'current-trigger' only shows the current trigger name. > > This new file follows the "one value per file" rule of sysfs. > We can find all available LED triggers by listing the > /sys/devices/virtual/led-trigger/ directory. > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > Cc: Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> > Cc: Pavel Machek <pavel@xxxxxx> > Cc: Dan Murphy <dmurphy@xxxxxx> > Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx> > --- > Documentation/ABI/testing/sysfs-class-led | 13 +++++++++++ > drivers/leds/led-class.c | 10 ++++++++ > drivers/leds/led-triggers.c | 38 +++++++++++++++++++++++++++---- > drivers/leds/leds.h | 5 ++++ > 4 files changed, 62 insertions(+), 4 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led > index 5f67f7a..fdfed3f 100644 > --- a/Documentation/ABI/testing/sysfs-class-led > +++ b/Documentation/ABI/testing/sysfs-class-led > @@ -61,3 +61,16 @@ Description: > gpio and backlight triggers. In case of the backlight trigger, > it is useful when driving a LED which is intended to indicate > a device in a standby like state. > + > +What: /sys/class/leds/<led>/current-trigger > +Date: September 2019 > +KernelVersion: 5.5 > +Contact: linux-leds@xxxxxxxxxxxxxxx > +Description: > + Set the trigger for this LED. A trigger is a kernel based source > + of LED events. > + Writing the trigger name to this file will change the current > + trigger. Trigger specific parameters can appear in > + /sys/class/leds/<led> once a given trigger is selected. For > + their documentation see sysfs-class-led-trigger-*. > + Reading this file will return the current LED trigger name. > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > index 3f04334..3cb0d8a 100644 > --- a/drivers/leds/led-class.c > +++ b/drivers/leds/led-class.c > @@ -74,12 +74,22 @@ static ssize_t max_brightness_show(struct device *dev, > static DEVICE_ATTR_RO(max_brightness); > > #ifdef CONFIG_LEDS_TRIGGERS > + > +static DEVICE_ATTR(current_trigger, 0644, led_current_trigger_show, > + led_current_trigger_store); DEVICE_ATTR_RW() please. > +static struct attribute *led_current_trigger_attrs[] = { > + &dev_attr_current_trigger.attr, > + NULL, > +}; > + > static BIN_ATTR(trigger, 0644, led_trigger_read, led_trigger_write, 0); > static struct bin_attribute *led_trigger_bin_attrs[] = { > &bin_attr_trigger, > NULL, > }; > static const struct attribute_group led_trigger_group = { > + .attrs = led_current_trigger_attrs, > .bin_attrs = led_trigger_bin_attrs, > }; > #endif > diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c > index 0b810cf..a2ef674 100644 > --- a/drivers/leds/led-triggers.c > +++ b/drivers/leds/led-triggers.c > @@ -27,11 +27,9 @@ LIST_HEAD(trigger_list); > > /* Used by LED Class */ > > -ssize_t led_trigger_write(struct file *filp, struct kobject *kobj, > - struct bin_attribute *bin_attr, char *buf, > - loff_t pos, size_t count) > +static ssize_t led_trigger_store(struct device *dev, const char *buf, > + size_t count) > { > - struct device *dev = kobj_to_dev(kobj); > struct led_classdev *led_cdev = dev_get_drvdata(dev); > struct led_trigger *trig; > int ret = count; > @@ -67,8 +65,25 @@ ssize_t led_trigger_write(struct file *filp, struct kobject *kobj, > mutex_unlock(&led_cdev->led_access); > return ret; > } > + > +ssize_t led_trigger_write(struct file *filp, struct kobject *kobj, > + struct bin_attribute *bin_attr, char *buf, > + loff_t pos, size_t count) > +{ > + struct device *dev = kobj_to_dev(kobj); > + > + return led_trigger_store(dev, buf, count); > +} > EXPORT_SYMBOL_GPL(led_trigger_write); > > +ssize_t led_current_trigger_store(struct device *dev, > + struct device_attribute *attr, const char *buf, > + size_t count) > +{ > + return led_trigger_store(dev, buf, count); > +} > +EXPORT_SYMBOL_GPL(led_current_trigger_store); > + > __printf(3, 4) > static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...) > { > @@ -144,6 +159,21 @@ ssize_t led_trigger_read(struct file *filp, struct kobject *kobj, > } > EXPORT_SYMBOL_GPL(led_trigger_read); > > +ssize_t led_current_trigger_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct led_classdev *led_cdev = dev_get_drvdata(dev); > + int len; > + > + down_read(&led_cdev->trigger_lock); > + len = scnprintf(buf, PAGE_SIZE, "%s\n", led_cdev->trigger ? No need for "scnprintf() when writing a single number to a buffer. Just use sprintf() please. > + led_cdev->trigger->name : "none"); Can you have a trigger named "none"? :) thanks, greg k-h