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Subject[PATCH 4/5] leds: add /sys/class/triggers/ that contains trigger sub-directories
Date
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/triggers directory that contains a number of
sub-directories, each representing an LED trigger. The name of the
sub-directory matches the LED trigger name.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
Documentation/ABI/testing/sysfs-class-led | 9 +++++++++
drivers/leds/led-class.c | 32 +++++++++++++++++++++++++++++++
drivers/leds/led-triggers.c | 19 ++++++++++++++++++
drivers/leds/leds.h | 1 +
include/linux/leds.h | 1 +
5 files changed, 62 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 5f67f7a..14d91af 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -61,3 +61,12 @@ 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/triggers/
+Date: September 2019
+KernelVersion: 5.5
+Contact: linux-leds@vger.kernel.org
+Description:
+ This directory contains a number of sub-directories, each
+ representing an LED trigger. The name of the sub-directory
+ matches the LED trigger name.
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 7d85181..04e6c14 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -81,6 +81,28 @@ static struct bin_attribute *led_trigger_bin_attrs[] = {
static const struct attribute_group led_trigger_group = {
.bin_attrs = led_trigger_bin_attrs,
};
+
+static int led_triggers_kobj_create(void)
+{
+ led_triggers_kobj = class_kobject_create_and_add("triggers",
+ leds_class);
+
+ return led_triggers_kobj ? 0 : -ENOMEM;
+}
+
+static void led_triggers_kobj_destroy(void)
+{
+ kobject_put(led_triggers_kobj);
+}
+
+#else
+static inline int led_triggers_kobj_create(void)
+{
+ return 0;
+}
+static void led_triggers_kobj_destroy(void)
+{
+}
#endif

static struct attribute *led_class_attrs[] = {
@@ -411,16 +433,26 @@ EXPORT_SYMBOL_GPL(devm_led_classdev_unregister);

static int __init leds_init(void)
{
+ int ret;
+
leds_class = class_create(THIS_MODULE, "leds");
if (IS_ERR(leds_class))
return PTR_ERR(leds_class);
leds_class->pm = &leds_class_dev_pm_ops;
leds_class->dev_groups = led_groups;
+
+ ret = led_triggers_kobj_create();
+ if (ret) {
+ class_unregister(leds_class);
+ return ret;
+ }
+
return 0;
}

static void __exit leds_exit(void)
{
+ led_triggers_kobj_destroy();
class_destroy(leds_class);
}

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index ed5a311..4a86964 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -268,16 +268,26 @@ void led_trigger_rename_static(const char *name, struct led_trigger *trig)
}
EXPORT_SYMBOL_GPL(led_trigger_rename_static);

+static struct kobj_type led_trigger_kobj_type = {
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+struct kobject *led_triggers_kobj;
+EXPORT_SYMBOL_GPL(led_triggers_kobj);
+
/* LED Trigger Interface */

int led_trigger_register(struct led_trigger *trig)
{
struct led_classdev *led_cdev;
struct led_trigger *_trig;
+ int ret;

rwlock_init(&trig->leddev_list_lock);
INIT_LIST_HEAD(&trig->led_cdevs);

+ kobject_init(&trig->kobj, &led_trigger_kobj_type);
+
down_write(&triggers_list_lock);
/* Make sure the trigger's name isn't already in use */
list_for_each_entry(_trig, &trigger_list, next_trig) {
@@ -286,6 +296,14 @@ int led_trigger_register(struct led_trigger *trig)
return -EEXIST;
}
}
+
+ WARN_ON_ONCE(!led_triggers_kobj);
+ ret = kobject_add(&trig->kobj, led_triggers_kobj, "%s", trig->name);
+ if (ret) {
+ up_write(&triggers_list_lock);
+ return ret;
+ }
+
/* Add to the list of led triggers */
list_add_tail(&trig->next_trig, &trigger_list);
up_write(&triggers_list_lock);
@@ -316,6 +334,7 @@ void led_trigger_unregister(struct led_trigger *trig)

/* Remove from the list of led triggers */
down_write(&triggers_list_lock);
+ kobject_put(&trig->kobj);
list_del_init(&trig->next_trig);
up_write(&triggers_list_lock);

diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index a0ee33c..52debe0 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -33,5 +33,6 @@ ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
extern struct rw_semaphore leds_list_lock;
extern struct list_head leds_list;
extern struct list_head trigger_list;
+extern struct kobject *led_triggers_kobj;

#endif /* __LEDS_H_INCLUDED */
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 33ae825..379f282 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -279,6 +279,7 @@ struct led_trigger {
struct list_head next_trig;

const struct attribute_group **groups;
+ struct kobject kobj;
};

/*
--
2.7.4
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