[PATCH v2 2/2] leds: trigger: pattern: notify usespace if pattern finished

[Martin Kurbanov]

In the current moment, userspace caller can schedule LED pattern with
appropriate parameters, but it doesn't have ability to listen to any
events indicated pattern finished. This patch implements such an event
using sysfs node and sysfs_notify_dirent() call.

Signed-off-by: Martin Kurbanov <mmkurbanov@xxxxxxxxxxxxxx>
---
 .../testing/sysfs-class-led-trigger-pattern   | 11 ++++
 drivers/leds/trigger/ledtrig-pattern.c        | 63 ++++++++++++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
index 8c57d2780554..b2564123b54b 100644
--- a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
@@ -38,3 +38,14 @@ Description:
 
 		It should be noticed that some leds, like EL15203000 may
 		only support indefinitely patterns, so they always store -1.
+
+What:		/sys/class/leds/<led>/is_running
+Date:		October 2022
+KernelVersion:	6.1
+Description:
+		Indicates running of a software pattern for the LED.
+
+		This file is read only and supports poll() to detect when the
+		software pattern ended.
+
+		1 means pattern is running and number 0 are finish or not run.
diff --git a/drivers/leds/trigger/ledtrig-pattern.c b/drivers/leds/trigger/ledtrig-pattern.c
index 354304b404aa..19a6b5dcd7af 100644
--- a/drivers/leds/trigger/ledtrig-pattern.c
+++ b/drivers/leds/trigger/ledtrig-pattern.c
@@ -33,7 +33,9 @@ struct pattern_trig_data {
 	int delta_t;
 	bool is_indefinite;
 	bool is_hw_pattern;
+	bool is_running;
 	struct timer_list timer;
+	struct kernfs_node *is_running_kn;
 };
 
 static void pattern_trig_update_patterns(struct pattern_trig_data *data)
@@ -76,8 +78,14 @@ static void pattern_trig_timer_function(struct timer_list *t)
 	struct pattern_trig_data *data = from_timer(data, t, timer);
 
 	for (;;) {
-		if (!data->is_indefinite && !data->repeat)
+		if (!data->is_indefinite && !data->repeat) {
+			data->is_running = false;
+
+			if (data->is_running_kn)
+				sysfs_notify_dirent(data->is_running_kn);
+
 			break;
+		}
 
 		if (data->curr->brightness == data->next->brightness) {
 			/* Step change of brightness */
@@ -137,6 +145,7 @@ static int pattern_trig_start_pattern(struct led_classdev *led_cdev)
 	data->curr = data->patterns;
 	data->next = data->patterns + 1;
 	data->timer.expires = jiffies;
+	data->is_running = true;
 	add_timer(&data->timer);
 
 	return 0;
@@ -176,6 +185,7 @@ static ssize_t repeat_store(struct device *dev, struct device_attribute *attr,
 	mutex_lock(&data->lock);
 
 	del_timer_sync(&data->timer);
+	data->is_running = false;
 
 	if (data->is_hw_pattern)
 		led_cdev->pattern_clear(led_cdev);
@@ -267,6 +277,7 @@ static ssize_t pattern_trig_store_patterns(struct led_classdev *led_cdev,
 	mutex_lock(&data->lock);
 
 	del_timer_sync(&data->timer);
+	data->is_running = false;
 
 	if (data->is_hw_pattern)
 		led_cdev->pattern_clear(led_cdev);
@@ -327,6 +338,16 @@ static ssize_t hw_pattern_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(hw_pattern);
 
+static ssize_t is_running_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct pattern_trig_data *data = led_get_trigger_data(led_cdev);
+
+	return sysfs_emit(buf, "%d\n", data->is_running);
+}
+static DEVICE_ATTR_RO(is_running);
+
 static umode_t pattern_trig_attrs_mode(struct kobject *kobj,
 				       struct attribute *attr, int index)
 {
@@ -382,9 +403,41 @@ static void pattern_init(struct led_classdev *led_cdev)
 	kfree(pattern);
 }
 
+static int pattern_trig_add_is_running(struct led_classdev *led_cdev)
+{
+	struct pattern_trig_data *data = led_get_trigger_data(led_cdev);
+	struct device *dev = led_cdev->dev;
+	int ret;
+
+	ret = device_create_file(dev, &dev_attr_is_running);
+	if (ret) {
+		dev_err(dev,
+			"Error creating is_running (%pe)\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	data->is_running_kn = sysfs_get_dirent(dev->kobj.sd, "is_running");
+	if (!data->is_running_kn) {
+		dev_err(dev, "Error getting is_running kernelfs\n");
+		device_remove_file(dev, &dev_attr_is_running);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static void pattern_trig_remove_is_running(struct led_classdev *led_cdev)
+{
+	struct pattern_trig_data *data = led_get_trigger_data(led_cdev);
+
+	sysfs_put(data->is_running_kn);
+	device_remove_file(led_cdev->dev, &dev_attr_is_running);
+}
+
 static int pattern_trig_activate(struct led_classdev *led_cdev)
 {
 	struct pattern_trig_data *data;
+	int err;
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
@@ -403,6 +456,13 @@ static int pattern_trig_activate(struct led_classdev *led_cdev)
 	data->led_cdev = led_cdev;
 	led_set_trigger_data(led_cdev, data);
 	timer_setup(&data->timer, pattern_trig_timer_function, 0);
+
+	err = pattern_trig_add_is_running(led_cdev);
+	if (err)
+		dev_warn(led_cdev->dev,
+			 "pattern ended notifications disabled (%pe)\n",
+			 ERR_PTR(err));
+
 	led_cdev->activated = true;
 
 	if (led_cdev->flags & LED_INIT_DEFAULT_TRIGGER) {
@@ -428,6 +488,7 @@ static void pattern_trig_deactivate(struct led_classdev *led_cdev)
 		led_cdev->pattern_clear(led_cdev);
 
 	del_timer_sync(&data->timer);
+	pattern_trig_remove_is_running(led_cdev);
 
 	led_set_brightness(led_cdev, LED_OFF);
 	kfree(data);
-- 
2.38.1