linux-kernel - [PATCH v2 5/5] leds: trigger: Add pattern initialization from Device Tree

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Date:   Mon, 10 Dec 2018 10:30:01 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Baolin Wang <baolin.wang@...aro.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 5/5] leds: trigger: Add pattern initialization from Device Tree

Allow initialization of pattern used in pattern trigger from Device Tree
property.

This is especially useful for embedded systems where the pattern trigger
would be used to indicate the process of boot status in a nice,
user-friendly blinking way.  This initialization pattern will be used
till user-space is brought up and sets its own pattern, indicating the
boot status is for example finished.

Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
---
 drivers/leds/trigger/ledtrig-pattern.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/leds/trigger/ledtrig-pattern.c b/drivers/leds/trigger/ledtrig-pattern.c
index 1870cf87afe1..1e7672eba2b8 100644
--- a/drivers/leds/trigger/ledtrig-pattern.c
+++ b/drivers/leds/trigger/ledtrig-pattern.c
@@ -11,6 +11,7 @@
 #include <linux/leds.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/timer.h>
 
@@ -331,6 +332,28 @@ static const struct attribute_group *pattern_trig_groups[] = {
 	NULL,
 };
 
+static void pattern_init(struct led_classdev *led_cdev)
+{
+	struct device_node *np = dev_of_node(led_cdev->dev);
+	const char *pattern;
+	int err;
+
+	if (!np)
+		return;
+
+	if (of_property_read_string(np, "linux,trigger-pattern", &pattern))
+		return;
+
+	if (!strlen(pattern))
+		return;
+
+	err = pattern_trig_store_patterns(led_cdev, pattern, strlen(pattern),
+					  false);
+	if (err)
+		dev_warn(led_cdev->dev,
+			 "Pattern initialization failed with error %d\n", err);
+}
+
 static int pattern_trig_activate(struct led_classdev *led_cdev)
 {
 	struct pattern_trig_data *data;
@@ -354,6 +377,15 @@ static int pattern_trig_activate(struct led_classdev *led_cdev)
 	timer_setup(&data->timer, pattern_trig_timer_function, 0);
 	led_cdev->activated = true;
 
+	if (led_cdev->flags & LED_INIT_DEFAULT_TRIGGER) {
+		pattern_init(led_cdev);
+		/*
+		 * Mark as initialized even on pattern_init() error because
+		 * any consecutive call to it would produce the same error.
+		 */
+		led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
+	}
+
 	return 0;
 }
 
-- 
2.7.4