linux-kernel - [PATCH v2 2/7] leds: leds-core: Implement the retain-state-shutdown property

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Message-Id: <20210716220331.49303-3-eajames@linux.ibm.com>
Date:   Fri, 16 Jul 2021 17:03:26 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     linux-leds@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        robh+dt@...nel.org, pavel@....cz,
        Eddie James <eajames@...ux.ibm.com>
Subject: [PATCH v2 2/7] leds: leds-core: Implement the retain-state-shutdown property

Read the retain-state-shutdown device tree property to set the
existing LED_RETAIN_AT_SHUTDOWN flag. Then check the flag when
unregistering, and if set, don't set the brightness to OFF. This
is useful for systems that want to keep the HW state of the LED
across reboots.

Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/leds/led-class.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index f704391d57a8..f4bb02f6e042 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -350,10 +350,15 @@ int led_classdev_register_ext(struct device *parent,
 		if (ret < 0)
 			return ret;
 
-		if (init_data->fwnode)
+		if (init_data->fwnode) {
 			fwnode_property_read_string(init_data->fwnode,
 				"linux,default-trigger",
 				&led_cdev->default_trigger);
+
+			if (fwnode_property_present(init_data->fwnode,
+						    "retain-state-shutdown"))
+				led_cdev->flags |= LED_RETAIN_AT_SHUTDOWN;
+		}
 	} else {
 		proposed_name = led_cdev->name;
 	}
@@ -444,7 +449,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 	/* Stop blinking */
 	led_stop_software_blink(led_cdev);
 
-	led_set_brightness(led_cdev, LED_OFF);
+	if (!(led_cdev->flags & LED_RETAIN_AT_SHUTDOWN))
+		led_set_brightness(led_cdev, LED_OFF);
 
 	flush_work(&led_cdev->set_brightness_work);
 
-- 
2.27.0