The patch titled
leds: add output inversion option to backlight trigger
has been added to the -mm tree. Its filename is
leds-add-output-inversion-option-to-backlight-trigger.patch
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------------------------------------------------------
Subject: leds: add output inversion option to backlight trigger
From: Janusz Krzysztofik <jkrzyszt@xxxxxxxxxxxx>
Extend the LED backlight tirgger driver with an option that allows for
inverting the trigger output polarity.
With the invertion option provided, I (ab)use the backlight trigger for
driving a LED that indicates LCD display blank condtition on my Amstrad
Delta videophone. Since the machine has no dedicated power LED, it was
not possible to distinguish if the display was blanked, or the machine was
turned off, without touching it.
The invert sysfs control is patterned after a similiar function of the GPIO
trigger driver.
Signed-off-by: Janusz Krzysztofik <jkrzyszt@xxxxxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Acked-by: Richard Purdie <richard.purdie@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/leds/ledtrig-backlight.c | 60 +++++++++++++++++++++++++++--
1 file changed, 56 insertions(+), 4 deletions(-)
diff -puN drivers/leds/ledtrig-backlight.c~leds-add-output-inversion-option-to-backlight-trigger drivers/leds/ledtrig-backlight.c
--- a/drivers/leds/ledtrig-backlight.c~leds-add-output-inversion-option-to-backlight-trigger
+++ a/drivers/leds/ledtrig-backlight.c
@@ -26,6 +26,7 @@ struct bl_trig_notifier {
int brightness;
int old_status;
struct notifier_block notifier;
+ unsigned invert;
};
static int fb_notifier_callback(struct notifier_block *p,
@@ -36,23 +37,63 @@ static int fb_notifier_callback(struct n
struct led_classdev *led = n->led;
struct fb_event *fb_event = data;
int *blank = fb_event->data;
+ int new_status = *blank ? BLANK : UNBLANK;
switch (event) {
case FB_EVENT_BLANK :
- if (*blank && n->old_status == UNBLANK) {
+ if (new_status == n->old_status)
+ break;
+
+ if ((n->old_status == UNBLANK) ^ n->invert) {
n->brightness = led->brightness;
led_set_brightness(led, LED_OFF);
- n->old_status = BLANK;
- } else if (!*blank && n->old_status == BLANK) {
+ } else {
led_set_brightness(led, n->brightness);
- n->old_status = UNBLANK;
}
+
+ n->old_status = new_status;
+
break;
}
return 0;
}
+static ssize_t bl_trig_invert_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct led_classdev *led = dev_get_drvdata(dev);
+ struct bl_trig_notifier *n = led->trigger_data;
+
+ return sprintf(buf, "%s\n", n->invert ? "yes" : "no");
+}
+
+static ssize_t bl_trig_invert_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t num)
+{
+ struct led_classdev *led = dev_get_drvdata(dev);
+ struct bl_trig_notifier *n = led->trigger_data;
+ unsigned invert;
+ int ret;
+
+ ret = sscanf(buf, "%u", &invert);
+ if (ret < 1) {
+ dev_err(dev, "invalid value\n");
+ return -EINVAL;
+ }
+
+ n->invert = !!invert;
+
+ /* After inverting, we need to update the LED. */
+ if ((n->old_status == BLANK) ^ n->invert)
+ led_set_brightness(led, LED_OFF);
+ else
+ led_set_brightness(led, n->brightness);
+
+ return num;
+}
+static DEVICE_ATTR(invert, 0644, bl_trig_invert_show, bl_trig_invert_store);
+
static void bl_trig_activate(struct led_classdev *led)
{
int ret;
@@ -66,6 +107,10 @@ static void bl_trig_activate(struct led_
return;
}
+ ret = device_create_file(led->dev, &dev_attr_invert);
+ if (ret)
+ goto err_invert;
+
n->led = led;
n->brightness = led->brightness;
n->old_status = UNBLANK;
@@ -74,6 +119,12 @@ static void bl_trig_activate(struct led_
ret = fb_register_client(&n->notifier);
if (ret)
dev_err(led->dev, "unable to register backlight trigger\n");
+
+ return;
+
+err_invert:
+ led->trigger_data = NULL;
+ kfree(n);
}
static void bl_trig_deactivate(struct led_classdev *led)
@@ -82,6 +133,7 @@ static void bl_trig_deactivate(struct le
(struct bl_trig_notifier *) led->trigger_data;
if (n) {
+ device_remove_file(led->dev, &dev_attr_invert);
fb_unregister_client(&n->notifier);
kfree(n);
}
_
Patches currently in -mm which might be from jkrzyszt@xxxxxxxxxxxx are
linux-next.patch
leds-add-output-inversion-option-to-backlight-trigger.patch
leds-add-output-inversion-option-to-backlight-trigger-fix.patch
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