In some cases an LED is controlled through a hardwired (taken care of
in firmware outside of the kernels control) trigger.
Add an LED_TRIGGER_READ_ONLY flag for this and disallow user-space
changing the trigger when this flag is set.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v5:
-This is a new patch in v5 of this patch-set
---
drivers/leds/led-class.c | 2 +-
drivers/leds/led-triggers.c | 5 +++++
include/linux/leds.h | 1 +
3 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 326ee6e..56f32cc 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -54,7 +54,7 @@ static ssize_t brightness_store(struct device *dev,
if (ret)
goto unlock;
- if (state == LED_OFF)
+ if (state == LED_OFF && !(led_cdev->flags & LED_TRIGGER_READ_ONLY))
led_trigger_remove(led_cdev);
led_set_brightness(led_cdev, state);
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index d2ed9c2..9669104 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -37,6 +37,11 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
struct led_trigger *trig;
int ret = count;
+ if (led_cdev->flags & LED_TRIGGER_READ_ONLY) {
+ dev_err(led_cdev->dev, "Error this led triggers is hardwired and cannot be changed\n");
+ return -EINVAL;
+ }
+
mutex_lock(&led_cdev->led_access);
if (led_sysfs_is_disabled(led_cdev)) {
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 870b8c2..e076b74 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -47,6 +47,7 @@ struct led_classdev {
#define LED_DEV_CAP_FLASH (1 << 18)
#define LED_HW_PLUGGABLE (1 << 19)
#define LED_PANIC_INDICATOR (1 << 20)
+#define LED_TRIGGER_READ_ONLY (1 << 21)
/* set_brightness_work / blink_timer flags, atomic, private. */
unsigned long work_flags;
--
2.9.3
--
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