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-rw-r--r--Documentation/ABI/testing/sysfs-class-led17
-rw-r--r--Documentation/leds/leds-class.txt15
-rw-r--r--drivers/leds/Kconfig9
-rw-r--r--drivers/leds/led-class.c76
-rw-r--r--include/linux/leds.h15
5 files changed, 132 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 491cdeedc195..5f67f7ab277b 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -23,6 +23,23 @@ Description:
If the LED does not support different brightness levels, this
should be 1.
+What: /sys/class/leds/<led>/brightness_hw_changed
+Date: January 2017
+KernelVersion: 4.11
+Description:
+ Last hardware set brightness level for this LED. Some LEDs
+ may be changed autonomously by hardware/firmware. Only LEDs
+ where this happens and the driver can detect this, will have
+ this file.
+
+ This file supports poll() to detect when the hardware changes
+ the brightness.
+
+ Reading this file will return the last brightness level set
+ by the hardware, this may be different from the current
+ brightness. Reading this file when no hw brightness change
+ event has happened will return an ENODATA error.
+
What: /sys/class/leds/<led>/trigger
Date: March 2006
KernelVersion: 2.6.17
diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
index f1f7ec9f5cc5..836cb16d6f09 100644
--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -65,6 +65,21 @@ LED subsystem core exposes following API for setting brightness:
blinking, returns -EBUSY if software blink fallback is enabled.
+LED registration API
+====================
+
+A driver wanting to register a LED classdev for use by other drivers /
+userspace needs to allocate and fill a led_classdev struct and then call
+[devm_]led_classdev_register. If the non devm version is used the driver
+must call led_classdev_unregister from its remove function before
+free-ing the led_classdev struct.
+
+If the driver can detect hardware initiated brightness changes and thus
+wants to have a brightness_hw_changed attribute then the LED_BRIGHT_HW_CHANGED
+flag must be set in flags before registering. Calling
+led_classdev_notify_brightness_hw_changed on a classdev not registered with
+the LED_BRIGHT_HW_CHANGED flag is a bug and will trigger a WARN_ON.
+
Hardware accelerated blink of LEDs
==================================
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index c621cbbb5768..275f467956ee 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -29,6 +29,15 @@ config LEDS_CLASS_FLASH
for the flash related features of a LED device. It can be built
as a module.
+config LEDS_BRIGHTNESS_HW_CHANGED
+ bool "LED Class brightness_hw_changed attribute support"
+ depends on LEDS_CLASS
+ help
+ This option enables support for the brightness_hw_changed attribute
+ for led sysfs class devices under /sys/class/leds.
+
+ See Documentation/ABI/testing/sysfs-class-led for details.
+
comment "LED drivers"
config LEDS_88PM860X
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 326ee6e925a2..f2b0a80a62b4 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -103,6 +103,68 @@ static const struct attribute_group *led_groups[] = {
NULL,
};
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+static ssize_t brightness_hw_changed_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+
+ if (led_cdev->brightness_hw_changed == -1)
+ return -ENODATA;
+
+ return sprintf(buf, "%u\n", led_cdev->brightness_hw_changed);
+}
+
+static DEVICE_ATTR_RO(brightness_hw_changed);
+
+static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+ struct device *dev = led_cdev->dev;
+ int ret;
+
+ ret = device_create_file(dev, &dev_attr_brightness_hw_changed);
+ if (ret) {
+ dev_err(dev, "Error creating brightness_hw_changed\n");
+ return ret;
+ }
+
+ led_cdev->brightness_hw_changed_kn =
+ sysfs_get_dirent(dev->kobj.sd, "brightness_hw_changed");
+ if (!led_cdev->brightness_hw_changed_kn) {
+ dev_err(dev, "Error getting brightness_hw_changed kn\n");
+ device_remove_file(dev, &dev_attr_brightness_hw_changed);
+ return -ENXIO;
+ }
+
+ return 0;
+}
+
+static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+ sysfs_put(led_cdev->brightness_hw_changed_kn);
+ device_remove_file(led_cdev->dev, &dev_attr_brightness_hw_changed);
+}
+
+void led_classdev_notify_brightness_hw_changed(struct led_classdev *led_cdev,
+ enum led_brightness brightness)
+{
+ if (WARN_ON(!led_cdev->brightness_hw_changed_kn))
+ return;
+
+ led_cdev->brightness_hw_changed = brightness;
+ sysfs_notify_dirent(led_cdev->brightness_hw_changed_kn);
+}
+EXPORT_SYMBOL_GPL(led_classdev_notify_brightness_hw_changed);
+#else
+static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+ return 0;
+}
+static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+}
+#endif
+
/**
* led_classdev_suspend - suspend an led_classdev.
* @led_cdev: the led_classdev to suspend.
@@ -204,10 +266,21 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
dev_warn(parent, "Led %s renamed to %s due to name collision",
led_cdev->name, dev_name(led_cdev->dev));
+ if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
+ ret = led_add_brightness_hw_changed(led_cdev);
+ if (ret) {
+ device_unregister(led_cdev->dev);
+ return ret;
+ }
+ }
+
led_cdev->work_flags = 0;
#ifdef CONFIG_LEDS_TRIGGERS
init_rwsem(&led_cdev->trigger_lock);
#endif
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+ led_cdev->brightness_hw_changed = -1;
+#endif
mutex_init(&led_cdev->led_access);
/* add to the list of leds */
down_write(&leds_list_lock);
@@ -256,6 +329,9 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
flush_work(&led_cdev->set_brightness_work);
+ if (led_cdev->flags & LED_BRIGHT_HW_CHANGED)
+ led_remove_brightness_hw_changed(led_cdev);
+
device_unregister(led_cdev->dev);
down_write(&leds_list_lock);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index bb50d0151e75..38c0bd7ca107 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -13,6 +13,7 @@
#define __LINUX_LEDS_H_INCLUDED
#include <linux/device.h>
+#include <linux/kernfs.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
@@ -47,6 +48,7 @@ struct led_classdev {
#define LED_DEV_CAP_FLASH (1 << 18)
#define LED_HW_PLUGGABLE (1 << 19)
#define LED_PANIC_INDICATOR (1 << 20)
+#define LED_BRIGHT_HW_CHANGED (1 << 21)
/* set_brightness_work / blink_timer flags, atomic, private. */
unsigned long work_flags;
@@ -111,6 +113,11 @@ struct led_classdev {
bool activated;
#endif
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+ int brightness_hw_changed;
+ struct kernfs_node *brightness_hw_changed_kn;
+#endif
+
/* Ensures consistent access to the LED Flash Class device */
struct mutex led_access;
};
@@ -423,4 +430,12 @@ static inline void ledtrig_cpu(enum cpu_led_event evt)
}
#endif
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+extern void led_classdev_notify_brightness_hw_changed(
+ struct led_classdev *led_cdev, enum led_brightness brightness);
+#else
+static inline void led_classdev_notify_brightness_hw_changed(
+ struct led_classdev *led_cdev, enum led_brightness brightness) { }
+#endif
+
#endif /* __LINUX_LEDS_H_INCLUDED */