| Message ID | 20170129134252.6185-1-hdegoede@redhat.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream, archived |
| Headers | show |
Hi, On 01/29/2017 02:42 PM, Hans de Goede wrote: > Some LEDs may have their brightness level changed autonomously > (outside of kernel control) by hardware / firmware. This commit > adds support for an optional brightness_hw_changed attribute to > signal such changes to userspace (if a driver can detect them): > > 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. > > Drivers which want to support this, simply add LED_BRIGHT_HW_CHANGED to > their flags field and call led_classdev_notify_brightness_hw_changed() > with the hardware set brightness when they detect a hardware / firmware > triggered brightness change. > > Signed-off-by: Hans de Goede <hdegoede@redhat.com> > Acked-by: Pavel Machek <pavel@ucw.cz> > --- > Changes in v6: > -New patch in v6 of this set, replacing previous trigger based API > Changes in v7 > -Return -ENODATA when brightness_hw_changed gets read before any > hw brightness change event as happened > -Make the hw_brightness_changed attr presence configurable through Kconfig > Changes in v8 > -Add WARN_ON in case a driver calls led_classdev_notify_brightness_hw_changed > without setting the LED_BRIGHT_HW_CHANGED flag > -Document the need for LED_BRIGHT_HW_CHANGED in > Documentation/leds/leds-class.txt > --- > Documentation/ABI/testing/sysfs-class-led | 17 +++++++ > Documentation/leds/leds-class.txt | 15 ++++++ > drivers/leds/Kconfig | 9 ++++ > drivers/leds/led-class.c | 76 +++++++++++++++++++++++++++++++ > include/linux/leds.h | 15 ++++++ > 5 files changed, 132 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led > index 491cdee..5f67f7a 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 f1f7ec9..836cb16 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 c621cbb..275f467 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 326ee6e..f2b0a80 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 569cb53..c771153 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> > @@ -46,6 +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_BRIGHT_HW_CHANGED (1 << 21) > > /* set_brightness_work / blink_timer flags, atomic, private. */ > unsigned long work_flags; > @@ -110,6 +112,11 @@ 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; > }; > @@ -422,4 +429,12 @@ 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 */ > Thanks for the addressing my remarks. Patch applied.
diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led index 491cdee..5f67f7a 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 f1f7ec9..836cb16 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 c621cbb..275f467 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 326ee6e..f2b0a80 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 569cb53..c771153 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> @@ -46,6 +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_BRIGHT_HW_CHANGED (1 << 21) /* set_brightness_work / blink_timer flags, atomic, private. */ unsigned long work_flags; @@ -110,6 +112,11 @@ 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; }; @@ -422,4 +429,12 @@ 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 */