From e381322b0190c1253d347de3f28b5c37756fb651 Mon Sep 17 00:00:00 2001 From: David Lechner Date: Fri, 16 Sep 2016 14:16:48 -0500 Subject: leds: Introduce userspace LED class driver This driver creates a userspace leds driver similar to uinput. New LEDs are created by opening /dev/uleds and writing a uleds_user_dev struct. A new LED class device is registered with the name given in the struct. Reading will return a single byte that is the current brightness. The poll() syscall is also supported. It will be triggered whenever the brightness changes. Closing the file handle to /dev/uleds will remove the leds class device. Signed-off-by: David Lechner Signed-off-by: Jacek Anaszewski --- include/uapi/linux/Kbuild | 1 + include/uapi/linux/uleds.h | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+) create mode 100644 include/uapi/linux/uleds.h (limited to 'include') diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild index 6965d0909554..f196c539021e 100644 --- a/include/uapi/linux/Kbuild +++ b/include/uapi/linux/Kbuild @@ -425,6 +425,7 @@ header-y += udp.h header-y += uhid.h header-y += uinput.h header-y += uio.h +header-y += uleds.h header-y += ultrasound.h header-y += un.h header-y += unistd.h diff --git a/include/uapi/linux/uleds.h b/include/uapi/linux/uleds.h new file mode 100644 index 000000000000..95186578c46e --- /dev/null +++ b/include/uapi/linux/uleds.h @@ -0,0 +1,24 @@ +/* + * Userspace driver support for the LED subsystem + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ +#ifndef _UAPI__ULEDS_H_ +#define _UAPI__ULEDS_H_ + +#define LED_MAX_NAME_SIZE 64 + +struct uleds_user_dev { + char name[LED_MAX_NAME_SIZE]; + int max_brightness; +}; + +#endif /* _UAPI__ULEDS_H_ */ -- cgit v1.2.1 From a9c6ce57ec2f136d08141e8220a0ffaca216f7b0 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Tue, 8 Nov 2016 14:38:46 +0100 Subject: led: core: Use atomic bit-field for the blink-flags All the LED_BLINK* flags are accessed read-modify-write from e.g. led_set_brightness and led_blink_set_oneshot while both set_brightness_work and the blink_timer may be running. If these race then the modify step done by one of them may be lost, switch the LED_BLINK* flags to a new atomic work_flags bit-field to avoid this race. Signed-off-by: Hans de Goede Signed-off-by: Jacek Anaszewski --- include/linux/leds.h | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'include') diff --git a/include/linux/leds.h b/include/linux/leds.h index ddfcb2df3656..21c598b366f8 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -42,16 +42,20 @@ struct led_classdev { #define LED_UNREGISTERING (1 << 1) /* Upper 16 bits reflect control information */ #define LED_CORE_SUSPENDRESUME (1 << 16) -#define LED_BLINK_SW (1 << 17) -#define LED_BLINK_ONESHOT (1 << 18) -#define LED_BLINK_ONESHOT_STOP (1 << 19) -#define LED_BLINK_INVERT (1 << 20) -#define LED_BLINK_BRIGHTNESS_CHANGE (1 << 21) -#define LED_BLINK_DISABLE (1 << 22) -#define LED_SYSFS_DISABLE (1 << 23) -#define LED_DEV_CAP_FLASH (1 << 24) -#define LED_HW_PLUGGABLE (1 << 25) -#define LED_PANIC_INDICATOR (1 << 26) +#define LED_SYSFS_DISABLE (1 << 17) +#define LED_DEV_CAP_FLASH (1 << 18) +#define LED_HW_PLUGGABLE (1 << 19) +#define LED_PANIC_INDICATOR (1 << 20) + + /* set_brightness_work / blink_timer flags, atomic, private. */ + unsigned long work_flags; + +#define LED_BLINK_SW 0 +#define LED_BLINK_ONESHOT 1 +#define LED_BLINK_ONESHOT_STOP 2 +#define LED_BLINK_INVERT 3 +#define LED_BLINK_BRIGHTNESS_CHANGE 4 +#define LED_BLINK_DISABLE 5 /* Set LED brightness level * Must not sleep. Use brightness_set_blocking for drivers -- cgit v1.2.1 From eb1610b4c273370f491c5e194e5a56e3470d81e8 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sun, 23 Oct 2016 21:47:26 +0200 Subject: led: core: Fix blink_brightness setting race All 3 of led_timer_func, led_set_brightness and led_set_software_blink set blink_brightness. If led_timer_func or led_set_software_blink race with led_set_brightness they may end up overwriting the new blink_brightness. The new atomic work_flags does not protect against this as it just protects the flags and not blink_brightness. This commit introduces a new new_blink_brightness value which gets set by led_set_brightness and read by led_timer_func on LED on, fixing this. Dealing with the new brightness at LED on time, makes the new brightness apply sooner, which also fixes a led_set_brightness which happens while a oneshot blink which ends in LED on is running not getting applied. Signed-off-by: Hans de Goede Signed-off-by: Jacek Anaszewski --- include/linux/leds.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/leds.h b/include/linux/leds.h index 21c598b366f8..569cb531094c 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -93,6 +93,7 @@ struct led_classdev { unsigned long blink_delay_on, blink_delay_off; struct timer_list blink_timer; int blink_brightness; + int new_blink_brightness; void (*flash_resume)(struct led_classdev *led_cdev); struct work_struct set_brightness_work; -- cgit v1.2.1