diff options
| author | Ivan Orlov <ivan.orlov0322@gmail.com> | 2024-08-13 13:07:00 +0100 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2024-08-18 09:55:54 +0200 |
| commit | 37745918e0e7575bc40f38da93a99b9fa6406224 (patch) | |
| tree | 2865a5c2eba53900f5e82a725ccf739428c5b04d /include/uapi | |
| parent | 8fad71b6771afc1f12f1cdf616ae0fca628802e9 (diff) | |
ALSA: timer: Introduce virtual userspace-driven timers
Implement two ioctl calls in order to support virtual userspace-driven
ALSA timers.
The first ioctl is SNDRV_TIMER_IOCTL_CREATE, which gets the
snd_timer_uinfo struct as a parameter and puts a file descriptor of a
virtual timer into the `fd` field of the snd_timer_unfo structure. It
also updates the `id` field of the snd_timer_uinfo struct, which
provides a unique identifier for the timer (basically, the subdevice
number which can be used when creating timer instances).
This patch also introduces a tiny id allocator for the userspace-driven
timers, which guarantees that we don't have more than 128 of them in the
system.
Another ioctl is SNDRV_TIMER_IOCTL_TRIGGER, which allows us to trigger
the virtual timer (and calls snd_timer_interrupt for the timer under
the hood), causing all of the timer instances binded to this timer to
execute their callbacks.
The maximum amount of ticks available for the timer is 1 for the sake of
simplicity of the userspace API. 'start', 'stop', 'open' and 'close'
callbacks for the userspace-driven timers are empty since we don't
really do any hardware initialization here.
Suggested-by: Axel Holzinger <aholzinger@gmx.de>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240813120701.171743-4-ivan.orlov0322@gmail.com
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/sound/asound.h | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index 8bf7e8a0eb6f..4cd513215bcd 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -869,7 +869,7 @@ struct snd_ump_block_info { * Timer section - /dev/snd/timer */ -#define SNDRV_TIMER_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 7) +#define SNDRV_TIMER_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 8) enum { SNDRV_TIMER_CLASS_NONE = -1, @@ -894,6 +894,7 @@ enum { #define SNDRV_TIMER_GLOBAL_RTC 1 /* unused */ #define SNDRV_TIMER_GLOBAL_HPET 2 #define SNDRV_TIMER_GLOBAL_HRTIMER 3 +#define SNDRV_TIMER_GLOBAL_UDRIVEN 4 /* info flags */ #define SNDRV_TIMER_FLG_SLAVE (1<<0) /* cannot be controlled */ @@ -974,6 +975,18 @@ struct snd_timer_status { }; #endif +/* + * This structure describes the userspace-driven timer. Such timers are purely virtual, + * and can only be triggered from software (for instance, by userspace application). + */ +struct snd_timer_uinfo { + /* To pretend being a normal timer, we need to know the resolution in ns. */ + __u64 resolution; + int fd; + unsigned int id; + unsigned char reserved[16]; +}; + #define SNDRV_TIMER_IOCTL_PVERSION _IOR('T', 0x00, int) #define SNDRV_TIMER_IOCTL_NEXT_DEVICE _IOWR('T', 0x01, struct snd_timer_id) #define SNDRV_TIMER_IOCTL_TREAD_OLD _IOW('T', 0x02, int) @@ -990,6 +1003,8 @@ struct snd_timer_status { #define SNDRV_TIMER_IOCTL_CONTINUE _IO('T', 0xa2) #define SNDRV_TIMER_IOCTL_PAUSE _IO('T', 0xa3) #define SNDRV_TIMER_IOCTL_TREAD64 _IOW('T', 0xa4, int) +#define SNDRV_TIMER_IOCTL_CREATE _IOWR('T', 0xa5, struct snd_timer_uinfo) +#define SNDRV_TIMER_IOCTL_TRIGGER _IO('T', 0xa6) #if __BITS_PER_LONG == 64 #define SNDRV_TIMER_IOCTL_TREAD SNDRV_TIMER_IOCTL_TREAD_OLD |