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/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef __SOUND_TIMER_H
#define __SOUND_TIMER_H
* Timer abstract layer
* Copyright (c) by Jaroslav Kysela <>,
* Abramo Bagnara <>
#include <sound/asound.h>
#include <linux/interrupt.h>
#define snd_timer_chip(timer) ((timer)->private_data)
#define SNDRV_TIMER_DEV_FLG_PCM 0x10000000
#define SNDRV_TIMER_HW_AUTO 0x00000001 /* auto trigger is supported */
#define SNDRV_TIMER_HW_STOP 0x00000002 /* call stop before start */
#define SNDRV_TIMER_HW_SLAVE 0x00000004 /* only slave timer (variable resolution) */
#define SNDRV_TIMER_HW_FIRST 0x00000008 /* first tick can be incomplete */
#define SNDRV_TIMER_HW_WORK 0x00000010 /* timer is called from work */
#define SNDRV_TIMER_IFLG_SLAVE 0x00000001
#define SNDRV_TIMER_IFLG_RUNNING 0x00000002
#define SNDRV_TIMER_IFLG_START 0x00000004
#define SNDRV_TIMER_IFLG_AUTO 0x00000008 /* auto restart */
#define SNDRV_TIMER_IFLG_FAST 0x00000010 /* fast callback (do not use work) */
#define SNDRV_TIMER_IFLG_CALLBACK 0x00000020 /* timer callback is active */
#define SNDRV_TIMER_IFLG_EXCLUSIVE 0x00000040 /* exclusive owner - no more instances */
#define SNDRV_TIMER_IFLG_EARLY_EVENT 0x00000080 /* write early event to the poll queue */
#define SNDRV_TIMER_FLG_CHANGE 0x00000001
#define SNDRV_TIMER_FLG_RESCHED 0x00000002 /* need reschedule */
struct snd_timer;
struct snd_timer_hardware {
/* -- must be filled with low-level driver */
unsigned int flags; /* various flags */
unsigned long resolution; /* average timer resolution for one tick in nsec */
unsigned long resolution_min; /* minimal resolution */
unsigned long resolution_max; /* maximal resolution */
unsigned long ticks; /* max timer ticks per interrupt */
/* -- low-level functions -- */
int (*open) (struct snd_timer * timer);
int (*close) (struct snd_timer * timer);
unsigned long (*c_resolution) (struct snd_timer * timer);
int (*start) (struct snd_timer * timer);
int (*stop) (struct snd_timer * timer);
int (*set_period) (struct snd_timer * timer, unsigned long period_num, unsigned long period_den);
int (*precise_resolution) (struct snd_timer * timer, unsigned long *num, unsigned long *den);
struct snd_timer {
int tmr_class;
struct snd_card *card;
struct module *module;
int tmr_device;
int tmr_subdevice;
char id[64];
char name[80];
unsigned int flags;
int running; /* running instances */
unsigned long sticks; /* schedule ticks */
void *private_data;
void (*private_free) (struct snd_timer *timer);
struct snd_timer_hardware hw;
spinlock_t lock;
struct list_head device_list;
struct list_head open_list_head;
struct list_head active_list_head;
struct list_head ack_list_head;
struct list_head sack_list_head; /* slow ack list head */
struct work_struct task_work;
int max_instances; /* upper limit of timer instances */
int num_instances; /* current number of timer instances */
struct snd_timer_instance {
struct snd_timer *timer;
char *owner;
unsigned int flags;
void *private_data;
void (*private_free) (struct snd_timer_instance *ti);
void (*callback) (struct snd_timer_instance *timeri,
unsigned long ticks, unsigned long resolution);
void (*ccallback) (struct snd_timer_instance * timeri,
int event,
struct timespec64 * tstamp,
unsigned long resolution);
void (*disconnect)(struct snd_timer_instance *timeri);
void *callback_data;
unsigned long ticks; /* auto-load ticks when expired */
unsigned long cticks; /* current ticks */
unsigned long pticks; /* accumulated ticks for callback */
unsigned long resolution; /* current resolution for work */
unsigned long lost; /* lost ticks */
int slave_class;
unsigned int slave_id;
struct list_head open_list;
struct list_head active_list;
struct list_head ack_list;
struct list_head slave_list_head;
struct list_head slave_active_head;
struct snd_timer_instance *master;
* Registering
int snd_timer_new(struct snd_card *card, char *id, struct snd_timer_id *tid, struct snd_timer **rtimer);
void snd_timer_notify(struct snd_timer *timer, int event, struct timespec64 *tstamp);
int snd_timer_global_new(char *id, int device, struct snd_timer **rtimer);
int snd_timer_global_free(struct snd_timer *timer);
int snd_timer_global_register(struct snd_timer *timer);
struct snd_timer_instance *snd_timer_instance_new(const char *owner);
void snd_timer_instance_free(struct snd_timer_instance *timeri);
int snd_timer_open(struct snd_timer_instance *timeri, struct snd_timer_id *tid, unsigned int slave_id);
void snd_timer_close(struct snd_timer_instance *timeri);
unsigned long snd_timer_resolution(struct snd_timer_instance *timeri);
int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks);
int snd_timer_stop(struct snd_timer_instance *timeri);
int snd_timer_continue(struct snd_timer_instance *timeri);
int snd_timer_pause(struct snd_timer_instance *timeri);
void snd_timer_interrupt(struct snd_timer *timer, unsigned long ticks_left);
#endif /* __SOUND_TIMER_H */