ALSA: Add hrtimer backend for ALSA timer interface

Added the hrtimer backend for ALSA timer interface.
It can be used for the sequencer timer source.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2008-10-24 18:16:50 +02:00
parent 52948b3f7c
commit bbaf5e9733
5 changed files with 167 additions and 1 deletions

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@ -575,6 +575,7 @@ enum {
#define SNDRV_TIMER_GLOBAL_SYSTEM 0
#define SNDRV_TIMER_GLOBAL_RTC 1
#define SNDRV_TIMER_GLOBAL_HPET 2
#define SNDRV_TIMER_GLOBAL_HRTIMER 3
/* info flags */
#define SNDRV_TIMER_FLG_SLAVE (1<<0) /* cannot be controlled */

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@ -95,6 +95,26 @@ config SND_SEQUENCER_OSS
this will be compiled as a module. The module will be called
snd-seq-oss.
config SND_HRTIMER
tristate "HR-timer backend support"
depends on HIGH_RES_TIMERS
select SND_TIMER
help
Say Y here to enable HR-timer backend for ALSA timer. ALSA uses
the hrtimer as a precise timing source. The ALSA sequencer code
also can use this timing source.
To compile this driver as a module, choose M here: the module
will be called snd-hrtimer.
config SND_SEQ_HRTIMER_DEFAULT
bool "Use HR-timer as default sequencer timer"
depends on SND_HRTIMER && SND_SEQUENCER
default y
help
Say Y here to use the HR-timer backend as the default sequencer
timer.
config SND_RTCTIMER
tristate "RTC Timer support"
depends on RTC
@ -114,6 +134,7 @@ config SND_RTCTIMER
config SND_SEQ_RTCTIMER_DEFAULT
bool "Use RTC as default sequencer timer"
depends on SND_RTCTIMER && SND_SEQUENCER
dpeends on !SND_SEQ_HRTIMER_DEFAULT
default y
help
Say Y here to use the RTC timer as the default sequencer

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@ -17,12 +17,14 @@ snd-page-alloc-$(CONFIG_HAS_DMA) += sgbuf.o
snd-rawmidi-objs := rawmidi.o
snd-timer-objs := timer.o
snd-hrtimer-objs := hrtimer.o
snd-rtctimer-objs := rtctimer.o
snd-hwdep-objs := hwdep.o
obj-$(CONFIG_SND) += snd.o
obj-$(CONFIG_SND_HWDEP) += snd-hwdep.o
obj-$(CONFIG_SND_TIMER) += snd-timer.o
obj-$(CONFIG_SND_HRTIMER) += snd-hrtimer.o
obj-$(CONFIG_SND_RTCTIMER) += snd-rtctimer.o
obj-$(CONFIG_SND_PCM) += snd-pcm.o snd-page-alloc.o
obj-$(CONFIG_SND_RAWMIDI) += snd-rawmidi.o

140
sound/core/hrtimer.c Normal file
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@ -0,0 +1,140 @@
/*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/hrtimer.h>
#include <sound/core.h>
#include <sound/timer.h>
MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
MODULE_DESCRIPTION("ALSA hrtimer backend");
MODULE_LICENSE("GPL");
MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
#define NANO_SEC 1000000000UL /* 10^9 in sec */
static unsigned int resolution;
struct snd_hrtimer {
struct snd_timer *timer;
struct hrtimer hrt;
};
static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
{
struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
struct snd_timer *t = stime->timer;
hrtimer_forward_now(hrt, ktime_set(0, t->sticks * resolution));
snd_timer_interrupt(stime->timer, t->sticks);
return HRTIMER_RESTART;
}
static int snd_hrtimer_open(struct snd_timer *t)
{
struct snd_hrtimer *stime;
stime = kmalloc(sizeof(*stime), GFP_KERNEL);
if (!stime)
return -ENOMEM;
hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
stime->timer = t;
stime->hrt.cb_mode = HRTIMER_CB_SOFTIRQ;
stime->hrt.function = snd_hrtimer_callback;
t->private_data = stime;
return 0;
}
static int snd_hrtimer_close(struct snd_timer *t)
{
struct snd_hrtimer *stime = t->private_data;
if (stime) {
hrtimer_cancel(&stime->hrt);
kfree(stime);
t->private_data = NULL;
}
return 0;
}
static int snd_hrtimer_start(struct snd_timer *t)
{
struct snd_hrtimer *stime = t->private_data;
hrtimer_start(&stime->hrt, ktime_set(0, t->sticks * resolution),
HRTIMER_MODE_REL);
return 0;
}
static int snd_hrtimer_stop(struct snd_timer *t)
{
struct snd_hrtimer *stime = t->private_data;
hrtimer_cancel(&stime->hrt);
return 0;
}
static struct snd_timer_hardware hrtimer_hw = {
.flags = (SNDRV_TIMER_HW_AUTO |
/*SNDRV_TIMER_HW_FIRST |*/
SNDRV_TIMER_HW_TASKLET),
.open = snd_hrtimer_open,
.close = snd_hrtimer_close,
.start = snd_hrtimer_start,
.stop = snd_hrtimer_stop,
};
/*
* entry functions
*/
static struct snd_timer *mytimer;
static int __init snd_hrtimer_init(void)
{
struct snd_timer *timer;
struct timespec tp;
int err;
hrtimer_get_res(CLOCK_MONOTONIC, &tp);
if (tp.tv_sec > 0 || !tp.tv_nsec) {
snd_printk(KERN_ERR
"snd-hrtimer: Invalid resolution %u.%09u",
(unsigned)tp.tv_sec, (unsigned)tp.tv_nsec);
return -EINVAL;
}
resolution = tp.tv_nsec;
/* Create a new timer and set up the fields */
err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
&timer);
if (err < 0)
return err;
timer->module = THIS_MODULE;
strcpy(timer->name, "HR timer");
timer->hw = hrtimer_hw;
timer->hw.resolution = resolution;
timer->hw.ticks = NANO_SEC / resolution;
err = snd_timer_global_register(timer);
if (err < 0) {
snd_timer_global_free(timer);
return err;
}
mytimer = timer; /* remember this */
return 0;
}
static void __exit snd_hrtimer_exit(void)
{
if (mytimer) {
snd_timer_global_free(mytimer);
mytimer = NULL;
}
}
module_init(snd_hrtimer_init);
module_exit(snd_hrtimer_exit);

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@ -43,7 +43,9 @@ int seq_default_timer_class = SNDRV_TIMER_CLASS_GLOBAL;
int seq_default_timer_sclass = SNDRV_TIMER_SCLASS_NONE;
int seq_default_timer_card = -1;
int seq_default_timer_device =
#ifdef CONFIG_SND_SEQ_RTCTIMER_DEFAULT
#ifdef CONFIG_SND_SEQ_HRTIMER_DEFAULT
SNDRV_TIMER_GLOBAL_HRTIMER
#elif defined(CONFIG_SND_SEQ_RTCTIMER_DEFAULT)
SNDRV_TIMER_GLOBAL_RTC
#else
SNDRV_TIMER_GLOBAL_SYSTEM