diff options
Diffstat (limited to 'sound/core/hrtimer.c')
| -rw-r--r-- | sound/core/hrtimer.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/sound/core/hrtimer.c b/sound/core/hrtimer.c new file mode 100644 index 000000000000..c1d285921f80 --- /dev/null +++ b/sound/core/hrtimer.c @@ -0,0 +1,155 @@ +/* + * ALSA timer back-end using hrtimer + * Copyright (C) 2008 Takashi Iwai + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ + +#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, ns_to_ktime(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_IRQSAFE_UNLOCKED; + 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, ns_to_ktime(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, + .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); |