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-rw-r--r--sound/core/hrtimer.c155
1 files changed, 155 insertions, 0 deletions
diff --git a/sound/core/hrtimer.c b/sound/core/hrtimer.c
new file mode 100644
index 0000000..c1d2859
--- /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);
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