ALSA: Add hrtimer backend for ALSA timer interface
Takashi Iwai [Fri, 24 Oct 2008 16:16:50 +0000 (18:16 +0200)]
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>

include/sound/asound.h
sound/core/Kconfig
sound/core/Makefile
sound/core/hrtimer.c [new file with mode: 0644]
sound/core/seq/seq.c

index 2c4dc90..1c02ed1 100644 (file)
@@ -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 */
index 66348c9..406a450 100644 (file)
@@ -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
index d57125a..4229052 100644 (file)
@@ -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
diff --git a/sound/core/hrtimer.c b/sound/core/hrtimer.c
new file mode 100644 (file)
index 0000000..b712d7f
--- /dev/null
@@ -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);
index ee0f840..bf09a5a 100644 (file)
@@ -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