+ struct dummy_systimer_pcm *dpcm;
+
+ dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
+ if (!dpcm)
+ return -ENOMEM;
+ substream->runtime->private_data = dpcm;
+ init_timer(&dpcm->timer);
+ dpcm->timer.data = (unsigned long) dpcm;
+ dpcm->timer.function = dummy_systimer_callback;
+ spin_lock_init(&dpcm->lock);
+ dpcm->substream = substream;
+ return 0;
+}
+
+static void dummy_systimer_free(struct snd_pcm_substream *substream)
+{
+ kfree(substream->runtime->private_data);
+}
+
+static struct dummy_timer_ops dummy_systimer_ops = {
+ .create = dummy_systimer_create,
+ .free = dummy_systimer_free,
+ .prepare = dummy_systimer_prepare,
+ .start = dummy_systimer_start,
+ .stop = dummy_systimer_stop,
+ .pointer = dummy_systimer_pointer,
+};
+
+#ifdef CONFIG_HIGH_RES_TIMERS
+/*
+ * hrtimer interface
+ */
+
+struct dummy_hrtimer_pcm {
+ ktime_t base_time;
+ ktime_t period_time;
+ atomic_t running;
+ struct hrtimer timer;
+ struct tasklet_struct tasklet;
+ struct snd_pcm_substream *substream;
+};
+
+static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
+{
+ struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
+ if (atomic_read(&dpcm->running))
+ snd_pcm_period_elapsed(dpcm->substream);
+}
+
+static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
+{
+ struct dummy_hrtimer_pcm *dpcm;
+
+ dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
+ if (!atomic_read(&dpcm->running))
+ return HRTIMER_NORESTART;
+ tasklet_schedule(&dpcm->tasklet);
+ hrtimer_forward_now(timer, dpcm->period_time);
+ return HRTIMER_RESTART;
+}
+
+static int dummy_hrtimer_start(struct snd_pcm_substream *substream)
+{
+ struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+
+ dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
+ hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
+ atomic_set(&dpcm->running, 1);
+ return 0;
+}
+
+static int dummy_hrtimer_stop(struct snd_pcm_substream *substream)
+{
+ struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+
+ atomic_set(&dpcm->running, 0);
+ hrtimer_cancel(&dpcm->timer);
+ return 0;
+}
+
+static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
+{
+ tasklet_kill(&dpcm->tasklet);
+}
+
+static snd_pcm_uframes_t
+dummy_hrtimer_pointer(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
+ u64 delta;
+ u32 pos;
+
+ delta = ktime_us_delta(hrtimer_cb_get_time(&dpcm->timer),
+ dpcm->base_time);
+ delta = div_u64(delta * runtime->rate + 999999, 1000000);
+ div_u64_rem(delta, runtime->buffer_size, &pos);
+ return pos;
+}
+
+static int dummy_hrtimer_prepare(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
+ unsigned int period, rate;
+ long sec;
+ unsigned long nsecs;
+
+ dummy_hrtimer_sync(dpcm);
+ period = runtime->period_size;
+ rate = runtime->rate;
+ sec = period / rate;
+ period %= rate;
+ nsecs = div_u64((u64)period * 1000000000UL + rate - 1, rate);
+ dpcm->period_time = ktime_set(sec, nsecs);
+
+ return 0;
+}
+
+static int dummy_hrtimer_create(struct snd_pcm_substream *substream)
+{
+ struct dummy_hrtimer_pcm *dpcm;
+
+ dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
+ if (!dpcm)
+ return -ENOMEM;
+ substream->runtime->private_data = dpcm;
+ hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ dpcm->timer.function = dummy_hrtimer_callback;
+ dpcm->substream = substream;
+ atomic_set(&dpcm->running, 0);
+ tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
+ (unsigned long)dpcm);
+ return 0;
+}
+
+static void dummy_hrtimer_free(struct snd_pcm_substream *substream)
+{
+ struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+ dummy_hrtimer_sync(dpcm);
+ kfree(dpcm);
+}
+
+static struct dummy_timer_ops dummy_hrtimer_ops = {
+ .create = dummy_hrtimer_create,
+ .free = dummy_hrtimer_free,
+ .prepare = dummy_hrtimer_prepare,
+ .start = dummy_hrtimer_start,
+ .stop = dummy_hrtimer_stop,
+ .pointer = dummy_hrtimer_pointer,