Merge branch 'topic/pcm-drain-nonblock' into for-linus
[pandora-kernel.git] / sound / drivers / dummy.c
index 54239d2..6ba066c 100644 (file)
 #include <linux/slab.h>
 #include <linux/time.h>
 #include <linux/wait.h>
+#include <linux/hrtimer.h>
+#include <linux/math64.h>
 #include <linux/moduleparam.h>
 #include <sound/core.h>
 #include <sound/control.h>
 #include <sound/tlv.h>
 #include <sound/pcm.h>
 #include <sound/rawmidi.h>
+#include <sound/info.h>
 #include <sound/initval.h>
 
 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
@@ -39,7 +42,7 @@ MODULE_LICENSE("GPL");
 MODULE_SUPPORTED_DEVICE("{{ALSA,Dummy soundcard}}");
 
 #define MAX_PCM_DEVICES                4
-#define MAX_PCM_SUBSTREAMS     16
+#define MAX_PCM_SUBSTREAMS     128
 #define MAX_MIDI_DEVICES       2
 
 #if 0 /* emu10k1 emulation */
@@ -148,6 +151,10 @@ static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
 static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
 //static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
+#ifdef CONFIG_HIGH_RES_TIMERS
+static int hrtimer = 1;
+#endif
+static int fake_buffer = 1;
 
 module_param_array(index, int, NULL, 0444);
 MODULE_PARM_DESC(index, "Index value for dummy soundcard.");
@@ -161,6 +168,12 @@ module_param_array(pcm_substreams, int, NULL, 0444);
 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-16) for dummy driver.");
 //module_param_array(midi_devs, int, NULL, 0444);
 //MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for dummy driver.");
+module_param(fake_buffer, bool, 0444);
+MODULE_PARM_DESC(fake_buffer, "Fake buffer allocations.");
+#ifdef CONFIG_HIGH_RES_TIMERS
+module_param(hrtimer, bool, 0644);
+MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
+#endif
 
 static struct platform_device *devices[SNDRV_CARDS];
 
@@ -171,137 +184,324 @@ static struct platform_device *devices[SNDRV_CARDS];
 #define MIXER_ADDR_CD          4
 #define MIXER_ADDR_LAST                4
 
+struct dummy_timer_ops {
+       int (*create)(struct snd_pcm_substream *);
+       void (*free)(struct snd_pcm_substream *);
+       int (*prepare)(struct snd_pcm_substream *);
+       int (*start)(struct snd_pcm_substream *);
+       int (*stop)(struct snd_pcm_substream *);
+       snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *);
+};
+
 struct snd_dummy {
        struct snd_card *card;
        struct snd_pcm *pcm;
        spinlock_t mixer_lock;
        int mixer_volume[MIXER_ADDR_LAST+1][2];
        int capture_source[MIXER_ADDR_LAST+1][2];
+       const struct dummy_timer_ops *timer_ops;
 };
 
-struct snd_dummy_pcm {
-       struct snd_dummy *dummy;
+/*
+ * system timer interface
+ */
+
+struct dummy_systimer_pcm {
        spinlock_t lock;
        struct timer_list timer;
-       unsigned int pcm_buffer_size;
-       unsigned int pcm_period_size;
-       unsigned int pcm_bps;           /* bytes per second */
-       unsigned int pcm_hz;            /* HZ */
-       unsigned int pcm_irq_pos;       /* IRQ position */
-       unsigned int pcm_buf_pos;       /* position in buffer */
+       unsigned long base_time;
+       unsigned int frac_pos;  /* fractional sample position (based HZ) */
+       unsigned int frac_period_rest;
+       unsigned int frac_buffer_size;  /* buffer_size * HZ */
+       unsigned int frac_period_size;  /* period_size * HZ */
+       unsigned int rate;
+       int elapsed;
        struct snd_pcm_substream *substream;
 };
 
-
-static inline void snd_card_dummy_pcm_timer_start(struct snd_dummy_pcm *dpcm)
+static void dummy_systimer_rearm(struct dummy_systimer_pcm *dpcm)
 {
-       dpcm->timer.expires = 1 + jiffies;
+       dpcm->timer.expires = jiffies +
+               (dpcm->frac_period_rest + dpcm->rate - 1) / dpcm->rate;
        add_timer(&dpcm->timer);
 }
 
-static inline void snd_card_dummy_pcm_timer_stop(struct snd_dummy_pcm *dpcm)
+static void dummy_systimer_update(struct dummy_systimer_pcm *dpcm)
 {
-       del_timer(&dpcm->timer);
+       unsigned long delta;
+
+       delta = jiffies - dpcm->base_time;
+       if (!delta)
+               return;
+       dpcm->base_time += delta;
+       delta *= dpcm->rate;
+       dpcm->frac_pos += delta;
+       while (dpcm->frac_pos >= dpcm->frac_buffer_size)
+               dpcm->frac_pos -= dpcm->frac_buffer_size;
+       while (dpcm->frac_period_rest <= delta) {
+               dpcm->elapsed++;
+               dpcm->frac_period_rest += dpcm->frac_period_size;
+       }
+       dpcm->frac_period_rest -= delta;
 }
 
-static int snd_card_dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+static int dummy_systimer_start(struct snd_pcm_substream *substream)
 {
-       struct snd_pcm_runtime *runtime = substream->runtime;
-       struct snd_dummy_pcm *dpcm = runtime->private_data;
-       int err = 0;
+       struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+       spin_lock(&dpcm->lock);
+       dpcm->base_time = jiffies;
+       dummy_systimer_rearm(dpcm);
+       spin_unlock(&dpcm->lock);
+       return 0;
+}
 
+static int dummy_systimer_stop(struct snd_pcm_substream *substream)
+{
+       struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
        spin_lock(&dpcm->lock);
-       switch (cmd) {
-       case SNDRV_PCM_TRIGGER_START:
-       case SNDRV_PCM_TRIGGER_RESUME:
-               snd_card_dummy_pcm_timer_start(dpcm);
-               break;
-       case SNDRV_PCM_TRIGGER_STOP:
-       case SNDRV_PCM_TRIGGER_SUSPEND:
-               snd_card_dummy_pcm_timer_stop(dpcm);
-               break;
-       default:
-               err = -EINVAL;
-               break;
-       }
+       del_timer(&dpcm->timer);
        spin_unlock(&dpcm->lock);
        return 0;
 }
 
-static int snd_card_dummy_pcm_prepare(struct snd_pcm_substream *substream)
+static int dummy_systimer_prepare(struct snd_pcm_substream *substream)
 {
        struct snd_pcm_runtime *runtime = substream->runtime;
-       struct snd_dummy_pcm *dpcm = runtime->private_data;
-       int bps;
-
-       bps = snd_pcm_format_width(runtime->format) * runtime->rate *
-               runtime->channels / 8;
-
-       if (bps <= 0)
-               return -EINVAL;
-
-       dpcm->pcm_bps = bps;
-       dpcm->pcm_hz = HZ;
-       dpcm->pcm_buffer_size = snd_pcm_lib_buffer_bytes(substream);
-       dpcm->pcm_period_size = snd_pcm_lib_period_bytes(substream);
-       dpcm->pcm_irq_pos = 0;
-       dpcm->pcm_buf_pos = 0;
+       struct dummy_systimer_pcm *dpcm = runtime->private_data;
 
-       snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
-                       bytes_to_samples(runtime, runtime->dma_bytes));
+       dpcm->frac_pos = 0;
+       dpcm->rate = runtime->rate;
+       dpcm->frac_buffer_size = runtime->buffer_size * HZ;
+       dpcm->frac_period_size = runtime->period_size * HZ;
+       dpcm->frac_period_rest = dpcm->frac_period_size;
+       dpcm->elapsed = 0;
 
        return 0;
 }
 
-static void snd_card_dummy_pcm_timer_function(unsigned long data)
+static void dummy_systimer_callback(unsigned long data)
 {
-       struct snd_dummy_pcm *dpcm = (struct snd_dummy_pcm *)data;
+       struct dummy_systimer_pcm *dpcm = (struct dummy_systimer_pcm *)data;
        unsigned long flags;
+       int elapsed = 0;
        
        spin_lock_irqsave(&dpcm->lock, flags);
-       dpcm->timer.expires = 1 + jiffies;
-       add_timer(&dpcm->timer);
-       dpcm->pcm_irq_pos += dpcm->pcm_bps;
-       dpcm->pcm_buf_pos += dpcm->pcm_bps;
-       dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size * dpcm->pcm_hz;
-       if (dpcm->pcm_irq_pos >= dpcm->pcm_period_size * dpcm->pcm_hz) {
-               dpcm->pcm_irq_pos %= dpcm->pcm_period_size * dpcm->pcm_hz;
-               spin_unlock_irqrestore(&dpcm->lock, flags);
+       dummy_systimer_update(dpcm);
+       dummy_systimer_rearm(dpcm);
+       elapsed = dpcm->elapsed;
+       dpcm->elapsed = 0;
+       spin_unlock_irqrestore(&dpcm->lock, flags);
+       if (elapsed)
+               snd_pcm_period_elapsed(dpcm->substream);
+}
+
+static snd_pcm_uframes_t
+dummy_systimer_pointer(struct snd_pcm_substream *substream)
+{
+       struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+       snd_pcm_uframes_t pos;
+
+       spin_lock(&dpcm->lock);
+       dummy_systimer_update(dpcm);
+       pos = dpcm->frac_pos / HZ;
+       spin_unlock(&dpcm->lock);
+       return pos;
+}
+
+static int dummy_systimer_create(struct snd_pcm_substream *substream)
+{
+       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);
-       } else
-               spin_unlock_irqrestore(&dpcm->lock, flags);
 }
 
-static snd_pcm_uframes_t snd_card_dummy_pcm_pointer(struct snd_pcm_substream *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 snd_dummy_pcm *dpcm = runtime->private_data;
+       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;
+}
 
-       return bytes_to_frames(runtime, dpcm->pcm_buf_pos / dpcm->pcm_hz);
+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 struct snd_pcm_hardware snd_card_dummy_playback =
+static int dummy_hrtimer_create(struct snd_pcm_substream *substream)
 {
-       .info =                 (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
-                                SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_MMAP_VALID),
-       .formats =              USE_FORMATS,
-       .rates =                USE_RATE,
-       .rate_min =             USE_RATE_MIN,
-       .rate_max =             USE_RATE_MAX,
-       .channels_min =         USE_CHANNELS_MIN,
-       .channels_max =         USE_CHANNELS_MAX,
-       .buffer_bytes_max =     MAX_BUFFER_SIZE,
-       .period_bytes_min =     64,
-       .period_bytes_max =     MAX_PERIOD_SIZE,
-       .periods_min =          USE_PERIODS_MIN,
-       .periods_max =          USE_PERIODS_MAX,
-       .fifo_size =            0,
+       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,
 };
 
-static struct snd_pcm_hardware snd_card_dummy_capture =
+#endif /* CONFIG_HIGH_RES_TIMERS */
+
+/*
+ * PCM interface
+ */
+
+static int dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 {
-       .info =                 (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
-                                SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_MMAP_VALID),
+       struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+
+       switch (cmd) {
+       case SNDRV_PCM_TRIGGER_START:
+       case SNDRV_PCM_TRIGGER_RESUME:
+               return dummy->timer_ops->start(substream);
+       case SNDRV_PCM_TRIGGER_STOP:
+       case SNDRV_PCM_TRIGGER_SUSPEND:
+               return dummy->timer_ops->stop(substream);
+       }
+       return -EINVAL;
+}
+
+static int dummy_pcm_prepare(struct snd_pcm_substream *substream)
+{
+       struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+
+       return dummy->timer_ops->prepare(substream);
+}
+
+static snd_pcm_uframes_t dummy_pcm_pointer(struct snd_pcm_substream *substream)
+{
+       struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+
+       return dummy->timer_ops->pointer(substream);
+}
+
+static struct snd_pcm_hardware dummy_pcm_hardware = {
+       .info =                 (SNDRV_PCM_INFO_MMAP |
+                                SNDRV_PCM_INFO_INTERLEAVED |
+                                SNDRV_PCM_INFO_RESUME |
+                                SNDRV_PCM_INFO_MMAP_VALID),
        .formats =              USE_FORMATS,
        .rates =                USE_RATE,
        .rate_min =             USE_RATE_MIN,
@@ -316,123 +516,152 @@ static struct snd_pcm_hardware snd_card_dummy_capture =
        .fifo_size =            0,
 };
 
-static void snd_card_dummy_runtime_free(struct snd_pcm_runtime *runtime)
-{
-       kfree(runtime->private_data);
-}
-
-static int snd_card_dummy_hw_params(struct snd_pcm_substream *substream,
-                                   struct snd_pcm_hw_params *hw_params)
+static int dummy_pcm_hw_params(struct snd_pcm_substream *substream,
+                              struct snd_pcm_hw_params *hw_params)
 {
-       return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+       if (fake_buffer) {
+               /* runtime->dma_bytes has to be set manually to allow mmap */
+               substream->runtime->dma_bytes = params_buffer_bytes(hw_params);
+               return 0;
+       }
+       return snd_pcm_lib_malloc_pages(substream,
+                                       params_buffer_bytes(hw_params));
 }
 
-static int snd_card_dummy_hw_free(struct snd_pcm_substream *substream)
+static int dummy_pcm_hw_free(struct snd_pcm_substream *substream)
 {
+       if (fake_buffer)
+               return 0;
        return snd_pcm_lib_free_pages(substream);
 }
 
-static struct snd_dummy_pcm *new_pcm_stream(struct snd_pcm_substream *substream)
-{
-       struct snd_dummy_pcm *dpcm;
-
-       dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
-       if (! dpcm)
-               return dpcm;
-       init_timer(&dpcm->timer);
-       dpcm->timer.data = (unsigned long) dpcm;
-       dpcm->timer.function = snd_card_dummy_pcm_timer_function;
-       spin_lock_init(&dpcm->lock);
-       dpcm->substream = substream;
-       return dpcm;
-}
-
-static int snd_card_dummy_playback_open(struct snd_pcm_substream *substream)
+static int dummy_pcm_open(struct snd_pcm_substream *substream)
 {
+       struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
-       struct snd_dummy_pcm *dpcm;
        int err;
 
-       if ((dpcm = new_pcm_stream(substream)) == NULL)
-               return -ENOMEM;
-       runtime->private_data = dpcm;
-       /* makes the infrastructure responsible for freeing dpcm */
-       runtime->private_free = snd_card_dummy_runtime_free;
-       runtime->hw = snd_card_dummy_playback;
+       dummy->timer_ops = &dummy_systimer_ops;
+#ifdef CONFIG_HIGH_RES_TIMERS
+       if (hrtimer)
+               dummy->timer_ops = &dummy_hrtimer_ops;
+#endif
+
+       err = dummy->timer_ops->create(substream);
+       if (err < 0)
+               return err;
+
+       runtime->hw = dummy_pcm_hardware;
        if (substream->pcm->device & 1) {
                runtime->hw.info &= ~SNDRV_PCM_INFO_INTERLEAVED;
                runtime->hw.info |= SNDRV_PCM_INFO_NONINTERLEAVED;
        }
        if (substream->pcm->device & 2)
-               runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);
-       err = add_playback_constraints(runtime);
-       if (err < 0)
+               runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP |
+                                     SNDRV_PCM_INFO_MMAP_VALID);
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               err = add_playback_constraints(substream->runtime);
+       else
+               err = add_capture_constraints(substream->runtime);
+       if (err < 0) {
+               dummy->timer_ops->free(substream);
                return err;
-
+       }
        return 0;
 }
 
-static int snd_card_dummy_capture_open(struct snd_pcm_substream *substream)
+static int dummy_pcm_close(struct snd_pcm_substream *substream)
 {
-       struct snd_pcm_runtime *runtime = substream->runtime;
-       struct snd_dummy_pcm *dpcm;
-       int err;
+       struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+       dummy->timer_ops->free(substream);
+       return 0;
+}
 
-       if ((dpcm = new_pcm_stream(substream)) == NULL)
-               return -ENOMEM;
-       runtime->private_data = dpcm;
-       /* makes the infrastructure responsible for freeing dpcm */
-       runtime->private_free = snd_card_dummy_runtime_free;
-       runtime->hw = snd_card_dummy_capture;
-       if (substream->pcm->device == 1) {
-               runtime->hw.info &= ~SNDRV_PCM_INFO_INTERLEAVED;
-               runtime->hw.info |= SNDRV_PCM_INFO_NONINTERLEAVED;
+/*
+ * dummy buffer handling
+ */
+
+static void *dummy_page[2];
+
+static void free_fake_buffer(void)
+{
+       if (fake_buffer) {
+               int i;
+               for (i = 0; i < 2; i++)
+                       if (dummy_page[i]) {
+                               free_page((unsigned long)dummy_page[i]);
+                               dummy_page[i] = NULL;
+                       }
        }
-       if (substream->pcm->device & 2)
-               runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);
-       err = add_capture_constraints(runtime);
-       if (err < 0)
-               return err;
+}
 
+static int alloc_fake_buffer(void)
+{
+       int i;
+
+       if (!fake_buffer)
+               return 0;
+       for (i = 0; i < 2; i++) {
+               dummy_page[i] = (void *)get_zeroed_page(GFP_KERNEL);
+               if (!dummy_page[i]) {
+                       free_fake_buffer();
+                       return -ENOMEM;
+               }
+       }
        return 0;
 }
 
-static int snd_card_dummy_playback_close(struct snd_pcm_substream *substream)
+static int dummy_pcm_copy(struct snd_pcm_substream *substream,
+                         int channel, snd_pcm_uframes_t pos,
+                         void __user *dst, snd_pcm_uframes_t count)
 {
-       return 0;
+       return 0; /* do nothing */
 }
 
-static int snd_card_dummy_capture_close(struct snd_pcm_substream *substream)
+static int dummy_pcm_silence(struct snd_pcm_substream *substream,
+                            int channel, snd_pcm_uframes_t pos,
+                            snd_pcm_uframes_t count)
 {
-       return 0;
+       return 0; /* do nothing */
+}
+
+static struct page *dummy_pcm_page(struct snd_pcm_substream *substream,
+                                  unsigned long offset)
+{
+       return virt_to_page(dummy_page[substream->stream]); /* the same page */
 }
 
-static struct snd_pcm_ops snd_card_dummy_playback_ops = {
-       .open =                 snd_card_dummy_playback_open,
-       .close =                snd_card_dummy_playback_close,
-       .ioctl =                snd_pcm_lib_ioctl,
-       .hw_params =            snd_card_dummy_hw_params,
-       .hw_free =              snd_card_dummy_hw_free,
-       .prepare =              snd_card_dummy_pcm_prepare,
-       .trigger =              snd_card_dummy_pcm_trigger,
-       .pointer =              snd_card_dummy_pcm_pointer,
+static struct snd_pcm_ops dummy_pcm_ops = {
+       .open =         dummy_pcm_open,
+       .close =        dummy_pcm_close,
+       .ioctl =        snd_pcm_lib_ioctl,
+       .hw_params =    dummy_pcm_hw_params,
+       .hw_free =      dummy_pcm_hw_free,
+       .prepare =      dummy_pcm_prepare,
+       .trigger =      dummy_pcm_trigger,
+       .pointer =      dummy_pcm_pointer,
 };
 
-static struct snd_pcm_ops snd_card_dummy_capture_ops = {
-       .open =                 snd_card_dummy_capture_open,
-       .close =                snd_card_dummy_capture_close,
-       .ioctl =                snd_pcm_lib_ioctl,
-       .hw_params =            snd_card_dummy_hw_params,
-       .hw_free =              snd_card_dummy_hw_free,
-       .prepare =              snd_card_dummy_pcm_prepare,
-       .trigger =              snd_card_dummy_pcm_trigger,
-       .pointer =              snd_card_dummy_pcm_pointer,
+static struct snd_pcm_ops dummy_pcm_ops_no_buf = {
+       .open =         dummy_pcm_open,
+       .close =        dummy_pcm_close,
+       .ioctl =        snd_pcm_lib_ioctl,
+       .hw_params =    dummy_pcm_hw_params,
+       .hw_free =      dummy_pcm_hw_free,
+       .prepare =      dummy_pcm_prepare,
+       .trigger =      dummy_pcm_trigger,
+       .pointer =      dummy_pcm_pointer,
+       .copy =         dummy_pcm_copy,
+       .silence =      dummy_pcm_silence,
+       .page =         dummy_pcm_page,
 };
 
 static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
                                        int substreams)
 {
        struct snd_pcm *pcm;
+       struct snd_pcm_ops *ops;
        int err;
 
        err = snd_pcm_new(dummy->card, "Dummy PCM", device,
@@ -440,17 +669,28 @@ static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
        if (err < 0)
                return err;
        dummy->pcm = pcm;
-       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_dummy_playback_ops);
-       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_dummy_capture_ops);
+       if (fake_buffer)
+               ops = &dummy_pcm_ops_no_buf;
+       else
+               ops = &dummy_pcm_ops;
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, ops);
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, ops);
        pcm->private_data = dummy;
        pcm->info_flags = 0;
        strcpy(pcm->name, "Dummy PCM");
-       snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
-                                             snd_dma_continuous_data(GFP_KERNEL),
-                                             0, 64*1024);
+       if (!fake_buffer) {
+               snd_pcm_lib_preallocate_pages_for_all(pcm,
+                       SNDRV_DMA_TYPE_CONTINUOUS,
+                       snd_dma_continuous_data(GFP_KERNEL),
+                       0, 64*1024);
+       }
        return 0;
 }
 
+/*
+ * mixer interface
+ */
+
 #define DUMMY_VOLUME(xname, xindex, addr) \
 { .iface = SNDRV_CTL_ELEM_IFACE_MIXER, \
   .access = SNDRV_CTL_ELEM_ACCESS_READWRITE | SNDRV_CTL_ELEM_ACCESS_TLV_READ, \
@@ -581,6 +821,131 @@ static int __devinit snd_card_dummy_new_mixer(struct snd_dummy *dummy)
        return 0;
 }
 
+#if defined(CONFIG_SND_DEBUG) && defined(CONFIG_PROC_FS)
+/*
+ * proc interface
+ */
+static void print_formats(struct snd_info_buffer *buffer)
+{
+       int i;
+
+       for (i = 0; i < SNDRV_PCM_FORMAT_LAST; i++) {
+               if (dummy_pcm_hardware.formats & (1ULL << i))
+                       snd_iprintf(buffer, " %s", snd_pcm_format_name(i));
+       }
+}
+
+static void print_rates(struct snd_info_buffer *buffer)
+{
+       static int rates[] = {
+               5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000,
+               64000, 88200, 96000, 176400, 192000,
+       };
+       int i;
+
+       if (dummy_pcm_hardware.rates & SNDRV_PCM_RATE_CONTINUOUS)
+               snd_iprintf(buffer, " continuous");
+       if (dummy_pcm_hardware.rates & SNDRV_PCM_RATE_KNOT)
+               snd_iprintf(buffer, " knot");
+       for (i = 0; i < ARRAY_SIZE(rates); i++)
+               if (dummy_pcm_hardware.rates & (1 << i))
+                       snd_iprintf(buffer, " %d", rates[i]);
+}
+
+#define get_dummy_int_ptr(ofs) \
+       (unsigned int *)((char *)&dummy_pcm_hardware + (ofs))
+#define get_dummy_ll_ptr(ofs) \
+       (unsigned long long *)((char *)&dummy_pcm_hardware + (ofs))
+
+struct dummy_hw_field {
+       const char *name;
+       const char *format;
+       unsigned int offset;
+       unsigned int size;
+};
+#define FIELD_ENTRY(item, fmt) {                  \
+       .name = #item,                             \
+       .format = fmt,                             \
+       .offset = offsetof(struct snd_pcm_hardware, item), \
+       .size = sizeof(dummy_pcm_hardware.item) }
+
+static struct dummy_hw_field fields[] = {
+       FIELD_ENTRY(formats, "%#llx"),
+       FIELD_ENTRY(rates, "%#x"),
+       FIELD_ENTRY(rate_min, "%d"),
+       FIELD_ENTRY(rate_max, "%d"),
+       FIELD_ENTRY(channels_min, "%d"),
+       FIELD_ENTRY(channels_max, "%d"),
+       FIELD_ENTRY(buffer_bytes_max, "%ld"),
+       FIELD_ENTRY(period_bytes_min, "%ld"),
+       FIELD_ENTRY(period_bytes_max, "%ld"),
+       FIELD_ENTRY(periods_min, "%d"),
+       FIELD_ENTRY(periods_max, "%d"),
+};
+
+static void dummy_proc_read(struct snd_info_entry *entry,
+                           struct snd_info_buffer *buffer)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(fields); i++) {
+               snd_iprintf(buffer, "%s ", fields[i].name);
+               if (fields[i].size == sizeof(int))
+                       snd_iprintf(buffer, fields[i].format,
+                                   *get_dummy_int_ptr(fields[i].offset));
+               else
+                       snd_iprintf(buffer, fields[i].format,
+                                   *get_dummy_ll_ptr(fields[i].offset));
+               if (!strcmp(fields[i].name, "formats"))
+                       print_formats(buffer);
+               else if (!strcmp(fields[i].name, "rates"))
+                       print_rates(buffer);
+               snd_iprintf(buffer, "\n");
+       }
+}
+
+static void dummy_proc_write(struct snd_info_entry *entry,
+                            struct snd_info_buffer *buffer)
+{
+       char line[64];
+
+       while (!snd_info_get_line(buffer, line, sizeof(line))) {
+               char item[20];
+               const char *ptr;
+               unsigned long long val;
+               int i;
+
+               ptr = snd_info_get_str(item, line, sizeof(item));
+               for (i = 0; i < ARRAY_SIZE(fields); i++) {
+                       if (!strcmp(item, fields[i].name))
+                               break;
+               }
+               if (i >= ARRAY_SIZE(fields))
+                       continue;
+               snd_info_get_str(item, ptr, sizeof(item));
+               if (strict_strtoull(item, 0, &val))
+                       continue;
+               if (fields[i].size == sizeof(int))
+                       *get_dummy_int_ptr(fields[i].offset) = val;
+               else
+                       *get_dummy_ll_ptr(fields[i].offset) = val;
+       }
+}
+
+static void __devinit dummy_proc_init(struct snd_dummy *chip)
+{
+       struct snd_info_entry *entry;
+
+       if (!snd_card_proc_new(chip->card, "dummy_pcm", &entry)) {
+               snd_info_set_text_ops(entry, chip, dummy_proc_read);
+               entry->c.text.write = dummy_proc_write;
+               entry->mode |= S_IWUSR;
+       }
+}
+#else
+#define dummy_proc_init(x)
+#endif /* CONFIG_SND_DEBUG && CONFIG_PROC_FS */
+
 static int __devinit snd_dummy_probe(struct platform_device *devptr)
 {
        struct snd_card *card;
@@ -610,6 +975,8 @@ static int __devinit snd_dummy_probe(struct platform_device *devptr)
        strcpy(card->shortname, "Dummy");
        sprintf(card->longname, "Dummy %i", dev + 1);
 
+       dummy_proc_init(dummy);
+
        snd_card_set_dev(card, &devptr->dev);
 
        err = snd_card_register(card);
@@ -670,6 +1037,7 @@ static void snd_dummy_unregister_all(void)
        for (i = 0; i < ARRAY_SIZE(devices); ++i)
                platform_device_unregister(devices[i]);
        platform_driver_unregister(&snd_dummy_driver);
+       free_fake_buffer();
 }
 
 static int __init alsa_card_dummy_init(void)
@@ -680,6 +1048,12 @@ static int __init alsa_card_dummy_init(void)
        if (err < 0)
                return err;
 
+       err = alloc_fake_buffer();
+       if (err < 0) {
+               platform_driver_unregister(&snd_dummy_driver);
+               return err;
+       }
+
        cards = 0;
        for (i = 0; i < SNDRV_CARDS; i++) {
                struct platform_device *device;