ALSA: usb-audio: refactor code

Clean up the usb audio driver by factoring out a lot of functions to
separate files. Code for procfs, quirks, urbs, format parsers etc all
got a new home now.

Moved almost all special quirk handling to quirks.c and introduced new
generic functions to handle them, so the exceptions do not pollute the
whole driver.

Renamed usbaudio.c to card.c because this is what it actually does now.
Renamed usbmidi.c to midi.c for namespace clarity.
Removed more things from usbaudio.h.

The non-standard drivers were adopted accordingly.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 845 insertions, 0 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
new file mode 100644
index 000000000000..87863ccf9068
--- /dev/null
+++ b/sound/usb/pcm.c
@@ -0,0 +1,845 @@
+/*
+ *   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/usb.h>
+#include <linux/usb/audio.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "quirks.h"
+#include "debug.h"
+#include "urb.h"
+#include "helper.h"
+#include "pcm.h"
+
+/*
+ * return the current pcm pointer.  just based on the hwptr_done value.
+ */
+static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream)
+{
+        struct snd_usb_substream *subs;
+        unsigned int hwptr_done;
+
+        subs = (struct snd_usb_substream *)substream->runtime->private_data;
+        spin_lock(&subs->lock);
+        hwptr_done = subs->hwptr_done;
+        spin_unlock(&subs->lock);
+        return hwptr_done / (substream->runtime->frame_bits >> 3);
+}
+
+/*
+ * find a matching audio format
+ */
+static struct audioformat *find_format(struct snd_usb_substream *subs, unsigned int format,
+                                       unsigned int rate, unsigned int channels)
+{
+        struct list_head *p;
+        struct audioformat *found = NULL;
+        int cur_attr = 0, attr;
+
+        list_for_each(p, &subs->fmt_list) {
+                struct audioformat *fp;
+                fp = list_entry(p, struct audioformat, list);
+                if (fp->format != format || fp->channels != channels)
+                        continue;
+                if (rate < fp->rate_min || rate > fp->rate_max)
+                        continue;
+                if (! (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)) {
+                        unsigned int i;
+                        for (i = 0; i < fp->nr_rates; i++)
+                                if (fp->rate_table[i] == rate)
+                                        break;
+                        if (i >= fp->nr_rates)
+                                continue;
+                }
+                attr = fp->ep_attr & USB_ENDPOINT_SYNCTYPE;
+                if (! found) {
+                        found = fp;
+                        cur_attr = attr;
+                        continue;
+                }
+                /* avoid async out and adaptive in if the other method
+                 * supports the same format.
+                 * this is a workaround for the case like
+                 * M-audio audiophile USB.
+                 */
+                if (attr != cur_attr) {
+                        if ((attr == USB_ENDPOINT_SYNC_ASYNC &&
+                             subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
+                            (attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
+                             subs->direction == SNDRV_PCM_STREAM_CAPTURE))
+                                continue;
+                        if ((cur_attr == USB_ENDPOINT_SYNC_ASYNC &&
+                             subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
+                            (cur_attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
+                             subs->direction == SNDRV_PCM_STREAM_CAPTURE)) {
+                                found = fp;
+                                cur_attr = attr;
+                                continue;
+                        }
+                }
+                /* find the format with the largest max. packet size */
+                if (fp->maxpacksize > found->maxpacksize) {
+                        found = fp;
+                        cur_attr = attr;
+                }
+        }
+        return found;
+}
+
+
+/*
+ * initialize the picth control and sample rate
+ */
+int snd_usb_init_pitch(struct usb_device *dev, int iface,
+                       struct usb_host_interface *alts,
+                       struct audioformat *fmt)
+{
+        unsigned int ep;
+        unsigned char data[1];
+        int err;
+
+        ep = get_endpoint(alts, 0)->bEndpointAddress;
+        /* if endpoint has pitch control, enable it */
+        if (fmt->attributes & UAC_EP_CS_ATTR_PITCH_CONTROL) {
+                data[0] = 1;
+                if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
+                                           USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
+                                           UAC_EP_CS_ATTR_PITCH_CONTROL << 8, ep, data, 1, 1000)) < 0) {
+                        snd_printk(KERN_ERR "%d:%d:%d: cannot set enable PITCH\n",
+                                   dev->devnum, iface, ep);
+                        return err;
+                }
+        }
+        return 0;
+}
+
+int snd_usb_init_sample_rate(struct usb_device *dev, int iface,
+                             struct usb_host_interface *alts,
+                             struct audioformat *fmt, int rate)
+{
+        unsigned int ep;
+        unsigned char data[3];
+        int err;
+
+        ep = get_endpoint(alts, 0)->bEndpointAddress;
+        /* if endpoint has sampling rate control, set it */
+        if (fmt->attributes & UAC_EP_CS_ATTR_SAMPLE_RATE) {
+                int crate;
+                data[0] = rate;
+                data[1] = rate >> 8;
+                data[2] = rate >> 16;
+                if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
+                                           USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
+                                           UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep, data, 3, 1000)) < 0) {
+                        snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d to ep %#x\n",
+                                   dev->devnum, iface, fmt->altsetting, rate, ep);
+                        return err;
+                }
+                if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC_GET_CUR,
+                                           USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_IN,
+                                           UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep, data, 3, 1000)) < 0) {
+                        snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq at ep %#x\n",
+                                   dev->devnum, iface, fmt->altsetting, ep);
+                        return 0; /* some devices don't support reading */
+                }
+                crate = data[0] | (data[1] << 8) | (data[2] << 16);
+                if (crate != rate) {
+                        snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
+                        // runtime->rate = crate;
+                }
+        }
+        return 0;
+}
+
+/*
+ * find a matching format and set up the interface
+ */
+static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
+{
+        struct usb_device *dev = subs->dev;
+        struct usb_host_interface *alts;
+        struct usb_interface_descriptor *altsd;
+        struct usb_interface *iface;
+        unsigned int ep, attr;
+        int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
+        int err;
+
+        iface = usb_ifnum_to_if(dev, fmt->iface);
+        if (WARN_ON(!iface))
+                return -EINVAL;
+        alts = &iface->altsetting[fmt->altset_idx];
+        altsd = get_iface_desc(alts);
+        if (WARN_ON(altsd->bAlternateSetting != fmt->altsetting))
+                return -EINVAL;
+
+        if (fmt == subs->cur_audiofmt)
+                return 0;
+
+        /* close the old interface */
+        if (subs->interface >= 0 && subs->interface != fmt->iface) {
+                if (usb_set_interface(subs->dev, subs->interface, 0) < 0) {
+                        snd_printk(KERN_ERR "%d:%d:%d: return to setting 0 failed\n",
+                                dev->devnum, fmt->iface, fmt->altsetting);
+                        return -EIO;
+                }
+                subs->interface = -1;
+                subs->format = 0;
+        }
+
+        /* set interface */
+        if (subs->interface != fmt->iface || subs->format != fmt->altset_idx) {
+                if (usb_set_interface(dev, fmt->iface, fmt->altsetting) < 0) {
+                        snd_printk(KERN_ERR "%d:%d:%d: usb_set_interface failed\n",
+                                   dev->devnum, fmt->iface, fmt->altsetting);
+                        return -EIO;
+                }
+                snd_printdd(KERN_INFO "setting usb interface %d:%d\n", fmt->iface, fmt->altsetting);
+                subs->interface = fmt->iface;
+                subs->format = fmt->altset_idx;
+        }
+
+        /* create a data pipe */
+        ep = fmt->endpoint & USB_ENDPOINT_NUMBER_MASK;
+        if (is_playback)
+                subs->datapipe = usb_sndisocpipe(dev, ep);
+        else
+                subs->datapipe = usb_rcvisocpipe(dev, ep);
+        subs->datainterval = fmt->datainterval;
+        subs->syncpipe = subs->syncinterval = 0;
+        subs->maxpacksize = fmt->maxpacksize;
+        subs->fill_max = 0;
+
+        /* we need a sync pipe in async OUT or adaptive IN mode */
+        /* check the number of EP, since some devices have broken
+         * descriptors which fool us.  if it has only one EP,
+         * assume it as adaptive-out or sync-in.
+         */
+        attr = fmt->ep_attr & USB_ENDPOINT_SYNCTYPE;
+        if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
+             (! is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
+            altsd->bNumEndpoints >= 2) {
+                /* check sync-pipe endpoint */
+                /* ... and check descriptor size before accessing bSynchAddress
+                   because there is a version of the SB Audigy 2 NX firmware lacking
+                   the audio fields in the endpoint descriptors */
+                if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != 0x01 ||
+                    (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+                     get_endpoint(alts, 1)->bSynchAddress != 0)) {
+                        snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
+                                   dev->devnum, fmt->iface, fmt->altsetting);
+                        return -EINVAL;
+                }
+                ep = get_endpoint(alts, 1)->bEndpointAddress;
+                if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+                    (( is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
+                     (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
+                        snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
+                                   dev->devnum, fmt->iface, fmt->altsetting);
+                        return -EINVAL;
+                }
+                ep &= USB_ENDPOINT_NUMBER_MASK;
+                if (is_playback)
+                        subs->syncpipe = usb_rcvisocpipe(dev, ep);
+                else
+                        subs->syncpipe = usb_sndisocpipe(dev, ep);
+                if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+                    get_endpoint(alts, 1)->bRefresh >= 1 &&
+                    get_endpoint(alts, 1)->bRefresh <= 9)
+                        subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
+                else if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+                        subs->syncinterval = 1;
+                else if (get_endpoint(alts, 1)->bInterval >= 1 &&
+                         get_endpoint(alts, 1)->bInterval <= 16)
+                        subs->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
+                else
+                        subs->syncinterval = 3;
+        }
+
+        /* always fill max packet size */
+        if (fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX)
+                subs->fill_max = 1;
+
+        if ((err = snd_usb_init_pitch(dev, subs->interface, alts, fmt)) < 0)
+                return err;
+
+        subs->cur_audiofmt = fmt;
+
+        snd_usb_set_format_quirk(subs, fmt);
+
+#if 0
+        printk(KERN_DEBUG
+               "setting done: format = %d, rate = %d..%d, channels = %d\n",
+               fmt->format, fmt->rate_min, fmt->rate_max, fmt->channels);
+        printk(KERN_DEBUG
+               "  datapipe = 0x%0x, syncpipe = 0x%0x\n",
+               subs->datapipe, subs->syncpipe);
+#endif
+
+        return 0;
+}
+
+/*
+ * hw_params callback
+ *
+ * allocate a buffer and set the given audio format.
+ *
+ * so far we use a physically linear buffer although packetize transfer
+ * doesn't need a continuous area.
+ * if sg buffer is supported on the later version of alsa, we'll follow
+ * that.
+ */
+static int snd_usb_hw_params(struct snd_pcm_substream *substream,
+                             struct snd_pcm_hw_params *hw_params)
+{
+        struct snd_usb_substream *subs = substream->runtime->private_data;
+        struct audioformat *fmt;
+        unsigned int channels, rate, format;
+        int ret, changed;
+
+        ret = snd_pcm_lib_alloc_vmalloc_buffer(substream,
+                                               params_buffer_bytes(hw_params));
+        if (ret < 0)
+                return ret;
+
+        format = params_format(hw_params);
+        rate = params_rate(hw_params);
+        channels = params_channels(hw_params);
+        fmt = find_format(subs, format, rate, channels);
+        if (!fmt) {
+                snd_printd(KERN_DEBUG "cannot set format: format = %#x, rate = %d, channels = %d\n",
+                           format, rate, channels);
+                return -EINVAL;
+        }
+
+        changed = subs->cur_audiofmt != fmt ||
+                subs->period_bytes != params_period_bytes(hw_params) ||
+                subs->cur_rate != rate;
+        if ((ret = set_format(subs, fmt)) < 0)
+                return ret;
+
+        if (subs->cur_rate != rate) {
+                struct usb_host_interface *alts;
+                struct usb_interface *iface;
+                iface = usb_ifnum_to_if(subs->dev, fmt->iface);
+                alts = &iface->altsetting[fmt->altset_idx];
+                ret = snd_usb_init_sample_rate(subs->dev, subs->interface, alts, fmt, rate);
+                if (ret < 0)
+                        return ret;
+                subs->cur_rate = rate;
+        }
+
+        if (changed) {
+                /* format changed */
+                snd_usb_release_substream_urbs(subs, 0);
+                /* influenced: period_bytes, channels, rate, format, */
+                ret = snd_usb_init_substream_urbs(subs, params_period_bytes(hw_params),
+                                                  params_rate(hw_params),
+                                                  snd_pcm_format_physical_width(params_format(hw_params)) *
+                                                        params_channels(hw_params));
+        }
+
+        return ret;
+}
+
+/*
+ * hw_free callback
+ *
+ * reset the audio format and release the buffer
+ */
+static int snd_usb_hw_free(struct snd_pcm_substream *substream)
+{
+        struct snd_usb_substream *subs = substream->runtime->private_data;
+
+        subs->cur_audiofmt = NULL;
+        subs->cur_rate = 0;
+        subs->period_bytes = 0;
+        if (!subs->stream->chip->shutdown)
+                snd_usb_release_substream_urbs(subs, 0);
+        return snd_pcm_lib_free_vmalloc_buffer(substream);
+}
+
+/*
+ * prepare callback
+ *
+ * only a few subtle things...
+ */
+static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
+{
+        struct snd_pcm_runtime *runtime = substream->runtime;
+        struct snd_usb_substream *subs = runtime->private_data;
+
+        if (! subs->cur_audiofmt) {
+                snd_printk(KERN_ERR "usbaudio: no format is specified!\n");
+                return -ENXIO;
+        }
+
+        /* some unit conversions in runtime */
+        subs->maxframesize = bytes_to_frames(runtime, subs->maxpacksize);
+        subs->curframesize = bytes_to_frames(runtime, subs->curpacksize);
+
+        /* reset the pointer */
+        subs->hwptr_done = 0;
+        subs->transfer_done = 0;
+        subs->phase = 0;
+        runtime->delay = 0;
+
+        return snd_usb_substream_prepare(subs, runtime);
+}
+
+static struct snd_pcm_hardware snd_usb_hardware =
+{
+        .info =                 SNDRV_PCM_INFO_MMAP |
+                                SNDRV_PCM_INFO_MMAP_VALID |
+                                SNDRV_PCM_INFO_BATCH |
+                                SNDRV_PCM_INFO_INTERLEAVED |
+                                SNDRV_PCM_INFO_BLOCK_TRANSFER |
+                                SNDRV_PCM_INFO_PAUSE,
+        .buffer_bytes_max =     1024 * 1024,
+        .period_bytes_min =     64,
+        .period_bytes_max =     512 * 1024,
+        .periods_min =          2,
+        .periods_max =          1024,
+};
+
+static int hw_check_valid_format(struct snd_usb_substream *subs,
+                                 struct snd_pcm_hw_params *params,
+                                 struct audioformat *fp)
+{
+        struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+        struct snd_interval *ct = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+        struct snd_mask *fmts = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+        struct snd_interval *pt = hw_param_interval(params, SNDRV_PCM_HW_PARAM_PERIOD_TIME);
+        unsigned int ptime;
+
+        /* check the format */
+        if (!snd_mask_test(fmts, fp->format)) {
+                hwc_debug("   > check: no supported format %d\n", fp->format);
+                return 0;
+        }
+        /* check the channels */
+        if (fp->channels < ct->min || fp->channels > ct->max) {
+                hwc_debug("   > check: no valid channels %d (%d/%d)\n", fp->channels, ct->min, ct->max);
+                return 0;
+        }
+        /* check the rate is within the range */
+        if (fp->rate_min > it->max || (fp->rate_min == it->max && it->openmax)) {
+                hwc_debug("   > check: rate_min %d > max %d\n", fp->rate_min, it->max);
+                return 0;
+        }
+        if (fp->rate_max < it->min || (fp->rate_max == it->min && it->openmin)) {
+                hwc_debug("   > check: rate_max %d < min %d\n", fp->rate_max, it->min);
+                return 0;
+        }
+        /* check whether the period time is >= the data packet interval */
+        if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH) {
+                ptime = 125 * (1 << fp->datainterval);
+                if (ptime > pt->max || (ptime == pt->max && pt->openmax)) {
+                        hwc_debug("   > check: ptime %u > max %u\n", ptime, pt->max);
+                        return 0;
+                }
+        }
+        return 1;
+}
+
+static int hw_rule_rate(struct snd_pcm_hw_params *params,
+                        struct snd_pcm_hw_rule *rule)
+{
+        struct snd_usb_substream *subs = rule->private;
+        struct list_head *p;
+        struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+        unsigned int rmin, rmax;
+        int changed;
+
+        hwc_debug("hw_rule_rate: (%d,%d)\n", it->min, it->max);
+        changed = 0;
+        rmin = rmax = 0;
+        list_for_each(p, &subs->fmt_list) {
+                struct audioformat *fp;
+                fp = list_entry(p, struct audioformat, list);
+                if (!hw_check_valid_format(subs, params, fp))
+                        continue;
+                if (changed++) {
+                        if (rmin > fp->rate_min)
+                                rmin = fp->rate_min;
+                        if (rmax < fp->rate_max)
+                                rmax = fp->rate_max;
+                } else {
+                        rmin = fp->rate_min;
+                        rmax = fp->rate_max;
+                }
+        }
+
+        if (!changed) {
+                hwc_debug("  --> get empty\n");
+                it->empty = 1;
+                return -EINVAL;
+        }
+
+        changed = 0;
+        if (it->min < rmin) {
+                it->min = rmin;
+                it->openmin = 0;
+                changed = 1;
+        }
+        if (it->max > rmax) {
+                it->max = rmax;
+                it->openmax = 0;
+                changed = 1;
+        }
+        if (snd_interval_checkempty(it)) {
+                it->empty = 1;
+                return -EINVAL;
+        }
+        hwc_debug("  --> (%d, %d) (changed = %d)\n", it->min, it->max, changed);
+        return changed;
+}
+
+
+static int hw_rule_channels(struct snd_pcm_hw_params *params,
+                            struct snd_pcm_hw_rule *rule)
+{
+        struct snd_usb_substream *subs = rule->private;
+        struct list_head *p;
+        struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+        unsigned int rmin, rmax;
+        int changed;
+
+        hwc_debug("hw_rule_channels: (%d,%d)\n", it->min, it->max);
+        changed = 0;
+        rmin = rmax = 0;
+        list_for_each(p, &subs->fmt_list) {
+                struct audioformat *fp;
+                fp = list_entry(p, struct audioformat, list);
+                if (!hw_check_valid_format(subs, params, fp))
+                        continue;
+                if (changed++) {
+                        if (rmin > fp->channels)
+                                rmin = fp->channels;
+                        if (rmax < fp->channels)
+                                rmax = fp->channels;
+                } else {
+                        rmin = fp->channels;
+                        rmax = fp->channels;
+                }
+        }
+
+        if (!changed) {
+                hwc_debug("  --> get empty\n");
+                it->empty = 1;
+                return -EINVAL;
+        }
+
+        changed = 0;
+        if (it->min < rmin) {
+                it->min = rmin;
+                it->openmin = 0;
+                changed = 1;
+        }
+        if (it->max > rmax) {
+                it->max = rmax;
+                it->openmax = 0;
+                changed = 1;
+        }
+        if (snd_interval_checkempty(it)) {
+                it->empty = 1;
+                return -EINVAL;
+        }
+        hwc_debug("  --> (%d, %d) (changed = %d)\n", it->min, it->max, changed);
+        return changed;
+}
+
+static int hw_rule_format(struct snd_pcm_hw_params *params,
+                          struct snd_pcm_hw_rule *rule)
+{
+        struct snd_usb_substream *subs = rule->private;
+        struct list_head *p;
+        struct snd_mask *fmt = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+        u64 fbits;
+        u32 oldbits[2];
+        int changed;
+
+        hwc_debug("hw_rule_format: %x:%x\n", fmt->bits[0], fmt->bits[1]);
+        fbits = 0;
+        list_for_each(p, &subs->fmt_list) {
+                struct audioformat *fp;
+                fp = list_entry(p, struct audioformat, list);
+                if (!hw_check_valid_format(subs, params, fp))
+                        continue;
+                fbits |= (1ULL << fp->format);
+        }
+
+        oldbits[0] = fmt->bits[0];
+        oldbits[1] = fmt->bits[1];
+        fmt->bits[0] &= (u32)fbits;
+        fmt->bits[1] &= (u32)(fbits >> 32);
+        if (!fmt->bits[0] && !fmt->bits[1]) {
+                hwc_debug("  --> get empty\n");
+                return -EINVAL;
+        }
+        changed = (oldbits[0] != fmt->bits[0] || oldbits[1] != fmt->bits[1]);
+        hwc_debug("  --> %x:%x (changed = %d)\n", fmt->bits[0], fmt->bits[1], changed);
+        return changed;
+}
+
+static int hw_rule_period_time(struct snd_pcm_hw_params *params,
+                               struct snd_pcm_hw_rule *rule)
+{
+        struct snd_usb_substream *subs = rule->private;
+        struct audioformat *fp;
+        struct snd_interval *it;
+        unsigned char min_datainterval;
+        unsigned int pmin;
+        int changed;
+
+        it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_PERIOD_TIME);
+        hwc_debug("hw_rule_period_time: (%u,%u)\n", it->min, it->max);
+        min_datainterval = 0xff;
+        list_for_each_entry(fp, &subs->fmt_list, list) {
+                if (!hw_check_valid_format(subs, params, fp))
+                        continue;
+                min_datainterval = min(min_datainterval, fp->datainterval);
+        }
+        if (min_datainterval == 0xff) {
+                hwc_debug("  --> get emtpy\n");
+                it->empty = 1;
+                return -EINVAL;
+        }
+        pmin = 125 * (1 << min_datainterval);
+        changed = 0;
+        if (it->min < pmin) {
+                it->min = pmin;
+                it->openmin = 0;
+                changed = 1;
+        }
+        if (snd_interval_checkempty(it)) {
+                it->empty = 1;
+                return -EINVAL;
+        }
+        hwc_debug("  --> (%u,%u) (changed = %d)\n", it->min, it->max, changed);
+        return changed;
+}
+
+/*
+ *  If the device supports unusual bit rates, does the request meet these?
+ */
+static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
+                                  struct snd_usb_substream *subs)
+{
+        struct audioformat *fp;
+        int count = 0, needs_knot = 0;
+        int err;
+
+        list_for_each_entry(fp, &subs->fmt_list, list) {
+                if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)
+                        return 0;
+                count += fp->nr_rates;
+                if (fp->rates & SNDRV_PCM_RATE_KNOT)
+                        needs_knot = 1;
+        }
+        if (!needs_knot)
+                return 0;
+
+        subs->rate_list.count = count;
+        subs->rate_list.list = kmalloc(sizeof(int) * count, GFP_KERNEL);
+        subs->rate_list.mask = 0;
+        count = 0;
+        list_for_each_entry(fp, &subs->fmt_list, list) {
+                int i;
+                for (i = 0; i < fp->nr_rates; i++)
+                        subs->rate_list.list[count++] = fp->rate_table[i];
+        }
+        err = snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+                                         &subs->rate_list);
+        if (err < 0)
+                return err;
+
+        return 0;
+}
+
+
+/*
+ * set up the runtime hardware information.
+ */
+
+static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substream *subs)
+{
+        struct list_head *p;
+        unsigned int pt, ptmin;
+        int param_period_time_if_needed;
+        int err;
+
+        runtime->hw.formats = subs->formats;
+
+        runtime->hw.rate_min = 0x7fffffff;
+        runtime->hw.rate_max = 0;
+        runtime->hw.channels_min = 256;
+        runtime->hw.channels_max = 0;
+        runtime->hw.rates = 0;
+        ptmin = UINT_MAX;
+        /* check min/max rates and channels */
+        list_for_each(p, &subs->fmt_list) {
+                struct audioformat *fp;
+                fp = list_entry(p, struct audioformat, list);
+                runtime->hw.rates |= fp->rates;
+                if (runtime->hw.rate_min > fp->rate_min)
+                        runtime->hw.rate_min = fp->rate_min;
+                if (runtime->hw.rate_max < fp->rate_max)
+                        runtime->hw.rate_max = fp->rate_max;
+                if (runtime->hw.channels_min > fp->channels)
+                        runtime->hw.channels_min = fp->channels;
+                if (runtime->hw.channels_max < fp->channels)
+                        runtime->hw.channels_max = fp->channels;
+                if (fp->fmt_type == UAC_FORMAT_TYPE_II && fp->frame_size > 0) {
+                        /* FIXME: there might be more than one audio formats... */
+                        runtime->hw.period_bytes_min = runtime->hw.period_bytes_max =
+                                fp->frame_size;
+                }
+                pt = 125 * (1 << fp->datainterval);
+                ptmin = min(ptmin, pt);
+        }
+
+        param_period_time_if_needed = SNDRV_PCM_HW_PARAM_PERIOD_TIME;
+        if (snd_usb_get_speed(subs->dev) != USB_SPEED_HIGH)
+                /* full speed devices have fixed data packet interval */
+                ptmin = 1000;
+        if (ptmin == 1000)
+                /* if period time doesn't go below 1 ms, no rules needed */
+                param_period_time_if_needed = -1;
+        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME,
+                                     ptmin, UINT_MAX);
+
+        if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+                                       hw_rule_rate, subs,
+                                       SNDRV_PCM_HW_PARAM_FORMAT,
+                                       SNDRV_PCM_HW_PARAM_CHANNELS,
+                                       param_period_time_if_needed,
+                                       -1)) < 0)
+                return err;
+        if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
+                                       hw_rule_channels, subs,
+                                       SNDRV_PCM_HW_PARAM_FORMAT,
+                                       SNDRV_PCM_HW_PARAM_RATE,
+                                       param_period_time_if_needed,
+                                       -1)) < 0)
+                return err;
+        if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
+                                       hw_rule_format, subs,
+                                       SNDRV_PCM_HW_PARAM_RATE,
+                                       SNDRV_PCM_HW_PARAM_CHANNELS,
+                                       param_period_time_if_needed,
+                                       -1)) < 0)
+                return err;
+        if (param_period_time_if_needed >= 0) {
+                err = snd_pcm_hw_rule_add(runtime, 0,
+                                          SNDRV_PCM_HW_PARAM_PERIOD_TIME,
+                                          hw_rule_period_time, subs,
+                                          SNDRV_PCM_HW_PARAM_FORMAT,
+                                          SNDRV_PCM_HW_PARAM_CHANNELS,
+                                          SNDRV_PCM_HW_PARAM_RATE,
+                                          -1);
+                if (err < 0)
+                        return err;
+        }
+        if ((err = snd_usb_pcm_check_knot(runtime, subs)) < 0)
+                return err;
+        return 0;
+}
+
+static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
+{
+        struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
+        struct snd_pcm_runtime *runtime = substream->runtime;
+        struct snd_usb_substream *subs = &as->substream[direction];
+
+        subs->interface = -1;
+        subs->format = 0;
+        runtime->hw = snd_usb_hardware;
+        runtime->private_data = subs;
+        subs->pcm_substream = substream;
+        return setup_hw_info(runtime, subs);
+}
+
+static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction)
+{
+        struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
+        struct snd_usb_substream *subs = &as->substream[direction];
+
+        if (!as->chip->shutdown && subs->interface >= 0) {
+                usb_set_interface(subs->dev, subs->interface, 0);
+                subs->interface = -1;
+        }
+        subs->pcm_substream = NULL;
+        return 0;
+}
+
+static int snd_usb_playback_open(struct snd_pcm_substream *substream)
+{
+        return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_PLAYBACK);
+}
+
+static int snd_usb_playback_close(struct snd_pcm_substream *substream)
+{
+        return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_PLAYBACK);
+}
+
+static int snd_usb_capture_open(struct snd_pcm_substream *substream)
+{
+        return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_CAPTURE);
+}
+
+static int snd_usb_capture_close(struct snd_pcm_substream *substream)
+{
+        return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_CAPTURE);
+}
+
+static struct snd_pcm_ops snd_usb_playback_ops = {
+        .open =         snd_usb_playback_open,
+        .close =        snd_usb_playback_close,
+        .ioctl =        snd_pcm_lib_ioctl,
+        .hw_params =    snd_usb_hw_params,
+        .hw_free =      snd_usb_hw_free,
+        .prepare =      snd_usb_pcm_prepare,
+        .trigger =      snd_usb_substream_playback_trigger,
+        .pointer =      snd_usb_pcm_pointer,
+        .page =         snd_pcm_lib_get_vmalloc_page,
+        .mmap =         snd_pcm_lib_mmap_vmalloc,
+};
+
+static struct snd_pcm_ops snd_usb_capture_ops = {
+        .open =         snd_usb_capture_open,
+        .close =        snd_usb_capture_close,
+        .ioctl =        snd_pcm_lib_ioctl,
+        .hw_params =    snd_usb_hw_params,
+        .hw_free =      snd_usb_hw_free,
+        .prepare =      snd_usb_pcm_prepare,
+        .trigger =      snd_usb_substream_capture_trigger,
+        .pointer =      snd_usb_pcm_pointer,
+        .page =         snd_pcm_lib_get_vmalloc_page,
+        .mmap =         snd_pcm_lib_mmap_vmalloc,
+};
+
+void snd_usb_set_pcm_ops(struct snd_pcm *pcm, int stream)
+{
+        snd_pcm_set_ops(pcm, stream,
+                        stream == SNDRV_PCM_STREAM_PLAYBACK ?
+                        &snd_usb_playback_ops : &snd_usb_capture_ops);
+}