[ALSA] usb-audio - add mixer control notifications

USB generic driver
Add support for the optional status interrupt endpoint in audio control
interfaces, and translate USB status notifications into ALSA mixer
control notifications.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

1 files changed, 98 insertions, 3 deletions

diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c
index 7bbccebd76c..dd045ea6fb0 100644
--- a/sound/usb/usbmixer.c
+++ b/sound/usb/usbmixer.c
@@ -55,6 +55,8 @@ struct usb_mixer_interface {
         unsigned int ctrlif;
         struct list_head list;
         unsigned int ignore_ctl_error;
+        struct urb *urb;
+        usb_mixer_elem_info_t **id_elems; /* array[256], indexed by unit id */
 };
 
 
@@ -83,13 +85,15 @@ struct usb_mixer_build {
 
 struct usb_mixer_elem_info {
         struct usb_mixer_interface *mixer;
+        usb_mixer_elem_info_t *next_id_elem; /* list of controls with same id */
+        snd_ctl_elem_id_t *elem_id;
         unsigned int id;
         unsigned int control;   /* CS or ICN (high byte) */
         unsigned int cmask; /* channel mask bitmap: 0 = master */
         int channels;
         int val_type;
         int min, max, res;
-        unsigned int initialized: 1;
+        u8 initialized;
 };
 
 
@@ -414,6 +418,7 @@ static int check_matrix_bitmap(unsigned char *bmap, int ich, int och, int num_ou
 
 static int add_control_to_empty(mixer_build_t *state, snd_kcontrol_t *kctl)
 {
+        usb_mixer_elem_info_t *cval = kctl->private_data;
         int err;
 
         while (snd_ctl_find_id(state->chip->card, &kctl->id))
@@ -421,8 +426,12 @@ static int add_control_to_empty(mixer_build_t *state, snd_kcontrol_t *kctl)
         if ((err = snd_ctl_add(state->chip->card, kctl)) < 0) {
                 snd_printd(KERN_ERR "cannot add control (err = %d)\n", err);
                 snd_ctl_free_one(kctl);
+                return err;
         }
-        return err;
+        cval->elem_id = &kctl->id;
+        cval->next_id_elem = state->mixer->id_elems[cval->id];
+        state->mixer->id_elems[cval->id] = cval;
+        return 0;
 }
 
 
@@ -1522,6 +1531,11 @@ static int parse_audio_unit(mixer_build_t *state, int unitid)
 
 static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
 {
+        kfree(mixer->id_elems);
+        if (mixer->urb) {
+                kfree(mixer->urb->transfer_buffer);
+                usb_free_urb(mixer->urb);
+        }
         kfree(mixer);
 }
 
@@ -1580,6 +1594,76 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
         return 0;
 }
 
+static void snd_usb_mixer_notify_id(struct usb_mixer_interface *mixer,
+                                    int unitid)
+{
+        usb_mixer_elem_info_t *info;
+
+        for (info = mixer->id_elems[unitid]; info; info = info->next_id_elem)
+                snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
+                               info->elem_id);
+}
+
+static void snd_usb_mixer_status_complete(struct urb *urb, struct pt_regs *regs)
+{
+        struct usb_mixer_interface *mixer = urb->context;
+
+        if (urb->status == 0) {
+                u8 *buf = urb->transfer_buffer;
+                int i;
+
+                for (i = urb->actual_length; i >= 2; buf += 2, i -= 2) {
+                        snd_printd(KERN_DEBUG "status interrupt: %02x %02x\n",
+                                   buf[0], buf[1]);
+                        /* ignore any notifications not from the control interface */
+                        if ((buf[0] & 0x0f) != 0)
+                                continue;
+                        if (!(buf[0] & 0x40))
+                                snd_usb_mixer_notify_id(mixer, buf[1]);
+                }
+        }
+        if (urb->status != -ENOENT && urb->status != -ECONNRESET) {
+                urb->dev = mixer->chip->dev;
+                usb_submit_urb(urb, GFP_ATOMIC);
+        }
+}
+
+/* create the handler for the optional status interrupt endpoint */
+static int snd_usb_mixer_status_create(struct usb_mixer_interface *mixer)
+{
+        struct usb_host_interface *hostif;
+        struct usb_endpoint_descriptor *ep;
+        void *transfer_buffer;
+        int buffer_length;
+        unsigned int epnum;
+
+        hostif = &usb_ifnum_to_if(mixer->chip->dev, mixer->ctrlif)->altsetting[0];
+        /* we need one interrupt input endpoint */
+        if (get_iface_desc(hostif)->bNumEndpoints < 1)
+                return 0;
+        ep = get_endpoint(hostif, 0);
+        if ((ep->bEndpointAddress & USB_ENDPOINT_DIR_MASK) != USB_DIR_IN ||
+            (ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_INT)
+                return 0;
+
+        epnum = ep->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
+        buffer_length = le16_to_cpu(ep->wMaxPacketSize);
+        transfer_buffer = kmalloc(buffer_length, GFP_KERNEL);
+        if (!transfer_buffer)
+                return -ENOMEM;
+        mixer->urb = usb_alloc_urb(0, GFP_KERNEL);
+        if (!mixer->urb) {
+                kfree(transfer_buffer);
+                return -ENOMEM;
+        }
+        usb_fill_int_urb(mixer->urb, mixer->chip->dev,
+                         usb_rcvintpipe(mixer->chip->dev, epnum),
+                         transfer_buffer, buffer_length,
+                         snd_usb_mixer_status_complete, mixer, ep->bInterval);
+        usb_submit_urb(mixer->urb, GFP_KERNEL);
+        return 0;
+}
+
 int snd_usb_create_mixer(snd_usb_audio_t *chip, int ctrlif)
 {
         static snd_device_ops_t dev_ops = {
@@ -1598,8 +1682,14 @@ int snd_usb_create_mixer(snd_usb_audio_t *chip, int ctrlif)
 #ifdef IGNORE_CTL_ERROR
         mixer->ignore_ctl_error = 1;
 #endif
+        mixer->id_elems = kcalloc(256, sizeof(*mixer->id_elems), GFP_KERNEL);
+        if (!mixer->id_elems) {
+                kfree(mixer);
+                return -ENOMEM;
+        }
 
-        if ((err = snd_usb_mixer_controls(mixer)) < 0) {
+        if ((err = snd_usb_mixer_controls(mixer)) < 0 ||
+            (err = snd_usb_mixer_status_create(mixer)) < 0) {
                 snd_usb_mixer_free(mixer);
                 return err;
         }
@@ -1615,4 +1705,9 @@ int snd_usb_create_mixer(snd_usb_audio_t *chip, int ctrlif)
 
 void snd_usb_mixer_disconnect(struct list_head *p)
 {
+        struct usb_mixer_interface *mixer;
+        
+        mixer = list_entry(p, struct usb_mixer_interface, list);
+        if (mixer->urb)
+                usb_kill_urb(mixer->urb);
 }