[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>

diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c
index 7bbcceb..dd045ea 100644 (file)
--- 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);
 }