[RFC PATCH 04/14] sound: usb: card: Introduce USB SND vendor op callbacks

Wesley Cheng
2022-12-23T23:33:27Z

Allow for different vendors to be notified on USB SND connect/disconnect
seqeunces. This allows for vendor USB SND modules to properly initialize
and populate internal structures with references to the USB SND chip
device.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
sound/usb/card.c | 22 ++++++++++++++++++++++
sound/usb/card.h | 7 +++++++
2 files changed, 29 insertions(+)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 26268ffb8274..212f55a7683c 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -117,6 +117,21 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no)
static DEFINE_MUTEX(register_mutex);
static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
static struct usb_driver usb_audio_driver;
+static struct snd_usb_vendor_ops *vendor_ops;
+
+int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops)
+{
+ vendor_ops = ops;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_usb_register_vendor_ops);
+
+int snd_usb_unregister_vendor_ops(void)
+{
+ vendor_ops = NULL;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_usb_unregister_vendor_ops);

/*
* disconnect streams
@@ -910,6 +925,10 @@ static int usb_audio_probe(struct usb_interface *intf,
usb_set_intfdata(intf, chip);
atomic_dec(&chip->active);
mutex_unlock(&register_mutex);
+
+ if (vendor_ops->connect_cb)
+ vendor_ops->connect_cb(intf, chip);
+
return 0;

__error:
@@ -943,6 +962,9 @@ static void usb_audio_disconnect(struct usb_interface *intf)
if (chip == USB_AUDIO_IFACE_UNUSED)
return;

+ if (vendor_ops->disconnect_cb)
+ vendor_ops->disconnect_cb(intf);
+
card = chip->card;

mutex_lock(&register_mutex);
diff --git a/sound/usb/card.h b/sound/usb/card.h
index 40061550105a..a785bb256b0d 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -206,4 +206,11 @@ struct snd_usb_stream {
struct list_head list;
};

+struct snd_usb_vendor_ops {
+ void (*connect_cb)(struct usb_interface *intf, struct snd_usb_audio *chip);
+ void (*disconnect_cb)(struct usb_interface *intf);
+};
+
+int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops);
+int snd_usb_unregister_vendor_ops(void);
#endif /* __USBAUDIO_CARD_H */