1 files changed, 66 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 8fff995b8dd5..566531bf6cab 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -1222,6 +1222,65 @@ static void f_midi_free_inst(struct usb_function_instance *f)
         }
 }
 
+#ifdef CONFIG_USB_CONFIGFS_UEVENT
+extern struct device *create_function_device(char *name);
+static ssize_t alsa_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct usb_function_instance *fi_midi = dev_get_drvdata(dev);
+        struct f_midi *midi;
+
+        if (!fi_midi->f)
+                dev_warn(dev, "f_midi: function not set\n");
+
+        if (fi_midi && fi_midi->f) {
+                midi = func_to_midi(fi_midi->f);
+                if (midi->rmidi && midi->card && midi->rmidi->card)
+                        return sprintf(buf, "%d %d\n",
+                        midi->rmidi->card->number, midi->rmidi->device);
+        }
+
+        /* print PCM card and device numbers */
+        return sprintf(buf, "%d %d\n", -1, -1);
+}
+
+static DEVICE_ATTR(alsa, S_IRUGO, alsa_show, NULL);
+
+static struct device_attribute *alsa_function_attributes[] = {
+        &dev_attr_alsa,
+        NULL
+};
+
+static int create_alsa_device(struct usb_function_instance *fi)
+{
+        struct device *dev;
+        struct device_attribute **attrs;
+        struct device_attribute *attr;
+        int err = 0;
+
+        dev = create_function_device("f_midi");
+        if (IS_ERR(dev))
+                return PTR_ERR(dev);
+
+        attrs = alsa_function_attributes;
+        if (attrs) {
+                while ((attr = *attrs++) && !err)
+                        err = device_create_file(dev, attr);
+                if (err) {
+                        device_destroy(dev->class, dev->devt);
+                        return -EINVAL;
+                }
+        }
+        dev_set_drvdata(dev, fi);
+        return 0;
+}
+#else
+static int create_alsa_device(struct usb_function_instance *fi)
+{
+        return 0;
+}
+#endif
+
 static struct usb_function_instance *f_midi_alloc_inst(void)
 {
         struct f_midi_opts *opts;
@@ -1240,6 +1299,11 @@ static struct usb_function_instance *f_midi_alloc_inst(void)
         opts->out_ports = 1;
         opts->refcnt = 1;
 
+        if (create_alsa_device(&opts->func_inst)) {
+                kfree(opts);
+                return ERR_PTR(-ENODEV);
+        }
+
         config_group_init_type_name(&opts->func_inst.group, "",
                                     &midi_func_type);
 
@@ -1260,6 +1324,7 @@ static void f_midi_free(struct usb_function *f)
                 kfifo_free(&midi->in_req_fifo);
                 kfree(midi);
                 free = true;
+                opts->func_inst.f = NULL;
         }
         mutex_unlock(&opts->lock);
 
@@ -1347,6 +1412,7 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
         midi->func.disable      = f_midi_disable;
         midi->func.free_func    = f_midi_free;
 
+        fi->f = &midi->func;
         return &midi->func;
 
 midi_free: