usb: gadget: uvc: add v4l2 enumeration api calls

This patch adds support to the v4l2 VIDIOCs for enum_format,
enum_framesizes and enum_frameintervals. This way, the userspace
application can use these VIDIOCS to query the via configfs exported
frame capabilities. With thes callbacks the userspace doesn't have to
bring its own configfs parser.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220909221335.15033-4-m.grzeschik@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index 09961f4ca981..e6948cf8def3 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -888,6 +888,7 @@ static void uvc_free(struct usb_function *f)
 	struct uvc_device *uvc = to_uvc(f);
 	struct f_uvc_opts *opts = container_of(f->fi, struct f_uvc_opts,
 					       func_inst);
+	config_item_put(&uvc->header->item);
 	--opts->refcnt;
 	kfree(uvc);
 }
@@ -945,6 +946,7 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
 	struct uvc_device *uvc;
 	struct f_uvc_opts *opts;
 	struct uvc_descriptor_header **strm_cls;
+	struct config_item *streaming, *header, *h;
 
 	uvc = kzalloc(sizeof(*uvc), GFP_KERNEL);
 	if (uvc == NULL)
@@ -977,6 +979,29 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
 	uvc->desc.fs_streaming = opts->fs_streaming;
 	uvc->desc.hs_streaming = opts->hs_streaming;
 	uvc->desc.ss_streaming = opts->ss_streaming;
+
+	streaming = config_group_find_item(&opts->func_inst.group, "streaming");
+	if (!streaming)
+		goto err_config;
+
+	header = config_group_find_item(to_config_group(streaming), "header");
+	config_item_put(streaming);
+	if (!header)
+		goto err_config;
+
+	h = config_group_find_item(to_config_group(header), "h");
+	config_item_put(header);
+	if (!h)
+		goto err_config;
+
+	uvc->header = to_uvcg_streaming_header(h);
+	config_item_put(h);
+	if (!uvc->header->linked) {
+		mutex_unlock(&opts->lock);
+		kfree(uvc);
+		return ERR_PTR(-EBUSY);
+	}
+
 	++opts->refcnt;
 	mutex_unlock(&opts->lock);
 
@@ -992,6 +1017,11 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
 	uvc->func.bind_deactivated = true;
 
 	return &uvc->func;
+
+err_config:
+	mutex_unlock(&opts->lock);
+	kfree(uvc);
+	return ERR_PTR(-ENOENT);
 }
 
 DECLARE_USB_FUNCTION_INIT(uvc, uvc_alloc_inst, uvc_alloc);