Re: [PATCH 3/4] usb: gadget: uvc: Allow definition of XUs in configfs

[Dan Scally <dan.scally@xxxxxxxxxxxxxxxx>]

Morning all

On 02/11/2022 15:17, Daniel Scally wrote:
> +
> +static struct configfs_attribute *uvcg_extension_attrs[] = {
> +	&uvcg_extension_attr_b_length,
> +	&uvcg_extension_attr_b_unit_id,
> +	&uvcg_extension_attr_b_num_controls,
> +	&uvcg_extension_attr_b_nr_in_pins,
> +	&uvcg_extension_attr_b_control_size,
> +	&uvcg_extension_attr_guid_extension_code,
> +	&uvcg_extension_attr_ba_source_id,
> +	&uvcg_extension_attr_bm_controls,
> +	NULL,
> +};
> +
> +static const struct config_item_type uvcg_extension_type = {
> +	.ct_item_ops	= &uvcg_config_item_ops,
> +	.ct_attrs	= uvcg_extension_attrs,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static void uvcg_extension_drop(struct config_group *group, struct config_item *item)
> +{
> +	struct uvcg_extension *xu = container_of(item, struct uvcg_extension, item);
> +	struct config_item *opts_item;
> +	struct f_uvc_opts *opts;
> +
> +	opts_item = group->cg_item.ci_parent->ci_parent;
> +	opts = to_f_uvc_opts(opts_item);
> +
> +	mutex_lock(&opts->lock);
> +
> +	config_item_put(item);
> +	list_del(&xu->list);
> +	kfree(xu->desc.baSourceID);
> +	kfree(xu->desc.bmControls);
> +	kfree(xu);


This should actually have gone in the .release() callback for the item - 
I'll fix that in v2.

> +
> +	mutex_unlock(&opts->lock);
> +}
> +
> +static struct config_item *uvcg_extension_make(struct config_group *group, const char *name)
> +{
> +	struct config_item *opts_item;
> +	struct uvcg_extension *xu;
> +	struct f_uvc_opts *opts;
> +
> +	opts_item = group->cg_item.ci_parent->ci_parent;
> +	opts = to_f_uvc_opts(opts_item);
> +
> +	mutex_lock(&opts->lock);
> +
> +	xu = kzalloc(sizeof(*xu), GFP_KERNEL);
> +	if (!xu)
> +		return ERR_PTR(-ENOMEM);
> +
> +	xu->desc.bLength = UVC_DT_EXTENSION_UNIT_SIZE(0, 0);
> +	xu->desc.bDescriptorType = USB_DT_CS_INTERFACE;
> +	xu->desc.bDescriptorSubType = UVC_VC_EXTENSION_UNIT;
> +	xu->desc.bUnitID = ++opts->last_unit_id;
> +	xu->desc.bNumControls = 0;
> +	xu->desc.bNrInPins = 0;
> +	xu->desc.baSourceID = NULL;
> +	xu->desc.bControlSize = 0;
> +	xu->desc.bmControls = NULL;
> +
> +	config_item_init_type_name(&xu->item, name, &uvcg_extension_type);
> +	list_add_tail(&xu->list, &opts->extension_units);
> +
> +	mutex_unlock(&opts->lock);
> +
> +	return &xu->item;
> +}
> +
> +static struct configfs_group_operations uvcg_extensions_grp_ops = {
> +	.make_item	= uvcg_extension_make,
> +	.drop_item	= uvcg_extension_drop,
> +};
> +
> +static const struct uvcg_config_group_type uvcg_extensions_grp_type = {
> +	.type = {
> +		.ct_item_ops	= &uvcg_config_item_ops,
> +		.ct_group_ops	= &uvcg_extensions_grp_ops,
> +		.ct_owner	= THIS_MODULE,
> +	},
> +	.name = "extensions",
> +};
> +
>   /* -----------------------------------------------------------------------------
>    * control/class/{fs|ss}
>    */
> @@ -844,6 +1255,7 @@ static const struct uvcg_config_group_type uvcg_control_grp_type = {
>   		&uvcg_processing_grp_type,
>   		&uvcg_terminal_grp_type,
>   		&uvcg_control_class_grp_type,
> +		&uvcg_extensions_grp_type,
>   		NULL,
>   	},
>   };
> diff --git a/drivers/usb/gadget/function/uvc_configfs.h b/drivers/usb/gadget/function/uvc_configfs.h
> index ad2ec8c4c78c..c9a4182fb26f 100644
> --- a/drivers/usb/gadget/function/uvc_configfs.h
> +++ b/drivers/usb/gadget/function/uvc_configfs.h
> @@ -132,6 +132,35 @@ static inline struct uvcg_mjpeg *to_uvcg_mjpeg(struct config_item *item)
>   	return container_of(to_uvcg_format(item), struct uvcg_mjpeg, fmt);
>   }
>   
> +/* -----------------------------------------------------------------------------
> + * control/extensions/<NAME>
> + */
> +
> +struct uvcg_extension_unit_descriptor {
> +	u8 bLength;
> +	u8 bDescriptorType;
> +	u8 bDescriptorSubType;
> +	u8 bUnitID;
> +	u8 guidExtensionCode[16];
> +	u8 bNumControls;
> +	u8 bNrInPins;
> +	u8 *baSourceID;
> +	u8 bControlSize;
> +	u8 *bmControls;
> +	u8 iExtension;
> +} __packed;
> +
> +struct uvcg_extension {
> +	struct config_item item;
> +	struct list_head list;
> +	struct uvcg_extension_unit_descriptor desc;
> +};
> +
> +static inline struct uvcg_extension *to_uvcg_extension(struct config_item *item)
> +{
> +	return container_of(item, struct uvcg_extension, item);
> +}
> +
>   int uvcg_attach_configfs(struct f_uvc_opts *opts);
>   
>   #endif /* UVC_CONFIGFS_H */