Commit fe625755 authored by Daniel Scally's avatar Daniel Scally Committed by Greg Kroah-Hartman
Browse files

usb: gadget: uvc: Allow linking function to string descs 



Currently the string descriptors for the IAD and VideoStreaming
Interfaces are hardcoded into f_uvc. Now that we can create arbitrary
string descriptors, add a mechanism to define string descriptors for
the IAD, VC and VS interfaces by linking to the appropriate directory
at function level.

Signed-off-by: default avatarDaniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230206161802.892954-11-dan.scally@ideasonboard.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9963f744

drivers/usb/gadget/function/u_uvc.h

+8 −0
Original line number Diff line number Diff line
@@ -82,6 +82,14 @@ struct f_uvc_opts { 
	struct uvc_descriptor_header			**uvc_hs_streaming_cls;

	struct uvc_descriptor_header			**uvc_ss_streaming_cls;



	/*

	 * Indexes into the function's string descriptors allowing users to set

	 * custom descriptions rather than the hard-coded defaults.

	 */

	u8						iad_index;

	u8						vs0_index;

	u8						vs1_index;



	/*

	 * Read/write access to configfs attributes is handled by configfs.

	 *

drivers/usb/gadget/function/uvc_configfs.c

+60 −0
Original line number Diff line number Diff line
@@ -3174,8 +3174,68 @@ static void uvc_func_item_release(struct config_item *item) 
	usb_put_function_instance(&opts->func_inst);

}



static int uvc_func_allow_link(struct config_item *src, struct config_item *tgt)

{

	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;

	struct gadget_string *string;

	struct config_item *strings;

	struct f_uvc_opts *opts;

	int ret = 0;



	mutex_lock(su_mutex); /* for navigating configfs hierarchy */



	/* Validate that the target is an entry in strings/<langid> */

	strings = config_group_find_item(to_config_group(src->ci_parent->ci_parent),

					 "strings");

	if (!strings || tgt->ci_parent->ci_parent != strings) {

		ret = -EINVAL;

		goto put_strings;

	}



	string = to_gadget_string(tgt);



	opts = to_f_uvc_opts(src);

	mutex_lock(&opts->lock);



	if (!strcmp(tgt->ci_name, "iad_desc"))

		opts->iad_index = string->usb_string.id;

	else if (!strcmp(tgt->ci_name, "vs0_desc"))

		opts->vs0_index = string->usb_string.id;

	else if (!strcmp(tgt->ci_name, "vs1_desc"))

		opts->vs1_index = string->usb_string.id;

	else

		ret = -EINVAL;



	mutex_unlock(&opts->lock);



put_strings:

	config_item_put(strings);

	mutex_unlock(su_mutex);



	return ret;

}



static void uvc_func_drop_link(struct config_item *src, struct config_item *tgt)

{

	struct f_uvc_opts *opts;



	opts = to_f_uvc_opts(src);

	mutex_lock(&opts->lock);



	if (!strcmp(tgt->ci_name, "iad_desc"))

		opts->iad_index = 0;

	else if (!strcmp(tgt->ci_name, "vs0_desc"))

		opts->vs0_index = 0;

	else if (!strcmp(tgt->ci_name, "vs1_desc"))

		opts->vs1_index = 0;



	mutex_unlock(&opts->lock);

}



static struct configfs_item_operations uvc_func_item_ops = {

	.release	= uvc_func_item_release,

	.allow_link	= uvc_func_allow_link,

	.drop_link	= uvc_func_drop_link,

};



#define UVCG_OPTS_ATTR(cname, aname, limit)				\