From 08ddd71bf020c3b713d343959df39bf8a48ddd0b Mon Sep 17 00:00:00 2001 From: Daniel Scally Date: Mon, 6 Feb 2023 16:17:59 +0000 Subject: [PATCH] usb: gadget: uvc: Allow linking XUs to string descriptors Add .allow_link() and .drop_link() callbacks to allow users to link an extension unit descriptor to a string descriptor. Signed-off-by: Daniel Scally Link: https://lore.kernel.org/r/20230206161802.892954-9-dan.scally@ideasonboard.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/uvc_configfs.c | 52 ++++++++++++++++++++++ drivers/usb/gadget/function/uvc_configfs.h | 1 + 2 files changed, 53 insertions(+) diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c index c365f323af45..3ac27838514c 100644 --- a/drivers/usb/gadget/function/uvc_configfs.c +++ b/drivers/usb/gadget/function/uvc_configfs.c @@ -1064,8 +1064,60 @@ static void uvcg_extension_release(struct config_item *item) kfree(xu); } +static int uvcg_extension_allow_link(struct config_item *src, struct config_item *tgt) +{ + struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex; + struct uvcg_extension *xu = to_uvcg_extension(src); + struct config_item *gadget_item; + struct gadget_string *string; + struct config_item *strings; + int ret = 0; + + mutex_lock(su_mutex); /* for navigating configfs hierarchy */ + + /* Validate that the target of the link is an entry in strings/ */ + gadget_item = src->ci_parent->ci_parent->ci_parent->ci_parent->ci_parent; + strings = config_group_find_item(to_config_group(gadget_item), "strings"); + if (!strings || tgt->ci_parent->ci_parent != strings) { + ret = -EINVAL; + goto put_strings; + } + + string = to_gadget_string(tgt); + xu->string_descriptor_index = string->usb_string.id; + +put_strings: + config_item_put(strings); + mutex_unlock(su_mutex); + + return ret; +} + +static void uvcg_extension_drop_link(struct config_item *src, struct config_item *tgt) +{ + struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex; + struct uvcg_extension *xu = to_uvcg_extension(src); + struct config_item *opts_item; + struct f_uvc_opts *opts; + + mutex_lock(su_mutex); /* for navigating configfs hierarchy */ + + opts_item = src->ci_parent->ci_parent->ci_parent; + opts = to_f_uvc_opts(opts_item); + + mutex_lock(&opts->lock); + + xu->string_descriptor_index = 0; + + mutex_unlock(&opts->lock); + + mutex_unlock(su_mutex); +} + static struct configfs_item_operations uvcg_extension_item_ops = { .release = uvcg_extension_release, + .allow_link = uvcg_extension_allow_link, + .drop_link = uvcg_extension_drop_link, }; static const struct config_item_type uvcg_extension_type = { diff --git a/drivers/usb/gadget/function/uvc_configfs.h b/drivers/usb/gadget/function/uvc_configfs.h index 5557813bcca9..c6a690158138 100644 --- a/drivers/usb/gadget/function/uvc_configfs.h +++ b/drivers/usb/gadget/function/uvc_configfs.h @@ -163,6 +163,7 @@ struct uvcg_extension_unit_descriptor { struct uvcg_extension { struct config_item item; struct list_head list; + u8 string_descriptor_index; struct uvcg_extension_unit_descriptor desc; };