usb: gadget: uvc: Allow creating new color matching descriptors

Allow users to create new color matching descriptors in addition to
the default one. These must be associated with a UVC format in order
to be transmitted to the host, which is achieved by symlinking from
the format to the newly created color matching descriptor - extend
the uncompressed and mjpeg formats to support that linking operation.

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230202114142.300858-7-dan.scally@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvc
index ef3b8b852cd2492f6accc53c17f800f122ca7625..fec205044c87e91c68f2bae6484818560e605048 100644 (file)
--- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
@@ -179,6 +179,23 @@ Description:       Default color matching descriptors
                                          white
                ========================  ======================================
 
+What:          /config/usb-gadget/gadget/functions/uvc.name/streaming/color_matching/name
+Date:          Dec 2022
+KernelVersion: 6.3
+Description:   Additional color matching descriptors
+
+               All attributes read/write:
+
+               ========================  ======================================
+               bMatrixCoefficients       matrix used to compute luma and
+                                         chroma values from the color primaries
+               bTransferCharacteristics  optoelectronic transfer
+                                         characteristic of the source picture,
+                                         also called the gamma function
+               bColorPrimaries           color primaries and the reference
+                                         white
+               ========================  ======================================
+
 What:          /config/usb-gadget/gadget/functions/uvc.name/streaming/mjpeg
 Date:          Dec 2014
 KernelVersion: 4.0

diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index a210b199008085c7e36645548e87dcc010f0e8fa..e2ffddb969fd3f95b69f5212d587ec20aee3786a 100644 (file)
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -824,6 +824,77 @@ uvcg_format_get_default_color_match(struct config_item *streaming)
        return color_match;
 }
 
+static int uvcg_format_allow_link(struct config_item *src, struct config_item *tgt)
+{
+       struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+       struct uvcg_color_matching *color_matching_desc;
+       struct config_item *streaming, *color_matching;
+       struct uvcg_format *fmt;
+       int ret = 0;
+
+       mutex_lock(su_mutex);
+
+       streaming = src->ci_parent->ci_parent;
+       color_matching = config_group_find_item(to_config_group(streaming), "color_matching");
+       if (!color_matching || color_matching != tgt->ci_parent) {
+               ret = -EINVAL;
+               goto out_put_cm;
+       }
+
+       fmt = to_uvcg_format(src);
+
+       /*
+        * There's always a color matching descriptor associated with the format
+        * but without a symlink it should only ever be the default one. If it's
+        * not the default, there's already a symlink and we should bail out.
+        */
+       color_matching_desc = uvcg_format_get_default_color_match(streaming);
+       if (fmt->color_matching != color_matching_desc) {
+               ret = -EBUSY;
+               goto out_put_cm;
+       }
+
+       color_matching_desc->refcnt--;
+
+       color_matching_desc = to_uvcg_color_matching(to_config_group(tgt));
+       fmt->color_matching = color_matching_desc;
+       color_matching_desc->refcnt++;
+
+out_put_cm:
+       config_item_put(color_matching);
+       mutex_unlock(su_mutex);
+
+       return ret;
+}
+
+static void uvcg_format_drop_link(struct config_item *src, struct config_item *tgt)
+{
+       struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+       struct uvcg_color_matching *color_matching_desc;
+       struct config_item *streaming;
+       struct uvcg_format *fmt;
+
+       mutex_lock(su_mutex);
+
+       color_matching_desc = to_uvcg_color_matching(to_config_group(tgt));
+       color_matching_desc->refcnt--;
+
+       streaming = src->ci_parent->ci_parent;
+       color_matching_desc = uvcg_format_get_default_color_match(streaming);
+
+       fmt = to_uvcg_format(src);
+       fmt->color_matching = color_matching_desc;
+       color_matching_desc->refcnt++;
+
+       mutex_unlock(su_mutex);
+}
+
+static struct configfs_item_operations uvcg_format_item_operations = {
+       .release        = uvcg_config_item_release,
+       .allow_link     = uvcg_format_allow_link,
+       .drop_link      = uvcg_format_drop_link,
+};
+
 static ssize_t uvcg_format_bma_controls_show(struct uvcg_format *f, char *page)
 {
        struct f_uvc_opts *opts;
@@ -1624,7 +1695,7 @@ static struct configfs_attribute *uvcg_uncompressed_attrs[] = {
 };
 
 static const struct config_item_type uvcg_uncompressed_type = {
-       .ct_item_ops    = &uvcg_config_item_ops,
+       .ct_item_ops    = &uvcg_format_item_operations,
        .ct_group_ops   = &uvcg_uncompressed_group_ops,
        .ct_attrs       = uvcg_uncompressed_attrs,
        .ct_owner       = THIS_MODULE,
@@ -1820,7 +1891,7 @@ static struct configfs_attribute *uvcg_mjpeg_attrs[] = {
 };
 
 static const struct config_item_type uvcg_mjpeg_type = {
-       .ct_item_ops    = &uvcg_config_item_ops,
+       .ct_item_ops    = &uvcg_format_item_operations,
        .ct_group_ops   = &uvcg_mjpeg_group_ops,
        .ct_attrs       = uvcg_mjpeg_attrs,
        .ct_owner       = THIS_MODULE,
@@ -1978,6 +2049,29 @@ static const struct config_item_type uvcg_color_matching_type = {
  * streaming/color_matching
  */
 
+static struct config_group *uvcg_color_matching_make(struct config_group *group,
+                                                    const char *name)
+{
+       struct uvcg_color_matching *color_match;
+
+       color_match = kzalloc(sizeof(*color_match), GFP_KERNEL);
+       if (!color_match)
+               return ERR_PTR(-ENOMEM);
+
+       color_match->desc.bLength = UVC_DT_COLOR_MATCHING_SIZE;
+       color_match->desc.bDescriptorType = USB_DT_CS_INTERFACE;
+       color_match->desc.bDescriptorSubType = UVC_VS_COLORFORMAT;
+
+       config_group_init_type_name(&color_match->group, name,
+                                   &uvcg_color_matching_type);
+
+       return &color_match->group;
+}
+
+static struct configfs_group_operations uvcg_color_matching_grp_group_ops = {
+       .make_group     = uvcg_color_matching_make,
+};
+
 static int uvcg_color_matching_create_children(struct config_group *parent)
 {
        struct uvcg_color_matching *color_match;
@@ -2003,6 +2097,7 @@ static int uvcg_color_matching_create_children(struct config_group *parent)
 static const struct uvcg_config_group_type uvcg_color_matching_grp_type = {
        .type = {
                .ct_item_ops    = &uvcg_config_item_ops,
+               .ct_group_ops   = &uvcg_color_matching_grp_group_ops,
                .ct_owner       = THIS_MODULE,
        },
        .name = "color_matching",