usb: gadget: uvc: Make bSourceID read/write

At the moment, the UVC function graph is hardcoded IT -> PU -> OT.
To add XU support we need the ability to insert the XU descriptors
into the chain. To facilitate that, make the output terminal's
bSourceID attribute writeable so that we can configure its source.

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230206161802.892954-2-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 9c716dd3ae6f378330d43891d4d0e99f310deed9..c2323f2b069b8ed79e84d39ac8657cd314e9586d 100644 (file)
--- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
@@ -54,7 +54,7 @@ Date:         Dec 2014
 KernelVersion: 4.0
 Description:   Default output terminal descriptors
 
-               All attributes read only:
+               All attributes read only except bSourceID:
 
                ==============  =============================================
                iTerminal       index of string descriptor

diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index e2ffddb969fd3f95b69f5212d587ec20aee3786a..b52aae924d662e228aaf5b44b3dacbd690ee45b3 100644 (file)
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -484,11 +484,68 @@ UVC_ATTR_RO(uvcg_default_output_, cname, aname)
 UVCG_DEFAULT_OUTPUT_ATTR(b_terminal_id, bTerminalID, 8);
 UVCG_DEFAULT_OUTPUT_ATTR(w_terminal_type, wTerminalType, 16);
 UVCG_DEFAULT_OUTPUT_ATTR(b_assoc_terminal, bAssocTerminal, 8);
-UVCG_DEFAULT_OUTPUT_ATTR(b_source_id, bSourceID, 8);
 UVCG_DEFAULT_OUTPUT_ATTR(i_terminal, iTerminal, 8);
 
 #undef UVCG_DEFAULT_OUTPUT_ATTR
 
+static ssize_t uvcg_default_output_b_source_id_show(struct config_item *item,
+                                                   char *page)
+{
+       struct config_group *group = to_config_group(item);
+       struct f_uvc_opts *opts;
+       struct config_item *opts_item;
+       struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+       struct uvc_output_terminal_descriptor *cd;
+       int result;
+
+       mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+       opts_item = group->cg_item.ci_parent->ci_parent->
+                       ci_parent->ci_parent;
+       opts = to_f_uvc_opts(opts_item);
+       cd = &opts->uvc_output_terminal;
+
+       mutex_lock(&opts->lock);
+       result = sprintf(page, "%u\n", le8_to_cpu(cd->bSourceID));
+       mutex_unlock(&opts->lock);
+
+       mutex_unlock(su_mutex);
+
+       return result;
+}
+
+static ssize_t uvcg_default_output_b_source_id_store(struct config_item *item,
+                                                    const char *page, size_t len)
+{
+       struct config_group *group = to_config_group(item);
+       struct f_uvc_opts *opts;
+       struct config_item *opts_item;
+       struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+       struct uvc_output_terminal_descriptor *cd;
+       int result;
+       u8 num;
+
+       mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+       opts_item = group->cg_item.ci_parent->ci_parent->
+                       ci_parent->ci_parent;
+       opts = to_f_uvc_opts(opts_item);
+       cd = &opts->uvc_output_terminal;
+
+       result = kstrtou8(page, 0, &num);
+       if (result)
+               return result;
+
+       mutex_lock(&opts->lock);
+       cd->bSourceID = num;
+       mutex_unlock(&opts->lock);
+
+       mutex_unlock(su_mutex);
+
+       return len;
+}
+UVC_ATTR(uvcg_default_output_, b_source_id, bSourceID);
+
 static struct configfs_attribute *uvcg_default_output_attrs[] = {
        &uvcg_default_output_attr_b_terminal_id,
        &uvcg_default_output_attr_w_terminal_type,