USB: gadget: composite: Process GetDescriptor(OTG) request
If gadget is OTG capable, respond to a GetDescriptor(OTG) request
with its OTG descriptor. This patch adds a utility to function
to find and fill the requested descriptor.
Change-Id: I5b3624b1145d46179b0c4737e82a47c68604cab4
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>
diff --git a/drivers/usb/gadget/config.c b/drivers/usb/gadget/config.c
index 09084fd..384332c 100644
--- a/drivers/usb/gadget/config.c
+++ b/drivers/usb/gadget/config.c
@@ -28,6 +28,40 @@
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
+/**
+ * usb_find_descriptor_fillbuf - fill buffer with the requested descriptor
+ * @buf: Buffer to be filled
+ * @buflen: Size of buf
+ * @src: Array of descriptor pointers, terminated by null pointer.
+ * @desc_type: bDescriptorType field of the requested descriptor.
+ *
+ * Copies the requested descriptor into the buffer, returning the length
+ * or a negative error code if it is not found or can't be copied. Useful
+ * when DT_OTG descriptor is requested.
+ */
+int
+usb_find_descriptor_fillbuf(void *buf, unsigned buflen,
+ const struct usb_descriptor_header **src, u8 desc_type)
+{
+ if (!src)
+ return -EINVAL;
+
+ for (; NULL != *src; src++) {
+ unsigned len;
+
+ if ((*src)->bDescriptorType != desc_type)
+ continue;
+
+ len = (*src)->bLength;
+ if (len > buflen)
+ return -EINVAL;
+
+ memcpy(buf, *src, len);
+ return len;
+ }
+
+ return -ENOENT;
+}
/**
* usb_descriptor_fillbuf - fill buffer with descriptors