Index: uspace/lib/usbhost/src/iface.c
===================================================================
--- uspace/lib/usbhost/src/iface.c	(revision 02fc5c403d52648f5ee6dcf5158ad19197c73795)
+++ uspace/lib/usbhost/src/iface.c	(revision 0b8a3e71b801831700b7f6d1c48c084755775ddd)
@@ -39,4 +39,14 @@
 #include <usb/host/hcd.h>
 
+/** Prepare generic usb_transfer_batch and schedule it.
+ * @param fun DDF fun
+ * @param target address and endpoint number.
+ * @param setup_data Data to use in setup stage (Control communication type)
+ * @param in Callback for device to host communication.
+ * @param out Callback for host to device communication.
+ * @param arg Callback parameter.
+ * @param name Communication identifier (for nicer output).
+ * @return Error code.
+ */
 static inline int send_batch(
     ddf_fun_t *fun, usb_target_t target, usb_direction_t direction,
@@ -89,4 +99,9 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Calls ep_add_hook upon endpoint registration.
+ * @param ep Endpoint to be registered.
+ * @param arg hcd_t in disguise.
+ * @return Error code.
+ */
 static int register_helper(endpoint_t *ep, void *arg)
 {
@@ -99,4 +114,8 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Calls ep_remove_hook upon endpoint removal.
+ * @param ep Endpoint to be unregistered.
+ * @param arg hcd_t in disguise.
+ */
 static void unregister_helper(endpoint_t *ep, void *arg)
 {
@@ -108,4 +127,8 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Calls ep_remove_hook upon endpoint removal. Prints warning.
+ * @param ep Endpoint to be unregistered.
+ * @param arg hcd_t in disguise.
+ */
 static void unregister_helper_warn(endpoint_t *ep, void *arg)
 {
@@ -119,9 +142,11 @@
 }
 /*----------------------------------------------------------------------------*/
-/** Request address interface function
+/** Request address interface function.
  *
  * @param[in] fun DDF function that was called.
+ * @param[in] address Pointer to preferred USB address.
+ * @param[out] address Place to write a new address.
+ * @param[in] strict Fail if the preferred address is not available.
  * @param[in] speed Speed to associate with the new default address.
- * @param[out] address Place to write a new address.
  * @return Error code.
  */
@@ -140,5 +165,5 @@
 }
 /*----------------------------------------------------------------------------*/
-/** Bind address interface function
+/** Bind address interface function.
  *
  * @param[in] fun DDF function that was called.
@@ -148,5 +173,5 @@
  */
 static int bind_address(
-  ddf_fun_t *fun, usb_address_t address, devman_handle_t handle)
+    ddf_fun_t *fun, usb_address_t address, devman_handle_t handle)
 {
 	assert(fun);
@@ -176,5 +201,5 @@
 }
 /*----------------------------------------------------------------------------*/
-/** Release address interface function
+/** Release address interface function.
  *
  * @param[in] fun DDF function that was called.
@@ -194,8 +219,18 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Register endpoint interface function.
+ * @param fun DDF function.
+ * @param address USB address of the device.
+ * @param endpoint USB endpoint number to be registered.
+ * @param transfer_type Endpoint's transfer type.
+ * @param direction USB communication direction the endpoint is capable of.
+ * @param max_packet_size Maximu size of packets the endpoint accepts.
+ * @param interval Preferred timeout between communication.
+ * @return Error code.
+ */
 static int register_endpoint(
     ddf_fun_t *fun, usb_address_t address, usb_endpoint_t endpoint,
     usb_transfer_type_t transfer_type, usb_direction_t direction,
-    size_t max_packet_size, unsigned int interval)
+    size_t max_packet_size, unsigned interval)
 {
 	assert(fun);
@@ -220,4 +255,11 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Unregister endpoint interface function.
+ * @param fun DDF function.
+ * @param address USB address of the endpoint.
+ * @param endpoint USB endpoint number.
+ * @param direction Communication direction of the enpdoint to unregister.
+ * @return Error code.
+ */
 static int unregister_endpoint(
     ddf_fun_t *fun, usb_address_t address,
@@ -233,4 +275,14 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Inbound communication interface function.
+ * @param fun DDF function.
+ * @param target Communication target.
+ * @param setup_data Data to use in setup stage (control transfers).
+ * @param data Pointer to data buffer.
+ * @param size Size of the data buffer.
+ * @param callback Function to call on communication end.
+ * @param arg Argument passed to the callback function.
+ * @return Error code.
+ */
 static int usb_read(ddf_fun_t *fun, usb_target_t target, uint64_t setup_data,
     uint8_t *data, size_t size, usbhc_iface_transfer_in_callback_t callback,
@@ -241,4 +293,14 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Outbound communication interface function.
+ * @param fun DDF function.
+ * @param target Communication target.
+ * @param setup_data Data to use in setup stage (control transfers).
+ * @param data Pointer to data buffer.
+ * @param size Size of the data buffer.
+ * @param callback Function to call on communication end.
+ * @param arg Argument passed to the callback function.
+ * @return Error code.
+ */
 static int usb_write(ddf_fun_t *fun, usb_target_t target, uint64_t setup_data,
     const uint8_t *data, size_t size,
@@ -249,4 +311,5 @@
 }
 /*----------------------------------------------------------------------------*/
+/** usbhc Interface implementation using hcd_t from libusbhost library. */
 usbhc_iface_t hcd_iface = {
 	.request_address = request_address,