Index: uspace/lib/c/generic/as.c
===================================================================
--- uspace/lib/c/generic/as.c	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/generic/as.c	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -35,4 +35,5 @@
 #include <as.h>
 #include <libc.h>
+#include <errno.h>
 #include <unistd.h>
 #include <align.h>
@@ -114,4 +115,30 @@
 }
 
+/** Find mapping to physical address.
+ *
+ * @param address Virtual address in question (virtual).
+ * @param[out] frame Frame address (physical).
+ * @return Error code.
+ * @retval EOK No error, @p frame holds the translation.
+ * @retval ENOENT Mapping not found.
+ */
+int as_get_physical_mapping(void *address, uintptr_t *frame)
+{
+	uintptr_t tmp_frame;
+	uintptr_t virt = (uintptr_t) address;
+	
+	int rc = (int) __SYSCALL2(SYS_PAGE_FIND_MAPPING,
+	    (sysarg_t) virt, (sysarg_t) &tmp_frame);
+	if (rc != EOK) {
+		return rc;
+	}
+	
+	if (frame != NULL) {
+		*frame = tmp_frame;
+	}
+	
+	return EOK;
+}
+
 /** @}
  */
Index: uspace/lib/c/generic/async.c
===================================================================
--- uspace/lib/c/generic/async.c	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/generic/async.c	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -1567,4 +1567,18 @@
 }
 
+/** Start IPC_M_DATA_READ using the async framework.
+ *
+ * @param phoneid Phone that will be used to contact the receiving side.
+ * @param dst Address of the beginning of the destination buffer.
+ * @param size Size of the destination buffer (in bytes).
+ * @param dataptr Storage of call data (arg 2 holds actual data size).
+ * @return Hash of the sent message or 0 on error.
+ */
+aid_t async_data_read(int phoneid, void *dst, size_t size, ipc_call_t *dataptr)
+{
+	return async_send_2(phoneid, IPC_M_DATA_READ, (sysarg_t) dst,
+	    (sysarg_t) size, dataptr);
+}
+
 /** Wrapper for IPC_M_DATA_READ calls using the async framework.
  *
Index: uspace/lib/c/generic/str_error.c
===================================================================
--- uspace/lib/c/generic/str_error.c	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/generic/str_error.c	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -33,4 +33,5 @@
  */
 
+#include <errno.h>
 #include <str_error.h>
 #include <stdio.h>
@@ -63,10 +64,22 @@
 static fibril_local char noerr[NOERR_LEN];
 
-const char *str_error(const int errno)
+const char *str_error(const int e)
 {
-	if ((errno <= 0) && (errno >= MIN_ERRNO))
-		return err_desc[-errno];
+	if ((e <= 0) && (e >= MIN_ERRNO))
+		return err_desc[-e];
 	
-	snprintf(noerr, NOERR_LEN, "Unkown error code %d", errno);
+	/* Ad hoc descriptions of error codes interesting for USB. */
+	switch (e) {
+		case EBADCHECKSUM:
+			return "Bad checksum";
+		case ESTALL:
+			return "Operation stalled";
+		case EAGAIN:
+			return "Resource temporarily unavailable";
+		default:
+			break;
+	}
+
+	snprintf(noerr, NOERR_LEN, "Unkown error code %d", e);
 	return noerr;
 }
Index: uspace/lib/c/include/as.h
===================================================================
--- uspace/lib/c/include/as.h	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/include/as.h	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -60,4 +60,5 @@
 extern void *set_maxheapsize(size_t mhs);
 extern void * as_get_mappable_page(size_t sz);
+extern int as_get_physical_mapping(void *address, uintptr_t *frame);
 
 #endif
Index: uspace/lib/c/include/async.h
===================================================================
--- uspace/lib/c/include/async.h	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/include/async.h	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -340,4 +340,5 @@
 	    (arg4), (answer))
 
+extern aid_t async_data_read(int, void *, size_t, ipc_call_t *);
 extern int async_data_read_start(int, void *, size_t);
 extern bool async_data_read_receive(ipc_callid_t *, size_t *);
Index: uspace/lib/c/include/errno.h
===================================================================
--- uspace/lib/c/include/errno.h	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/include/errno.h	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -56,4 +56,10 @@
 #define EMLINK        (-266)
 
+/** Bad checksum. */
+#define EBADCHECKSUM  (-300)
+
+/** USB: stalled operation. */
+#define ESTALL (-301)
+
 /** An API function is called while another blocking function is in progress. */
 #define EINPROGRESS  (-10036)
Index: uspace/lib/c/include/ipc/dev_iface.h
===================================================================
--- uspace/lib/c/include/ipc/dev_iface.h	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/include/ipc/dev_iface.h	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -37,4 +37,10 @@
 	HW_RES_DEV_IFACE = 0,
 	CHAR_DEV_IFACE,
+
+	/** Interface provided by any USB device. */
+	USB_DEV_IFACE,
+	/** Interface provided by USB host controller. */
+	USBHC_DEV_IFACE,
+
 	DEV_IFACE_MAX
 } dev_inferface_idx_t;
@@ -48,4 +54,14 @@
 	DEV_IFACE_ID(DEV_FIRST_CUSTOM_METHOD_IDX)
 
+/*
+ * The first argument is actually method (as the "real" method is used
+ * for indexing into interfaces.
+ */
+
+#define DEV_IPC_GET_ARG1(call) IPC_GET_ARG2((call))
+#define DEV_IPC_GET_ARG2(call) IPC_GET_ARG3((call))
+#define DEV_IPC_GET_ARG3(call) IPC_GET_ARG4((call))
+#define DEV_IPC_GET_ARG4(call) IPC_GET_ARG5((call))
+
 
 #endif
Index: uspace/lib/c/include/ipc/kbd.h
===================================================================
--- uspace/lib/c/include/ipc/kbd.h	(revision a99330e895a4dda435b60de880a00bc40762016a)
+++ uspace/lib/c/include/ipc/kbd.h	(revision 071b5f8b430d55dd20be1939acd8b6ab73672e65)
@@ -39,7 +39,8 @@
 
 #include <ipc/common.h>
+#include <ipc/dev_iface.h>
 
 typedef enum {
-	KBD_YIELD = IPC_FIRST_USER_METHOD,
+	KBD_YIELD = DEV_FIRST_CUSTOM_METHOD,
 	KBD_RECLAIM
 } kbd_request_t;