Index: uspace/drv/char/i8042/i8042.c
===================================================================
--- uspace/drv/char/i8042/i8042.c	(revision c657bd7f48e0cda0c4e65bc45f24367c51318513)
+++ uspace/drv/char/i8042/i8042.c	(revision 677cad5e3bf910241afff855ef729cbe70035d68)
@@ -67,6 +67,6 @@
 
 static void i8042_char_conn(ipc_callid_t, ipc_call_t *, void *);
-static int i8042_read(chardev_srv_t *, void *, size_t);
-static int i8042_write(chardev_srv_t *, const void *, size_t);
+static int i8042_read(chardev_srv_t *, void *, size_t, size_t *);
+static int i8042_write(chardev_srv_t *, const void *, size_t, size_t *);
 
 static chardev_ops_t i8042_chardev_ops = {
@@ -333,9 +333,11 @@
  * @param buffer Data source
  * @param size   Data size
- *
- * @return Bytes written.
- *
- */
-static int i8042_write(chardev_srv_t *srv, const void *data, size_t size)
+ * @param nwr    Place to store number of bytes successfully written
+ *
+ * @return EOK on success or non-zero error code
+ *
+ */
+static int i8042_write(chardev_srv_t *srv, const void *data, size_t size,
+    size_t *nwr)
 {
 	i8042_port_t *port = (i8042_port_t *)srv->srvs->sarg;
@@ -357,5 +359,6 @@
 	
 	fibril_mutex_unlock(&i8042->write_guard);
-	return size;
+	*nwr = size;
+	return EOK;
 }
 
@@ -365,9 +368,11 @@
  * @param buffer Data place
  * @param size   Data place size
- *
- * @return Bytes read.
- *
- */
-static int i8042_read(chardev_srv_t *srv, void *dest, size_t size)
+ * @param nread  Place to store number of bytes successfully read
+ *
+ * @return EOK on success or non-zero error code
+ *
+ */
+static int i8042_read(chardev_srv_t *srv, void *dest, size_t size,
+    size_t *nread)
 {
 	i8042_port_t *port = (i8042_port_t *)srv->srvs->sarg;
@@ -387,5 +392,6 @@
 	}
 	
-	return i;
+	*nread = i;
+	return EOK;
 }
 
Index: uspace/drv/char/pl050/pl050.c
===================================================================
--- uspace/drv/char/pl050/pl050.c	(revision c657bd7f48e0cda0c4e65bc45f24367c51318513)
+++ uspace/drv/char/pl050/pl050.c	(revision 677cad5e3bf910241afff855ef729cbe70035d68)
@@ -54,6 +54,6 @@
 static int pl050_fun_offline(ddf_fun_t *);
 static void pl050_char_conn(ipc_callid_t, ipc_call_t *, void *);
-static int pl050_read(chardev_srv_t *, void *, size_t);
-static int pl050_write(chardev_srv_t *, const void *, size_t);
+static int pl050_read(chardev_srv_t *, void *, size_t, size_t *);
+static int pl050_write(chardev_srv_t *, const void *, size_t, size_t *);
 
 static driver_ops_t driver_ops = {
@@ -236,5 +236,6 @@
 }
 
-static int pl050_read(chardev_srv_t *srv, void *buffer, size_t size)
+static int pl050_read(chardev_srv_t *srv, void *buffer, size_t size,
+    size_t *nread)
 {
 	pl050_t *pl050 = (pl050_t *)srv->srvs->sarg;
@@ -257,8 +258,10 @@
 	fibril_mutex_unlock(&pl050->buf_lock);
 
-	return size - left;
-}
-
-static int pl050_write(chardev_srv_t *srv, const void *data, size_t size)
+	*nread = size - left;
+	return EOK;
+}
+
+static int pl050_write(chardev_srv_t *srv, const void *data, size_t size,
+    size_t *nwritten)
 {
 	pl050_t *pl050 = (pl050_t *)srv->srvs->sarg;
@@ -278,5 +281,6 @@
 	ddf_msg(LVL_NOTE, "%s/pl050_write() success", pl050->name);
 
-	return size;
+	*nwritten = size;
+	return EOK;
 }