usb: document revision and typo fixing

This slightly revised the USB host documentation and fixed typos
encountered in the document and some source files.

Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>

Documentation/components/drivers/special/usbhost.rst

@@ -2,36 +2,36 @@
 USB Host-Side Drivers
 =====================
 
--  ``include/nuttx/usb/usbhost.h``. All structures and APIs
+-  **USB host controller driver** abstracts the host controller
-   needed to work with USB host-side drivers are provided in this
+   device in the target chip. Each USB host controller driver
-   header file.
+   must implement an instance of ``struct usbhost_driver_s`` and
+   ``struct usbhost_connection_s`` defined in
+   ``include/nuttx/usb/usbhost.h``.
+
+   -  ``struct usbhost_driver_s`` provides the interface between 
+      the USB host driver and the USB host class driver.
+
+   -  ``struct usbhost_connection_s`` provides the interface between
+      the USB host driver and platform-specific connection management
+      and device enumeration logic.
 
--  ``struct usbhost_driver_s`` and
-   ``struct usbhost_connection_s``. Each USB host controller
-   driver must implement an instance of
-   ``struct usbhost_driver_s`` and
-   ``struct usbhost_connection_s``: ``struct usbhost_driver_s``
-   provides the interface between the USB host driver and the USB
-   class driver; ``struct usbhost_connection_s`` provides the
-   interface between the USB host driver and platform-specific
-   connection management and device enumeration logic. These
-   structures are defined in ``include/nuttx/usb/usbhost.h``.
 
    **Examples**: ``arch/arm/src/lpc17xx_40xx/lpc17_40_usbhost.c``,
    ``arch/arm/src/stm32/stm32_otgfshost.c``,
    ``arch/arm/src/sama5/sam_ohci.c``, and
    ``arch/arm/src/sama5/sam_ehci.c``.
 
--  ``struct usbhost_class_s``. Each USB host class driver must
+-  **USB host class driver** abstracts USB peripherals conected to
-   implement an instance of ``struct usbhost_class_s``. This
+   the USB host controller. Each USB host class driver must implement
-   structure is also defined in ``include/nuttx/usb/usbhost.h``.
+   an instance of ``struct usbhost_class_s`` defined also in
+   ``include/nuttx/usb/usbhost.h``.
 
    **Examples**: ``drivers/usbhost/usbhost_storage.c``
 
 -  **USB Host Class Driver Registry**. The NuttX USB host
    infrastructure includes a *registry*. During its
    initialization, each USB host class driver must call the
-   interface, ``usbhost_registerclass()`` in order add its
+   interface, ``usbhost_registerclass()`` in order to add its
    interface to the registry. Later, when a USB device is
    connected, the USB host controller will look up the USB host
    class driver that is needed to support the connected device in
@@ -84,7 +84,7 @@ USB Host-Side Drivers
       **Examples**: The function ``usbhost_msc_initialize()`` in
       the file ``drivers/usbhost/usbhost_storage.c``
 
-   #. Each application must include a *waiter* thread thread that
+   #. Each application must include a *waiter* thread that
       (1) calls the USB host controller driver's ``wait()`` to
       detect the connection of a device, and then (2) call the USB
       host controller driver's ``enumerate`` method to bind the

drivers/usbdev/cdcecm.c

@@ -348,8 +348,8 @@ static int cdcecm_txpoll(FAR struct net_driver_s *dev)
  *
  * Description:
  *   After a packet has been received and dispatched to the network, it
- *   may return return with an outgoing packet.  This function checks for
+ *   may return with an outgoing packet.  This function checks for that
- *   that case and performs the transmission if necessary.
+ *   case and performs the transmission if necessary.
  *
  * Input Parameters:
  *   priv - Reference to the driver state structure
@@ -401,7 +401,7 @@ static void cdcecm_receive(FAR struct cdcecm_driver_s *self)
    * configuration.
    */
 
-  /* Copy the data data from the hardware to self->dev.d_buf.  Set
+  /* Copy the data from the hardware to self->dev.d_buf.  Set
    * amount of data in self->dev.d_len
    */
 

drivers/usbhost/usbhost_cdcmbim.c

@@ -256,6 +256,7 @@ static void usbhost_notification_work(FAR void *arg);
 static void usbhost_notification_callback(FAR void *arg, ssize_t nbytes);
 static void usbhost_rxdata_work(FAR void *arg);
 static void usbhost_bulkin_work(FAR void *arg);
+static void usbhost_bulkin_callback(FAR void *arg, ssize_t nbytes);
 
 static void usbhost_destroy(FAR void *arg);
 

drivers/usbhost/usbhost_skeleton.c

@@ -53,8 +53,8 @@
 
 /* Driver support ***********************************************************/
 
-/* This format is used to construct the /dev/skel[n] device driver path.  It
+/* The format used to construct device file path, defined for consistent use
- * defined here so that it will be used consistently in all places.
+ * from all places.
  */
 
 #define DEV_FORMAT          "/dev/skel%c"
@@ -73,9 +73,7 @@
  * Private Types
  ****************************************************************************/
 
-/* This structure contains the internal, private state of the USB host class
+/* This is the internal, private state of the USB host class driver. */
- * driver.
- */
 
 struct usbhost_state_s
 {
@@ -85,16 +83,16 @@ struct usbhost_state_s
 
   /* The remainder of the fields are provide to the class driver */
 
-  char                    devchar;      /* Character identifying the /dev/skel[n] device */
+  char            devchar;      /* char in /dev/skel[n] format name */
-  volatile bool           disconnected; /* TRUE: Device has been disconnected */
+  volatile bool   disconnected; /* TRUE: Device has been disconnected */
-  uint8_t                 ifno;         /* Interface number */
+  uint8_t         ifno;         /* Interface number */
-  int16_t                 crefs;        /* Reference count on the driver instance */
+  int16_t         crefs;        /* Reference count on the driver instance */
-  mutex_t                 lock;         /* Used to maintain mutual exclusive access */
+  mutex_t         lock;         /* Used for mutual exclusive access */
-  struct work_s           work;         /* For interacting with the worker thread */
+  struct work_s   work;         /* For interacting with the worker thread */
-  FAR uint8_t            *tbuffer;      /* The allocated transfer buffer */
+  FAR uint8_t    *tbuffer;      /* The allocated transfer buffer */
-  size_t                  tbuflen;      /* Size of the allocated transfer buffer */
+  size_t          tbuflen;      /* Size of the allocated transfer buffer */
-  usbhost_ep_t            epin;         /* IN endpoint */
+  usbhost_ep_t    epin;         /* IN endpoint */
-  usbhost_ep_t            epout;        /* OUT endpoint */
+  usbhost_ep_t    epout;        /* OUT endpoint */
 };
 
 /****************************************************************************
@@ -156,8 +154,8 @@ static int usbhost_disconnected(FAR struct usbhost_class_s *usbclass);
  * Private Data
  ****************************************************************************/
 
-/* This structure provides the registry entry ID information that will  be
+/* This structure provides the registry entry ID information that will be
- * used to associate the USB class driver to a connected USB device.
+ * used to associate the USB host class driver to a connected USB device.
  */
 
 static const struct usbhost_id_s g_id =
@@ -169,7 +167,7 @@ static const struct usbhost_id_s g_id =
   0   /* pid      */
 };
 
-/* This is the USB host storage class's registry entry */
+/* This is the USB host class' registry entry */
 
 static struct usbhost_registry_s g_skeleton =
 {
@@ -179,7 +177,7 @@ static struct usbhost_registry_s g_skeleton =
   &g_id                   /* id[]     */
 };
 
-/* This is a bitmap that is used to allocate device names /dev/skela-z. */
+/* The bitmap depicting allocated device names in "/dev/skel[a-z]". */
 
 static uint32_t g_devinuse;