240 lines
11 KiB
Plaintext
240 lines
11 KiB
Plaintext
/*
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ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
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2011 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @defgroup USB USB Driver
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* @brief Generic USB Driver.
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* @details This module implements a generic USB (Universal Serial Bus) driver
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* supporting device-mode operations.
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* @pre In order to use the USB driver the @p HAL_USE_USB option
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* must be enabled in @p halconf.h.
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*
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* @section usb_1 Driver State Machine
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* The driver implements a state machine internally, not all the driver
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* functionalities can be used in any moment, any transition not explicitly
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* shown in the following diagram has to be considered an error and shall
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* be captured by an assertion (if enabled).
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* @if LATEX_PDF
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* @dot
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digraph example {
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size="5, 7";
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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stop [label="USB_STOP\nLow Power"];
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uninit [label="USB_UNINIT", style="bold"];
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ready [label="USB_READY\nClock Enabled"];
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selected [label="\nUSB_SELECTED\naddress\nassigned"];
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configured [label="\nUSB_ACTIVE\nconfiguration\nselected"];
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uninit -> stop [label=" usbInit()", constraint=false];
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stop -> stop [label="\nusbStop()"];
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stop -> ready [label="\nusbStart()"];
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ready -> stop [label="\nusbStop()"];
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ready -> ready [label="\n\nusbStart()"];
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ready -> ready [label="\nSUSPEND/WAKEUP\n>event_cb<"];
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ready -> selected [label="\nSET_ADDRESS\n>event_cb<"];
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selected -> ready [label="\nUSB RESET\n>event_cb<"];
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selected -> selected [label="\nSUSPEND/WAKEUP\n>event_cb<\n\nValid EP0 Message\n>requests_hook_cb<\n\nGET DESCRIPTOR\n>get_descriptor_cb<"];
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selected -> configured [label="\nSET_CONF(n)\n>event_cb<"];
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configured -> selected [label="\nSET_CONF(0)\n>event_cb<"];
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configured -> configured [label="\nSUSPEND/WAKEUP\n>event_cb<\n\nValid EP0 Message\n>requests_hook_cb<\n\nGET DESCRIPTOR\n>get_descriptor_cb<\n\nEndpoints Activity\n >in_cb< or >out_cb<"];
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configured -> ready [label="\nUSB RESET\n>event_cb<"];
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}
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* @enddot
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* @else
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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stop [label="USB_STOP\nLow Power"];
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uninit [label="USB_UNINIT", style="bold"];
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ready [label="USB_READY\nClock Enabled"];
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selected [label="\nUSB_SELECTED\naddress\nassigned"];
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configured [label="\nUSB_ACTIVE\nconfiguration\nselected"];
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uninit -> stop [label=" usbInit()", constraint=false];
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stop -> stop [label="\nusbStop()"];
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stop -> ready [label="\nusbStart()"];
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ready -> stop [label="\nusbStop()"];
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ready -> ready [label="\n\nusbStart()"];
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ready -> ready [label="\nSUSPEND/WAKEUP\n>event_cb<"];
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ready -> selected [label="\nSET_ADDRESS\n>event_cb<"];
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selected -> ready [label="\nUSB RESET\n>event_cb<"];
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selected -> selected [label="\nSUSPEND/WAKEUP\n>event_cb<\n\nValid EP0 Message\n>requests_hook_cb<\n\nGET DESCRIPTOR\n>get_descriptor_cb<"];
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selected -> configured [label="\nSET_CONF(n)\n>event_cb<"];
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configured -> selected [label="\nSET_CONF(0)\n>event_cb<"];
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configured -> configured [label="\nSUSPEND/WAKEUP\n>event_cb<\n\nValid EP0 Message\n>requests_hook_cb<\n\nGET DESCRIPTOR\n>get_descriptor_cb<\n\nEndpoints Activity\n >in_cb< or >out_cb<"];
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configured -> ready [label="\nUSB RESET\n>event_cb<"];
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}
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* @enddot
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* @endif
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*
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* @section usb_2 USB Operations
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* The USB driver is quite complex and USB is complex in itself, it is
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* recommended to study the USB specification before trying to use the
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* driver.
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*
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* @subsection usb_2_1 USB Implementation
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* The USB driver abstracts the inner details of the underlying USB hardware.
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* The driver works asynchronously and communicates with the application
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* using callbacks. The application is responsible of the descriptors and
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* strings required by the USB device class to be implemented and of the
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* handling of the specific messages sent over the endpoint zero. Standard
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* messages are handled internally to the driver. The application can use
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* hooks in order to handle custom messages or override the handling of the
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* default handling of standard messages.
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*
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* @subsection usb_2_2 USB Endpoints
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* USB endpoints are the objects that the application uses to exchange
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* data with the host. There are two kind of endpoints:
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* - <b>IN</b> endpoints are used by the application to transmit data to
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* the host.<br>
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* - <b>OUT</b> endpoints are used by the application to receive data from
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* the host.
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* .
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* In ChibiOS/RT the endpoints can be configured in two distinct ways:
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* - <b>Packet Mode</b>. In this mode the driver invokes a callback each
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* time a packet has been received or transmitted. This mode is especially
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* suited for those applications handling continuous streams of data.
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* <br><br>
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* States diagram for OUT endpoints in packet mode:
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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disabled [label="EP_DISABLED\nDisabled", style="bold"];
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receiving [label="EP_BUSY\nReceiving Packet"];
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idle [label="EP_IDLE\nPacket in Buffer"];
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disabled -> receiving [label="\nusbInitEndpointI()"];
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receiving -> idle [label="\npacket received\n>out_cb<"];
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idle -> receiving [label="\nusbReadPacketBuffer()\nusbStartReceiveI()"];
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receiving -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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idle -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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}
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* @enddot
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* <br><br>
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* States diagram for IN endpoints in packet mode:
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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disabled [label="EP_DISABLED\nDisabled", style="bold"];
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transmitting [label="EP_BUSY\nSending Packet"];
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idle [label="EP_IDLE\nBuffer Empty"];
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disabled -> idle [label="\nusbInitEndpointI()"];
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idle -> transmitting [label="\nusbWritePacketBuffer()\nusbStartTransmitI()"];
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transmitting -> idle [label="\npacket sent\n>in_cb<"];
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transmitting -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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idle -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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}
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* @enddot
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* <br><br>
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* - <b>Transaction Mode</b>. In this mode the driver invokes a callback
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* only after a large, potentially multi-packet, transfer has been
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* completed, a callback is invoked only at the end of the transfer.
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* <br><br>
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* States diagram for OUT endpoints in transaction mode:
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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disabled [label="EP_DISABLED\nDisabled", style="bold"];
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receiving [label="EP_BUSY\nReceiving"];
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idle [label="EP_IDLE\nReady"];
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disabled -> idle [label="\nusbInitEndpointI()"];
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idle -> receiving [label="\nusbPrepareReceive()\nusbStartReceiveI()"];
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receiving -> receiving [label="\nmore packets"];
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receiving -> idle [label="\nreception end\n>out_cb<"];
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receiving -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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idle -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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}
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* @enddot
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* <br><br>
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* States diagram for IN endpoints in transaction mode:
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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disabled [label="EP_DISABLED\nDisabled", style="bold"];
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transmitting [label="EP_BUSY\nTransmitting"];
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idle [label="EP_IDLE\nReady"];
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disabled -> idle [label="\usbInitEndpointI()"];
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idle -> transmitting [label="\nusbPrepareTransmit()\nusbStartTransmitI()"];
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transmitting -> transmitting [label="\nmore packets"];
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transmitting -> idle [label="\ntransmission end\n>in_cb<"];
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transmitting -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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idle -> disabled [label="\nUSB RESET\nusbDisableEndpointsI()"];
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}
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* @enddot
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* <br><br>
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* .
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* @subsection usb_2_3 USB Packet Buffers
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* An important difference between packet and transaction modes is that there
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* is a dedicated endpoint buffer in packet mode while in transaction mode
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* the application has to specify its own buffer for duration of the whole
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* transfer.<br>
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* Packet buffers cannot be accessed directly by the application because those
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* could not be necessarily memory mapped, a buffer could be a FIFO or some
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* other kind of memory accessible in a special way depending on the
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* underlying hardware architecture, the functions @p usbReadPacketI() and
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* @p usbWritePacketI() allow to access packet buffers in an abstract way.
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*
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* @subsection usb_2_4 USB Callbacks
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* The USB driver uses callbacks in order to interact with the application.
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* There are several kinds of callbacks to be handled:
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* - Driver events callback. As example errors, suspend event, reset event
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* etc.
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* - Messages Hook callback. This hook allows the application to implement
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* handling of custom messages or to override the default handling of
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* standard messages on endpoint zero.
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* - Descriptor Requested callback. When the driver endpoint zero handler
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* receives a GET DESCRIPTOR message and needs to send a descriptor to
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* the host it queries the application using this callback.
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* - Start of Frame callback. This callback is invoked each time a SOF
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* packet is received.
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* - Endpoint callbacks. Each endpoint informs the application about I/O
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* conditions using those callbacks.
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* .
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*
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* @ingroup IO
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*/
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