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#ifndef CYGONCE_USBS_ETH_H

#define  CYGONCE_USBS_ETH_H_

//==========================================================================

//

//      include/usbs_eth.h

//

//      Description of the USB slave-side ethernet support

//

//==========================================================================

// ####ECOSGPLCOPYRIGHTBEGIN####                                            

// -------------------------------------------                              

// This file is part of eCos, the Embedded Configurable Operating System.   

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//

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// the terms of the GNU General Public License as published by the Free     

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// for more details.                                                        

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//

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//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):    bartv

// Contributors: bartv

// Date:         2000-10-04

// Purpose:

// Description:  USB slave-side ethernet support

//

//

//####DESCRIPTIONEND####

//==========================================================================

#ifdef __cplusplus

extern "C" {

#endif

//

// The primary purpose of the USB slave-side ethernet code is to

// provide an ethernet service for the host. Essentially this means

// the following:

//

// 1) the host can transmit an ethernet frame to the USB peripheral.

//    This frame is received by the code in this package and then

//    passed up to higher-level code for processing. Typically the

//    frame will originate from a TCP/IP stack running inside the

//    host, and the higher-level code will forward the frame via a

//    real ethernet chip or some other ethernet-style device.

//

// 2) higher-level code will provide ethernet frames to be sent to

//    the host, usually to a TCP/IP stack running on the host. The

//    exact source of the ethernet frame is not known.

//

// 3) the host may initiate a number of control operations, for

//    example it may request the MAC address or it may want to

//    control the filtering mode (e.g. enable promiscuous mode).

//

// 4) there are USB control-related operations, for example actions

//    to be taken when the peripheral is disconnected from the

//    bus or when the host wants to disable the ethernet interface.

//

// It is possible to develop a USB ethernet peripheral that does not

// involve a TCP/IP stack inside the peripheral, in fact that is the

// most common implementation. Instead a typical peripheral would

// involve a USB port, an ethernet port, and a cheap microcontroller

// just powerful enough to forward packets between the two. The eCos

// USB code can be used in this way, and the primary external

// interface provides enough functionality for this to work.

//

//                  +---------------+   ethernet

//   +----+         |               |     |

//   |    |   USB   |      app      |     |

//   |host|---------|     /   \     |-----o

//   |    |         |    /     \    |     |

//   +----+         | USB-eth   eth |     |

//                  +---------------+     |

//                   USB peripheral

//

// Note that the USB-ethernet code does not know anything about the

// real ethernet device or what the application gets up to, it just

// provides an interface to the app. The above represents just one

// possible use for a USB-ethernet device.

//

// Also worth mentioning: when the host TCP/IP stack requests the MAC

// address USB-eth would normally respond with the MAC address for the

// real ethernet device. That way things like host-side DHCP should

// just work.

//

// Alternatively for some applications it is desirable to run a TCP/IP

// stack inside the peripheral as well as on the host. This makes

// things a fair bit more complicated, something like this.

//

//                  +---------------+

//                  |      app      |

//                  |       |       |  ethernet

//   +----+         |       |       |     |

//   |    |   USB   |     TCP/IP    |     |

//   |host|---------|     /   \     |-----o

//   |    |         |    /     \    |     |

//   +----+         | USB-eth   eth |     |

//                  +---------------+     |

//                   USB peripheral

//

// 

// Usually this will involve enabling the bridge code in the TCP/IP

// stack, or possibly performing some sort of bridging below the

// TCP/IP stack. One way of getting things to work is to view the

// USB connection as a small ethernet segment with just two

// attached machines, the host and the peripheral. The two will

// need separate MAC addresses, in addition to the MAC address

// for the real ethernet device. This way the bridge code

// sees things the way it expects.    

//

// There will still be some subtle differences between a setup like

// this and a conventional ethernet bridge, mainly because there

// is a host-side TCP/IP stack which can perform control operations.

// For example the host stack may request that USB-eth go into

// promiscuous mode. A conventional ethernet bridge just deals

// with ethernet segments and does not need to worry about

// control requests coming in from one of the segments.

//

// It is not absolutely essential that there is another network.

// However without another network this setup would look to the host

// like an ethernet segment with just two machines attached to it, the

// host itself and the USB peripheral, yet it still involves all the

// complexities of ethernet such as broadcast masks and IP subnets.

// Anything along these lines is likely to prove somewhat confusing,

// and the USB peripheral should probably act like some other class

// of USB device instead.

//

// One special setup has the host acting as a bridge to another

// network, rather than the peripheral. This might make sense for

// mobile peripherals such as PDA's, as a way of connecting the

// peripheral to an existing LAN without needing a LAN adapter.

// Enabling bridging in the host may be a complex operation, limiting

// the applicability of such a setup.

//

// This package will only implement the eCos network driver interface

// if explicitly enabled. The package-specific interface is always

// provided, although trying to mix and match the two may lead to

// terrible confusion: once the network driver is active nothing else

// should use the lower-level USB ethernet code. However application

// code is responsible for initializing the package, and specifically

// for providing details of the USB endpoints that should be used.

//

// The package assumes that it needs to provide just one

// instantiation. Conceivably there may be applications where it makes

// sense for a USB peripheral to supply two separate ethernet devices

// to the host, but that would be an unusual setup. Also a peripheral

// might provide two or more USB slave ports to allow multiple hosts

// to be connected, with a separate USB-ethernet instantiation for

// each port, but again that would be an unusual setup. Applications

// which do require more than one instantiation are responsible

// for doing this inside the application code.

// The public interface depends on configuration options.

#include <pkgconf/io_usb_slave_eth.h>

// Define the interface in terms of eCos data types.

#include <cyg/infra/cyg_type.h>

// The generic USB support

#include <cyg/io/usb/usbs.h>

// Network driver definition, to support cloning of usbs_eth_netdev0

#ifdef CYGPKG_USBS_ETHDRV

# include <cyg/io/eth/netdev.h>

#endif

// Cache details, to allow alignment to cache line boundaries etc.

#include <cyg/hal/hal_cache.h>    

// ----------------------------------------------------------------------------

// Maximum transfer size. This is not specified by io/eth. It can be

// determined from <netinet/if_ether.h> but the TCP/IP stack may not

// be loaded so that header file cannot be used.

//

// Some (most?) USB implementations have implementation problems. For

// example the SA11x0 family cannot support transfers that are exact

// multiples of the 64-byte USB bulk packet size, instead it is

// necessary to add explicit size information. This can be encoded

// conveniently at the start of the buffer.

//

// So the actual MTU consists of:

//  1) a 1500 byte payload

//  2) the usual ethernet header with a six-byte source MAC

//     address, a six-byte destination MAC address, and a

//     two-byte protocol or length field, for a total header

//     size of 14 bytes.

//  3) an extra two bytes of size info.

//

// For a total of 1516 bytes.

#define CYGNUM_USBS_ETH_MAX_FRAME_SIZE 1514

#define CYGNUM_USBS_ETH_MAXTU (CYGNUM_USBS_ETH_MAX_FRAME_SIZE + 2)

// Although the minimum ethernet frame size is 60 bytes, this includes

// padding which is not needed when transferring over USB. Hence the

// actual minimum is just the 14 byte ethernet header plus two bytes

// for the length.

#define CYGNUM_USBS_ETH_MIN_FRAME_SIZE 14

#define CYGNUM_USBS_ETH_MINTU (CYGNUM_USBS_ETH_MIN_FRAME_SIZE + 2)

// Typical USB devices involve DMA operations and hence confusion

// between cached and uncached memory. To make life easier for

// the underlying USB device drivers, this package ensures that

// receive operations always involve buffers that are aligned to

// a cache-line boundary and that are a multiple of the cacheline

// size.

#ifndef HAL_DCACHE_LINE_SIZE

# define CYGNUM_USBS_ETH_RXBUFSIZE      CYGNUM_USBS_ETH_MAXTU

# define CYGNUM_USBS_ETH_RXSIZE         CYGNUM_USBS_ETH_MAXTU    

#else

# define CYGNUM_USBS_ETH_RXBUFSIZE      ((CYGNUM_USBS_ETH_MAXTU + HAL_DCACHE_LINE_SIZE + HAL_DCACHE_LINE_SIZE - 1) \

                                         & ~(HAL_DCACHE_LINE_SIZE - 1))

# define CYGNUM_USBS_ETH_RXSIZE         ((CYGNUM_USBS_ETH_MAXTU + HAL_DCACHE_LINE_SIZE - 1) & ~(HAL_DCACHE_LINE_SIZE - 1))

#endif    

// ----------------------------------------------------------------------------

// This data structure serves two purposes. First, it keeps track of

// the information needed by the low-level USB ethernet code, for

// example which endpoints should be used for incoming and outgoing

// packets. Second, if the support for the TCP/IP stack is enabled

// then there are additional fields to support that (e.g. for keeping

// track of statistics).

//

// Arguably the two uses should be separated into distinct data

// structures. That would make it possible to instantiate multiple

// low-level USB-ethernet devices but only have a network driver for

// one of them. Achieving that flexibility would require some extra

// indirection, affecting performance and code-size, and it is not

// clear that that flexibility would ever prove useful. For now having

// a single data structure seems more appropriate.

typedef struct usbs_eth {

    // What endpoints should be used for communication?

    usbs_control_endpoint*      control_endpoint;

    usbs_rx_endpoint*           rx_endpoint;

    usbs_tx_endpoint*           tx_endpoint;

    // Is the host ready to receive packets? This state is determined

    // largely by control packets sent from the host. It can change at

    // DSR level.

    volatile cyg_bool   host_up;

    // Has the host-side set promiscuous mode? This is relevant to the

    // network driver which may need to do filtering based on the MAC

    // address and host-side promiscuity.

    volatile cyg_bool   host_promiscuous;

    // The host MAC address. This is the address supplied to the

    // host's TCP/IP stack and filled in by the init function. There

    // is no real hardware to extract the address from.

    unsigned char       host_MAC[6];

    // Needed for callback operations.

    void                (*tx_callback_fn)(struct usbs_eth*, void*, int);

    void*               tx_callback_arg;

    void                (*rx_callback_fn)(struct usbs_eth*, void*, int);

    void*               rx_callback_arg;

    // RX operations just block if the host is not connected, resuming

    // when a connection is established. This means saving the buffer

    // pointer so that when the host comes back up the rx operation

    // proper can start. This is not quite consistent because if the

    // connection breaks while an RX is in progress there will be a

    // callback with an error code whereas an RX on a broken

    // connection just blocks, but this does fit neatly into an

    // event-driven I/O model.

    unsigned char*      rx_pending_buf;

#ifdef CYGPKG_USBS_ETHDRV

    // Has the TCP/IP stack brought up this interface yet?

    cyg_bool            ecos_up;

    // Is there an ongoing receive? Cancelling a receive operation

    // during a stop() may be difficult, and a stop() may be followed

    // immediately by a restart.

    cyg_bool            rx_active;

    // The eCos-side MAC. If the host and the eCos stack are to

    // communicate then they must be able to address each other, i.e.

    // they need separate addresses. Again there is no real hardware

    // to extract the address from so it has to be supplied by higher

    // level code via e.g. an ioctl().

    unsigned char       ecos_MAC[6];

    // SNMP statistics

# ifdef CYGFUN_USBS_ETHDRV_STATISTICS

    unsigned int        interrupts;

    unsigned int        tx_count;

    unsigned int        rx_count;

    unsigned int        rx_short_frames;

    unsigned int        rx_too_long_frames;

# endif

    // The need for a receive buffer is unavoidable for now because

    // the network driver interface does not support pre-allocating an

    // mbuf and then passing it back to the stack later. Ideally the

    // rx operation would read a single USB packet, determine the

    // required mbuf size from the 2-byte header, copy the initial

    // data, and then read more USB packets. Alternatively, a

    // 1516 byte mbuf could be pre-allocated and then the whole

    // transfer could go there, potentially wasting some mbuf space.

    // None of this is possible at present.

    //

    // Also, typically there will be complications because of

    // dependencies on DMA, cached vs. uncached memory, etc.

    unsigned char       rx_buffer[CYGNUM_USBS_ETH_RXBUFSIZE];

    unsigned char*      rx_bufptr;

    cyg_bool            rx_buffer_full;

    // It should be possible to eliminate the tx buffer. The problem

    // is that the protocol requires 2 bytes to be prepended, and that

    // may not be possible with the buffer supplied by higher-level

    // code. Eliminating this buffer would either require USB

    // device drivers to implement gather functionality on transmits,

    // or it would impose a dependency on higher-level code.

    unsigned char       tx_buffer[CYGNUM_USBS_ETH_MAXTU];

    cyg_bool            tx_buffer_full;

    cyg_bool            tx_done;

    unsigned long       tx_key;

    // Prevent recursion send()->tx_done()->can_send()/send()

    cyg_bool            tx_in_send;

#endif

} usbs_eth;

// The package automatically instantiates one USB ethernet device.

extern usbs_eth usbs_eth0;

// ----------------------------------------------------------------------------

// If the network driver option is enabled then the package also

// provides a single cyg_netdevtab_entry. This is exported so that

// application code can clone the entry.

#ifdef CYGPKG_USBS_ETHDRV

extern cyg_netdevtab_entry_t usbs_eth_netdev0;

#endif    

// ----------------------------------------------------------------------------

// A C interface to the low-level USB code.

// Initialize the USBS-eth support for a particular usbs_eth device.

// This associates a usbs_eth structure with specific endpoints.

extern void usbs_eth_init(usbs_eth*, usbs_control_endpoint*, usbs_rx_endpoint*, usbs_tx_endpoint*, unsigned char*);

// Start an asynchronous transmit of a single buffer of up to

// CYGNUM_USBS_ETH_MAXTU bytes. This buffer should contain a 2-byte

// size field, a 14-byte ethernet header, and upto 1500 bytes of

// payload. When the transmit has completed the callback function (if

// any) will be invoked with the specified pointer. NOTE: figure out

// what to do about error reporting

extern void usbs_eth_start_tx(usbs_eth*, unsigned char*, void (*)(usbs_eth*, void*, int), void*);

// Start an asynchronous receive of an ethernet packet. The supplied

// buffer should be at least CYGNUM_USBS_ETH_MAXTU bytes. When a

// complete ethernet frame has been received or when some sort of

// error occurs the callback function will be invoked. The third

// argument

extern void usbs_eth_start_rx(usbs_eth*, unsigned char*, void (*)(usbs_eth*, void*, int), void*);

// The handler for application class control messages. The init call

// will install this in the control endpoint by default. However the

// handler is fairly dumb: it assumes that all application control

// messages are for the ethernet interface and does not bother to

// check the control message's destination. This is fine for simple

// USB ethernet devices, but for any kind of multi-function peripheral

// higher-level code will have to perform multiplexing and invoke this

// handler only when appropriate.

extern usbs_control_return usbs_eth_class_control_handler(usbs_control_endpoint*, void*);

// Similarly a handler for state change messages. Installing this

// means that the ethernet code will have sufficient knowledge about

// the state of the USB connection for simple ethernet-only

// peripherals, but not for anything more complicated. In the latter

// case higher-level code will need to keep track of which

// configuration, interfaces, etc. are currently active and explicitly

// enable or disable the ethernet device using the functions below.

extern void usbs_eth_state_change_handler(usbs_control_endpoint*, void*, usbs_state_change, int);

extern void usbs_eth_disable(usbs_eth*);

extern void usbs_eth_enable(usbs_eth*);

#ifdef __cplusplus

} // extern "C"

#endif

#endif // CYGONCE_USBS_ETH_H_