Ethernet Driver Changes

for NET+OS V5.1

Design Changes

• Resides in bsp\devices\ethernet directory.

• Source code broken into more C files.

• Native driver code is separated from the TCP/IP stack and the operating system.

• Global variables are combined in one structure.

• Added a transmit task.

Hardware related Changes

• Added support for NS7520 chip.

• Added transmitter lockup detection and reset.

• The driver supports multiple receive DMA channels.

• Mii.c identifies PHY address dynamically.

• Both MAC and EFE run in half-duplex.

Driver Header Files

• h\efe_def.h - Ethernet driver public API, and statistics

• bsp\mii.h - MII public API

• In bsp\devices\ethernet directory:

• eth.h - Internal Ethernet definitions

Driver C Files

• eth_init.c - Initialization routines

• eth_reset.c - Hardware initialization

• eth_dma.c - DMA related routines

• eth_isr.c - Interrupt service routines

• eth_mcast.c - Multicast routines

Driver C Files

• eth_recv.c - Receive task and related routines

• eth_send.c - Transmit task and related routines

• eth_watchdog.c – Code to reset receiver and transmitter lockups

Driver C Files

• eth_os.c - Code dependant on the OS eth_stack.c - Code dependant on the

TCP/IP stack

• mii.c - MII routines

NS7520 Support

• NS7520 has a different MAC.

• Ethernet register addresses and layout have changed.

• Most of the chip revision support is in eth_reset.c and mii.c.

Transmitter Lockup Reset

• Reset function - eth_reset_tx

• The eth_tx_complete in the transmit thread detects the lockup condition.

• Lockup condition - transmit complete interrupt has not cleared the Full bit in the DMA buffer descriptor.

Half – Duplex operation

• Full duplex for EFE causes transmit under-runs, which cause transmitter lockups.

• MAC and EFE duplex is set to the same value.

• ETH_NEGOTIATE_100MB_FULLD is defined to 0 is mii.h.

Other MII changes

• MII tries to identify PHY on different addresses.

• After reading the status, mii.c clears the status bit in the MII Command Register, because NS7520 hardware does not do it.

Multiple receive DMA channels

#define ETH_RX_CHANNELS 1#define ETH_MAX_RXA_DESCRIPTORS 64#define ETH_MAX_RXB_DESCRIPTORS 1#define ETH_MAX_RXC_DESCRIPTORS 1#define ETH_MAX_RXD_DESCRIPTORS 1

Change ETH_RX_CHANNELS and number of buffer descriptors for channels B, C, and D to run more than one receive channel.

Multiple receive DMA channels

#define ETH_MAX_PACKET_LENGTH 1518

#define ETH_RX_PACKET_SIZEA 64

#define ETH_RX_PACKET_SIZEB 128

#define ETH_RX_PACKET_SIZEC 256

#define ETH_RX_PACKET_SIZED ETH_MAX_PACKET_LENGTH

• Last DMA channel always receives maximum size packets.

• BSP is compiled to use 1 receive DMA channel

DMA Buffer Descriptors

• They are made global for debug purposes.

• DMA buffer descriptors are defined in eth_dma.c.

• / * Transmit DMA Buffer descriptor ring */fb_buffer_desc_t

eth_tx_buffer_descriptors[ETH_MAX_TX_DESCRIPTORS];

DMA Buffer Descriptors

/ * Receive DMA Buffer descriptors rings for channels A, B, C, and D */

fb_buffer_desc_t eth_rxa_buffer_descriptors[ETH_MAX_RXA_DESCRIPTORS];

• fb_buffer_desc_t eth_rxb_buffer_descriptors[ETH_MAX_RXB_DESCRIPTORS];

• fb_buffer_desc_t eth_rxc_buffer_descriptors[ETH_MAX_RXC_DESCRIPTORS];

• fb_buffer_desc_t eth_rxd_buffer_descriptors[ETH_MAX_RXD_DESCRIPTORS];

DMA Buffer Descriptors

/* Array Pointers to Receive DMA Buffer descriptor rings for channels A, B, C, and D */

fb_buffer_desc_t *eth_rx_buffer_descriptors[] = • {• eth_rxa_buffer_descriptors, • eth_rxb_buffer_descriptors, • eth_rxc_buffer_descriptors, • eth_rxd_buffer_descriptors• };

Sending Packets

• Packets are transmitted from application threads and the Ethernet transmit thread.

• TCP/IP stack owns device transmit queues.

• TCP/IP stack calls driver’s transmit routines in critical section.

Transmit Task

• Transmit DMA ISR wakes up the transmit thread.

• The transmit thread calls eth_restart in a loop.

• eth_restart calls a stack function to free the transmitted packet, and send the next queued packet.

eth.h

• eth.h explains what definitions are BSP configurable.

• eth.h defines ethData structure.

• Driver modules use and a global pointer: ethData *eth_datap.

• typedef struct • { • void *pnetdev; /* pointer to TCP/IP stack device data */• unsigned int min_packet_len; /* minimum packet length */• unsigned int max_packet_len[ETH_RX_CHANNELS]; /*minimum packet length*/• char state; /* drive state */• char efe_mii_100; /* 1 = 100Mb, 0 = 10 Mb */• char mac_fulld; /* MAC is running full duplex */• char efe_fulld; /* EFE is running full duplex */• char pna_mode; /* TRUE = pNa mode is set */• char loopback; /* loopback mode */• char rx_reset_in_progress; /* receiver reset in progress */

int rx_bd_index[ETH_RX_CHANNELS]; /* Receive DMA software index */

• int tx_bd_head; /* Transmit DMA head index */

• int tx_bd_tail; /* Transmit DMA tail index */• char mac_addr[ETH_MAC_ADDR_SIZE]; /* MAC adddress */• ethFunction recv_task; /* receive task function pointer */• ethFunction xmit_task; /* transmit task function pointer */• ethFunction watchdog; /* watchdog function pointer */

• } ethData;

eth_os.c

• eth_init_os_services allocates memory and creates threads, timers, event flags, etc. without starting them.

• eth_start_os_services starts threads, timers. eth_stop_os_services stops threads, timers.

• eth_task_wake wakes up a driver thread.• eth_task_sleep suspends a driver thread

until it’s waken up by eth_task_wake.

eth_stack.c

• Provides a glue layer between the driver and TCP/IP stack.

• The only file to include stack headers.

• Handles everything about struct m.