Ethernet Driver Changes

1. Ethernet Driver Changes for NET+OS V5.1

2. 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.

3. 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.

4. 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

5. 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

6. 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

7. 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

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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

14. 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];

15. 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];

16. 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 • };

17. 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.

18. 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.

19. 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.

20. 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;

21. 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.

22. 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.