UM0851 datasheet(57/245 Pages) STMICROELECTRONICS

57 / 245 page

UM0851

Communication device drivers

Doc ID 16604 Rev 2

57/245

In system applications where no DMA is required, the DMA interface can be replaced with a

FIFO interface using a compile option. In this configuration, the MACB may be used with a

larger external FIFO.

4.2.2

Software overview

The MACB Ethernet driver sits on top of the MACB controller and interfaces to the Linux

TCP/IP stack through the standard Linux Network interface.

The figure below shows the framework of the MACB Ethernet software.

Figure 12.

MACB software layers

The related Linux files are:

●

drivers/net/arm/macb_top.c

●

drivers/net/arm/spear_macb.c

4.2.3

MACB driver interface

Device registration

The MACB driver inserts a data structure for each newly detected interface into a global list

of network devices.

Each interface is described by a struct net_device item, which is defined in

<linux/netdevice.h>. The structure must be allocated dynamically. The kernel function

provided to perform this allocation is alloc_etherdev(), which has the following prototype:

struct net_device *alloc_etherdev(int sizeof_priv)

/*Here, sizeof_priv is the size of the SPEAr MACB driver's "private data" area.

Once the net_device structure has been initialized, the process of registration

is complete by passing the structure to register_netdev().

The access to the SPEAr MACB private data is done via standard call provided by

kernel

Kernel space

Hardware

Application

Socket API

TCP/IP stack

Netif I/F

MACB Ethernet driver

MACB controller

User space

SMII

Eth Phy

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