UM0851 datasheet(114/245 Pages) STMICROELECTRONICS

Part #	UM0851

Description	SPEAr is a family of highly customizable ARM-based embedded

PDF	245 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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114 / 245 page

Communication device drivers

UM0851

114/245

Doc ID 16604 Rev 2

Figure 29.

HDLC software system architecture

SPEAr HDLC driver talks to the HDLC controller hardware. It carries out transmit requests

coming from the upper layers. In parallel, it collects incoming data from hardware and

queues them up to the upper layers.

The generic HDLC layer is between the HDLC driver and Linux network layer. It implements

several protocols based on HDLC, such as Raw HDLC, PPP, Frame Relay etc. It works as a

translator or a multiplexer between the physical HDLC driver and Linux network layer.

The application uses the standard BSD socket API to access the HDLC interfaces.

Main data structures of the driver

The main driver structures include port_t, channel_t, hdlc_dev, net_device.

The relationship between these structures is shown in the following figure.

Kernel space

Application

Socket API

Netif I/F

SPEAr HDLC driver

Hardware

HDLC controller

User space

Generic HDLC layer

UM0851 Datasheet(PDF) 114 Page - STMicroelectronics