Driver for the Gaisler GRETH Ethernet MAC with EDCL support. More...

Detailed Description

Driver for the Gaisler GRETH Ethernet MAC with EDCL support.

Overview

GRETH is a DMA-based Ethernet MAC from Frontgrade Gaisler, commonly found in GRLIB-based FPGA designs (LEON, NOEL-V). This driver implements the RIOT netdev interface for Ethernet.

Hardware operation

The controller uses two rings of buffer descriptors in RAM — one for TX, one for RX. Each descriptor is 8 bytes: a 32-bit control word and a 32-bit buffer address. The CPU prepares descriptors with EN=1 (owned by DMA). The DMA engine processes them and clears EN=0 when done, then raises IRQ 5.

Files
file	greth.h
	Interface definitions for the GRETH Ethernet driver.

file	greth_params.h
	Default configuration for the GRETH Ethernet driver.

file	greth_regs.h
	Register definitions for the Gaisler GRETH Ethernet MAC.

Data Structures
struct	greth_desc_t
	GRETH buffer descriptor (8 bytes, must be kept at natural alignment) More...

struct	greth_params_t
	GRETH driver parameters (board-level configuration) More...

struct	greth_t
	GRETH driver device descriptor. More...

Functions
void	greth_setup (greth_t dev, const greth_params_t params, uint8_t index)
	Set up the GRETH device descriptor.

Driver configuration constants
#define	CONFIG_GRETH_RX_DESC_NUM (8U)
	Number of RX descriptors (and pre-allocated RX buffers)

#define	CONFIG_GRETH_TX_DESC_NUM (4U)
	Number of TX descriptors.

#define	GRETH_MAX_FRAME_LEN (1518U)
	Maximum Ethernet frame size (excluding FCS added by MAC)

#define	GRETH_BUF_SIZE (1536U)
	RX/TX buffer size — rounded up to 32-byte boundary.

#define	GRETH_ANEG_TIMEOUT (100000U)
	PHY auto-negotiate timeout in poll iterations.

Macro Definition Documentation

◆ CONFIG_GRETH_RX_DESC_NUM

#define CONFIG_GRETH_RX_DESC_NUM (8U)

Number of RX descriptors (and pre-allocated RX buffers)

Must be a power of 2. More descriptors = better throughput at cost of RAM.

Definition at line 55 of file greth.h.

◆ CONFIG_GRETH_TX_DESC_NUM

#define CONFIG_GRETH_TX_DESC_NUM (4U)

Number of TX descriptors.

Must be a power of 2.

Definition at line 64 of file greth.h.

◆ GRETH_ANEG_TIMEOUT

#define GRETH_ANEG_TIMEOUT (100000U)

PHY auto-negotiate timeout in poll iterations.

Definition at line 80 of file greth.h.

◆ GRETH_BUF_SIZE

#define GRETH_BUF_SIZE (1536U)

RX/TX buffer size — rounded up to 32-byte boundary.

Definition at line 75 of file greth.h.

◆ GRETH_MAX_FRAME_LEN

#define GRETH_MAX_FRAME_LEN (1518U)

Maximum Ethernet frame size (excluding FCS added by MAC)

Definition at line 70 of file greth.h.

Function Documentation

◆ greth_setup()

void greth_setup	(	greth_t *	dev,
		const greth_params_t *	params,
		uint8_t	index )

Set up the GRETH device descriptor.

Must be called before the netdev init callback. Wires the netdev driver pointer and stores the board parameters. Does not touch hardware.

Parameters

[out]	dev	Driver state to initialise
[in]	params	Board-level configuration (address, IRQ, MAC)
[in]	index	Instance index for netdev_register