altera_avgen4freebsd

Usage

Overview

The altera_avgen device driver provides generic support for memory-mapped devices on the Altera Avalon bus. device.hints entries configure the address, size, I/O disposition, and /dev device node name that will be used. The open(2), read(2), write(2), and mmap(2) system calls (and variations) may be used on altera_avgen device nodes, subject to constraints imposed using device.hints entries. Although reading and writing mapped memory is supported, altera_avgen does not currently support directing device interrupts to userspace.

A number of device.hints sub-fields are available to configure altera_avgen device instances:

maddr

base physical address of the memory region to export; must be aligned to width

msize

length of the memory region export; must be aligned to width

width

Granularity at which read(2) and write(2) operations will be performed. Larger requests will be broken down into width -sized operations; smaller requests will be rejected. I/O operations must be aligned to width.

fileio

allowed file descriptor operations; r authorizes read(2); w authorizes write(2).

mmapio

allowed mmap(2) permissions; w authorizes PROT_WRITE; r authorizes PROT_READ; x authorizes PROT_EXEC.

devname

specifies a device name relative to /dev.

devunit

specifies a device unit number; no unit number is used if this is unspecified.