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.
|
|
