I've composed a small program which mmap()'s SYS_BASE and then tries to read at the appropriate GPIO offset, as defined in the Au1500 databook.
For some reason, I keep getting that magical value, 0x10000001 for EVERY address I try to read, be it SYS_BASE (0xB1900000) or every other address. (for example,
I've tried reading the MAC address from the MAC0 base address
of 0xB1500000, offset 0x0008, and I always get 0x10000001).
Any reason I shouldn't succeed in reading the au1500 hardware addresses through /dev/mem?
Attached is the code I'm using:
#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/mman.h>
#define SYS_BASE 0xB1900000
int
main () {
volatile unsigned long *base;
unsigned char val;
int f, i;
f = open ("/dev/mem", O_RDWR | O_SYNC);
if (f < 0) {
perror ("fopen");
exit (-1);
}base = (unsigned long *) mmap (NULL, getpagesize (), PROT_READ | PROT_WRITE, MAP_SHARED, f,
SYS_BASE);
if (base == (unsigned long *) (-1)) {
perror ("mmap");
exit (-1);
}printf ("data at %p: 0x%x\n", base, (unsigned long) *base);
*base = 0xffffffff;
printf ("data at %p: 0x%x\n", base, (unsigned long) *base);
close (f);
return (0);
}Thanks! Gilad.
----- Original Message ----- From: "Gilad Rom" <gilad@xxxxxxxxx>
To: <ppopov@xxxxxxxxxxxxxxxxx>; <linux-mips@xxxxxxxxxxxxxx>
Sent: Sunday, November 14, 2004 10:35 AM
Subject: Re: GPIO on the Au1500
Thanks. Can't I just mmap /dev/mem and use the
GPIO offset from SYS_BASE?
Gilad.
----- Original Message ----- From: "Pete Popov" <ppopov@xxxxxxxxxxxxxxxxx>
To: "Gilad Rom" <gilad@xxxxxxxxx>; <linux-mips@xxxxxxxxxxxxxx>
Sent: Friday, November 12, 2004 8:13 PM
Subject: Re: GPIO on the Au1500
--- Gilad Rom <gilad@xxxxxxxxx> wrote:
Hello,
I am trying to use the au1000_gpio driver, but I'm a
little clueless as to how it is meant to be used. Can I use the GPIO ioctl's from a userland program, or must I write a kernel module?
I'll see if I can dig up some docs and the example userland program this weekend. That driver hasn't been tested in a while though.
Pete
Thank you, Gilad Rom Romat Telecom
