From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from web33312.mail.mud.yahoo.com (web33312.mail.mud.yahoo.com [68.142.206.127]) by ozlabs.org (Postfix) with SMTP id E4F6567B56 for ; Sat, 29 Jul 2006 03:35:21 +1000 (EST) Message-ID: <20060728173519.55388.qmail@web33312.mail.mud.yahoo.com> Date: Fri, 28 Jul 2006 10:35:19 -0700 (PDT) From: scott Subject: using /dev/mem to talk to peripherals on VIIP system To: linuxppc-embedded@ozlabs.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1827274702-1154108119=:54274" List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --0-1827274702-1154108119=:54274 Content-Type: text/plain; charset=us-ascii Hello again, well i didn't get any responses at all to my last post so I thought i'd try this again. I have kernel 2.4.26 installed on a Xilinx XUP board and everything works well except I can't seem to communicate with peripherals on the OPB or PLB bus through devfs. devfs is on and mounted and everything, and I'm able open a file handle to it w/ the following code: int main (int argc, char *argv[]) { int fd; int *ptr; fd = open("/dev/mem", O_RDWR); if(fd == -1) { printf("Err: cannot open /dev/mem\n"); return -1; } ptr = MAP_FAILED; // Initialize to bad value ptr = (int *) mmap(0, 256, PROT_READ|PROT_WRITE, MAP_SHARED, fd, USER_LOGIC_BASEADDR); if(ptr==MAP_FAILED) { printf("Err: cannot access address!\n"); return -1; } *ptr = 0xA0000000; ... mmap also seems to work, and returns a virtual address that is supposed to point to the location in physical memory at USER_LOGIC_BASEADDR. when I try to use ptr, however, I either get bus error or do_wp_page: bogus page at address 3001a000 (page 0xc2c4c004) VM: killing process led_test.o depending on whether I use MAP_SHARED or MAP_PRIVATE. These errors occur if I try to access any device on either PLB or OPB - even the OPB UART (which i KNOW is working). This technique DOES work, however, for address ranges in RAM. This indicates to me that it's some sort of higher level memory management problem w/ linuxppc such that it doesn't realize these address ranges are valid. I assume this is a function of the BSP that gets generated in EDK? Anybody have any idea how I can tell linux to let me use these addresses? Any other thoughts? If I'm being too vague or something please let me know and I'll resolve it immediately... Thanks much, --scott Other details: linuxppc-2.4.26 busybox 1.1.0 powerpc-405-linux-gnu-gcc 3.4.1 --0-1827274702-1154108119=:54274 Content-Type: text/html; charset=us-ascii

Hello again,
well i didn't get any responses at all to my last post so I thought i'd try this again.

I have kernel 2.4.26 installed on a Xilinx XUP board and everything works well except I can't seem to communicate with peripherals on the OPB or PLB bus through devfs. devfs is on and mounted and everything, and I'm able open a file handle to it w/ the following code:

int main (int argc, char *argv[]) {
int fd;
int *ptr;

fd = open("/dev/mem", O_RDWR);
if(fd == -1) {
    printf("Err: cannot open /dev/mem\n");
    return -1;
}

ptr = MAP_FAILED; // Initialize to bad value
ptr = (int *) mmap(0, 256, PROT_READ|PROT_WRITE, MAP_SHARED, fd, USER_LOGIC_BASEADDR);

if(ptr==MAP_FAILED) {
    printf("Err: cannot access address!\n");
    return -1;
}

*ptr = 0xA0000000;
...

mmap also seems to work, and returns a virtual address that is supposed to point to the location in physical memory at USER_LOGIC_BASEADDR. when I try to use ptr, however, I either get
bus error

or

do_wp_page: bogus page at address 3001a000 (page 0xc2c4c004)
VM: killing process led_test.o

depending on whether I use MAP_SHARED or MAP_PRIVATE.

These errors occur if I try to access any device on either PLB or OPB - even the OPB UART (which i KNOW is working). This technique DOES work, however, for address ranges in RAM. This indicates to me that it's some sort of higher level memory management problem w/ linuxppc such that it doesn't realize these address ranges are valid. I assume this is a function of the BSP that gets generated in EDK? Anybody have any idea how I can tell linux to let me use these addresses? Any other thoughts?

If I'm being too vague or something please let me know and I'll resolve it immediately...

Thanks much, --scott

Other details:
linuxppc-2.4.26
busybox 1.1.0
powerpc-405-linux-gnu-gcc 3.4.1

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