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List: linux-mips
Subject: mmap problem
From: Dmitriy Tochansky <toch () dfpost ! ru>
Date: 2004-12-07 15:42:58
Message-ID: 20041207184258.071bf401.toch () dfpost ! ru
[Download RAW message or body]
Hi!
I try to write small driver to make access to pci device resource from
userland using mmap.
Code below didnt work. :(
From I module in debug I make some testes - I can read from device registers
but after mmap from userspace I reading just part of memory. :(
Some cache?
CPU - au1500
.....
static unsigned long *offset;
static int mdrv_mmap(struct file * file, struct vm_area_struct *vma) \
{ \
\
int ret; \
struct inode *inode; \
inode = file->f_dentry->d_inode; \
ret = -EINVAL; \
unsigned long start = vma->vm_start; \
unsigned long size = (vma->vm_end-vma->vm_start); \
offset = ioremap(0x40000000,0x40);
printk("0x%p\n",__pa(offset));
printk("lb 0x%X\n",offset[ 0x3C>>2 ] );
vma->vm_flags |= VM_LOCKED;
printk("+++++0x%X 0x%X\n",start,size);
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
ret = remap_page_range( start, 0x40000000, size, vma->vm_page_prot ); //0x40000000 \
is first iomem range of pci device
return ret;
}
struct file_operations mdrv_fops = {
.open = mdrv_open,
.release = mdrv_close,
.read = mdrv_read,
.write = mdrv_write,
.mmap = mdrv_mmap
};
....
Here is userland
#include "mdrv.h"
#include <sys/mman.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <linux/kernel.h>
#include <string.h>
int fd,fd2;
int
main ()
{
fd = open("/dev/mboard0",O_RDWR);
unsigned long *x;
x = mmap(NULL,64,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
printf("mmap return: 0x%X",x);
if(x == MAP_FAILED)
{
printf(" it is very bad! :(\n");
perror("mmap:");
return -1;
}
printf(" its ok!\n");
int i;
for(i=0;i<16;i++)
{
printf(" %d = 0x%X\n",i,x[i]);
}
munmap(x,64);
return 0;
}
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