On Thu, 9 Dec 2004 09:36:11 -0500
Dan Malek <dan@xxxxxxxxxxxxxxxx> wrote:
> Read the memory mapping docuemntation and understand the APIs.
> All of the Linux mapping functions, whether mmap() from an application
> or in the kernel are going to align on page boundaries.
>
> The address of 0x40002040 is going to be aligned to a page boundary,
> so you have to consider the offset into that page to the base of the
> device, plus the register offset. The kernel mapping functions,
> like remap_page_range, are going to force the alignment because
> that is what we expect in the kernel. An mmap() with an unaligned
> address will generate an error.
Ok. I understand. But still havent fun. :(
Yes, Im assume that offset if pagealligned:
static int
mdrv_mmap (struct file *file, struct vm_area_struct *vma)
{
unsigned long offset = 0;
int ret;
struct inode *inode;
inode = file->f_dentry->d_inode;
struct pci_dev *curdev = NULL;
int minor = MINOR (inode->i_rdev);
printk("minor = 0x%X\n",minor);
curdev = (devs[minor]);
unsigned long start = vma->vm_start;
unsigned long size = (vma->vm_end - vma->vm_start);
offset = pci_resource_start (curdev, IOMEM0);
offset &= PAGE_MASK;
printk("start= 0x%X offset = 0x%X size=0x%X\n",start, (unsigned int)offset, (unsigned int) size);
ret = remap_page_range_high(start, offset, size, vma->vm_page_prot);
return ret;
}
This code, AFAIK will return me a pointer to begin of page where my ioaddr is. ?
Then in my testcode I compensate shift by adding it to addr:
---
#include "mdrv.h"
#include <sys/mman.h>
#include <stdio.h>
#include <fcntl.h>
#define MMAP_SIZE 0x40
int fd, fd2;
int
main ()
{
fd = open ("/dev/mboard1", O_RDWR);
unsigned long *x;
x = mmap (NULL, MMAP_SIZE, 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");
printf("x = 0x%X\n",x);
#define CONS 0
//0x2040 >> 2
x += CONS;
printf("x = 0x%X\n",x);
unsigned long m = 0xEF;
printf("m = 0x%X\n",m);
//printf ("%p\n", x[(0x3C)>>2]); //We have to get 0xE6 here
m = x[(0x40>>2)+(0x3C>>2)];
printf("m = 0x%p\n", m);
x -= CONS;
munmap (x, MMAP_SIZE);
close(fd);
return 0;
}
---
DEbug output shows that mmap - success. I get pointer and size = 0x1000(one page). Then
I try to read m from board register. BTW, if I just read apps finishing but when I try to output
to console(as in src) "m" programm hangs.
Have no idea what the ... is goin on. Some hints please.
