I am trying to give user space application access to I/O. Previously I
used 2.6.14 with RT Linux and made a kernel device driver with a mmap
routine on a 440EP.
I am converting to a PPC460Ex with 2.6.26-2 with Xenomai the same code
results in a Machine Check in Kernel mode when I attempt to use the code
in user space.
The io memory is in the device tree and with ioremap and I can read and
write to it in kernel mode with
of_address_to_resource(np,0,&res)
piom = (unsigned *) ioremap( res.start, RTL_SHIOM_SIZE);
In addition I tried
void *map_base, * virtAddr;
off_t target = ((unsigned int)addr) & ~MAP_MASK;
int fd;
if ((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) {
printf("/dev/mem could not be opened.\n");
exit(1);
}
/* Map one page */
map_base = mmap((void *)target, length, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, target);
if (map_base == (void *) -1) {
printf("Memory map failed for address 0x%lx\n", addr);
exit(1);
}
In my own driver I did the following for my mmap but it gives an error
as well.
//---------------------------------------
// map a pointer back for user mode usage
//----------------------------------------
static int ubus_mmap(struct file * filp, void * pvoidvma)
{
int ret;
struct vm_area_struct * vma = (struct vm_area_struct *)pvoidvma;
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
ret = remap_pfn_range(vma,
vma->vm_start,
UBUS_BASE_ADDRESS >> PAGE_SHIFT,
vma->vm_end-vma->vm_start,
vma->vm_page_prot);
if(ret != 0)
{
return -EAGAIN;
}
return 0;
}
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