* Problems mapping OCM memory from 460EX to user space
@ 2010-07-07 19:48 ayman
2010-07-11 4:14 ` Ayman El-Khashab
0 siblings, 1 reply; 2+ messages in thread
From: ayman @ 2010-07-07 19:48 UTC (permalink / raw)
To: linuxppc-dev
I've got an issue with the new rev B 460EX processors that I am trying to isolate.
(Rev A worked fine). In order to do that, I am trying to modify my driver to
map the OCM (on chip memory) from the 460EX to user space so that the rest of the
application and codebase don't really know the difference.
My driver implements the mmap and this works fine when I point it to areas of
memory that have been setup with kmalloc. My sequence is basically kmalloc,
adjust for page boundaries, and then remap_pfn_range. For regular DRAM this
works fine.
Now I want to modfiy it to use OCM. I've modified the code to use ioremap so
that the driver has access to the memory. This seems to work. But the kernel
gives a register dump when I call
#define PLB_OCM_BASE_ADDR 0x400040000ull
...
static int mapper_mmap(struct file *fip, struct vm_area_struct *vma)
{
int rc;
/*
* make sure to allocate the proper number of pages when using
* mmap. We check it for correctness here.
*/
unsigned long len = vma->vm_end - vma->vm_start;
/* if user tries to map bigger space than we have, error */
if (PAGE_COUNT * PAGE_SIZE < len)
return -EIO;
rc = io_remap_pfn_range(vma, PLB_OCM_BASE_ADDR>>PAGE_SHIFT, vma->vm_start, len, vma->vm_page_prot);
#if 0
/* map the physical area into one buffer */
rc = remap_pfn_range(vma, vma->vm_start,
virt_to_phys( (void*)km.pal)>>PAGE_SHIFT,
len,
vma->vm_page_prot);
#endif
MDEBUG("Mapped %ld bytes at virt address 0x%lx to mapper file descriptor...\n", len, vma->vm_start);
/* return an error to the caller if remap fails */
return (rc < 0 ? rc : 0);
}
The "#if 0" code is the working code for using DRAM. MDEBUG is just a printk.
I am fairly certain the physical address is correct, I've verified that the
TLB entries in u-boot look ok. Any tips on how to make this work?
Thanks
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Problems mapping OCM memory from 460EX to user space
2010-07-07 19:48 Problems mapping OCM memory from 460EX to user space ayman
@ 2010-07-11 4:14 ` Ayman El-Khashab
0 siblings, 0 replies; 2+ messages in thread
From: Ayman El-Khashab @ 2010-07-11 4:14 UTC (permalink / raw)
To: linuxppc-dev
On 7/7/2010 2:48 PM, ayman@austin.rr.com wrote:
> rc = io_remap_pfn_range(vma, PLB_OCM_BASE_ADDR>>PAGE_SHIFT, vma->vm_start, len, vma->vm_page_prot);
>
> I am fairly certain the physical address is correct, I've verified that the
> TLB entries in u-boot look ok. Any tips on how to make this work?
>
>
I found / fixed the issue. The first problem is that start and offset
are swapped in the io_remap_pfn_range invocation. The 2nd was that
there were some TLB changes that were needed to map the OCM.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-07-07 19:48 Problems mapping OCM memory from 460EX to user space ayman
2010-07-11 4:14 ` Ayman El-Khashab
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