All:
I'm trying again to get mmapping working from user space to a cards
device registers.
The platform is X86, linux 2.6.18 .
Under linux 2.4, the following code snippet was able to map 1 page of
PLX register
and 1 page of card registers:
-----
bus_adr = pCrd->pPciDevInfo->resource[ bar_nmbr ].start;
bus_adr &= PCI_BASE_ADDRESS_MEM_MASK;
page_adr = bus_adr & (PAGE_MASK);
offset = bus_adr & ~(PAGE_MASK);
vma->vm_flags |= VM_IO | VM_RESERVED ;
prot = pgprot_noncached(__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER |
_PAGE_GLOBAL) );
vma->vm_page_prot = prot ;
rtv = remap_page_range(vma->vm_start, page_adr, length, vma->vm_page_prot);
vma->vm_start += offset;
-----
Under linux 2.6.18, documentation indicates remap_pfn_range() is the
routine to use.
Indeed, this works for kmallocd() pages. However for device registers
it is unclear
as to which pfn ( presumably the pfn for the bus adrs ... like the
kernel mapping ),
vm flags, and page flags are needed.
The current 2.6.18 code snippet looks like:
+++++
bus_adr = pCrd->pPciDevInfo->resource[ bar_nmbr ].start;
bus_adr &= PCI_BASE_ADDRESS_MEM_MASK;
page_adr = bus_adr & (PAGE_MASK);
offset = bus_adr & ~(PAGE_MASK);
show_page_flags( (adr_t)bus_adr, "bus_adr:: "); }
show_page_flags( (adr_t)mAddr, " mAddr:: "); }
rtv = io_remap_pfn_range( vma, vma->vm_start, (__pa(bus_adr) >> PAGE_SHIFT),
length, vma->vm_page_prot );
show_page_flags( (addr_t)vma->vm_start, (addr_t)0);
vma->vm_start += offset;
+++++
mAddr is the kernel virtual address of the PLX area on the card.
Results from the show_page_flags():
bus_adr:: c1738fe0:pg* f9c7ff00:va 39c7ff00:pa 00039c7f:pfn ::
c0000000:flags :: < himem > 0:ct
mAddr:: c17147c0:pg* f8a3ef00:va 38a3ef00:pa 00038a3e:pfn ::
c0000000:flags :: < himem > 0:ct
vm->strt: c2eff4e0:pg* b7fa7000:va f7fa7000:pa 000f7fa7:pfn ::
00000000:flags :: < > 0:ct
=====================
The pfn returned is bogus, based solely upon the virtual address. For
the platform running on
the following parameters are in effect:
0007fe86:max_mapnr 0007fe86:num_physpages
f8000000:high_mem 38000000:va(himem) 00038000:hi_start_pfn
======================
So, what am I missing. I would hate to lose this feature when debugging
cards/drivers.
How should the call to remap_pfn_range() be setup so that it properly
maps the registers?
TIA
klink
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