On 05/30/2013 11:42 AM, wolfking wrote:
hi, all
I'm doing some developing on the windriver's sbc8548 board. The kernel I
use
is 3.6.10 and the u-boot version is 2012-10. I changed the board's
configuration:
the board now boot from the 64MB SODIMM Flash (not the default 8MB on-board
Flash
memory), and the PCI clock rate is changed to 33MHZ.
Now the trouble I am in is that: the PCI card (a NIC card rtl8139) can be
accessed OK, while the PCIe card can't work, that is, the kernel can't
access
its internal register. The kernel can correctly probe the PCIe card. its
BAR0
is a I/O mapped register, I use ioport_map to map the BAR0 to kernel's
address
space, then use ioread8/iowrite8 to access its internal register, it doesn't
work.
I analyse the ioport_map function and find it just add the input parameter
to
a fixed _IO_BASE value, below is the function:
void __iomem *ioport_map(unsigned long port, unsigned int len)
{
return (void __iomem *) (port + _IO_BASE);
}
the _IO_BASE value under sbc8548 is 0xfd7fd000, the value of ioport_map
paramenter
"port" is 0xfefff000. Obviously the add overflows, so the follow-up
operations
can't succeed. The value of "port" is got from the function
pci_resource_start.
In PPC case I/O is memory-mapped, so you should use ioremap() instead of
ioport_map()..
Tiejun
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