pci_iomap() and pci_ioremap_bar()
christof.warlich at siemens.com
Wed Jun 26 03:12:36 EDT 2013
can anyone explain when I should use
void __iomem *regs = pci_iomap(device, barNumber, 0);
void __iomem *regs = pci_ioremap_bar(device, barNumber);
is more appropriate to map PCI memory?
Furthermore, after the mapping succeeded, when may I
directly access the mapped memory, e.g.:
char firstByte = *regs;
and when should I better use ioread8() instead?:
char firstBype = ioread8(regs);
All listed alternatives from above seems to work equally
well for me (on x86), so I'm curious to learn what might
be the difference. A guess: Does ioread8() work for both
memory mapped _and_ IO mapped registers, while the direct
access only works for the memory mapped case?
Thanks for any clarification.
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