Wolfgang Grandegger wrote: > Hello, > > I'm trying to read from mmapped PCI memory space on an alchemy board, > but I can't get it to work. Here's the lspci output of the PCI card: > > bash-3.00# lspci -v > 00:00.0 Class 0200: 168c:001b (rev 01) > Subsystem: 168c:2063 > Flags: bus master, medium devsel, latency 168, IRQ 9 > Memory at 0000000040000000 (32-bit, non-prefetchable) [size=64K] > Capabilities: [44] Power Management version 2 > > I used mmap on "/dev/mem" and "/sys/bus/pci/.../resource0", but I do not > read the expected values using "*(volatile u32 *)mmap_addr" from that > region. The value also changes from read to read. Reading from kernel > space just work fine. Am I doing something illegal? Any idea why it does > not work? Form here I'm not sure how you did exactly. Theoretically, you can mmap() directly that at least from the sys resource. But I think you have to notice the aligning requirement for a page. I means you should firstly map one given base_address & ~(PAGE_SIZE - 1). Then access the last destination address with adding the corresponding offset as you want. Hope its useful. Tiejun > > TIA, > > Wolfgang. > >
