On Tue, Feb 04, 2003 at 12:34:07PM +0100, Jules Bj?rn Colding wrote: > This is what I know: > > 1) I have to enable all GPIOs on the board before I can access the > co-processor. This is done by writing 0x2 to register offset 0x40 at the > PCI data configuration register. Before doing so I have to enable reads > and writes to this register. These two lines does that: > > /* Write to the pci configuration address register */ > outl(0x80000000 | (0xc << 11) | (0x40 << 2), 0xcf8) > > /* Write to the pci configuration data register */ > outb(0x02, 0xcfc) Don't fiddle with the PCI config space like that. We have the function pci_write_config_byte() and friends for that. If you use those functions, your driver will be portable, so it will work without changing a single line of code the minute you put it in a PowerPC machine. Another advantage is that using the pci_*() functions make your code much more readable. > But.. > > a) Do I need to do a request_region()/release_region() for both > addresses around these lines of code ? No, just use the pci_*() functions. First pci_enable() the device, then get request the regions with pci_request_regions() and enable bus mastering with pci_set_master(). In my opinion drivers/net/8139too.c is a nice example of proper PCI usage. > b) Do I need to disable interrupts while writing to these registers ? If you do it like you're doing right now you have to, but if you use the pci_*() functions the necessary precautions will be done automatically. > c) Do I need to reset 0xcf8 after having written to 0xcfc ? Use the pci_*() functions and don't worry about the implementation details. Erik -- J.A.K. (Erik) Mouw Email: J.A.K.Mouw@its.tudelft.nl mouw@nl.linux.org
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