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Jeff Garzik wrote:
> David Stroupe wrote:
> >
> > I am creating a PCI driver for a custom card and
want to write 0xffff to
> > a location offset from the base by 0x48 and
> > have the following code:
> >
> > <snip>
> > unsigned int io_addr;
> > unsigned int io_size;
> > void* base;
> > pci_enable_device (pdev)
> > io_addr = pci_resource_start(pdev, 0);
> > io_size = pci_resource_len(pdev, 0);
> > if ((pci_resource_flags(pdev, 0) &
IORESOURCE_MEM)){
> > if(check_mem_region(io_addr, io_size))
> > DBG("Already In Use");//this is never
reached
> > request_mem_region(io_addr, io_size ,
"Card Driver");

> In 2.4 and later, check request_mem_region return
> value, and never call
> check_mem_region.

Gasp! Are you sure we should never call
check_mem_region, Jeff?

This check has worked for me under kernels 2.4.7 &
2.4.7-10. If check_mem_region returns < 0 my driver
bails with a message to the effect that my chip's
memory region is already in use...

Could this lead to screw-ups?
Should I lose the check?
(my pci initialization code follows)

>
> > base=ioremap(io_addr, io_size);
> > if(base==0)
> > DBG("memory mapped wrong\n");//this is
never reached
> > writew(0xffff, base + 0x48);
> > <snip>
> >
> > The card is found, io_addr = 0xe9011000 and
io_size = 0x200.
> >
> > The write is unsuccessful or at least the data
never reaches the card.
> > What am I doing incorrectly?
>
> Looks correct to me... maybe you need to do
> readw(base + 0x48)
> to flush the transaction?
>

David, I realize this is a "no-brainer" but, if Jeff's

comments don't help double-check that your I/O space
begins at PCI BAR 0 (as opposed to PCI BARs 1-5).

<snip>
// enable the device
if( pci_enable_device( pdev )) {
printk( KERN_ERR "init_pci_device:
pci_enable_device failed\n" );
return 0;
}

// set dma mask for device
// since we handle 32-bit dma, I don't think this is
necessary...
if( pci_set_dma_mask( pdev, DMA_MASK ) != 0 ) {
printk( KERN_ERR "init_pci_device:
pci_set_dma_mask failed\n");
return 0;
}

// enable bus master bit in PCI_COMMAND register
pci_set_master( pdev );

#ifdef DEBUG
debug_display_pci_dev( pdev );
#endif // DEBUG

// access I/O space
// registers begin at BAR 4
phys_addr = pdev->resource[ 4 ].start;

// make sure nobody else is using the same device
if( check_mem_region( phys_addr, REG_MAP_SIZE ) < 0
) {
printk( KERN_ERR "init_pci_device: memory region
already in use!\n" );
return 0;
}

if( request_mem_region( phys_addr, REG_MAP_SIZE,
pdc_ptr->name ) == NULL ) {
printk( KERN_ERR "init_pci_device: memory region
not available!\n" );
return 0;
}

// remap physical pci space into virtual memory space
pdc_ptr->regs = ioremap_nocache( phys_addr,
REG_MAP_SIZE );

// initialize pdev private driver data
pdev->driver_data = pdc_ptr;

return 1;
<snip>


--Christine



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