Charles Brown wrote:
> Grant,
>
> Early on I was using the altpciechdma driver as reference, but the
> hardware engineer doesn't want me controlling the DMA on the card. So,
> we're just using memcpy_toio/fromio.
>
> That design also has the card providing host->board IO memory using
> BAR0 and board->host using BAR2, but the HW engineer only wants to
> provide host->board memory in BAR0, and me to provide the memory for
> board->host - by allocating appropriate memory and handing back a
> physical address. He has BAR2 set to 0.
>
> At this point, my best reference has been discarded, and I'm looking
> for another. So, I'll track down the two you mention. In the
> meanintime, my code snippets are below - I've left out all my debug
> printk's and error checking cruft. The iomstart is an address
> calculated from /proc/iomem, hence my mis-calling it "I/O memory".
>
> Thank you for spending some time with me on this.
>
> --CB
>
> /** start address for iomem block to allocate for read space */
> unsigned long iomstart = 0, iomlength = 0;
> module_param(iomstart,ulong,0);
> module_param(iomlength,ulong,0);
>
> ...snip...
>
> void alt_onInit(void)
> {
> int i, status = 0;
> struct resource * resource = NULL;
>
> /* request IO memory for incoming data */
> resource = request_mem_region(iomstart, iomlength, DEVNAME);
Ehm, no, this functions is to request a memory range for something supplied
from a hardware device, not you requesting RAM to pass to the device.
I would have done it like this:
void __iomem *mem;
void *outmem;
dma_addr_t outmem_phys;
// enable device (managed mode)
pcim_enable_device(pdev);
// claim BARs
pci_request_regions(pdev, DRIVER_NAME);
// map BAR0, full size
mem = pcim_iomap(pdev, 0, 0);
// get memory that is usable by DMA
outmem = pci_alloc_consistent(pdev, PAGE_SIZE, &outmem_phys);
// tell board about it
memcpy_toio(dest + 4, &outmem_phys, sizeof(outmem_phys));
Greetings,
Eike
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