Hello,
I have an application where I would like to do DMA writes from within
the kernel memory space out to a device on the PCI bus.
The 'device' is an FPGA.
After reading all I could find on DMA/Linux/PCI I don't see any
reference to how I can DMA directly to a single address on the FPGA.
All the examples imply what basically are block to block transfers
(i.e. something like what memcpy_fromio() does)
I do this all the time (read and write) over VME busses with non-
linux OSs so I'm fairly sure the PCI should support this as well.
My needs are simple enough:
transfer a buffer in my driver to a single bus address.
The way I currently do this is (pseudo code):
char *pBuf = dataBuffer; /* pointer to my data buffer */
unsigned int count = BUFSIZE; /* number of bytes to transfer */
do
{
writeb (*pBuf++, dataRegister); /* write to a well known and
properly mapped bus address */
}
while (count--);
This works but my device should work fine with 33MHz writes and I
could gain about 10x.
Any ideas or references to look at?
Thanks,
-Bruce
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