Messages in this thread | | | Date | Wed, 10 May 2006 11:39:50 -0400 | Subject | Re: LPC bus in a geode sc1200 | From | (Lennart Sorensen) |
| |
On Wed, May 10, 2006 at 09:55:47AM +0200, Carlos Ojea Castro wrote: > Thank you very much for your reply, Len. > I will also have an FPGA (I think it will be on port 0x1400 or so). I > am writing to LPC using 'outb' like this: outb (data, port); > So I see an I/O write on the LPC bus, that is: 2 bytes for address and > 1 byte for data (it tooks one microsecond per transfer). > > To speed up things, I wish to transmit more than 1 byte for data in > each transfer (if possible). > Accordingly with page 194 of the sc1200 processor data book, it is > also possible to do a "Bus Master Memory Write" to transmit 1,2 or 4 > bytes. > Do you know how can I make a "Bus Master Memory Write" to the LPC?
Well I know we don't do that. We have very little data, just board status information from various places on the board. LPC does support doing DMA, which I believe is done in the same way it was done on ISA at least as far as the software is concerned. How to implement DMA for LPC in the FPGA I have no idea. The LPC specifications would probably tell you. I imagine it involves setting up a DMA buffer in RAM (in the first 16MB probably) and then sending a command to the FPGA telling it to do a DMA transfer from that memory location using the LPC DMA commands.
Len Sorensen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |