On Wed, Jul 02, 2014 at 09:13:12AM +0200, Uwe Kleine-König wrote: > I expected something like that. Is it possible to "have" the device on a > cpu != StrongARM? If so I wonder why ARCH_FOOTBRIDGE is a "ARM system > type". And if not, wouldn't it be possible and better to have all > platforms which select CPU_SA110 (ARCH_EBSA110, ARCH_FOOTBRIDGE; what > about RPC?) in a single mach dir and make FOOTBRIDGE an option there? > > It's hard to find information on the net about these chips, even > http://developer.intel.com/design/strong/sa110.htm only talks about x86 > stuff only, so please excuse my unknowingness. The Footbridge is a companion device to the StrongARM - the two are designed to work together. It probably is possible that the Footbridge could have been connected to another CPU with appropriate interfacing, but that never happened. The thing to realise is that the Footbridge is a little more than just a pure PCI bridge. It's also the SDRAM controller, UART port and provides support for a non-PCI expansion bus. Probably the best model which represents it is in actual fact the x86 PC in years gone by. The separate processor (StrongARM) with the PCI northbridge (Footbridge) which couples the processor to the rest of the system. Some Footbridge systems really do approximate the x86 PC with a southbridge attached (eg, Netwinder did this, with a real southbridge providing keyboard, mouse, bridge to the ISA bus, IDE etc). You could also think of it as an early SoC which hasn't quite integrated the CPU, as the Footbridge defines quite a lot about how the physical system memory map looks. The difference between the CO285 and the EBSA285 is that CO285 was exclusively add-in mode (in other words, CO285 was Linux running on a DC21285 based card you could plug into your PC and wanted to map large spaces of PCI memory space) whereas the EBSA285 was the much smaller end of the add-in mode, and also host mode (StrongARM being responsible for PCI configuration etc.) -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
