On Mon, Nov 24, 2008 at 02:55:42AM +0100, Michael Schmitz wrote: > > We probably should have an SCC/ESCC core driver the way we have for > > a lot of the other common chips like 8390 ethernet or ESP SCSI. I > > know there's lots of systems with these chips that each have drivers. > > Didn't seem too many of those in drivers/serial ... I must admit I didn't go count them. > > Most of the m68k mac serial quirks are the same as the ones in the > > pmac serial driver. There is only one interrupt for both ports, but > > According to my 2.2.25 source, SCC A is at interrupt number 33, SCC B is > at 34. Did that change with tha A/UX interrupt style? No, those are synthetic interrupt sources. If you look at the interrupt code, there is a fake interrupt controller registered on IRQ 4 that looks at the SCC status bits and triggers the correct interrupt. Take a look at mac_scc_dispatch in arch/m68k/mac/macints.c for details. The pmac_zilog code does it a little different by tying the two devices together and only registering for one interrupt and passing them off. > What seems to be true is all interrupt types for a given channel go to > the same handler... That is definitely true on any Mac. Apple was generally stingy with interrupt sources. For example, some mac systems don't even have a real IRQ per NuBus slot even though they do all at least have a way to detect which slot asserted the interrupt. > The platform device would need to have one interrupt number each for TX, RX, > status and special condition for each channel, plus data/control ports forr > each, plus flags. The Mac platform device would have only one interrupt per > channel (and perhaps a flag indicating that). I'm sure we could do something like that with flags. > > built-in modems need enable/disable code for that on m68k macs > > Are there any Macs with builtin modems in the standard configuration? It depends on what you mean by standard configuration. Some PowerBooks shipped with internal modems, but I don't think there is any model that always had one. It was an option on most later m68k PowerBooks while most early ppc PowerBooks always had an internal modem. > > There isn't much m68k mac specific, and I don't think the issues > > you mention for Atari are issues on macs. The AV systems have > > DMA but don't have a tx-dma channel for the second port. The one > > interrupt is hooked up to IRQ 4, which means it doesn't go through > > This is on AV Macs only (because the PSC interrupts are at 32-35 there)? The AV Macs are quite a bit different from an IRQ perspective. They don't hook much of anything up directly, so the layout is slightly more logical. In particular, the registration of mac_scc_dispatch to IRQ 4 is conditionalized on !psc_present to exclude the AV models. It's all the models using VIA1 as the main interrupt controller that need it. The SCC interrupt line is never hooked up to a VIA chip, but it is connected to the PSC on AV macs and the SCC IOP on the IIfx. Sorry if the way I wrote this was confusing. > > We could probably do something along those lines, but I can't see > > tying it directly to the platform bus. I think it would be better > > to make a zilog SCC/ESCC core driver and write a driver for each > > bus interface type the way the ESP driver now works. It just seems > > simpler from a code maintenance perspective. > > I don't think using callbacks would be a clean way of handling this, so your > idea may be better. It's hard to say for sure without trying it to see how it turns out. > VME and Atari used to use the same driver in 2.2 so that should still be > possible now. Seems reasonable. Brad Boyer flar@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
