On Wed, 2010-10-13 at 21:45 +0200, Arnd Bergmann wrote: > On Wednesday 13 October 2010 20:08:35 Daniel Walker wrote: > > On Wed, 2010-10-13 at 19:44 +0200, Arnd Bergmann wrote: > > > On Wednesday 13 October 2010 18:17:03 Daniel Walker wrote: > > > > > I think you would be much better off making it a "hvc" driver, where > > > > > you just need to provide a read character and write character function > > > > > and an optional interrupt handler but otherwise have the common hvc > > > > > code take care of polling the hardware and talking to the tty layer. > > > > > > > > I don't know what the "hvc" driver is "Hypervisor Virtual Console" > > > > maybe? > > > > > > Yes, it originally was used only on hypervisors that had simple > > > read/write type consoles, but has now turned into a generic facility > > > that is used by a number of consoles that don't look like classic > > > serial ports. > > > > > > > Can you give any sort of example driver which does what you > > > > suggesting? > > > > > > Look at drivers/char/hvc_tile.c for the simplest case or > > > drivers/char/hvc_vio.c for one that uses interrupts. > > > > I found it independently actually .. It looks like there's at least two > > problems. This jtag driver has a status register which flags when RX is > > available, and TX is possible. I'm not sure this status register fits > > into the model. > > I think that is how they all work. The read/write functions simply return > the number of characters transferred, which may be zero if the output > is busy or the input is empty. > > > The other thing is that we have a ttyJ registered for > > this driver, and it would be nice to use that over something like ttyHVC > > (I'm not sure if that name is correct, just a guess). > > It's hvc0, but I don't see this as a problem because the driver was never > upstream before -- you don't really get to complain about compatibility > with out-of-tree code :-) I'm complaining about naming issues, not compatibility. > Seriously, I don't think you need it, but if you really do, we can probably > find a way to work around this by changing the base hvc driver. I think we would have to add something that allows different major/minor numbers, because something that includes the name "Hypervisor" shouldn't be used for something general.. /dev/hvcX is also registered for "IBM iSeries/pSeries virtual console" (according to www.lanana.org) which is confusing .. Daniel -- Sent by a consultant of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html