Messages in this thread | | | Date | Mon, 13 Oct 2008 12:27:27 +0200 | From | Haavard Skinnemoen <> | Subject | Re: [PATCH] Make ATNGW100 serial ports configurable |
| |
Anders Blomdell <anders.blomdell@control.lth.se> wrote: > Haavard Skinnemoen wrote: > > Anders Blomdell <anders.blomdell@control.lth.se> wrote: > >> Make configuration of ATNGW100 serial ports selectable in kernel configuration. > >> > >> Signed-off-by: Anders Blomdell <anders.blomdell@control.lth.se> > > > > Gak. If we're going down this path, why not add #ifdefs for every other > > conceivable hardware mod as well and turn the ATNGW100 board code into > > an even worse mess than the ATSTK1000 board code? > OK, good point. The reason I sent in the patch is that people on AVRFreaks had > asked how to do it, and putting it in the configuration would (theoretically) > make it possible to catch pin conflicts.
Yes, I do realize people want this kind of thing. But I also think there's more than one way to do it, and while a Kconfig option might make things easier while trying it out, I think it will cause maintenance pains in the long run.
> > The ATNGW100 has one serial port on board, so IMO the standard board > > code should only initialize that one port. > Which was my intention, unless SERIAL_ATMEL_USARTn was selected.
Yes, but it's not sensible to even offer the option of other ports when the board just doesn't have them.
> > However, it might be sensible to add some sort of interface for > > expansion board code. For example something like this: > > > > #ifdef CONFIG_ATNGW100_EXPANSION > > atngw100_setup_expansion_board(); > > #endif > Since that file has to reside inside the kernel tree (?), one could almost as > easily replace the entire setup.c.
True...but it would take quite a bit of duplication, and you'll have to sync up whenever the "main" setup.c changes.
> Shouldn't this be something like: > > void __init setup_board(void) > { > ... > #ifdef CONFIG_ATNGW100_EXPANSION > atngw100_setup_expansion_board(); > #endif > } > > static int __init atngw100_init(void) > { > ... > #ifdef CONFIG_ATNGW100_EXPANSION > atngw100_init_expansion_board(); > #endif > }
Well, you could do it like that, but you could also just add another postcore_initcall. The only hook which is really needed is the "setup" part, and only if you have additional serial ports.
In fact, it's probably better to just add a weak definition for it since not all expansion boards will need to override it.
> > This will allow people with hardware mods to add all the extra devices > > they need, including serial ports, by simply adding another file with > > expansion board code. People who aren't afraid to solder stuff on their > > boards shouldn't be afraid of writing some board code too, right? > > > > What do you think? > An even nicer way of handling it (provided that initialization does not need to > take place during boot), might be to do EXPORT_SYMBOL() on > at32_add_device_usart, at32_map_usart, etc and then write a loadable module that > handles the initialization.
Hmm...why would that be nicer exactly?
What _I_ think would be a nicer way to do it is to implement support for flattened device trees and get rid of the board code entirely. Or almost entirely; it depends on how complete we can make the device tree.
Haavard
| |