serial_ns16550 driver question

[Juergen Beisert]

Sascha Hauer wrote:
> On Thu, Jul 21, 2011 at 05:12:24AM +0200, Jean-Christophe PLAGNIOL-VILLARD 
wrote:
> > On 22:31 Wed 20 Jul     , Sascha Hauer wrote:
> > > On Wed, Jul 20, 2011 at 11:51:04PM +0400, Antony Pavlov wrote:
> > > > Hi!
> > > >
> > > > In include/ns16550.h we have:
> > > >
> > > > struct NS16550_plat {
> > > >         unsigned int clock;
> > > >         unsigned char f_caps;
> > > >         /**
> > > >          * register read access capability
> > > >          */
> > > >         unsigned int (*reg_read) (unsigned long base, unsigned char
> > > > reg_offset); /**
> > > >          * register write access capability
> > > >          */
> > > >         void (*reg_write) (unsigned int val, unsigned long base,
> > > >                                     unsigned char reg_offset);
> > > > };
> > > >
> > > > Why reg_read and reg_write's argument base has type unsigned long?
> > > > IMHO pointer type (void * or char *)  is more natural.
> > >
> > > You're right, I also wondered about this recently when looking at a
> > > patch on the list. I would also rather see void __iomem *. The problem
> > > is that this driver is also used on X86 which uses inb/outb which take
> > > an integer argument.
> > > The Linux driver works around this by having a membase and a iobase
> > > field along with different register accessors. While being cleaner
> > > I'm unsure if we want to go this way.
> >
> > we can do it via resoure and the flasgs IORESOURCE_MEM_8BIT,
> > IORESOURCE_MEM_168BITi etc..
>
> Yes, but this does not solve the problem with different accessor
> functions (and their argument type).

Why not adapt the x86 inb/outb function to the same arguments types than other 
archs are using for their memory mapped access? We are in Barebox, not in the 
kernel. I think we can do so, without damaging something in our _small_ x86 
Barebox world.

jbe

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