Re: [PATCH v2 02/22] asm-generic/io.h: add ioremap_nopost remap interface

[Russell King - ARM Linux]

On Tue, Mar 28, 2017 at 03:45:43PM +0100, Lorenzo Pieralisi wrote:
> On Mon, Mar 27, 2017 at 08:41:10PM -0500, Bjorn Helgaas wrote:
> > On Mon, Mar 27, 2017 at 10:49:30AM +0100, Lorenzo Pieralisi wrote:
> > > diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
> > > index 7afb0e2..50b292f 100644
> > > --- a/arch/x86/include/asm/io.h
> > > +++ b/arch/x86/include/asm/io.h
> > > @@ -171,6 +171,7 @@ static inline unsigned int isa_virt_to_bus(volatile void *address)
> > >  extern void __iomem *ioremap_nocache(resource_size_t offset, unsigned long size);
> > >  extern void __iomem *ioremap_uc(resource_size_t offset, unsigned long size);
> > >  #define ioremap_uc ioremap_uc
> > > +#define ioremap_nopost ioremap_nocache
> > 
> > These are all the same as the default from asm-generic.h.  Do we really
> > need these definitions in alpha, avr32, frv, ia64, x86?
> 
> Those arches do not include asm-generic.h (I suppose for a good reason)
> but a definition is needed anyway if we want code using ioremap_nopost()
> to be unconditional. This is one way of doing it, there are others not
> sure they are any better, I am open to suggestions.

We do have linux/io.h, which should be included in preference to asm/io.h.
linux/io.h has existed for years, but I still see (from time to time)
patches adding drivers that (imho incorrectly) use asm/io.h.

Also, this:

> > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> > > index 7ef015e..0e81938 100644
> > > --- a/include/asm-generic/io.h
> > > +++ b/include/asm-generic/io.h
> > > @@ -915,6 +915,10 @@ extern void ioport_unmap(void __iomem *p);
> > >  #endif /* CONFIG_GENERIC_IOMAP */
> > >  #endif /* CONFIG_HAS_IOPORT_MAP */
> > >  
> > > +#ifndef ioremap_nopost
> > > +#define ioremap_nopost ioremap_nocache
> > > +#endif
> > > +
> > >  #ifndef xlate_dev_kmem_ptr
> > >  #define xlate_dev_kmem_ptr xlate_dev_kmem_ptr
> > >  static inline void *xlate_dev_kmem_ptr(void *addr)

could well be located in linux/io.h, which would make it available
everywhere.

I'd suggest one change to this though:

#ifndef ioremap_nopost
static inline void __iomem *ioremap_nopost(resource_size_t offset,
					   unsigned long size)
{
	return ioremap_nocache(offset, size);
}
#endif

This way, if someone forgets to define ioremap_nopost() in their
asm/io.h but provides a definition or extern prototype for
ioremap_nopost(), we end up with a compile error to highlight the
error, rather than the error being hidden by the preprocessor.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.