Re: [balbi-usb:xceiv 3/3] drivers/usb/phy/rcar-phy.c:75:3: error: implicit declaration of function 'iowrite32'

["Bjørn Mork" <bjorn-yOkvZcmFvRU@public.gmane.org>]

Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org> writes:
> On Thu, Nov 01, 2012 at 11:06:58AM -0400, David Miller wrote:
>> From: Bjørn Mork <bjorn-yOkvZcmFvRU@public.gmane.org>
>> Date: Thu, 01 Nov 2012 14:38:29 +0100
>> 
>> > Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org> writes:
>> > 
>> >> btw, only alpha and x86 seem to be providing all of those, but if you
>> >> look into our documentation, it's said that drivers are supposed to use
>> >> write/read{b,w,l,q} for all memory-mapped io. I'd expect all platforms
>> >> to provide those even if just to allow compilation of drivers.
>> > 
>> > Only if HAS_IOMEM is true, I believe.
>> 
>> This is correct.
>
> fair enough, then we can depend on HAS_IOMEM.
>
> Another question, if HAS_IOMEM is true, is the arch expected to provide
> *all* accessor methods ?

I'll leave this for those with more clue...

But there is a comment in arch/alpha/include/asm/io.h indicating that
writeq/readq support is tested separately, so I guess it must be
optional:

/*
 * Some mucking forons use if[n]def writeq to check if platform has it.
 * It's a bloody bad idea and we probably want ARCH_HAS_WRITEQ for them
 * to play with; for now just use cpp anti-recursion logics and make sure
 * that damn thing is defined and expands to itself.
 */

#define writeq writeq
#define readq readq


> And the last one: if the arch provides
> read/write{b,w,l,q}, should it be selecting HAS_IOMEM ??

But that one is easy: HAS_IOMEM is true by default.  The arch sets
NO_IOMEM to disable it. Similar to HAS_DMA.  So you can be pretty sure
that HAS_IOMEM is selected unless the arch has reasons not to.  From
lib/Kconfig:

config HAS_IOMEM
        boolean
        depends on !NO_IOMEM
        select GENERIC_IO
        default y



Bjørn
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