mtdcr and mfdcr macros

[Verberk, Bep]

I realized soon after I sent this that there are
problems with the  changes I made :(

Any advise on how to use these in a loop, or changes
that would allow them to be used in a loop ?

I'll try a few other ideas....

Cheers,
Bep

On Wed, 3 Dec 2003, Verberk, Bep [CAR:7M00:EXCH] wrote:
>
> I'd like a sanity check on a change I am considering to
> these macros....
>
> I had some difficulty executing these macros
> (found in include/asm/processor.h) in a loop, eg:
>
> #define DMA0_BANKS 	4
> #define DCRN_DMA0_BASE	0x100
> #define DCRN_DMA0_CR(bank)  (DCRN_DMA0_BASE + (8 * (bank)))
>
> 		for(i=0;i<DMA0_BANKS;i++){
> 			dma0_cr = mfdcr(DCRN_DMA0_CR(i));
> 			CLEARBITS(dma0_cr, DMA0_CR_PCE);
> 			mtdcr(DCRN_DMA0_CR(i), dma0_cr);
> 		};
>
> compiling results in the assembler error
> /tmp/cca8HPJ4.s:282: Error: undefined symbol `i' in operation
>
> Compiling with the -E to see what the pre-processor is generating
> --
> for(i=0;i< 4 ;i++) {
>      	dma0_cr = ({unsigned int rval;
> 	asm volatile("mfdcr %0," "(0x100 + (8 * (i)))"
> 		  : "=r" (rval)); rval;}) ;
>         ( dma0_cr  =  dma0_cr  |   0x00000008  ) ;
>         asm volatile("mtdcr " "(0x100 + (8 * (i)))" ",%0"
> 		: : "r" (  dma0_cr )) ;
> };
>
> Looking at the definition of mtdcr and mfdcr in processor.h
> --
> #define mfdcr(rn)       ({unsigned int rval; \
>                         asm volatile("mfdcr %0," __stringify(rn) \
>                                      : "=r" (rval)); rval;})
> #define mtdcr(rn, v)    asm volatile("mtdcr " __stringify(rn) ",%0" \
> 				: : "r" (v))
>
> I was suspicious that the use of __stringify was buggering up my
> index parameter. I made a slight tweak to these macros to take
> (rn) as a numeric input param.
>
> #define mfdcr(rn)       ({unsigned int rval; \
>                         asm volatile("mfdcr %0, %1" \
>                                      : "=r" (rval) \
> 				     : "n" (rn));  \
> 				rval;})
>
> #define mtdcr(rn, v)    asm volatile("mtdcr %1 ,%0" \
> 				: : "r" (v), "n" (rn));
>
> Testing this morning so far seems to indicate the new version is
> working for me, but my usage is fairly limited. Am I missing
> anything ??

--
Bep Verberk
verberk at nortelnetworks.com

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