[U-Boot-Users] [PATCH] PPC: add accessor macros to clear and set bits in one shot

[Detlev Zundel]

Hi Wolfgang,

> PPC: add accessor macros to clear and set bits in one shot

Although I think this is a good idea, I do not particularly like some
details.

>
> This patch adds macros from linux/include/asm-powerpc/io.h to clear and
> set bits in one shot using the in_be32, out_be32, etc. accessor functions.
> They are very handy to manipulate bits it I/O registers.
>
> This patch is required for my forthcoming FSL NAND UPM driver re-write and
> the support for the TQM8548 module.
>
> Signed-off-by: Wolfgang Grandegger <wg at grandegger.com>
> ---
>  include/asm-ppc/io.h |   28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> Index: u-boot/include/asm-ppc/io.h
> ===================================================================
> --- u-boot.orig/include/asm-ppc/io.h
> +++ u-boot/include/asm-ppc/io.h
> @@ -238,6 +238,34 @@ extern inline void out_be32(volatile uns
>  	__asm__ __volatile__("sync; stw%U0%X0 %1,%0" : "=m" (*addr) : "r" (val));
>  }
>  
> +/* access ports */
> +#define setbits32(_addr, _v) out_be32((_addr), in_be32(_addr) |  (_v))
> +#define clrbits32(_addr, _v) out_be32((_addr), in_be32(_addr) & ~(_v))
> +
> +#define setbits16(_addr, _v) out_be16((_addr), in_be16(_addr) |  (_v))
> +#define clrbits16(_addr, _v) out_be16((_addr), in_be16(_addr) & ~(_v))

Below are versions for _{be,le} which makes total sense to me, but the
variants here miss the endianness, _implicitely_ doing big-endian
transfers.  That is neither consistent, nor usable, i.e. how do I set a
bit in a le-register?

> +
> +#define setbits8(_addr, _v) out_8((_addr), in_8(_addr) |  (_v))
> +#define clrbits8(_addr, _v) out_8((_addr), in_8(_addr) & ~(_v))
> +
> +/* Clear and set bits in one shot.  These macros can be used to clear and
> + * set multiple bits in a register using a single read-modify-write.  These
> + * macros can also be used to set a multiple-bit bit pattern using a mask,
> + * by specifying the mask in the 'clear' parameter and the new bit pattern
> + * in the 'set' parameter.
> + */
> +
> +#define clrsetbits(type, addr, clear, set) \
> +	out_##type((addr), (in_##type(addr) & ~(clear)) | (set))
> +
> +#define clrsetbits_be32(addr, clear, set) clrsetbits(be32, addr, clear, set)
> +#define clrsetbits_le32(addr, clear, set) clrsetbits(le32, addr, clear, set)
> +
> +#define clrsetbits_be16(addr, clear, set) clrsetbits(be16, addr, clear, set)
> +#define clrsetbits_le16(addr, clear, set) clrsetbits(le32, addr, clear, set)

Error --------------------------------------------------^^^^

> +
> +#define clrsetbits_8(addr, clear, set) clrsetbits(8, addr, clear, set)
> +
>  /*
>   * Given a physical address and a length, return a virtual address
>   * that can be used to access the memory range with the caching

Cheers
  Detlev

-- 
The best way to predict the future is to invent it.
                                           -- Alan Kay
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