Re: [PATCH 2/7] iomap: implement ioread64 and iowrite64

Arnd Bergmann
2017-06-26T20:43:41Z

> +u64 ioread64(void __iomem *addr)
> +{
> + u64 low, high;
> +
> + low = ioread32(addr);
> + high = ioread32(addr + sizeof(u32));
> + return low | (high << 32);
> +}
> +u64 ioread64be(void __iomem *addr)
> +{
> + u64 low, high;
> +
> + low = ioread32be(addr + sizeof(u32));
> + high = ioread32be(addr);
> + return low | (high << 32);
> +}
> +#endif

This hardcodes the behavior of include/linux/io-64-nonatomic-hi-lo.h, which
I find rather confusing, as only about one in five drivers wants this
behavior.

I'd suggest you don't add it in lib/iomap.c at all for 32-bit architectures,
but rather use the same logic that we have for readq/writeq in
io-64-nonatomic-hi-lo.h and io-64-nonatomic-lo-hi.h, adding
{lo_hi,hi_lo}_{ioread,iowrite}{,be} to the same files, and provide
the {ioread,iowrite}{,be} macros only if they have not been defined
at that point.

Arnd