On Fri, Feb 20, 2009 at 3:07 PM, Ira Snyder <i...@ovro.caltech.edu> wrote: > On Fri, Feb 20, 2009 at 02:05:08PM -0600, Matt Sealey wrote: >> On Fri, Feb 20, 2009 at 1:11 PM, Ira Snyder <i...@ovro.caltech.edu> wrote: >> > On Fri, Feb 20, 2009 at 12:57:36PM -0600, Matt Sealey wrote: >> > >> > I'm pretty sure memcpy_fromio() and memcpy_toio() will get you what you >> > want. They don't change byte ordering. >> >> Are they guaranteed to only do 32-bit, aligned accesses? >> > > I don't think so. I certainly wouldn't count on anything better than a > byte-by-byte memcpy. > >> I made some cheats on my CPLD to ignore byte enables and so on, >> because it makes the design cleaner and easier to read (for students) >> plus, saves a ton of logic cells. It's totally within the PCI >> standard, but it means if you do a byte read memcpy() you get.. very >> weird results (i.e. not great). >> > > Right, I understand how that works :) > > Some usage of cscope shows that __raw_readl() might be what you want, > as well as __raw_writel() for writing. I'm not sure it is universally > available, but maybe they are. > > The comment on PowerPC says "Non ordered and non-swapping "raw" > accessors". Looks about right. ARM's implementation uses them to > implement ioread32() and friends by adding byteswapping.
Am I correct in saying that cpu_to_le32 and le32_to_cpu are the functions/macros I need to use to do byte swapping to make everything go little endian (and back again when I read them back in the kernel)? Or is there some cleverer way already implemented in the kernel? -- Matt Sealey <m...@genesi-usa.com> Genesi, Manager, Developer Relations _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
