LXR linux/arch/x86/lib/iomem.c

   1#include <linux/string.h>
   2#include <linux/module.h>
   3#include <linux/io.h>
   4
   5#define movs(type,to,from) \
   6        asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
   7
   8/* Originally from i386/string.h */
   9static __always_inline void rep_movs(void *to, const void *from, size_t n)
  10{
  11        unsigned long d0, d1, d2;
  12        asm volatile("rep ; movsl\n\t"
  13                     "testb $2,%b4\n\t"
  14                     "je 1f\n\t"
  15                     "movsw\n"
  16                     "1:\ttestb $1,%b4\n\t"
  17                     "je 2f\n\t"
  18                     "movsb\n"
  19                     "2:"
  20                     : "=&c" (d0), "=&D" (d1), "=&S" (d2)
  21                     : "0" (n / 4), "q" (n), "1" ((long)to), "2" ((long)from)
  22                     : "memory");
  23}
  24
  25void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
  26{
  27        if (unlikely(!n))
  28                return;
  29
  30        /* Align any unaligned source IO */
  31        if (unlikely(1 & (unsigned long)from)) {
  32                movs("b", to, from);
  33                n--;
  34        }
  35        if (n > 1 && unlikely(2 & (unsigned long)from)) {
  36                movs("w", to, from);
  37                n-=2;
  38        }
  39        rep_movs(to, (const void *)from, n);
  40}
  41EXPORT_SYMBOL(memcpy_fromio);
  42
  43void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
  44{
  45        if (unlikely(!n))
  46                return;
  47
  48        /* Align any unaligned destination IO */
  49        if (unlikely(1 & (unsigned long)to)) {
  50                movs("b", to, from);
  51                n--;
  52        }
  53        if (n > 1 && unlikely(2 & (unsigned long)to)) {
  54                movs("w", to, from);
  55                n-=2;
  56        }
  57        rep_movs((void *)to, (const void *) from, n);
  58}
  59EXPORT_SYMBOL(memcpy_toio);
  60
  61void memset_io(volatile void __iomem *a, int b, size_t c)
  62{
  63        /*
  64         * TODO: memset can mangle the IO patterns quite a bit.
  65         * perhaps it would be better to use a dumb one:
  66         */
  67        memset((void *)a, b, c);
  68}
  69EXPORT_SYMBOL(memset_io);
  70