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 */
   9 static __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
  25 void 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 }
  41 EXPORT_SYMBOL(memcpy_fromio);
  42
  43 void 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 }
  59 EXPORT_SYMBOL(memcpy_toio);
  60
  61 void 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 }
  69 EXPORT_SYMBOL(memset_io);