arch/parisc/include/asm/ldcw.h

   1 #ifndef __PARISC_LDCW_H
   2 #define __PARISC_LDCW_H
   3
   4 #ifndef CONFIG_PA20
   5 /* Because kmalloc only guarantees 8-byte alignment for kmalloc'd data,
   6    and GCC only guarantees 8-byte alignment for stack locals, we can't
   7    be assured of 16-byte alignment for atomic lock data even if we
   8    specify "__attribute ((aligned(16)))" in the type declaration.  So,
   9    we use a struct containing an array of four ints for the atomic lock
  10    type and dynamically select the 16-byte aligned int from the array
  11    for the semaphore.  */
  12
  13 #define __PA_LDCW_ALIGNMENT     16
  14 #define __ldcw_align(a) ({                                      \
  15         unsigned long __ret = (unsigned long) &(a)->lock[0];    \
  16         __ret = (__ret + __PA_LDCW_ALIGNMENT - 1)               \
  17                 & ~(__PA_LDCW_ALIGNMENT - 1);                   \
  18         (volatile unsigned int *) __ret;                        \
  19 })
  20 #define __LDCW  "ldcw"
  21
  22 #else /*CONFIG_PA20*/
  23 /* From: "Jim Hull" <jim.hull of hp.com>
  24    I've attached a summary of the change, but basically, for PA 2.0, as
  25    long as the ",CO" (coherent operation) completer is specified, then the
  26    16-byte alignment requirement for ldcw and ldcd is relaxed, and instead
  27    they only require "natural" alignment (4-byte for ldcw, 8-byte for
  28    ldcd). */
  29
  30 #define __PA_LDCW_ALIGNMENT     4
  31 #define __ldcw_align(a) (&(a)->slock)
  32 #define __LDCW  "ldcw,co"
  33
  34 #endif /*!CONFIG_PA20*/
  35
  36 /* LDCW, the only atomic read-write operation PA-RISC has. *sigh*.  */
  37 #define __ldcw(a) ({                                            \
  38         unsigned __ret;                                         \
  39         __asm__ __volatile__(__LDCW " 0(%2),%0"                 \
  40                 : "=r" (__ret), "+m" (*(a)) : "r" (a));         \
  41         __ret;                                                  \
  42 })
  43
  44 #ifdef CONFIG_SMP
  45 # define __lock_aligned __attribute__((__section__(".data..lock_aligned")))
  46 #endif
  47
  48 #endif /* __PARISC_LDCW_H */