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   1 /* spinlock.h: 64-bit Sparc spinlock support.
   2  *
   3  * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
   4  */
   5
   6 #ifndef __SPARC64_SPINLOCK_H
   7 #define __SPARC64_SPINLOCK_H
   8
   9 #include <linux/config.h>
  10 #include <linux/threads.h>      /* For NR_CPUS */
  11
  12 #ifndef __ASSEMBLY__
  13
  14 /* To get debugging spinlocks which detect and catch
  15  * deadlock situations, set CONFIG_DEBUG_SPINLOCK
  16  * and rebuild your kernel.
  17  */
  18
  19 /* All of these locking primitives are expected to work properly
  20  * even in an RMO memory model, which currently is what the kernel
  21  * runs in.
  22  *
  23  * There is another issue.  Because we play games to save cycles
  24  * in the non-contention case, we need to be extra careful about
  25  * branch targets into the "spinning" code.  They live in their
  26  * own section, but the newer V9 branches have a shorter range
  27  * than the traditional 32-bit sparc branch variants.  The rule
  28  * is that the branches that go into and out of the spinner sections
  29  * must be pre-V9 branches.
  30  */
  31
  32 #define __raw_spin_is_locked(lp)        ((lp)->lock != 0)
  33
  34 #define __raw_spin_unlock_wait(lp)      \
  35         do {    rmb();                  \
  36         } while((lp)->lock)
  37
  38 static inline void __raw_spin_lock(raw_spinlock_t *lock)
  39 {
  40         unsigned long tmp;
  41
  42         __asm__ __volatile__(
  43 "1:     ldstub          [%1], %0\n"
  44 "       membar          #StoreLoad | #StoreStore\n"
  45 "       brnz,pn         %0, 2f\n"
  46 "        nop\n"
  47 "       .subsection     2\n"
  48 "2:     ldub            [%1], %0\n"
  49 "       membar          #LoadLoad\n"
  50 "       brnz,pt         %0, 2b\n"
  51 "        nop\n"
  52 "       ba,a,pt         %%xcc, 1b\n"
  53 "       .previous"
  54         : "=&r" (tmp)
  55         : "r" (lock)
  56         : "memory");
  57 }
  58
  59 static inline int __raw_spin_trylock(raw_spinlock_t *lock)
  60 {
  61         unsigned long result;
  62
  63         __asm__ __volatile__(
  64 "       ldstub          [%1], %0\n"
  65 "       membar          #StoreLoad | #StoreStore"
  66         : "=r" (result)
  67         : "r" (lock)
  68         : "memory");
  69
  70         return (result == 0UL);
  71 }
  72
  73 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
  74 {
  75         __asm__ __volatile__(
  76 "       membar          #StoreStore | #LoadStore\n"
  77 "       stb             %%g0, [%0]"
  78         : /* No outputs */
  79         : "r" (lock)
  80         : "memory");
  81 }
  82
  83 static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
  84 {
  85         unsigned long tmp1, tmp2;
  86
  87         __asm__ __volatile__(
  88 "1:     ldstub          [%2], %0\n"
  89 "       membar          #StoreLoad | #StoreStore\n"
  90 "       brnz,pn         %0, 2f\n"
  91 "        nop\n"
  92 "       .subsection     2\n"
  93 "2:     rdpr            %%pil, %1\n"
  94 "       wrpr            %3, %%pil\n"
  95 "3:     ldub            [%2], %0\n"
  96 "       membar          #LoadLoad\n"
  97 "       brnz,pt         %0, 3b\n"
  98 "        nop\n"
  99 "       ba,pt           %%xcc, 1b\n"
 100 "        wrpr           %1, %%pil\n"
 101 "       .previous"
 102         : "=&r" (tmp1), "=&r" (tmp2)
 103         : "r"(lock), "r"(flags)
 104         : "memory");
 105 }
 106
 107 /* Multi-reader locks, these are much saner than the 32-bit Sparc ones... */
 108
 109 static void inline __read_lock(raw_rwlock_t *lock)
 110 {
 111         unsigned long tmp1, tmp2;
 112
 113         __asm__ __volatile__ (
 114 "1:     ldsw            [%2], %0\n"
 115 "       brlz,pn         %0, 2f\n"
 116 "4:      add            %0, 1, %1\n"
 117 "       cas             [%2], %0, %1\n"
 118 "       cmp             %0, %1\n"
 119 "       membar          #StoreLoad | #StoreStore\n"
 120 "       bne,pn          %%icc, 1b\n"
 121 "        nop\n"
 122 "       .subsection     2\n"
 123 "2:     ldsw            [%2], %0\n"
 124 "       membar          #LoadLoad\n"
 125 "       brlz,pt         %0, 2b\n"
 126 "        nop\n"
 127 "       ba,a,pt         %%xcc, 4b\n"
 128 "       .previous"
 129         : "=&r" (tmp1), "=&r" (tmp2)
 130         : "r" (lock)
 131         : "memory");
 132 }
 133
 134 static void inline __read_unlock(raw_rwlock_t *lock)
 135 {
 136         unsigned long tmp1, tmp2;
 137
 138         __asm__ __volatile__(
 139 "       membar  #StoreLoad | #LoadLoad\n"
 140 "1:     lduw    [%2], %0\n"
 141 "       sub     %0, 1, %1\n"
 142 "       cas     [%2], %0, %1\n"
 143 "       cmp     %0, %1\n"
 144 "       bne,pn  %%xcc, 1b\n"
 145 "        nop"
 146         : "=&r" (tmp1), "=&r" (tmp2)
 147         : "r" (lock)
 148         : "memory");
 149 }
 150
 151 static void inline __write_lock(raw_rwlock_t *lock)
 152 {
 153         unsigned long mask, tmp1, tmp2;
 154
 155         mask = 0x80000000UL;
 156
 157         __asm__ __volatile__(
 158 "1:     lduw            [%2], %0\n"
 159 "       brnz,pn         %0, 2f\n"
 160 "4:      or             %0, %3, %1\n"
 161 "       cas             [%2], %0, %1\n"
 162 "       cmp             %0, %1\n"
 163 "       membar          #StoreLoad | #StoreStore\n"
 164 "       bne,pn          %%icc, 1b\n"
 165 "        nop\n"
 166 "       .subsection     2\n"
 167 "2:     lduw            [%2], %0\n"
 168 "       membar          #LoadLoad\n"
 169 "       brnz,pt         %0, 2b\n"
 170 "        nop\n"
 171 "       ba,a,pt         %%xcc, 4b\n"
 172 "       .previous"
 173         : "=&r" (tmp1), "=&r" (tmp2)
 174         : "r" (lock), "r" (mask)
 175         : "memory");
 176 }
 177
 178 static void inline __write_unlock(raw_rwlock_t *lock)
 179 {
 180         __asm__ __volatile__(
 181 "       membar          #LoadStore | #StoreStore\n"
 182 "       stw             %%g0, [%0]"
 183         : /* no outputs */
 184         : "r" (lock)
 185         : "memory");
 186 }
 187
 188 static int inline __write_trylock(raw_rwlock_t *lock)
 189 {
 190         unsigned long mask, tmp1, tmp2, result;
 191
 192         mask = 0x80000000UL;
 193
 194         __asm__ __volatile__(
 195 "       mov             0, %2\n"
 196 "1:     lduw            [%3], %0\n"
 197 "       brnz,pn         %0, 2f\n"
 198 "        or             %0, %4, %1\n"
 199 "       cas             [%3], %0, %1\n"
 200 "       cmp             %0, %1\n"
 201 "       membar          #StoreLoad | #StoreStore\n"
 202 "       bne,pn          %%icc, 1b\n"
 203 "        nop\n"
 204 "       mov             1, %2\n"
 205 "2:"
 206         : "=&r" (tmp1), "=&r" (tmp2), "=&r" (result)
 207         : "r" (lock), "r" (mask)
 208         : "memory");
 209
 210         return result;
 211 }
 212
 213 #define __raw_read_lock(p)      __read_lock(p)
 214 #define __raw_read_unlock(p)    __read_unlock(p)
 215 #define __raw_write_lock(p)     __write_lock(p)
 216 #define __raw_write_unlock(p)   __write_unlock(p)
 217 #define __raw_write_trylock(p)  __write_trylock(p)
 218
 219 #define __raw_read_trylock(lock)        generic__raw_read_trylock(lock)
 220 #define __raw_read_can_lock(rw)         (!((rw)->lock & 0x80000000UL))
 221 #define __raw_write_can_lock(rw)        (!(rw)->lock)
 222
 223 #endif /* !(__ASSEMBLY__) */
 224
 225 #endif /* !(__SPARC64_SPINLOCK_H) */