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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 #ifndef __ASSEMBLY__
  10
  11 /* To get debugging spinlocks which detect and catch
  12  * deadlock situations, set CONFIG_DEBUG_SPINLOCK
  13  * and rebuild your kernel.
  14  */
  15
  16 /* All of these locking primitives are expected to work properly
  17  * even in an RMO memory model, which currently is what the kernel
  18  * runs in.
  19  *
  20  * There is another issue.  Because we play games to save cycles
  21  * in the non-contention case, we need to be extra careful about
  22  * branch targets into the "spinning" code.  They live in their
  23  * own section, but the newer V9 branches have a shorter range
  24  * than the traditional 32-bit sparc branch variants.  The rule
  25  * is that the branches that go into and out of the spinner sections
  26  * must be pre-V9 branches.
  27  */
  28
  29 #define __raw_spin_is_locked(lp)        ((lp)->lock != 0)
  30
  31 #define __raw_spin_unlock_wait(lp)      \
  32         do {    rmb();                  \
  33         } while((lp)->lock)
  34
  35 static inline void __raw_spin_lock(raw_spinlock_t *lock)
  36 {
  37         unsigned long tmp;
  38
  39         __asm__ __volatile__(
  40 "1:     ldstub          [%1], %0\n"
  41 "       membar          #StoreLoad | #StoreStore\n"
  42 "       brnz,pn         %0, 2f\n"
  43 "        nop\n"
  44 "       .subsection     2\n"
  45 "2:     ldub            [%1], %0\n"
  46 "       membar          #LoadLoad\n"
  47 "       brnz,pt         %0, 2b\n"
  48 "        nop\n"
  49 "       ba,a,pt         %%xcc, 1b\n"
  50 "       .previous"
  51         : "=&r" (tmp)
  52         : "r" (lock)
  53         : "memory");
  54 }
  55
  56 static inline int __raw_spin_trylock(raw_spinlock_t *lock)
  57 {
  58         unsigned long result;
  59
  60         __asm__ __volatile__(
  61 "       ldstub          [%1], %0\n"
  62 "       membar          #StoreLoad | #StoreStore"
  63         : "=r" (result)
  64         : "r" (lock)
  65         : "memory");
  66
  67         return (result == 0UL);
  68 }
  69
  70 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
  71 {
  72         __asm__ __volatile__(
  73 "       membar          #StoreStore | #LoadStore\n"
  74 "       stb             %%g0, [%0]"
  75         : /* No outputs */
  76         : "r" (lock)
  77         : "memory");
  78 }
  79
  80 static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
  81 {
  82         unsigned long tmp1, tmp2;
  83
  84         __asm__ __volatile__(
  85 "1:     ldstub          [%2], %0\n"
  86 "       membar          #StoreLoad | #StoreStore\n"
  87 "       brnz,pn         %0, 2f\n"
  88 "        nop\n"
  89 "       .subsection     2\n"
  90 "2:     rdpr            %%pil, %1\n"
  91 "       wrpr            %3, %%pil\n"
  92 "3:     ldub            [%2], %0\n"
  93 "       membar          #LoadLoad\n"
  94 "       brnz,pt         %0, 3b\n"
  95 "        nop\n"
  96 "       ba,pt           %%xcc, 1b\n"
  97 "        wrpr           %1, %%pil\n"
  98 "       .previous"
  99         : "=&r" (tmp1), "=&r" (tmp2)
 100         : "r"(lock), "r"(flags)
 101         : "memory");
 102 }
 103
 104 /* Multi-reader locks, these are much saner than the 32-bit Sparc ones... */
 105
 106 static void inline __read_lock(raw_rwlock_t *lock)
 107 {
 108         unsigned long tmp1, tmp2;
 109
 110         __asm__ __volatile__ (
 111 "1:     ldsw            [%2], %0\n"
 112 "       brlz,pn         %0, 2f\n"
 113 "4:      add            %0, 1, %1\n"
 114 "       cas             [%2], %0, %1\n"
 115 "       cmp             %0, %1\n"
 116 "       membar          #StoreLoad | #StoreStore\n"
 117 "       bne,pn          %%icc, 1b\n"
 118 "        nop\n"
 119 "       .subsection     2\n"
 120 "2:     ldsw            [%2], %0\n"
 121 "       membar          #LoadLoad\n"
 122 "       brlz,pt         %0, 2b\n"
 123 "        nop\n"
 124 "       ba,a,pt         %%xcc, 4b\n"
 125 "       .previous"
 126         : "=&r" (tmp1), "=&r" (tmp2)
 127         : "r" (lock)
 128         : "memory");
 129 }
 130
 131 static int inline __read_trylock(raw_rwlock_t *lock)
 132 {
 133         int tmp1, tmp2;
 134
 135         __asm__ __volatile__ (
 136 "1:     ldsw            [%2], %0\n"
 137 "       brlz,a,pn       %0, 2f\n"
 138 "        mov            0, %0\n"
 139 "       add             %0, 1, %1\n"
 140 "       cas             [%2], %0, %1\n"
 141 "       cmp             %0, %1\n"
 142 "       membar          #StoreLoad | #StoreStore\n"
 143 "       bne,pn          %%icc, 1b\n"
 144 "        mov            1, %0\n"
 145 "2:"
 146         : "=&r" (tmp1), "=&r" (tmp2)
 147         : "r" (lock)
 148         : "memory");
 149
 150         return tmp1;
 151 }
 152
 153 static void inline __read_unlock(raw_rwlock_t *lock)
 154 {
 155         unsigned long tmp1, tmp2;
 156
 157         __asm__ __volatile__(
 158 "       membar  #StoreLoad | #LoadLoad\n"
 159 "1:     lduw    [%2], %0\n"
 160 "       sub     %0, 1, %1\n"
 161 "       cas     [%2], %0, %1\n"
 162 "       cmp     %0, %1\n"
 163 "       bne,pn  %%xcc, 1b\n"
 164 "        nop"
 165         : "=&r" (tmp1), "=&r" (tmp2)
 166         : "r" (lock)
 167         : "memory");
 168 }
 169
 170 static void inline __write_lock(raw_rwlock_t *lock)
 171 {
 172         unsigned long mask, tmp1, tmp2;
 173
 174         mask = 0x80000000UL;
 175
 176         __asm__ __volatile__(
 177 "1:     lduw            [%2], %0\n"
 178 "       brnz,pn         %0, 2f\n"
 179 "4:      or             %0, %3, %1\n"
 180 "       cas             [%2], %0, %1\n"
 181 "       cmp             %0, %1\n"
 182 "       membar          #StoreLoad | #StoreStore\n"
 183 "       bne,pn          %%icc, 1b\n"
 184 "        nop\n"
 185 "       .subsection     2\n"
 186 "2:     lduw            [%2], %0\n"
 187 "       membar          #LoadLoad\n"
 188 "       brnz,pt         %0, 2b\n"
 189 "        nop\n"
 190 "       ba,a,pt         %%xcc, 4b\n"
 191 "       .previous"
 192         : "=&r" (tmp1), "=&r" (tmp2)
 193         : "r" (lock), "r" (mask)
 194         : "memory");
 195 }
 196
 197 static void inline __write_unlock(raw_rwlock_t *lock)
 198 {
 199         __asm__ __volatile__(
 200 "       membar          #LoadStore | #StoreStore\n"
 201 "       stw             %%g0, [%0]"
 202         : /* no outputs */
 203         : "r" (lock)
 204         : "memory");
 205 }
 206
 207 static int inline __write_trylock(raw_rwlock_t *lock)
 208 {
 209         unsigned long mask, tmp1, tmp2, result;
 210
 211         mask = 0x80000000UL;
 212
 213         __asm__ __volatile__(
 214 "       mov             0, %2\n"
 215 "1:     lduw            [%3], %0\n"
 216 "       brnz,pn         %0, 2f\n"
 217 "        or             %0, %4, %1\n"
 218 "       cas             [%3], %0, %1\n"
 219 "       cmp             %0, %1\n"
 220 "       membar          #StoreLoad | #StoreStore\n"
 221 "       bne,pn          %%icc, 1b\n"
 222 "        nop\n"
 223 "       mov             1, %2\n"
 224 "2:"
 225         : "=&r" (tmp1), "=&r" (tmp2), "=&r" (result)
 226         : "r" (lock), "r" (mask)
 227         : "memory");
 228
 229         return result;
 230 }
 231
 232 #define __raw_read_lock(p)      __read_lock(p)
 233 #define __raw_read_trylock(p)   __read_trylock(p)
 234 #define __raw_read_unlock(p)    __read_unlock(p)
 235 #define __raw_write_lock(p)     __write_lock(p)
 236 #define __raw_write_unlock(p)   __write_unlock(p)
 237 #define __raw_write_trylock(p)  __write_trylock(p)
 238
 239 #define __raw_read_can_lock(rw)         (!((rw)->lock & 0x80000000UL))
 240 #define __raw_write_can_lock(rw)        (!(rw)->lock)
 241
 242 #define _raw_spin_relax(lock)   cpu_relax()
 243 #define _raw_read_relax(lock)   cpu_relax()
 244 #define _raw_write_relax(lock)  cpu_relax()
 245
 246 #endif /* !(__ASSEMBLY__) */
 247
 248 #endif /* !(__SPARC64_SPINLOCK_H) */