arch/arm/lib/bitops.h

   1
   2 #if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_CPU_32v6K)
   3         .macro  bitop, instr
   4         mov     r2, #1
   5         and     r3, r0, #7              @ Get bit offset
   6         add     r1, r1, r0, lsr #3      @ Get byte offset
   7         mov     r3, r2, lsl r3
   8 1:      ldrexb  r2, [r1]
   9         \instr  r2, r2, r3
  10         strexb  r0, r2, [r1]
  11         cmp     r0, #0
  12         bne     1b
  13         mov     pc, lr
  14         .endm
  15
  16         .macro  testop, instr, store
  17         and     r3, r0, #7              @ Get bit offset
  18         mov     r2, #1
  19         add     r1, r1, r0, lsr #3      @ Get byte offset
  20         mov     r3, r2, lsl r3          @ create mask
  21         smp_dmb
  22 1:      ldrexb  r2, [r1]
  23         ands    r0, r2, r3              @ save old value of bit
  24         \instr  r2, r2, r3                      @ toggle bit
  25         strexb  ip, r2, [r1]
  26         cmp     ip, #0
  27         bne     1b
  28         smp_dmb
  29         cmp     r0, #0
  30         movne   r0, #1
  31 2:      mov     pc, lr
  32         .endm
  33 #else
  34         .macro  bitop, instr
  35         and     r2, r0, #7
  36         mov     r3, #1
  37         mov     r3, r3, lsl r2
  38         save_and_disable_irqs ip
  39         ldrb    r2, [r1, r0, lsr #3]
  40         \instr  r2, r2, r3
  41         strb    r2, [r1, r0, lsr #3]
  42         restore_irqs ip
  43         mov     pc, lr
  44         .endm
  45
  46 /**
  47  * testop - implement a test_and_xxx_bit operation.
  48  * @instr: operational instruction
  49  * @store: store instruction
  50  *
  51  * Note: we can trivially conditionalise the store instruction
  52  * to avoid dirtying the data cache.
  53  */
  54         .macro  testop, instr, store
  55         add     r1, r1, r0, lsr #3
  56         and     r3, r0, #7
  57         mov     r0, #1
  58         save_and_disable_irqs ip
  59         ldrb    r2, [r1]
  60         tst     r2, r0, lsl r3
  61         \instr  r2, r2, r0, lsl r3
  62         \store  r2, [r1]
  63         moveq   r0, #0
  64         restore_irqs ip
  65         mov     pc, lr
  66         .endm
  67 #endif