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powerpc: expose the multi-bit ops that underlie single-bit ops.
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The bitops.h functions that operate on a single bit in a bitfield are
implemented by operating on the corresponding word location. In all
cases the inner logic is valid if the mask being applied has more than
one bit set, so this patch exposes those inner operations. Indeed,
set_bits() was already available, but it duplicated code from
set_bit() (rather than making the latter a wrapper) - it was also
missing the PPC405_ERR77() workaround and the "volatile" address
qualifier present in other APIs. This corrects that, and exposes the
other multi-bit equivalents.

One advantage of these multi-bit forms is that they allow word-sized
variables to essentially be their own spinlocks, eg. very useful for
state machines where an atomic "flags" variable can obviate the need
for any additional locking.

Signed-off-by: Geoff Thorpe <geoff@geoffthorpe.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Geoff Thorpe authored and Benjamin Herrenschmidt committed Aug 20, 2009
1 parent 11a6b29 commit 0d2d3e3
Showing 1 changed file with 62 additions and 134 deletions.
196 changes: 62 additions & 134 deletions arch/powerpc/include/asm/bitops.h
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Original file line number Diff line number Diff line change
Expand Up @@ -56,174 +56,102 @@
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
#define BITOP_LE_SWIZZLE ((BITS_PER_LONG-1) & ~0x7)

/* Macro for generating the ***_bits() functions */
#define DEFINE_BITOP(fn, op, prefix, postfix) \
static __inline__ void fn(unsigned long mask, \
volatile unsigned long *_p) \
{ \
unsigned long old; \
unsigned long *p = (unsigned long *)_p; \
__asm__ __volatile__ ( \
prefix \
"1:" PPC_LLARX "%0,0,%3\n" \
stringify_in_c(op) "%0,%0,%2\n" \
PPC405_ERR77(0,%3) \
PPC_STLCX "%0,0,%3\n" \
"bne- 1b\n" \
postfix \
: "=&r" (old), "+m" (*p) \
: "r" (mask), "r" (p) \
: "cc", "memory"); \
}

DEFINE_BITOP(set_bits, or, "", "")
DEFINE_BITOP(clear_bits, andc, "", "")
DEFINE_BITOP(clear_bits_unlock, andc, LWSYNC_ON_SMP, "")
DEFINE_BITOP(change_bits, xor, "", "")

static __inline__ void set_bit(int nr, volatile unsigned long *addr)
{
unsigned long old;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
"1:" PPC_LLARX "%0,0,%3 # set_bit\n"
"or %0,%0,%2\n"
PPC405_ERR77(0,%3)
PPC_STLCX "%0,0,%3\n"
"bne- 1b"
: "=&r" (old), "+m" (*p)
: "r" (mask), "r" (p)
: "cc" );
set_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
}

static __inline__ void clear_bit(int nr, volatile unsigned long *addr)
{
unsigned long old;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
"1:" PPC_LLARX "%0,0,%3 # clear_bit\n"
"andc %0,%0,%2\n"
PPC405_ERR77(0,%3)
PPC_STLCX "%0,0,%3\n"
"bne- 1b"
: "=&r" (old), "+m" (*p)
: "r" (mask), "r" (p)
: "cc" );
clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
}

static __inline__ void clear_bit_unlock(int nr, volatile unsigned long *addr)
{
unsigned long old;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
LWSYNC_ON_SMP
"1:" PPC_LLARX "%0,0,%3 # clear_bit_unlock\n"
"andc %0,%0,%2\n"
PPC405_ERR77(0,%3)
PPC_STLCX "%0,0,%3\n"
"bne- 1b"
: "=&r" (old), "+m" (*p)
: "r" (mask), "r" (p)
: "cc", "memory");
clear_bits_unlock(BITOP_MASK(nr), addr + BITOP_WORD(nr));
}

static __inline__ void change_bit(int nr, volatile unsigned long *addr)
{
unsigned long old;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
"1:" PPC_LLARX "%0,0,%3 # change_bit\n"
"xor %0,%0,%2\n"
PPC405_ERR77(0,%3)
PPC_STLCX "%0,0,%3\n"
"bne- 1b"
: "=&r" (old), "+m" (*p)
: "r" (mask), "r" (p)
: "cc" );
change_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
}

/* Like DEFINE_BITOP(), with changes to the arguments to 'op' and the output
* operands. */
#define DEFINE_TESTOP(fn, op, prefix, postfix) \
static __inline__ unsigned long fn( \
unsigned long mask, \
volatile unsigned long *_p) \
{ \
unsigned long old, t; \
unsigned long *p = (unsigned long *)_p; \
__asm__ __volatile__ ( \
prefix \
"1:" PPC_LLARX "%0,0,%3\n" \
stringify_in_c(op) "%1,%0,%2\n" \
PPC405_ERR77(0,%3) \
PPC_STLCX "%1,0,%3\n" \
"bne- 1b\n" \
postfix \
: "=&r" (old), "=&r" (t) \
: "r" (mask), "r" (p) \
: "cc", "memory"); \
return (old & mask); \
}

DEFINE_TESTOP(test_and_set_bits, or, LWSYNC_ON_SMP, ISYNC_ON_SMP)
DEFINE_TESTOP(test_and_set_bits_lock, or, "", ISYNC_ON_SMP)
DEFINE_TESTOP(test_and_clear_bits, andc, LWSYNC_ON_SMP, ISYNC_ON_SMP)
DEFINE_TESTOP(test_and_change_bits, xor, LWSYNC_ON_SMP, ISYNC_ON_SMP)

static __inline__ int test_and_set_bit(unsigned long nr,
volatile unsigned long *addr)
{
unsigned long old, t;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
LWSYNC_ON_SMP
"1:" PPC_LLARX "%0,0,%3 # test_and_set_bit\n"
"or %1,%0,%2 \n"
PPC405_ERR77(0,%3)
PPC_STLCX "%1,0,%3 \n"
"bne- 1b"
ISYNC_ON_SMP
: "=&r" (old), "=&r" (t)
: "r" (mask), "r" (p)
: "cc", "memory");

return (old & mask) != 0;
return test_and_set_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
}

static __inline__ int test_and_set_bit_lock(unsigned long nr,
volatile unsigned long *addr)
{
unsigned long old, t;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
"1:" PPC_LLARX "%0,0,%3 # test_and_set_bit_lock\n"
"or %1,%0,%2 \n"
PPC405_ERR77(0,%3)
PPC_STLCX "%1,0,%3 \n"
"bne- 1b"
ISYNC_ON_SMP
: "=&r" (old), "=&r" (t)
: "r" (mask), "r" (p)
: "cc", "memory");

return (old & mask) != 0;
return test_and_set_bits_lock(BITOP_MASK(nr),
addr + BITOP_WORD(nr)) != 0;
}

static __inline__ int test_and_clear_bit(unsigned long nr,
volatile unsigned long *addr)
{
unsigned long old, t;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
LWSYNC_ON_SMP
"1:" PPC_LLARX "%0,0,%3 # test_and_clear_bit\n"
"andc %1,%0,%2 \n"
PPC405_ERR77(0,%3)
PPC_STLCX "%1,0,%3 \n"
"bne- 1b"
ISYNC_ON_SMP
: "=&r" (old), "=&r" (t)
: "r" (mask), "r" (p)
: "cc", "memory");

return (old & mask) != 0;
return test_and_clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
}

static __inline__ int test_and_change_bit(unsigned long nr,
volatile unsigned long *addr)
{
unsigned long old, t;
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);

__asm__ __volatile__(
LWSYNC_ON_SMP
"1:" PPC_LLARX "%0,0,%3 # test_and_change_bit\n"
"xor %1,%0,%2 \n"
PPC405_ERR77(0,%3)
PPC_STLCX "%1,0,%3 \n"
"bne- 1b"
ISYNC_ON_SMP
: "=&r" (old), "=&r" (t)
: "r" (mask), "r" (p)
: "cc", "memory");

return (old & mask) != 0;
}

static __inline__ void set_bits(unsigned long mask, unsigned long *addr)
{
unsigned long old;

__asm__ __volatile__(
"1:" PPC_LLARX "%0,0,%3 # set_bits\n"
"or %0,%0,%2\n"
PPC_STLCX "%0,0,%3\n"
"bne- 1b"
: "=&r" (old), "+m" (*addr)
: "r" (mask), "r" (addr)
: "cc");
return test_and_change_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
}

#include <asm-generic/bitops/non-atomic.h>
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