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authorPeter Zijlstra <peterz@infradead.org>2014-04-09 21:51:29 +0200
committerIngo Molnar <mingo@kernel.org>2014-08-14 12:48:05 +0200
commitd325209b6000dcd13404ee946d2292e15a56718c (patch)
tree9adc93bd2a6a2b2f69c2b2034603c1c619106d4a /arch/avr32
parent92ba1f530b4f90db78eb45f4b6598e75939146bd (diff)
downloadlinux-d325209b6000dcd13404ee946d2292e15a56718c.tar.gz
locking,arch,avr32: Fold atomic_ops
Many of the atomic op implementations are the same except for one instruction; fold the lot into a few CPP macros and reduce LoC. This also prepares for easy addition of new ops. Requires the asm_op because of eor. AVR32 is a bit special in that its ADD/SUB instructions are not symmetric. Its SUB instruction allows for an 21bit immediate. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20140531141445.GD16155@laptop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/avr32')
-rw-r--r--arch/avr32/include/asm/atomic.h123
1 files changed, 62 insertions, 61 deletions
diff --git a/arch/avr32/include/asm/atomic.h b/arch/avr32/include/asm/atomic.h
index 0780f3f2415..83e980a4e48 100644
--- a/arch/avr32/include/asm/atomic.h
+++ b/arch/avr32/include/asm/atomic.h
@@ -22,30 +22,43 @@
#define atomic_read(v) (*(volatile int *)&(v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)
+#define ATOMIC_OP_RETURN(op, asm_op, asm_con) \
+static inline int __atomic_##op##_return(int i, atomic_t *v) \
+{ \
+ int result; \
+ \
+ asm volatile( \
+ "/* atomic_" #op "_return */\n" \
+ "1: ssrf 5\n" \
+ " ld.w %0, %2\n" \
+ " " #asm_op " %0, %3\n" \
+ " stcond %1, %0\n" \
+ " brne 1b" \
+ : "=&r" (result), "=o" (v->counter) \
+ : "m" (v->counter), #asm_con (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
+ATOMIC_OP_RETURN(sub, sub, rKs21)
+ATOMIC_OP_RETURN(add, add, r)
+
+#undef ATOMIC_OP_RETURN
+
/*
- * atomic_sub_return - subtract the atomic variable
- * @i: integer value to subtract
- * @v: pointer of type atomic_t
+ * Probably found the reason why we want to use sub with the signed 21-bit
+ * limit, it uses one less register than the add instruction that can add up to
+ * 32-bit values.
*
- * Atomically subtracts @i from @v. Returns the resulting value.
+ * Both instructions are 32-bit, to use a 16-bit instruction the immediate is
+ * very small; 4 bit.
+ *
+ * sub 32-bit, type IV, takes a register and subtracts a 21-bit immediate.
+ * add 32-bit, type II, adds two register values together.
*/
-static inline int atomic_sub_return(int i, atomic_t *v)
-{
- int result;
-
- asm volatile(
- "/* atomic_sub_return */\n"
- "1: ssrf 5\n"
- " ld.w %0, %2\n"
- " sub %0, %3\n"
- " stcond %1, %0\n"
- " brne 1b"
- : "=&r"(result), "=o"(v->counter)
- : "m"(v->counter), "rKs21"(i)
- : "cc");
-
- return result;
-}
+#define IS_21BIT_CONST(i) \
+ (__builtin_constant_p(i) && ((i) >= -1048575) && ((i) <= 1048576))
/*
* atomic_add_return - add integer to atomic variable
@@ -56,51 +69,25 @@ static inline int atomic_sub_return(int i, atomic_t *v)
*/
static inline int atomic_add_return(int i, atomic_t *v)
{
- int result;
-
- if (__builtin_constant_p(i) && (i >= -1048575) && (i <= 1048576))
- result = atomic_sub_return(-i, v);
- else
- asm volatile(
- "/* atomic_add_return */\n"
- "1: ssrf 5\n"
- " ld.w %0, %1\n"
- " add %0, %3\n"
- " stcond %2, %0\n"
- " brne 1b"
- : "=&r"(result), "=o"(v->counter)
- : "m"(v->counter), "r"(i)
- : "cc", "memory");
+ if (IS_21BIT_CONST(i))
+ return __atomic_sub_return(-i, v);
- return result;
+ return __atomic_add_return(i, v);
}
/*
- * atomic_sub_unless - sub unless the number is a given value
+ * atomic_sub_return - subtract the atomic variable
+ * @i: integer value to subtract
* @v: pointer of type atomic_t
- * @a: the amount to subtract from v...
- * @u: ...unless v is equal to u.
*
- * Atomically subtract @a from @v, so long as it was not @u.
- * Returns the old value of @v.
-*/
-static inline void atomic_sub_unless(atomic_t *v, int a, int u)
+ * Atomically subtracts @i from @v. Returns the resulting value.
+ */
+static inline int atomic_sub_return(int i, atomic_t *v)
{
- int tmp;
+ if (IS_21BIT_CONST(i))
+ return __atomic_sub_return(i, v);
- asm volatile(
- "/* atomic_sub_unless */\n"
- "1: ssrf 5\n"
- " ld.w %0, %2\n"
- " cp.w %0, %4\n"
- " breq 1f\n"
- " sub %0, %3\n"
- " stcond %1, %0\n"
- " brne 1b\n"
- "1:"
- : "=&r"(tmp), "=o"(v->counter)
- : "m"(v->counter), "rKs21"(a), "rKs21"(u)
- : "cc", "memory");
+ return __atomic_add_return(-i, v);
}
/*
@@ -116,9 +103,21 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
int tmp, old = atomic_read(v);
- if (__builtin_constant_p(a) && (a >= -1048575) && (a <= 1048576))
- atomic_sub_unless(v, -a, u);
- else {
+ if (IS_21BIT_CONST(a)) {
+ asm volatile(
+ "/* __atomic_sub_unless */\n"
+ "1: ssrf 5\n"
+ " ld.w %0, %2\n"
+ " cp.w %0, %4\n"
+ " breq 1f\n"
+ " sub %0, %3\n"
+ " stcond %1, %0\n"
+ " brne 1b\n"
+ "1:"
+ : "=&r"(tmp), "=o"(v->counter)
+ : "m"(v->counter), "rKs21"(-a), "rKs21"(u)
+ : "cc", "memory");
+ } else {
asm volatile(
"/* __atomic_add_unless */\n"
"1: ssrf 5\n"
@@ -137,6 +136,8 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
return old;
}
+#undef IS_21BIT_CONST
+
/*
* atomic_sub_if_positive - conditionally subtract integer from atomic variable
* @i: integer value to subtract