Commit d325209b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent 92ba1f53

arch/avr32/include/asm/atomic.h

+62 −61
Original line number Diff line number Diff line
@@ -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 (IS_21BIT_CONST(i))

		return __atomic_sub_return(-i, v);



	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");



	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.

 * Atomically subtracts @i from @v. Returns the resulting value.

 */

static inline void atomic_sub_unless(atomic_t *v, int a, int u)

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

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