[mirror_ubuntu-zesty-kernel.git] / arch / hexagon / include / asm / cmpxchg.h

/*
 * xchg/cmpxchg operations for the Hexagon architecture
 *
 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#ifndef _ASM_CMPXCHG_H
#define _ASM_CMPXCHG_H

/*
 * __xchg - atomically exchange a register and a memory location
 * @x: value to swap
 * @ptr: pointer to memory
 * @size:  size of the value
 *
 * Only 4 bytes supported currently.
 *
 * Note:  there was an errata for V2 about .new's and memw_locked.
 *
 */
static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
				   int size)
{
	unsigned long retval;

	/*  Can't seem to use printk or panic here, so just stop  */
	if (size != 4) do { asm volatile("brkpt;\n"); } while (1);

	__asm__ __volatile__ (
	"1:	%0 = memw_locked(%1);\n"    /*  load into retval */
	"	memw_locked(%1,P0) = %2;\n" /*  store into memory */
	"	if !P0 jump 1b;\n"
	: "=&r" (retval)
	: "r" (ptr), "r" (x)
	: "memory", "p0"
	);
	return retval;
}

/*
 * Atomically swap the contents of a register with memory.  Should be atomic
 * between multiple CPU's and within interrupts on the same CPU.
 */
#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), \
	sizeof(*(ptr))))

/*
 *  see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps.
 *  looks just like atomic_cmpxchg on our arch currently with a bunch of
 *  variable casting.
 */

#define cmpxchg(ptr, old, new)					\
({								\
	__typeof__(ptr) __ptr = (ptr);				\
	__typeof__(*(ptr)) __old = (old);			\
	__typeof__(*(ptr)) __new = (new);			\
	__typeof__(*(ptr)) __oldval = 0;			\
								\
	asm volatile(						\
		"1:	%0 = memw_locked(%1);\n"		\
		"	{ P0 = cmp.eq(%0,%2);\n"		\
		"	  if (!P0.new) jump:nt 2f; }\n"		\
		"	memw_locked(%1,p0) = %3;\n"		\
		"	if (!P0) jump 1b;\n"			\
		"2:\n"						\
		: "=&r" (__oldval)				\
		: "r" (__ptr), "r" (__old), "r" (__new)		\
		: "memory", "p0"				\
	);							\
	__oldval;						\
})

#endif /* _ASM_CMPXCHG_H */
Commit	Line	Data
8335896b DH	1	/*
	2	* xchg/cmpxchg operations for the Hexagon architecture
	3	*
e1858b2a	4	* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
8335896b DH	5	*
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 and
	9	* only version 2 as published by the Free Software Foundation.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	19	* 02110-1301, USA.
	20	*/
	21
	22	#ifndef _ASM_CMPXCHG_H
	23	#define _ASM_CMPXCHG_H
	24
	25	/*
	26	* __xchg - atomically exchange a register and a memory location
	27	* @x: value to swap
	28	* @ptr: pointer to memory
	29	* @size: size of the value
	30	*
	31	* Only 4 bytes supported currently.
	32	*
	33	* Note: there was an errata for V2 about .new's and memw_locked.
	34	*
	35	*/
	36	static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
	37	int size)
	38	{
	39	unsigned long retval;
	40
	41	/* Can't seem to use printk or panic here, so just stop */
	42	if (size != 4) do { asm volatile("brkpt;\n"); } while (1);
	43
	44	__asm__ __volatile__ (
	45	"1: %0 = memw_locked(%1);\n" /* load into retval */
	46	" memw_locked(%1,P0) = %2;\n" /* store into memory */
	47	" if !P0 jump 1b;\n"
	48	: "=&r" (retval)
	49	: "r" (ptr), "r" (x)
	50	: "memory", "p0"
	51	);
	52	return retval;
	53	}
	54
	55	/*
	56	* Atomically swap the contents of a register with memory. Should be atomic
	57	* between multiple CPU's and within interrupts on the same CPU.
	58	*/
	59	#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), \
	60	sizeof(*(ptr))))
	61
	62	/*
	63	* see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps.
	64	* looks just like atomic_cmpxchg on our arch currently with a bunch of
	65	* variable casting.
	66	*/
8335896b DH	67
	68	#define cmpxchg(ptr, old, new) \
	69	({ \
	70	__typeof__(ptr) __ptr = (ptr); \
	71	__typeof__(*(ptr)) __old = (old); \
	72	__typeof__(*(ptr)) __new = (new); \
	73	__typeof__(*(ptr)) __oldval = 0; \
	74	\
	75	asm volatile( \
	76	"1: %0 = memw_locked(%1);\n" \
	77	" { P0 = cmp.eq(%0,%2);\n" \
	78	" if (!P0.new) jump:nt 2f; }\n" \
	79	" memw_locked(%1,p0) = %3;\n" \
	80	" if (!P0) jump 1b;\n" \
	81	"2:\n" \
	82	: "=&r" (__oldval) \
	83	: "r" (__ptr), "r" (__old), "r" (__new) \
	84	: "memory", "p0" \
	85	); \
	86	__oldval; \
	87	})
	88
	89	#endif /* _ASM_CMPXCHG_H */