90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
/*
|
|
* 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 */
|