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1 /*
2  * Copyright 2012 Calxeda, Inc.
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms and conditions of the GNU General Public License,
6  * version 2, as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  * more details.
12  *
13  * You should have received a copy of the GNU General Public License along with
14  * this program.  If not, see <http://www.gnu.org/licenses/>.
15  */
16 #ifndef _ASM_ARM_PERCPU_H_
17 #define _ASM_ARM_PERCPU_H_
18 
19 #include <asm/thread_info.h>
20 
21 /*
22  * Same as asm-generic/percpu.h, except that we store the per cpu offset
23  * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
24  */
25 #if defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)
set_my_cpu_offset(unsigned long off)26 static inline void set_my_cpu_offset(unsigned long off)
27 {
28 	/* Set TPIDRPRW */
29 	asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
30 }
31 
__my_cpu_offset(void)32 static inline unsigned long __my_cpu_offset(void)
33 {
34 	unsigned long off;
35 
36 	/*
37 	 * Read TPIDRPRW.
38 	 * We want to allow caching the value, so avoid using volatile and
39 	 * instead use a fake stack read to hazard against barrier().
40 	 */
41 	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
42 		: "Q" (*(const unsigned long *)current_stack_pointer));
43 
44 	return off;
45 }
46 #define __my_cpu_offset __my_cpu_offset()
47 #else
48 #define set_my_cpu_offset(x)	do {} while(0)
49 
50 #endif /* CONFIG_SMP */
51 
52 #include <asm-generic/percpu.h>
53 
54 #endif /* _ASM_ARM_PERCPU_H_ */
55