1/* SPDX-License-Identifier: GPL-2.0-only */
 2/*
 3 * Copyright 2012 Calxeda, Inc.
 4 */
 5#ifndef _ASM_ARM_PERCPU_H_
 6#define _ASM_ARM_PERCPU_H_
 7
 8register unsigned long current_stack_pointer asm ("sp");
 9
10/*
11 * Same as asm-generic/percpu.h, except that we store the per cpu offset
12 * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
13 */
14#if defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)
15static inline void set_my_cpu_offset(unsigned long off)
16{
17	/* Set TPIDRPRW */
18	asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
19}
20
21static inline unsigned long __my_cpu_offset(void)
22{
23	unsigned long off;
24
25	/*
26	 * Read TPIDRPRW.
27	 * We want to allow caching the value, so avoid using volatile and
28	 * instead use a fake stack read to hazard against barrier().
29	 */
30	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
31		: "Q" (*(const unsigned long *)current_stack_pointer));
32
33	return off;
34}
35#define __my_cpu_offset __my_cpu_offset()
36#else
37#define set_my_cpu_offset(x)	do {} while(0)
38
39#endif /* CONFIG_SMP */
40
41#include <asm-generic/percpu.h>
42
43#endif /* _ASM_ARM_PERCPU_H_ */