arch/arm/include/asm/percpu.h

   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 /*
  20  * Same as asm-generic/percpu.h, except that we store the per cpu offset
  21  * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
  22  */
  23 #if defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)
  24 static inline void set_my_cpu_offset(unsigned long off)
  25 {
  26         /* Set TPIDRPRW */
  27         asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
  28 }
  29
  30 static inline unsigned long __my_cpu_offset(void)
  31 {
  32         unsigned long off;
  33
  34         /*
  35          * Read TPIDRPRW.
  36          * We want to allow caching the value, so avoid using volatile and
  37          * instead use a fake stack read to hazard against barrier().
  38          */
  39         asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
  40                 : "Q" (*(const unsigned long *)current_stack_pointer));
  41
  42         return off;
  43 }
  44 #define __my_cpu_offset __my_cpu_offset()
  45 #else
  46 #define set_my_cpu_offset(x)    do {} while(0)
  47
  48 #endif /* CONFIG_SMP */
  49
  50 #include <asm-generic/percpu.h>
  51
  52 #endif /* _ASM_ARM_PERCPU_H_ */