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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                 :            : /*
      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                 :            :         register unsigned long *sp asm ("sp");
      34                 :            : 
      35                 :            :         /*
      36                 :            :          * Read TPIDRPRW.
      37                 :            :          * We want to allow caching the value, so avoid using volatile and
      38                 :            :          * instead use a fake stack read to hazard against barrier().
      39                 :            :          */
      40                 : 1263940223 :         asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off) : "Q" (*sp));
      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_ */