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kernel/linux-rt-4.4.41/arch/tile/include/asm/barrier.h 2.56 KB
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  /*
   * Copyright 2010 Tilera Corporation. 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
   *   as published by the Free Software Foundation, version 2.
   *
   *   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, GOOD TITLE or
   *   NON INFRINGEMENT.  See the GNU General Public License for
   *   more details.
   */
  
  #ifndef _ASM_TILE_BARRIER_H
  #define _ASM_TILE_BARRIER_H
  
  #ifndef __ASSEMBLY__
  
  #include <linux/types.h>
  #include <arch/chip.h>
  #include <arch/spr_def.h>
  #include <asm/timex.h>
  
  #define __sync()	__insn_mf()
  
  #include <hv/syscall_public.h>
  /*
   * Issue an uncacheable load to each memory controller, then
   * wait until those loads have completed.
   */
  static inline void __mb_incoherent(void)
  {
  	long clobber_r10;
  	asm volatile("swint2"
  		     : "=R10" (clobber_r10)
  		     : "R10" (HV_SYS_fence_incoherent)
  		     : "r0", "r1", "r2", "r3", "r4",
  		       "r5", "r6", "r7", "r8", "r9",
  		       "r11", "r12", "r13", "r14",
  		       "r15", "r16", "r17", "r18", "r19",
  		       "r20", "r21", "r22", "r23", "r24",
  		       "r25", "r26", "r27", "r28", "r29");
  }
  
  /* Fence to guarantee visibility of stores to incoherent memory. */
  static inline void
  mb_incoherent(void)
  {
  	__insn_mf();
  
  	{
  #if CHIP_HAS_TILE_WRITE_PENDING()
  		const unsigned long WRITE_TIMEOUT_CYCLES = 400;
  		unsigned long start = get_cycles_low();
  		do {
  			if (__insn_mfspr(SPR_TILE_WRITE_PENDING) == 0)
  				return;
  		} while ((get_cycles_low() - start) < WRITE_TIMEOUT_CYCLES);
  #endif /* CHIP_HAS_TILE_WRITE_PENDING() */
  		(void) __mb_incoherent();
  	}
  }
  
  #define fast_wmb()	__sync()
  #define fast_rmb()	__sync()
  #define fast_mb()	__sync()
  #define fast_iob()	mb_incoherent()
  
  #define wmb()		fast_wmb()
  #define rmb()		fast_rmb()
  #define mb()		fast_mb()
  #define iob()		fast_iob()
  
  #ifndef __tilegx__ /* 32 bit */
  /*
   * We need to barrier before modifying the word, since the _atomic_xxx()
   * routines just tns the lock and then read/modify/write of the word.
   * But after the word is updated, the routine issues an "mf" before returning,
   * and since it's a function call, we don't even need a compiler barrier.
   */
  #define smp_mb__before_atomic()	smp_mb()
  #define smp_mb__after_atomic()	do { } while (0)
  #else /* 64 bit */
  #define smp_mb__before_atomic()	smp_mb()
  #define smp_mb__after_atomic()	smp_mb()
  #endif
  
  #include <asm-generic/barrier.h>
  
  #endif /* !__ASSEMBLY__ */
  #endif /* _ASM_TILE_BARRIER_H */