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kernel/linux-rt-4.4.41/arch/mips/include/asm/maar.h 4.03 KB
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  /*
   * Copyright (C) 2014 Imagination Technologies
   * Author: Paul Burton <paul.burton@imgtec.com>
   *
   * 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;  either version 2 of the  License, or (at your
   * option) any later version.
   */
  
  #ifndef __MIPS_ASM_MIPS_MAAR_H__
  #define __MIPS_ASM_MIPS_MAAR_H__
  
  #include <asm/hazards.h>
  #include <asm/mipsregs.h>
  
  /**
   * platform_maar_init() - perform platform-level MAAR configuration
   * @num_pairs:	The number of MAAR pairs present in the system.
   *
   * Platforms should implement this function such that it configures as many
   * MAAR pairs as required, from 0 up to the maximum of num_pairs-1, and returns
   * the number that were used. Any further MAARs will be configured to be
   * invalid. The default implementation of this function will simply indicate
   * that it has configured 0 MAAR pairs.
   *
   * Return:	The number of MAAR pairs configured.
   */
  unsigned platform_maar_init(unsigned num_pairs);
  
  /**
   * write_maar_pair() - write to a pair of MAARs
   * @idx:	The index of the pair (ie. use MAARs idx*2 & (idx*2)+1).
   * @lower:	The lowest address that the MAAR pair will affect. Must be
   *		aligned to a 2^16 byte boundary.
   * @upper:	The highest address that the MAAR pair will affect. Must be
   *		aligned to one byte before a 2^16 byte boundary.
   * @attrs:	The accessibility attributes to program, eg. MIPS_MAAR_S. The
   *		MIPS_MAAR_V attribute will automatically be set.
   *
   * Program the pair of MAAR registers specified by idx to apply the attributes
   * specified by attrs to the range of addresses from lower to higher.
   */
  static inline void write_maar_pair(unsigned idx, phys_addr_t lower,
  				   phys_addr_t upper, unsigned attrs)
  {
  	/* Addresses begin at bit 16, but are shifted right 4 bits */
  	BUG_ON(lower & (0xffff | ~(MIPS_MAAR_ADDR << 4)));
  	BUG_ON(((upper & 0xffff) != 0xffff)
  		|| ((upper & ~0xffffull) & ~(MIPS_MAAR_ADDR << 4)));
  
  	/* Automatically set MIPS_MAAR_V */
  	attrs |= MIPS_MAAR_V;
  
  	/* Write the upper address & attributes (only MIPS_MAAR_V matters) */
  	write_c0_maari(idx << 1);
  	back_to_back_c0_hazard();
  	write_c0_maar(((upper >> 4) & MIPS_MAAR_ADDR) | attrs);
  	back_to_back_c0_hazard();
  
  	/* Write the lower address & attributes */
  	write_c0_maari((idx << 1) | 0x1);
  	back_to_back_c0_hazard();
  	write_c0_maar((lower >> 4) | attrs);
  	back_to_back_c0_hazard();
  }
  
  /**
   * maar_init() - initialise MAARs
   *
   * Performs initialisation of MAARs for the current CPU, making use of the
   * platforms implementation of platform_maar_init where necessary and
   * duplicating the setup it provides on secondary CPUs.
   */
  extern void maar_init(void);
  
  /**
   * struct maar_config - MAAR configuration data
   * @lower:	The lowest address that the MAAR pair will affect. Must be
   *		aligned to a 2^16 byte boundary.
   * @upper:	The highest address that the MAAR pair will affect. Must be
   *		aligned to one byte before a 2^16 byte boundary.
   * @attrs:	The accessibility attributes to program, eg. MIPS_MAAR_S. The
   *		MIPS_MAAR_V attribute will automatically be set.
   *
   * Describes the configuration of a pair of Memory Accessibility Attribute
   * Registers - applying attributes from attrs to the range of physical
   * addresses from lower to upper inclusive.
   */
  struct maar_config {
  	phys_addr_t lower;
  	phys_addr_t upper;
  	unsigned attrs;
  };
  
  /**
   * maar_config() - configure MAARs according to provided data
   * @cfg:	Pointer to an array of struct maar_config.
   * @num_cfg:	The number of structs in the cfg array.
   * @num_pairs:	The number of MAAR pairs present in the system.
   *
   * Configures as many MAARs as are present and specified in the cfg
   * array with the values taken from the cfg array.
   *
   * Return:	The number of MAAR pairs configured.
   */
  static inline unsigned maar_config(const struct maar_config *cfg,
  				   unsigned num_cfg, unsigned num_pairs)
  {
  	unsigned i;
  
  	for (i = 0; i < min(num_cfg, num_pairs); i++)
  		write_maar_pair(i, cfg[i].lower, cfg[i].upper, cfg[i].attrs);
  
  	return i;
  }
  
  #endif /* __MIPS_ASM_MIPS_MAAR_H__ */