text: /*
   * CRIS MMU constants and PTE layout
   */
  
  #ifndef _CRIS_ARCH_MMU_H
  #define _CRIS_ARCH_MMU_H
  
  /* type used in struct mm to couple an MMU context to an active mm */
  
  typedef unsigned int mm_context_t;
  
  /* kernel memory segments */
  
  #define KSEG_F 0xf0000000UL
  #define KSEG_E 0xe0000000UL
  #define KSEG_D 0xd0000000UL
  #define KSEG_C 0xc0000000UL
  #define KSEG_B 0xb0000000UL
  #define KSEG_A 0xa0000000UL
  #define KSEG_9 0x90000000UL
  #define KSEG_8 0x80000000UL
  #define KSEG_7 0x70000000UL
  #define KSEG_6 0x60000000UL
  #define KSEG_5 0x50000000UL
  #define KSEG_4 0x40000000UL
  #define KSEG_3 0x30000000UL
  #define KSEG_2 0x20000000UL
  #define KSEG_1 0x10000000UL
  #define KSEG_0 0x00000000UL
  
  /* CRIS PTE bits (see R_TLB_LO in the register description)
   *
   *   Bit:  31-13 12-------4    3        2       1       0  
   *         ________________________________________________
   *        | pfn | reserved | global | valid | kernel | we  |
   *        |_____|__________|________|_______|________|_____|
   *
   * (pfn = physical frame number)
   */
  
  /* Real HW-based PTE bits. We use some synonym names so that
   * things become less confusing in combination with the SW-based
   * bits further below.
   *
   */
  
  #define _PAGE_WE	   (1<<0) /* page is write-enabled */
  #define _PAGE_SILENT_WRITE (1<<0) /* synonym */
  #define _PAGE_KERNEL	   (1<<1) /* page is kernel only */
  #define _PAGE_VALID	   (1<<2) /* page is valid */
  #define _PAGE_SILENT_READ  (1<<2) /* synonym */
  #define _PAGE_GLOBAL       (1<<3) /* global page - context is ignored */
  
  /* Bits the HW doesn't care about but the kernel uses them in SW */
  
  #define _PAGE_PRESENT   (1<<4)  /* page present in memory */
  #define _PAGE_FILE      (1<<5)  /* set: pagecache, unset: swap (when !PRESENT) */
  #define _PAGE_ACCESSED	(1<<5)  /* simulated in software using valid bit */
  #define _PAGE_MODIFIED	(1<<6)  /* simulated in software using we bit */
  #define _PAGE_READ      (1<<7)  /* read-enabled */
  #define _PAGE_WRITE     (1<<8)  /* write-enabled */
  
  /* Define some higher level generic page attributes. */
  
  #define __READABLE      (_PAGE_READ | _PAGE_SILENT_READ | _PAGE_ACCESSED)
  #define __WRITEABLE     (_PAGE_WRITE | _PAGE_SILENT_WRITE | _PAGE_MODIFIED)
  
  #define _PAGE_TABLE     (_PAGE_PRESENT | __READABLE | __WRITEABLE)
  #define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_ACCESSED | _PAGE_MODIFIED)
  
  #define PAGE_NONE       __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)
  #define PAGE_SHARED     __pgprot(_PAGE_PRESENT | __READABLE | _PAGE_WRITE | \
  				 _PAGE_ACCESSED)
  #define PAGE_COPY       __pgprot(_PAGE_PRESENT | __READABLE)  // | _PAGE_COW
  #define PAGE_READONLY   __pgprot(_PAGE_PRESENT | __READABLE)
  #define PAGE_KERNEL     __pgprot(_PAGE_GLOBAL | _PAGE_KERNEL | \
  				 _PAGE_PRESENT | __READABLE | __WRITEABLE)
  #define _KERNPG_TABLE   (_PAGE_TABLE | _PAGE_KERNEL)
  
  /*
   * CRIS can't do page protection for execute, and considers read the same.
   * Also, write permissions imply read permissions. This is the closest we can
   * get..
   */
  
  #define __P000	PAGE_NONE
  #define __P001	PAGE_READONLY
  #define __P010	PAGE_COPY
  #define __P011	PAGE_COPY
  #define __P100	PAGE_READONLY
  #define __P101	PAGE_READONLY
  #define __P110	PAGE_COPY
  #define __P111	PAGE_COPY
  
  #define __S000	PAGE_NONE
  #define __S001	PAGE_READONLY
  #define __S010	PAGE_SHARED
  #define __S011	PAGE_SHARED
  #define __S100	PAGE_READONLY
  #define __S101	PAGE_READONLY
  #define __S110	PAGE_SHARED
  #define __S111	PAGE_SHARED
  
  #define PTE_FILE_MAX_BITS	26
  
  #endif
  