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v850e_cache.c

/*
 * arch/v850/kernel/v850e_cache.c -- Cache control for V850E cache memories
 *
 *  Copyright (C) 2003  NEC Electronics Corporation
 *  Copyright (C) 2003  Miles Bader <miles@gnu.org>
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of this
 * archive for more details.
 *
 * Written by Miles Bader <miles@gnu.org>
 */

/* This file implements cache control for the rather simple cache used on
   some V850E CPUs, specifically the NB85E/TEG CPU-core and the V850E/ME2
   CPU.  V850E2 processors have their own (better) cache
   implementation.  */

#include <asm/entry.h>
#include <asm/cacheflush.h>
#include <asm/v850e_cache.h>

#define WAIT_UNTIL_CLEAR(value) while (value) {}

/* Set caching params via the BHC and DCC registers.  */
void v850e_cache_enable (u16 bhc, u16 icc, u16 dcc)
{
      unsigned long *r0_ram = (unsigned long *)R0_RAM_ADDR;
      register u16 bhc_val asm ("r6") = bhc;

      /* Read the instruction cache control register (ICC) and confirm
         that bits 0 and 1 (TCLR0, TCLR1) are all cleared.  */
      WAIT_UNTIL_CLEAR (V850E_CACHE_ICC & 0x3);
      V850E_CACHE_ICC = icc;

#ifdef V850E_CACHE_DCC
      /* Configure data-cache.  */
      V850E_CACHE_DCC = dcc;
#endif /* V850E_CACHE_DCC */

      /* Configure caching for various memory regions by writing the BHC
         register.  The documentation says that an instruction _cannot_
         enable/disable caching for the memory region in which the
         instruction itself exists; to work around this, we store
         appropriate instructions into the on-chip RAM area (which is never
         cached), and briefly jump there to do the work.  */
#ifdef V850E_CACHE_WRITE_IBS
      *r0_ram++   = 0xf0720760;     /* st.h r0, 0xfffff072[r0] */
#endif
      *r0_ram++   = 0xf06a3760;     /* st.h r6, 0xfffff06a[r0] */
      *r0_ram     = 0x5640006b;     /* jmp [r11] */

      asm ("mov hilo(1f), r11; jmp [%1]; 1:;"
           :: "r" (bhc_val), "r" (R0_RAM_ADDR) : "r11");
}

static void clear_icache (void)
{
      /* 1. Read the instruction cache control register (ICC) and confirm
            that bits 0 and 1 (TCLR0, TCLR1) are all cleared.  */
      WAIT_UNTIL_CLEAR (V850E_CACHE_ICC & 0x3);

      /* 2. Read the ICC register and confirm that bit 12 (LOCK0) is
            cleared.  Bit 13 of the ICC register is always cleared.  */
      WAIT_UNTIL_CLEAR (V850E_CACHE_ICC & 0x1000);

      /* 3. Set the TCLR0 and TCLR1 bits of the ICC register as follows,
            when clearing way 0 and way 1 at the same time:
              (a) Set the TCLR0 and TCLR1 bits.
            (b) Read the TCLR0 and TCLR1 bits to confirm that these bits
                are cleared.
            (c) Perform (a) and (b) above again.  */
      V850E_CACHE_ICC |= 0x3;
      WAIT_UNTIL_CLEAR (V850E_CACHE_ICC & 0x3);

#ifdef V850E_CACHE_REPEAT_ICC_WRITE
      /* Do it again.  */
      V850E_CACHE_ICC |= 0x3;
      WAIT_UNTIL_CLEAR (V850E_CACHE_ICC & 0x3);
#endif
}

#ifdef V850E_CACHE_DCC
/* Flush or clear (or both) the data cache, depending on the value of FLAGS;
   the procedure is the same for both, just the control bits used differ (and
   both may be performed simultaneously).  */
static void dcache_op (unsigned short flags)
{
      /* 1. Read the data cache control register (DCC) and confirm that bits
            0, 1, 4, and 5 (DC00, DC01, DC04, DC05) are all cleared.  */
      WAIT_UNTIL_CLEAR (V850E_CACHE_DCC & 0x33);

      /* 2. Clear DCC register bit 12 (DC12), bit 13 (DC13), or both
            depending on the way for which tags are to be cleared.  */
      V850E_CACHE_DCC &= ~0xC000;

      /* 3. Set DCC register bit 0 (DC00), bit 1 (DC01) or both depending on
            the way for which tags are to be cleared.
            ...
            Set DCC register bit 4 (DC04), bit 5 (DC05), or both depending
            on the way to be data flushed.  */
      V850E_CACHE_DCC |= flags;

      /* 4. Read DCC register bit DC00, DC01 [DC04, DC05], or both depending
            on the way for which tags were cleared [flushed] and confirm
            that that bit is cleared.  */
      WAIT_UNTIL_CLEAR (V850E_CACHE_DCC & flags);
}
#endif /* V850E_CACHE_DCC */

/* Flushes the contents of the dcache to memory.  */
static inline void flush_dcache (void)
{
#ifdef V850E_CACHE_DCC
      /* We only need to do something if in write-back mode.  */
      if (V850E_CACHE_DCC & 0x0400)
            dcache_op (0x30);
#endif /* V850E_CACHE_DCC */
}

/* Flushes the contents of the dcache to memory, and then clears it.  */
static inline void clear_dcache (void)
{
#ifdef V850E_CACHE_DCC
      /* We only need to do something if the dcache is enabled.  */
      if (V850E_CACHE_DCC & 0x0C00)
            dcache_op (0x33);
#endif /* V850E_CACHE_DCC */
}

/* Clears the dcache without flushing to memory first.  */
static inline void clear_dcache_no_flush (void)
{
#ifdef V850E_CACHE_DCC
      /* We only need to do something if the dcache is enabled.  */
      if (V850E_CACHE_DCC & 0x0C00)
            dcache_op (0x3);
#endif /* V850E_CACHE_DCC */
}

static inline void cache_exec_after_store (void)
{
      flush_dcache ();
      clear_icache ();
}


/* Exported functions.  */

void flush_icache (void)
{
      cache_exec_after_store ();
}

void flush_icache_range (unsigned long start, unsigned long end)
{
      cache_exec_after_store ();
}

void flush_icache_page (struct vm_area_struct *vma, struct page *page)
{
      cache_exec_after_store ();
}

void flush_icache_user_range (struct vm_area_struct *vma, struct page *page,
                        unsigned long adr, int len)
{
      cache_exec_after_store ();
}

void flush_cache_sigtramp (unsigned long addr)
{
      cache_exec_after_store ();
}

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