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tlb.c

/*
 * AVR32 TLB operations
 *
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/mm.h>

#include <asm/mmu_context.h>

/* TODO: Get the correct number from the CONFIG1 system register */
#define NR_TLB_ENTRIES 32

static void show_dtlb_entry(unsigned int index)
{
      u32 tlbehi, tlbehi_save, tlbelo, mmucr, mmucr_save;
      unsigned long flags;

      local_irq_save(flags);
      mmucr_save = sysreg_read(MMUCR);
      tlbehi_save = sysreg_read(TLBEHI);
      mmucr = SYSREG_BFINS(DRP, index, mmucr_save);
      sysreg_write(MMUCR, mmucr);

      __builtin_tlbr();
      cpu_sync_pipeline();

      tlbehi = sysreg_read(TLBEHI);
      tlbelo = sysreg_read(TLBELO);

      printk("%2u: %c %c %02x   %05x %05x %o  %o  %c %c %c %c\n",
             index,
             SYSREG_BFEXT(TLBEHI_V, tlbehi) ? '1' : '0',
             SYSREG_BFEXT(G, tlbelo) ? '1' : '0',
             SYSREG_BFEXT(ASID, tlbehi),
             SYSREG_BFEXT(VPN, tlbehi) >> 2,
             SYSREG_BFEXT(PFN, tlbelo) >> 2,
             SYSREG_BFEXT(AP, tlbelo),
             SYSREG_BFEXT(SZ, tlbelo),
             SYSREG_BFEXT(TLBELO_C, tlbelo) ? 'C' : ' ',
             SYSREG_BFEXT(B, tlbelo) ? 'B' : ' ',
             SYSREG_BFEXT(W, tlbelo) ? 'W' : ' ',
             SYSREG_BFEXT(TLBELO_D, tlbelo) ? 'D' : ' ');

      sysreg_write(MMUCR, mmucr_save);
      sysreg_write(TLBEHI, tlbehi_save);
      cpu_sync_pipeline();
      local_irq_restore(flags);
}

void dump_dtlb(void)
{
      unsigned int i;

      printk("ID  V G ASID VPN   PFN   AP SZ C B W D\n");
      for (i = 0; i < NR_TLB_ENTRIES; i++)
            show_dtlb_entry(i);
}

static void update_dtlb(unsigned long address, pte_t pte)
{
      u32 tlbehi;
      u32 mmucr;

      /*
       * We're not changing the ASID here, so no need to flush the
       * pipeline.
       */
      tlbehi = sysreg_read(TLBEHI);
      tlbehi = SYSREG_BF(ASID, SYSREG_BFEXT(ASID, tlbehi));
      tlbehi |= address & MMU_VPN_MASK;
      tlbehi |= SYSREG_BIT(TLBEHI_V);
      sysreg_write(TLBEHI, tlbehi);

      /* Does this mapping already exist? */
      __builtin_tlbs();
      mmucr = sysreg_read(MMUCR);

      if (mmucr & SYSREG_BIT(MMUCR_N)) {
            /* Not found -- pick a not-recently-accessed entry */
            unsigned int rp;
            u32 tlbar = sysreg_read(TLBARLO);

            rp = 32 - fls(tlbar);
            if (rp == 32) {
                  rp = 0;
                  sysreg_write(TLBARLO, -1L);
            }

            mmucr = SYSREG_BFINS(DRP, rp, mmucr);
            sysreg_write(MMUCR, mmucr);
      }

      sysreg_write(TLBELO, pte_val(pte) & _PAGE_FLAGS_HARDWARE_MASK);

      /* Let's go */
      __builtin_tlbw();
}

void update_mmu_cache(struct vm_area_struct *vma,
                  unsigned long address, pte_t *ptep)
{
      unsigned long flags;

      /* ptrace may call this routine */
      if (vma && current->active_mm != vma->vm_mm)
            return;

      local_irq_save(flags);
      update_dtlb(address, *ptep);
      local_irq_restore(flags);
}

static void __flush_tlb_page(unsigned long asid, unsigned long page)
{
      u32 mmucr, tlbehi;

      /*
       * Caller is responsible for masking out non-PFN bits in page
       * and changing the current ASID if necessary. This means that
       * we don't need to flush the pipeline after writing TLBEHI.
       */
      tlbehi = page | asid;
      sysreg_write(TLBEHI, tlbehi);

      __builtin_tlbs();
      mmucr = sysreg_read(MMUCR);

      if (!(mmucr & SYSREG_BIT(MMUCR_N))) {
            unsigned int entry;
            u32 tlbarlo;

            /* Clear the "valid" bit */
            sysreg_write(TLBEHI, tlbehi);

            /* mark the entry as "not accessed" */
            entry = SYSREG_BFEXT(DRP, mmucr);
            tlbarlo = sysreg_read(TLBARLO);
            tlbarlo |= (0x80000000UL >> entry);
            sysreg_write(TLBARLO, tlbarlo);

            /* update the entry with valid bit clear */
            __builtin_tlbw();
      }
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
      if (vma->vm_mm && vma->vm_mm->context != NO_CONTEXT) {
            unsigned long flags, asid;
            unsigned long saved_asid = MMU_NO_ASID;

            asid = vma->vm_mm->context & MMU_CONTEXT_ASID_MASK;
            page &= PAGE_MASK;

            local_irq_save(flags);
            if (vma->vm_mm != current->mm) {
                  saved_asid = get_asid();
                  set_asid(asid);
            }

            __flush_tlb_page(asid, page);

            if (saved_asid != MMU_NO_ASID)
                  set_asid(saved_asid);
            local_irq_restore(flags);
      }
}

void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
                 unsigned long end)
{
      struct mm_struct *mm = vma->vm_mm;

      if (mm->context != NO_CONTEXT) {
            unsigned long flags;
            int size;

            local_irq_save(flags);
            size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;

            if (size > (MMU_DTLB_ENTRIES / 4)) { /* Too many entries to flush */
                  mm->context = NO_CONTEXT;
                  if (mm == current->mm)
                        activate_context(mm);
            } else {
                  unsigned long asid;
                  unsigned long saved_asid;

                  asid = mm->context & MMU_CONTEXT_ASID_MASK;
                  saved_asid = MMU_NO_ASID;

                  start &= PAGE_MASK;
                  end += (PAGE_SIZE - 1);
                  end &= PAGE_MASK;

                  if (mm != current->mm) {
                        saved_asid = get_asid();
                        set_asid(asid);
                  }

                  while (start < end) {
                        __flush_tlb_page(asid, start);
                        start += PAGE_SIZE;
                  }
                  if (saved_asid != MMU_NO_ASID)
                        set_asid(saved_asid);
            }
            local_irq_restore(flags);
      }
}

/*
 * This function depends on the pages to be flushed having the G
 * (global) bit set in their pte. This is true for all
 * PAGE_KERNEL(_RO) pages.
 */
void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
      unsigned long flags;
      int size;

      size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
      if (size > (MMU_DTLB_ENTRIES / 4)) { /* Too many entries to flush */
            flush_tlb_all();
      } else {
            unsigned long asid;

            local_irq_save(flags);
            asid = get_asid();

            start &= PAGE_MASK;
            end += (PAGE_SIZE - 1);
            end &= PAGE_MASK;

            while (start < end) {
                  __flush_tlb_page(asid, start);
                  start += PAGE_SIZE;
            }
            local_irq_restore(flags);
      }
}

void flush_tlb_mm(struct mm_struct *mm)
{
      /* Invalidate all TLB entries of this process by getting a new ASID */
      if (mm->context != NO_CONTEXT) {
            unsigned long flags;

            local_irq_save(flags);
            mm->context = NO_CONTEXT;
            if (mm == current->mm)
                  activate_context(mm);
            local_irq_restore(flags);
      }
}

void flush_tlb_all(void)
{
      unsigned long flags;

      local_irq_save(flags);
      sysreg_write(MMUCR, sysreg_read(MMUCR) | SYSREG_BIT(MMUCR_I));
      local_irq_restore(flags);
}

#ifdef CONFIG_PROC_FS

#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/init.h>

static void *tlb_start(struct seq_file *tlb, loff_t *pos)
{
      static unsigned long tlb_index;

      if (*pos >= NR_TLB_ENTRIES)
            return NULL;

      tlb_index = 0;
      return &tlb_index;
}

static void *tlb_next(struct seq_file *tlb, void *v, loff_t *pos)
{
      unsigned long *index = v;

      if (*index >= NR_TLB_ENTRIES - 1)
            return NULL;

      ++*pos;
      ++*index;
      return index;
}

static void tlb_stop(struct seq_file *tlb, void *v)
{

}

static int tlb_show(struct seq_file *tlb, void *v)
{
      unsigned int tlbehi, tlbehi_save, tlbelo, mmucr, mmucr_save;
      unsigned long flags;
      unsigned long *index = v;

      if (*index == 0)
            seq_puts(tlb, "ID  V G ASID VPN   PFN   AP SZ C B W D\n");

      BUG_ON(*index >= NR_TLB_ENTRIES);

      local_irq_save(flags);
      mmucr_save = sysreg_read(MMUCR);
      tlbehi_save = sysreg_read(TLBEHI);
      mmucr = SYSREG_BFINS(DRP, *index, mmucr_save);
      sysreg_write(MMUCR, mmucr);

      /* TLBR might change the ASID */
      __builtin_tlbr();
      cpu_sync_pipeline();

      tlbehi = sysreg_read(TLBEHI);
      tlbelo = sysreg_read(TLBELO);

      sysreg_write(MMUCR, mmucr_save);
      sysreg_write(TLBEHI, tlbehi_save);
      cpu_sync_pipeline();
      local_irq_restore(flags);

      seq_printf(tlb, "%2lu: %c %c %02x   %05x %05x %o  %o  %c %c %c %c\n",
               *index,
               SYSREG_BFEXT(TLBEHI_V, tlbehi) ? '1' : '0',
               SYSREG_BFEXT(G, tlbelo) ? '1' : '0',
               SYSREG_BFEXT(ASID, tlbehi),
               SYSREG_BFEXT(VPN, tlbehi) >> 2,
               SYSREG_BFEXT(PFN, tlbelo) >> 2,
               SYSREG_BFEXT(AP, tlbelo),
               SYSREG_BFEXT(SZ, tlbelo),
               SYSREG_BFEXT(TLBELO_C, tlbelo) ? '1' : '0',
               SYSREG_BFEXT(B, tlbelo) ? '1' : '0',
               SYSREG_BFEXT(W, tlbelo) ? '1' : '0',
               SYSREG_BFEXT(TLBELO_D, tlbelo) ? '1' : '0');

      return 0;
}

static const struct seq_operations tlb_ops = {
      .start            = tlb_start,
      .next       = tlb_next,
      .stop       = tlb_stop,
      .show       = tlb_show,
};

static int tlb_open(struct inode *inode, struct file *file)
{
      return seq_open(file, &tlb_ops);
}

static const struct file_operations proc_tlb_operations = {
      .open       = tlb_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = seq_release,
};

static int __init proctlb_init(void)
{
      proc_create("tlb", 0, NULL, &proc_tlb_operations);
      return 0;
}
late_initcall(proctlb_init);
#endif /* CONFIG_PROC_FS */

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