arch/sh/mm/tlb-urb.c

   1 /*
   2  * arch/sh/mm/tlb-urb.c
   3  *
   4  * TLB entry wiring helpers for URB-equipped parts.
   5  *
   6  * Copyright (C) 2010  Matt Fleming
   7  *
   8  * This file is subject to the terms and conditions of the GNU General Public
   9  * License.  See the file "COPYING" in the main directory of this archive
  10  * for more details.
  11  */
  12 #include <linux/mm.h>
  13 #include <linux/io.h>
  14 #include <asm/tlb.h>
  15 #include <asm/mmu_context.h>
  16
  17 /*
  18  * Load the entry for 'addr' into the TLB and wire the entry.
  19  */
  20 void tlb_wire_entry(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
  21 {
  22         unsigned long status, flags;
  23         int urb;
  24
  25         local_irq_save(flags);
  26
  27         status = __raw_readl(MMUCR);
  28         urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
  29         status &= ~MMUCR_URC;
  30
  31         /*
  32          * Make sure we're not trying to wire the last TLB entry slot.
  33          */
  34         BUG_ON(!--urb);
  35
  36         urb = urb % MMUCR_URB_NENTRIES;
  37
  38         /*
  39          * Insert this entry into the highest non-wired TLB slot (via
  40          * the URC field).
  41          */
  42         status |= (urb << MMUCR_URC_SHIFT);
  43         __raw_writel(status, MMUCR);
  44         ctrl_barrier();
  45
  46         /* Load the entry into the TLB */
  47         __update_tlb(vma, addr, pte);
  48
  49         /* ... and wire it up. */
  50         status = __raw_readl(MMUCR);
  51
  52         status &= ~MMUCR_URB;
  53         status |= (urb << MMUCR_URB_SHIFT);
  54
  55         __raw_writel(status, MMUCR);
  56         ctrl_barrier();
  57
  58         local_irq_restore(flags);
  59 }
  60
  61 /*
  62  * Unwire the last wired TLB entry.
  63  *
  64  * It should also be noted that it is not possible to wire and unwire
  65  * TLB entries in an arbitrary order. If you wire TLB entry N, followed
  66  * by entry N+1, you must unwire entry N+1 first, then entry N. In this
  67  * respect, it works like a stack or LIFO queue.
  68  */
  69 void tlb_unwire_entry(void)
  70 {
  71         unsigned long status, flags;
  72         int urb;
  73
  74         local_irq_save(flags);
  75
  76         status = __raw_readl(MMUCR);
  77         urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
  78         status &= ~MMUCR_URB;
  79
  80         /*
  81          * Make sure we're not trying to unwire a TLB entry when none
  82          * have been wired.
  83          */
  84         BUG_ON(urb++ == MMUCR_URB_NENTRIES);
  85
  86         urb = urb % MMUCR_URB_NENTRIES;
  87
  88         status |= (urb << MMUCR_URB_SHIFT);
  89         __raw_writel(status, MMUCR);
  90         ctrl_barrier();
  91
  92         local_irq_restore(flags);
  93 }