LXR linux/arch/arm/kernel/fiq.c

   1/*
   2 *  linux/arch/arm/kernel/fiq.c
   3 *
   4 *  Copyright (C) 1998 Russell King
   5 *  Copyright (C) 1998, 1999 Phil Blundell
   6 *
   7 *  FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
   8 *
   9 *  FIQ support re-written by Russell King to be more generic
  10 *
  11 * We now properly support a method by which the FIQ handlers can
  12 * be stacked onto the vector.  We still do not support sharing
  13 * the FIQ vector itself.
  14 *
  15 * Operation is as follows:
  16 *  1. Owner A claims FIQ:
  17 *     - default_fiq relinquishes control.
  18 *  2. Owner A:
  19 *     - inserts code.
  20 *     - sets any registers,
  21 *     - enables FIQ.
  22 *  3. Owner B claims FIQ:
  23 *     - if owner A has a relinquish function.
  24 *       - disable FIQs.
  25 *       - saves any registers.
  26 *       - returns zero.
  27 *  4. Owner B:
  28 *     - inserts code.
  29 *     - sets any registers,
  30 *     - enables FIQ.
  31 *  5. Owner B releases FIQ:
  32 *     - Owner A is asked to reacquire FIQ:
  33 *       - inserts code.
  34 *       - restores saved registers.
  35 *       - enables FIQ.
  36 *  6. Goto 3
  37 */
  38#include <linux/module.h>
  39#include <linux/kernel.h>
  40#include <linux/init.h>
  41#include <linux/interrupt.h>
  42#include <linux/seq_file.h>
  43
  44#include <asm/cacheflush.h>
  45#include <asm/cp15.h>
  46#include <asm/fiq.h>
  47#include <asm/irq.h>
  48#include <asm/traps.h>
  49
  50#define FIQ_OFFSET ({                                   \
  51                extern void *vector_fiq_offset;         \
  52                (unsigned)&vector_fiq_offset;           \
  53        })
  54
  55static unsigned long no_fiq_insn;
  56
  57/* Default reacquire function
  58 * - we always relinquish FIQ control
  59 * - we always reacquire FIQ control
  60 */
  61static int fiq_def_op(void *ref, int relinquish)
  62{
  63        if (!relinquish)
  64                set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
  65
  66        return 0;
  67}
  68
  69static struct fiq_handler default_owner = {
  70        .name   = "default",
  71        .fiq_op = fiq_def_op,
  72};
  73
  74static struct fiq_handler *current_fiq = &default_owner;
  75
  76int show_fiq_list(struct seq_file *p, int prec)
  77{
  78        if (current_fiq != &default_owner)
  79                seq_printf(p, "%*s:              %s\n", prec, "FIQ",
  80                        current_fiq->name);
  81
  82        return 0;
  83}
  84
  85void set_fiq_handler(void *start, unsigned int length)
  86{
  87        void *base = vectors_page;
  88        unsigned offset = FIQ_OFFSET;
  89
  90        memcpy(base + offset, start, length);
  91        if (!cache_is_vipt_nonaliasing())
  92                flush_icache_range((unsigned long)base + offset, offset +
  93                                   length);
  94        flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
  95}
  96
  97int claim_fiq(struct fiq_handler *f)
  98{
  99        int ret = 0;
 100
 101        if (current_fiq) {
 102                ret = -EBUSY;
 103
 104                if (current_fiq->fiq_op != NULL)
 105                        ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
 106        }
 107
 108        if (!ret) {
 109                f->next = current_fiq;
 110                current_fiq = f;
 111        }
 112
 113        return ret;
 114}
 115
 116void release_fiq(struct fiq_handler *f)
 117{
 118        if (current_fiq != f) {
 119                printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
 120                       f->name, current_fiq->name);
 121                dump_stack();
 122                return;
 123        }
 124
 125        do
 126                current_fiq = current_fiq->next;
 127        while (current_fiq->fiq_op(current_fiq->dev_id, 0));
 128}
 129
 130static int fiq_start;
 131
 132void enable_fiq(int fiq)
 133{
 134        enable_irq(fiq + fiq_start);
 135}
 136
 137void disable_fiq(int fiq)
 138{
 139        disable_irq(fiq + fiq_start);
 140}
 141
 142EXPORT_SYMBOL(set_fiq_handler);
 143EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
 144EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
 145EXPORT_SYMBOL(claim_fiq);
 146EXPORT_SYMBOL(release_fiq);
 147EXPORT_SYMBOL(enable_fiq);
 148EXPORT_SYMBOL(disable_fiq);
 149
 150void __init init_FIQ(int start)
 151{
 152        unsigned offset = FIQ_OFFSET;
 153        no_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
 154        fiq_start = start;
 155}
 156