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/fiq.h>
  46#include <asm/irq.h>
  47#include <asm/system.h>
  48#include <asm/traps.h>
  49
  50static unsigned long no_fiq_insn;
  51
  52/* Default reacquire function
  53 * - we always relinquish FIQ control
  54 * - we always reacquire FIQ control
  55 */
  56static int fiq_def_op(void *ref, int relinquish)
  57{
  58        if (!relinquish)
  59                set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
  60
  61        return 0;
  62}
  63
  64static struct fiq_handler default_owner = {
  65        .name   = "default",
  66        .fiq_op = fiq_def_op,
  67};
  68
  69static struct fiq_handler *current_fiq = &default_owner;
  70
  71int show_fiq_list(struct seq_file *p, int prec)
  72{
  73        if (current_fiq != &default_owner)
  74                seq_printf(p, "%*s:              %s\n", prec, "FIQ",
  75                        current_fiq->name);
  76
  77        return 0;
  78}
  79
  80void set_fiq_handler(void *start, unsigned int length)
  81{
  82#if defined(CONFIG_CPU_USE_DOMAINS)
  83        memcpy((void *)0xffff001c, start, length);
  84#else
  85        memcpy(vectors_page + 0x1c, start, length);
  86#endif
  87        flush_icache_range(0xffff001c, 0xffff001c + length);
  88        if (!vectors_high())
  89                flush_icache_range(0x1c, 0x1c + length);
  90}
  91
  92int claim_fiq(struct fiq_handler *f)
  93{
  94        int ret = 0;
  95
  96        if (current_fiq) {
  97                ret = -EBUSY;
  98
  99                if (current_fiq->fiq_op != NULL)
 100                        ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
 101        }
 102
 103        if (!ret) {
 104                f->next = current_fiq;
 105                current_fiq = f;
 106        }
 107
 108        return ret;
 109}
 110
 111void release_fiq(struct fiq_handler *f)
 112{
 113        if (current_fiq != f) {
 114                printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
 115                       f->name, current_fiq->name);
 116                dump_stack();
 117                return;
 118        }
 119
 120        do
 121                current_fiq = current_fiq->next;
 122        while (current_fiq->fiq_op(current_fiq->dev_id, 0));
 123}
 124
 125void enable_fiq(int fiq)
 126{
 127        enable_irq(fiq + FIQ_START);
 128}
 129
 130void disable_fiq(int fiq)
 131{
 132        disable_irq(fiq + FIQ_START);
 133}
 134
 135EXPORT_SYMBOL(set_fiq_handler);
 136EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
 137EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
 138EXPORT_SYMBOL(claim_fiq);
 139EXPORT_SYMBOL(release_fiq);
 140EXPORT_SYMBOL(enable_fiq);
 141EXPORT_SYMBOL(disable_fiq);
 142
 143void __init init_FIQ(void)
 144{
 145        no_fiq_insn = *(unsigned long *)0xffff001c;
 146}
 147