linux/arch/arm/kernel/fiq.c
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   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 dfl_fiq_insn;
  56static struct pt_regs dfl_fiq_regs;
  57
  58/* Default reacquire function
  59 * - we always relinquish FIQ control
  60 * - we always reacquire FIQ control
  61 */
  62static int fiq_def_op(void *ref, int relinquish)
  63{
  64        if (!relinquish) {
  65                /* Restore default handler and registers */
  66                local_fiq_disable();
  67                set_fiq_regs(&dfl_fiq_regs);
  68                set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
  69                local_fiq_enable();
  70
  71                /* FIXME: notify irq controller to standard enable FIQs */
  72        }
  73
  74        return 0;
  75}
  76
  77static struct fiq_handler default_owner = {
  78        .name   = "default",
  79        .fiq_op = fiq_def_op,
  80};
  81
  82static struct fiq_handler *current_fiq = &default_owner;
  83
  84int show_fiq_list(struct seq_file *p, int prec)
  85{
  86        if (current_fiq != &default_owner)
  87                seq_printf(p, "%*s:              %s\n", prec, "FIQ",
  88                        current_fiq->name);
  89
  90        return 0;
  91}
  92
  93void set_fiq_handler(void *start, unsigned int length)
  94{
  95        void *base = vectors_page;
  96        unsigned offset = FIQ_OFFSET;
  97
  98        memcpy(base + offset, start, length);
  99        if (!cache_is_vipt_nonaliasing())
 100                flush_icache_range((unsigned long)base + offset, offset +
 101                                   length);
 102        flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
 103}
 104
 105int claim_fiq(struct fiq_handler *f)
 106{
 107        int ret = 0;
 108
 109        if (current_fiq) {
 110                ret = -EBUSY;
 111
 112                if (current_fiq->fiq_op != NULL)
 113                        ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
 114        }
 115
 116        if (!ret) {
 117                f->next = current_fiq;
 118                current_fiq = f;
 119        }
 120
 121        return ret;
 122}
 123
 124void release_fiq(struct fiq_handler *f)
 125{
 126        if (current_fiq != f) {
 127                pr_err("%s FIQ trying to release %s FIQ\n",
 128                       f->name, current_fiq->name);
 129                dump_stack();
 130                return;
 131        }
 132
 133        do
 134                current_fiq = current_fiq->next;
 135        while (current_fiq->fiq_op(current_fiq->dev_id, 0));
 136}
 137
 138static int fiq_start;
 139
 140void enable_fiq(int fiq)
 141{
 142        enable_irq(fiq + fiq_start);
 143}
 144
 145void disable_fiq(int fiq)
 146{
 147        disable_irq(fiq + fiq_start);
 148}
 149
 150EXPORT_SYMBOL(set_fiq_handler);
 151EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
 152EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
 153EXPORT_SYMBOL(claim_fiq);
 154EXPORT_SYMBOL(release_fiq);
 155EXPORT_SYMBOL(enable_fiq);
 156EXPORT_SYMBOL(disable_fiq);
 157
 158void __init init_FIQ(int start)
 159{
 160        unsigned offset = FIQ_OFFSET;
 161        dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
 162        get_fiq_regs(&dfl_fiq_regs);
 163        fiq_start = start;
 164}
 165