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 static unsigned long no_fiq_insn;
  51
  52 /* Default reacquire function
  53  * - we always relinquish FIQ control
  54  * - we always reacquire FIQ control
  55  */
  56 static 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
  64 static struct fiq_handler default_owner = {
  65         .name   = "default",
  66         .fiq_op = fiq_def_op,
  67 };
  68
  69 static struct fiq_handler *current_fiq = &default_owner;
  70
  71 int 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
  80 void 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
  92 int 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
 111 void 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
 125 static int fiq_start;
 126
 127 void enable_fiq(int fiq)
 128 {
 129         enable_irq(fiq + fiq_start);
 130 }
 131
 132 void disable_fiq(int fiq)
 133 {
 134         disable_irq(fiq + fiq_start);
 135 }
 136
 137 EXPORT_SYMBOL(set_fiq_handler);
 138 EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
 139 EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
 140 EXPORT_SYMBOL(claim_fiq);
 141 EXPORT_SYMBOL(release_fiq);
 142 EXPORT_SYMBOL(enable_fiq);
 143 EXPORT_SYMBOL(disable_fiq);
 144
 145 void __init init_FIQ(int start)
 146 {
 147         no_fiq_insn = *(unsigned long *)0xffff001c;
 148         fiq_start = start;
 149 }