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
  55 static unsigned long no_fiq_insn;
  56
  57 /* Default reacquire function
  58  * - we always relinquish FIQ control
  59  * - we always reacquire FIQ control
  60  */
  61 static 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
  69 static struct fiq_handler default_owner = {
  70         .name   = "default",
  71         .fiq_op = fiq_def_op,
  72 };
  73
  74 static struct fiq_handler *current_fiq = &default_owner;
  75
  76 int 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
  85 void set_fiq_handler(void *start, unsigned int length)
  86 {
  87 #if defined(CONFIG_CPU_USE_DOMAINS)
  88         void *base = (void *)0xffff0000;
  89 #else
  90         void *base = vectors_page;
  91 #endif
  92         unsigned offset = FIQ_OFFSET;
  93
  94         memcpy(base + offset, start, length);
  95         flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
  96         if (!vectors_high())
  97                 flush_icache_range(offset, offset + length);
  98 }
  99
 100 int claim_fiq(struct fiq_handler *f)
 101 {
 102         int ret = 0;
 103
 104         if (current_fiq) {
 105                 ret = -EBUSY;
 106
 107                 if (current_fiq->fiq_op != NULL)
 108                         ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
 109         }
 110
 111         if (!ret) {
 112                 f->next = current_fiq;
 113                 current_fiq = f;
 114         }
 115
 116         return ret;
 117 }
 118
 119 void release_fiq(struct fiq_handler *f)
 120 {
 121         if (current_fiq != f) {
 122                 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
 123                        f->name, current_fiq->name);
 124                 dump_stack();
 125                 return;
 126         }
 127
 128         do
 129                 current_fiq = current_fiq->next;
 130         while (current_fiq->fiq_op(current_fiq->dev_id, 0));
 131 }
 132
 133 static int fiq_start;
 134
 135 void enable_fiq(int fiq)
 136 {
 137         enable_irq(fiq + fiq_start);
 138 }
 139
 140 void disable_fiq(int fiq)
 141 {
 142         disable_irq(fiq + fiq_start);
 143 }
 144
 145 EXPORT_SYMBOL(set_fiq_handler);
 146 EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
 147 EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
 148 EXPORT_SYMBOL(claim_fiq);
 149 EXPORT_SYMBOL(release_fiq);
 150 EXPORT_SYMBOL(enable_fiq);
 151 EXPORT_SYMBOL(disable_fiq);
 152
 153 void __init init_FIQ(int start)
 154 {
 155         unsigned offset = FIQ_OFFSET;
 156         no_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
 157         fiq_start = start;
 158 }