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 dfl_fiq_insn;
  56 static struct pt_regs dfl_fiq_regs;
  57
  58 /* Default reacquire function
  59  * - we always relinquish FIQ control
  60  * - we always reacquire FIQ control
  61  */
  62 static 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
  77 static struct fiq_handler default_owner = {
  78         .name   = "default",
  79         .fiq_op = fiq_def_op,
  80 };
  81
  82 static struct fiq_handler *current_fiq = &default_owner;
  83
  84 int 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
  93 void 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
 105 int 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
 124 void 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
 138 static int fiq_start;
 139
 140 void enable_fiq(int fiq)
 141 {
 142         enable_irq(fiq + fiq_start);
 143 }
 144
 145 void disable_fiq(int fiq)
 146 {
 147         disable_irq(fiq + fiq_start);
 148 }
 149
 150 EXPORT_SYMBOL(set_fiq_handler);
 151 EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
 152 EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
 153 EXPORT_SYMBOL(claim_fiq);
 154 EXPORT_SYMBOL(release_fiq);
 155 EXPORT_SYMBOL(enable_fiq);
 156 EXPORT_SYMBOL(disable_fiq);
 157
 158 void __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 }