arch/m68k/hp300/ints.c

   1 /*
   2  *  linux/arch/m68k/hp300/ints.c
   3  *
   4  *  Copyright (C) 1998 Philip Blundell <philb@gnu.org>
   5  *
   6  *  This file contains the HP300-specific interrupt handling.
   7  *  We only use the autovector interrupts, and therefore we need to
   8  *  maintain lists of devices sharing each ipl.
   9  *  [ipl list code added by Peter Maydell <pmaydell@chiark.greenend.org.uk> 06/1998]
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/types.h>
  14 #include <linux/init.h>
  15 #include <linux/sched.h>
  16 #include <linux/kernel_stat.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/spinlock.h>
  19 #include <asm/machdep.h>
  20 #include <asm/irq.h>
  21 #include <asm/io.h>
  22 #include <asm/system.h>
  23 #include <asm/traps.h>
  24 #include <asm/ptrace.h>
  25 #include "ints.h"
  26
  27 /* Each ipl has a linked list of interrupt service routines.
  28  * Service routines are added via hp300_request_irq() and removed
  29  * via hp300_free_irq(). The device driver should set IRQ_FLG_FAST
  30  * if it needs to be serviced early (eg FIFOless UARTs); this will
  31  * cause it to be added at the front of the queue rather than
  32  * the back.
  33  * Currently IRQ_FLG_SLOW and flags=0 are treated identically; if
  34  * we needed three levels of priority we could distinguish them
  35  * but this strikes me as mildly ugly...
  36  */
  37
  38 /* we start with no entries in any list */
  39 static irq_node_t *hp300_irq_list[HP300_NUM_IRQS] = { [0 ... HP300_NUM_IRQS-1] = NULL };
  40
  41 static spinlock_t irqlist_lock;
  42
  43 /* This handler receives all interrupts, dispatching them to the registered handlers */
  44 static void hp300_int_handler(int irq, void *dev_id, struct pt_regs *fp)
  45 {
  46         irq_node_t *t;
  47         /* We just give every handler on the chain an opportunity to handle
  48          * the interrupt, in priority order.
  49          */
  50         for(t = hp300_irq_list[irq]; t; t=t->next)
  51                 t->handler(irq, t->dev_id, fp);
  52         /* We could put in some accounting routines, checks for stray interrupts,
  53          * etc, in here. Note that currently we can't tell whether or not
  54          * a handler handles the interrupt, though.
  55          */
  56 }
  57
  58 void (*hp300_default_handler[SYS_IRQS])(int, void *, struct pt_regs *) = {
  59         hp300_int_handler, hp300_int_handler, hp300_int_handler, hp300_int_handler,
  60         hp300_int_handler, hp300_int_handler, hp300_int_handler, NULL
  61 };
  62
  63 /* dev_id had better be unique to each handler because it's the only way we have
  64  * to distinguish handlers when removing them...
  65  *
  66  * It would be pretty easy to support IRQ_FLG_LOCK (handler is not replacable)
  67  * and IRQ_FLG_REPLACE (handler replaces existing one with this dev_id)
  68  * if we wanted to. IRQ_FLG_FAST is needed for devices where interrupt latency
  69  * matters (eg the dreaded FIFOless UART...)
  70  */
  71 int hp300_request_irq(unsigned int irq,
  72                       void (*handler) (int, void *, struct pt_regs *),
  73                       unsigned long flags, const char *devname, void *dev_id)
  74 {
  75         irq_node_t *t, *n = new_irq_node();
  76
  77         if (!n)                                   /* oops, no free nodes */
  78                 return -ENOMEM;
  79
  80         spin_lock_irqsave(&irqlist_lock, flags);
  81
  82         if (!hp300_irq_list[irq]) {
  83                 /* no list yet */
  84                 hp300_irq_list[irq] = n;
  85                 n->next = NULL;
  86         } else if (flags & IRQ_FLG_FAST) {
  87                 /* insert at head of list */
  88                 n->next = hp300_irq_list[irq];
  89                 hp300_irq_list[irq] = n;
  90         } else {
  91                 /* insert at end of list */
  92                 for(t = hp300_irq_list[irq]; t->next; t = t->next)
  93                         /* do nothing */;
  94                 n->next = NULL;
  95                 t->next = n;
  96         }
  97
  98         /* Fill in n appropriately */
  99         n->handler = handler;
 100         n->flags = flags;
 101         n->dev_id = dev_id;
 102         n->devname = devname;
 103         spin_unlock_irqrestore(&irqlist_lock, flags);
 104         return 0;
 105 }
 106
 107 void hp300_free_irq(unsigned int irq, void *dev_id)
 108 {
 109         irq_node_t *t;
 110         unsigned long flags;
 111
 112         spin_lock_irqsave(&irqlist_lock, flags);
 113
 114         t = hp300_irq_list[irq];
 115         if (!t)                                   /* no handlers at all for that IRQ */
 116         {
 117                 printk(KERN_ERR "hp300_free_irq: attempt to remove nonexistent handler for IRQ %d\n", irq);
 118                 spin_unlock_irqrestore(&irqlist_lock, flags);
 119                 return;
 120         }
 121
 122         if (t->dev_id == dev_id)
 123         {                                         /* removing first handler on chain */
 124                 t->flags = IRQ_FLG_STD;           /* we probably don't really need these */
 125                 t->dev_id = NULL;
 126                 t->devname = NULL;
 127                 t->handler = NULL;                /* frees this irq_node_t */
 128                 hp300_irq_list[irq] = t->next;
 129                 spin_unlock_irqrestore(&irqlist_lock, flags);
 130                 return;
 131         }
 132
 133         /* OK, must be removing from middle of the chain */
 134
 135         for (t = hp300_irq_list[irq]; t->next && t->next->dev_id != dev_id; t = t->next)
 136                 /* do nothing */;
 137         if (!t->next)
 138         {
 139                 printk(KERN_ERR "hp300_free_irq: attempt to remove nonexistent handler for IRQ %d\n", irq);
 140                 spin_unlock_irqrestore(&irqlist_lock, flags);
 141                 return;
 142         }
 143         /* remove the entry after t: */
 144         t->next->flags = IRQ_FLG_STD;
 145         t->next->dev_id = t->next->devname = t->next->handler = NULL;
 146         t->next = t->next->next;
 147
 148         spin_unlock_irqrestore(&irqlist_lock, flags);
 149 }
 150
 151 int hp300_get_irq_list(char *buf)
 152 {
 153         return 0;
 154 }
 155
 156 void __init hp300_init_IRQ(void)
 157 {
 158         spin_lock_init(&irqlist_lock);
 159 }