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 <asm/errno.h>
  26 #include "ints.h"
  27
  28 /* Each ipl has a linked list of interrupt service routines.
  29  * Service routines are added via hp300_request_irq() and removed
  30  * via hp300_free_irq(). The device driver should set IRQ_FLG_FAST
  31  * if it needs to be serviced early (eg FIFOless UARTs); this will
  32  * cause it to be added at the front of the queue rather than
  33  * the back.
  34  * Currently IRQ_FLG_SLOW and flags=0 are treated identically; if
  35  * we needed three levels of priority we could distinguish them
  36  * but this strikes me as mildly ugly...
  37  */
  38
  39 /* we start with no entries in any list */
  40 static irq_node_t *hp300_irq_list[HP300_NUM_IRQS];
  41
  42 static spinlock_t irqlist_lock;
  43
  44 /* This handler receives all interrupts, dispatching them to the registered handlers */
  45 static irqreturn_t hp300_int_handler(int irq, void *dev_id, struct pt_regs *fp)
  46 {
  47         irq_node_t *t;
  48         /* We just give every handler on the chain an opportunity to handle
  49          * the interrupt, in priority order.
  50          */
  51         for(t = hp300_irq_list[irq]; t; t=t->next)
  52                 t->handler(irq, t->dev_id, fp);
  53         /* We could put in some accounting routines, checks for stray interrupts,
  54          * etc, in here. Note that currently we can't tell whether or not
  55          * a handler handles the interrupt, though.
  56          */
  57         return IRQ_HANDLED;
  58 }
  59
  60 static irqreturn_t hp300_badint(int irq, void *dev_id, struct pt_regs *fp)
  61 {
  62         num_spurious += 1;
  63         return IRQ_NONE;
  64 }
  65
  66 irqreturn_t (*hp300_default_handler[SYS_IRQS])(int, void *, struct pt_regs *) = {
  67         [0] = hp300_badint,
  68         [1] = hp300_int_handler,
  69         [2] = hp300_int_handler,
  70         [3] = hp300_int_handler,
  71         [4] = hp300_int_handler,
  72         [5] = hp300_int_handler,
  73         [6] = hp300_int_handler,
  74         [7] = hp300_int_handler
  75 };
  76
  77 /* dev_id had better be unique to each handler because it's the only way we have
  78  * to distinguish handlers when removing them...
  79  *
  80  * It would be pretty easy to support IRQ_FLG_LOCK (handler is not replacable)
  81  * and IRQ_FLG_REPLACE (handler replaces existing one with this dev_id)
  82  * if we wanted to. IRQ_FLG_FAST is needed for devices where interrupt latency
  83  * matters (eg the dreaded FIFOless UART...)
  84  */
  85 int hp300_request_irq(unsigned int irq,
  86                       irqreturn_t (*handler) (int, void *, struct pt_regs *),
  87                       unsigned long flags, const char *devname, void *dev_id)
  88 {
  89         irq_node_t *t, *n = new_irq_node();
  90
  91         if (!n)                                   /* oops, no free nodes */
  92                 return -ENOMEM;
  93
  94         spin_lock_irqsave(&irqlist_lock, flags);
  95
  96         if (!hp300_irq_list[irq]) {
  97                 /* no list yet */
  98                 hp300_irq_list[irq] = n;
  99                 n->next = NULL;
 100         } else if (flags & IRQ_FLG_FAST) {
 101                 /* insert at head of list */
 102                 n->next = hp300_irq_list[irq];
 103                 hp300_irq_list[irq] = n;
 104         } else {
 105                 /* insert at end of list */
 106                 for(t = hp300_irq_list[irq]; t->next; t = t->next)
 107                         /* do nothing */;
 108                 n->next = NULL;
 109                 t->next = n;
 110         }
 111
 112         /* Fill in n appropriately */
 113         n->handler = handler;
 114         n->flags = flags;
 115         n->dev_id = dev_id;
 116         n->devname = devname;
 117         spin_unlock_irqrestore(&irqlist_lock, flags);
 118         return 0;
 119 }
 120
 121 void hp300_free_irq(unsigned int irq, void *dev_id)
 122 {
 123         irq_node_t *t;
 124         unsigned long flags;
 125
 126         spin_lock_irqsave(&irqlist_lock, flags);
 127
 128         t = hp300_irq_list[irq];
 129         if (!t)                                   /* no handlers at all for that IRQ */
 130         {
 131                 printk(KERN_ERR "hp300_free_irq: attempt to remove nonexistent handler for IRQ %d\n", irq);
 132                 spin_unlock_irqrestore(&irqlist_lock, flags);
 133                 return;
 134         }
 135
 136         if (t->dev_id == dev_id)
 137         {                                         /* removing first handler on chain */
 138                 t->flags = IRQ_FLG_STD;           /* we probably don't really need these */
 139                 t->dev_id = NULL;
 140                 t->devname = NULL;
 141                 t->handler = NULL;                /* frees this irq_node_t */
 142                 hp300_irq_list[irq] = t->next;
 143                 spin_unlock_irqrestore(&irqlist_lock, flags);
 144                 return;
 145         }
 146
 147         /* OK, must be removing from middle of the chain */
 148
 149         for (t = hp300_irq_list[irq]; t->next && t->next->dev_id != dev_id; t = t->next)
 150                 /* do nothing */;
 151         if (!t->next)
 152         {
 153                 printk(KERN_ERR "hp300_free_irq: attempt to remove nonexistent handler for IRQ %d\n", irq);
 154                 spin_unlock_irqrestore(&irqlist_lock, flags);
 155                 return;
 156         }
 157         /* remove the entry after t: */
 158         t->next->flags = IRQ_FLG_STD;
 159         t->next->dev_id = NULL;
 160         t->next->devname = NULL;
 161         t->next->handler = NULL;
 162         t->next = t->next->next;
 163
 164         spin_unlock_irqrestore(&irqlist_lock, flags);
 165 }
 166
 167 int show_hp300_interrupts(struct seq_file *p, void *v)
 168 {
 169         return 0;
 170 }
 171
 172 void __init hp300_init_IRQ(void)
 173 {
 174         spin_lock_init(&irqlist_lock);
 175 }