kernel/irq.c

/* */
This source file includes following definitions.
do_bottom_half
do_IRQ
do_fast_IRQ
irqaction
request_irq
free_irq
math_error_irq
no_action
init_IRQ
   1 /*
   2  *      linux/kernel/irq.c
   3  *
   4  *      Copyright (C) 1992 Linus Torvalds
   5  *
   6  * This file contains the code used by various IRQ handling routines:
   7  * asking for different IRQ's should be done through these routines
   8  * instead of just grabbing them. Thus setups with different IRQ numbers
   9  * shouldn't result in any weird surprises, and installing new handlers
  10  * should be easier.
  11  */
  12 
  13 /*
  14  * IRQ's are in fact implemented a bit like signal handlers for the kernel.
  15  * The same sigaction struct is used, and with similar semantics (ie there
  16  * is a SA_INTERRUPT flag etc). Naturally it's not a 1:1 relation, but there
  17  * are similarities.
  18  *
  19  * sa_handler(int irq_NR) is the default function called.
  20  * sa_mask is 0 if nothing uses this IRQ
  21  * sa_flags contains various info: SA_INTERRUPT etc
  22  * sa_restorer is the unused
  23  */
  24 
  25 #include <linux/ptrace.h>
  26 #include <linux/errno.h>
  27 #include <linux/signal.h>
  28 #include <linux/sched.h>
  29 #include <linux/interrupt.h>
  30 
  31 #include <asm/system.h>
  32 #include <asm/io.h>
  33 #include <asm/irq.h>
  34 
  35 #define CR0_NE 32
  36 
  37 static unsigned char cache_21 = 0xff;
  38 static unsigned char cache_A1 = 0xff;
  39 
  40 unsigned long intr_count = 0;
  41 unsigned long bh_active = 0;
  42 unsigned long bh_mask = 0xFFFFFFFF;
  43 struct bh_struct bh_base[32]; 
  44 
  45 /*
  46  * do_bottom_half() runs at normal kernel priority: all interrupts
  47  * enabled.  do_bottom_half() is atomic with respect to itself: a
  48  * bottom_half handler need not be re-entrant.
  49  */
  50 extern "C" void do_bottom_half(void)
     /*  */
  51 {
  52         unsigned long active;
  53         unsigned long mask, left;
  54         struct bh_struct *bh;
  55 
  56         bh = bh_base;
  57         active = bh_active & bh_mask;
  58         for (mask = 1, left = ~0 ; left & active ; bh++,mask += mask,left += left) {
  59                 if (mask & active) {
  60                         void (*fn)(void *);
  61                         bh_active &= ~mask;
  62                         fn = bh->routine;
  63                         if (!fn)
  64                                 goto bad_bh;
  65                         fn(bh->data);
  66                 }
  67         }
  68         return;
  69 bad_bh:
  70         printk ("irq.c:bad bottom half entry\n");
  71 }
  72 
  73 /*
  74  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  75  *
  76  * These macros create the low-level assembly IRQ routines that do all
  77  * the operations that are needed to keep the AT interrupt-controller
  78  * happy. They are also written to be fast - and to disable interrupts
  79  * as little as humanly possible.
  80  *
  81  * NOTE! These macros expand to three different handlers for each line: one
  82  * complete handler that does all the fancy stuff (including signal handling),
  83  * and one fast handler that is meant for simple IRQ's that want to be
  84  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
  85  * flag when installing a handler. Finally, one "bad interrupt" handler, that
  86  * is used when no handler is present.
  87  */
  88 BUILD_IRQ(FIRST,0,0x01)
  89 BUILD_IRQ(FIRST,1,0x02)
  90 BUILD_IRQ(FIRST,2,0x04)
  91 BUILD_IRQ(FIRST,3,0x08)
  92 BUILD_IRQ(FIRST,4,0x10)
  93 BUILD_IRQ(FIRST,5,0x20)
  94 BUILD_IRQ(FIRST,6,0x40)
  95 BUILD_IRQ(FIRST,7,0x80)
  96 BUILD_IRQ(SECOND,8,0x01)
  97 BUILD_IRQ(SECOND,9,0x02)
  98 BUILD_IRQ(SECOND,10,0x04)
  99 BUILD_IRQ(SECOND,11,0x08)
 100 BUILD_IRQ(SECOND,12,0x10)
 101 BUILD_IRQ(SECOND,13,0x20)
 102 BUILD_IRQ(SECOND,14,0x40)
 103 BUILD_IRQ(SECOND,15,0x80)
 104 
 105 /*
 106  * Pointers to the low-level handlers: first the general ones, then the
 107  * fast ones, then the bad ones.
 108  */
 109 static void (*interrupt[16])(void) = {
 110         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 111         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 112         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 113         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
 114 };
 115 
 116 static void (*fast_interrupt[16])(void) = {
 117         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 118         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 119         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 120         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 121         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 122         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 123         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 124         fast_IRQ14_interrupt, fast_IRQ15_interrupt
 125 };
 126 
 127 static void (*bad_interrupt[16])(void) = {
 128         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 129         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 130         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 131         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 132         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 133         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 134         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 135         bad_IRQ14_interrupt, bad_IRQ15_interrupt
 136 };
 137 
 138 /*
 139  * Initial irq handlers.
 140  */
 141 static struct sigaction irq_sigaction[16] = {
 142         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 143         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 144         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 145         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 146         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 147         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 148         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 149         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 150 };
 151 
 152 /*
 153  * do_IRQ handles IRQ's that have been installed without the
 154  * SA_INTERRUPT flag: it uses the full signal-handling return
 155  * and runs with other interrupts enabled. All relatively slow
 156  * IRQ's should use this format: notably the keyboard/timer
 157  * routines.
 158  */
 159 extern "C" void do_IRQ(int irq, struct pt_regs * regs)
     /*  */
 160 {
 161         struct sigaction * sa = irq + irq_sigaction;
 162 
 163         sa->sa_handler((int) regs);
 164 }
 165 
 166 /*
 167  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 168  * stuff - the handler is also running with interrupts disabled unless
 169  * it explicitly enables them later.
 170  */
 171 extern "C" void do_fast_IRQ(int irq)
     /*  */
 172 {
 173         struct sigaction * sa = irq + irq_sigaction;
 174 
 175         sa->sa_handler(irq);
 176 }
 177 
 178 int irqaction(unsigned int irq, struct sigaction * new_sa)
     /*  */
 179 {
 180         struct sigaction * sa;
 181         unsigned long flags;
 182 
 183         if (irq > 15)
 184                 return -EINVAL;
 185         sa = irq + irq_sigaction;
 186         if (sa->sa_mask)
 187                 return -EBUSY;
 188         if (!new_sa->sa_handler)
 189                 return -EINVAL;
 190         save_flags(flags);
 191         cli();
 192         *sa = *new_sa;
 193         sa->sa_mask = 1;
 194         if (sa->sa_flags & SA_INTERRUPT)
 195                 set_intr_gate(0x20+irq,fast_interrupt[irq]);
 196         else
 197                 set_intr_gate(0x20+irq,interrupt[irq]);
 198         if (irq < 8) {
 199                 cache_21 &= ~(1<<irq);
 200                 outb(cache_21,0x21);
 201         } else {
 202                 cache_21 &= ~(1<<2);
 203                 cache_A1 &= ~(1<<(irq-8));
 204                 outb(cache_21,0x21);
 205                 outb(cache_A1,0xA1);
 206         }
 207         restore_flags(flags);
 208         return 0;
 209 }
 210                 
 211 int request_irq(unsigned int irq, void (*handler)(int))
     /*  */
 212 {
 213         struct sigaction sa;
 214 
 215         sa.sa_handler = handler;
 216         sa.sa_flags = 0;
 217         sa.sa_mask = 0;
 218         sa.sa_restorer = NULL;
 219         return irqaction(irq,&sa);
 220 }
 221 
 222 void free_irq(unsigned int irq)
     /*  */
 223 {
 224         struct sigaction * sa = irq + irq_sigaction;
 225         unsigned long flags;
 226 
 227         if (irq > 15) {
 228                 printk("Trying to free IRQ%d\n",irq);
 229                 return;
 230         }
 231         if (!sa->sa_mask) {
 232                 printk("Trying to free free IRQ%d\n",irq);
 233                 return;
 234         }
 235         save_flags(flags);
 236         cli();
 237         if (irq < 8) {
 238                 cache_21 |= 1 << irq;
 239                 outb(cache_21,0x21);
 240         } else {
 241                 cache_A1 |= 1 << (irq-8);
 242                 outb(cache_A1,0xA1);
 243         }
 244         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 245         sa->sa_handler = NULL;
 246         sa->sa_flags = 0;
 247         sa->sa_mask = 0;
 248         sa->sa_restorer = NULL;
 249         restore_flags(flags);
 250 }
 251 
 252 /*
 253  * Note that on a 486, we don't want to do a SIGFPE on a irq13
 254  * as the irq is unreliable, and exception 16 works correctly
 255  * (ie as explained in the intel litterature). On a 386, you
 256  * can't use exception 16 due to bad IBM design, so we have to
 257  * rely on the less exact irq13.
 258  *
 259  * Careful.. Not only is IRQ13 unreliable, but it is also
 260  * leads to races. IBM designers who came up with it should
 261  * be shot.
 262  */
 263 static void math_error_irq(int cpl)
     /*  */
 264 {
 265         outb(0,0xF0);
 266         if (ignore_irq13)
 267                 return;
 268         math_error();
 269 }
 270 
 271 static void no_action(int cpl) { }
     /*  */
 272 
 273 static struct sigaction ignore_IRQ = {
 274         no_action,
 275         0,
 276         SA_INTERRUPT,
 277         NULL
 278 };
 279 
 280 void init_IRQ(void)
     /*  */
 281 {
 282         int i;
 283 
 284         for (i = 0; i < 16 ; i++)
 285                 set_intr_gate(0x20+i,bad_interrupt[i]);
 286         if (irqaction(2,&ignore_IRQ))
 287                 printk("Unable to get IRQ2 for cascade\n");
 288         if (request_irq(13,math_error_irq))
 289                 printk("Unable to get IRQ13 for math-error handler\n");
 290 
 291         /* intialize the bottom half routines. */
 292         for (i = 0; i < 32; i++) {
 293                 bh_base[i].routine = NULL;
 294                 bh_base[i].data = NULL;
 295         }
 296         bh_active = 0;
 297         intr_count = 0;
 298 }
/* */
root/kernel/irq.c

DEFINITIONS
