root/arch/i386/kernel/irq.c

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DEFINITIONS

This source file includes following definitions.
  1. disable_irq
  2. enable_irq
  3. get_irq_list
  4. do_IRQ
  5. do_fast_IRQ
  6. request_irq
  7. free_irq
  8. math_error_irq
  9. no_action
  10. probe_irq_on
  11. probe_irq_off
  12. init_IRQ

   1 /*
   2  *      linux/arch/i386/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  * Naturally it's not a 1:1 relation, but there are similarities.
  16  */
  17 
  18 #include <linux/ptrace.h>
  19 #include <linux/errno.h>
  20 #include <linux/kernel_stat.h>
  21 #include <linux/signal.h>
  22 #include <linux/sched.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/timex.h>
  25 
  26 #include <asm/system.h>
  27 #include <asm/io.h>
  28 #include <asm/irq.h>
  29 #include <asm/bitops.h>
  30 
  31 #define CR0_NE 32
  32 
  33 static unsigned char cache_21 = 0xff;
  34 static unsigned char cache_A1 = 0xff;
  35 
  36 void disable_irq(unsigned int irq_nr)
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  37 {
  38         unsigned long flags;
  39         unsigned char mask;
  40 
  41         mask = 1 << (irq_nr & 7);
  42         save_flags(flags);
  43         if (irq_nr < 8) {
  44                 cli();
  45                 cache_21 |= mask;
  46                 outb(cache_21,0x21);
  47                 restore_flags(flags);
  48                 return;
  49         }
  50         cli();
  51         cache_A1 |= mask;
  52         outb(cache_A1,0xA1);
  53         restore_flags(flags);
  54 }
  55 
  56 void enable_irq(unsigned int irq_nr)
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  57 {
  58         unsigned long flags;
  59         unsigned char mask;
  60 
  61         mask = ~(1 << (irq_nr & 7));
  62         save_flags(flags);
  63         if (irq_nr < 8) {
  64                 cli();
  65                 cache_21 &= mask;
  66                 outb(cache_21,0x21);
  67                 restore_flags(flags);
  68                 return;
  69         }
  70         cli();
  71         cache_A1 &= mask;
  72         outb(cache_A1,0xA1);
  73         restore_flags(flags);
  74 }
  75 
  76 /*
  77  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  78  *
  79  * These macros create the low-level assembly IRQ routines that do all
  80  * the operations that are needed to keep the AT interrupt-controller
  81  * happy. They are also written to be fast - and to disable interrupts
  82  * as little as humanly possible.
  83  *
  84  * NOTE! These macros expand to three different handlers for each line: one
  85  * complete handler that does all the fancy stuff (including signal handling),
  86  * and one fast handler that is meant for simple IRQ's that want to be
  87  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
  88  * flag when installing a handler. Finally, one "bad interrupt" handler, that
  89  * is used when no handler is present.
  90  */
  91 BUILD_IRQ(FIRST,0,0x01)
  92 BUILD_IRQ(FIRST,1,0x02)
  93 BUILD_IRQ(FIRST,2,0x04)
  94 BUILD_IRQ(FIRST,3,0x08)
  95 BUILD_IRQ(FIRST,4,0x10)
  96 BUILD_IRQ(FIRST,5,0x20)
  97 BUILD_IRQ(FIRST,6,0x40)
  98 BUILD_IRQ(FIRST,7,0x80)
  99 BUILD_IRQ(SECOND,8,0x01)
 100 BUILD_IRQ(SECOND,9,0x02)
 101 BUILD_IRQ(SECOND,10,0x04)
 102 BUILD_IRQ(SECOND,11,0x08)
 103 BUILD_IRQ(SECOND,12,0x10)
 104 BUILD_IRQ(SECOND,13,0x20)
 105 BUILD_IRQ(SECOND,14,0x40)
 106 BUILD_IRQ(SECOND,15,0x80)
 107 
 108 /*
 109  * Pointers to the low-level handlers: first the general ones, then the
 110  * fast ones, then the bad ones.
 111  */
 112 static void (*interrupt[16])(void) = {
 113         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 114         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 115         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 116         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
 117 };
 118 
 119 static void (*fast_interrupt[16])(void) = {
 120         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 121         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 122         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 123         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 124         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 125         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 126         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 127         fast_IRQ14_interrupt, fast_IRQ15_interrupt
 128 };
 129 
 130 static void (*bad_interrupt[16])(void) = {
 131         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 132         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 133         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 134         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 135         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 136         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 137         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 138         bad_IRQ14_interrupt, bad_IRQ15_interrupt
 139 };
 140 
 141 /*
 142  * Initial irq handlers.
 143  */
 144 struct irqaction {
 145         void (*handler)(int, struct pt_regs *);
 146         unsigned long flags;
 147         unsigned long mask;
 148         const char *name;
 149 };
 150 
 151 static struct irqaction irq_action[16] = {
 152         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 153         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 154         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 155         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 156         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 157         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 158         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 159         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 160 };
 161 
 162 int get_irq_list(char *buf)
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 163 {
 164         int i, len = 0;
 165         struct irqaction * action = irq_action;
 166 
 167         for (i = 0 ; i < 16 ; i++, action++) {
 168                 if (!action->handler)
 169                         continue;
 170                 len += sprintf(buf+len, "%2d: %8d %c %s\n",
 171                         i, kstat.interrupts[i],
 172                         (action->flags & SA_INTERRUPT) ? '+' : ' ',
 173                         action->name);
 174         }
 175         return len;
 176 }
 177 
 178 /*
 179  * do_IRQ handles IRQ's that have been installed without the
 180  * SA_INTERRUPT flag: it uses the full signal-handling return
 181  * and runs with other interrupts enabled. All relatively slow
 182  * IRQ's should use this format: notably the keyboard/timer
 183  * routines.
 184  */
 185 asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
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 186 {
 187         struct irqaction * action = irq + irq_action;
 188 
 189         kstat.interrupts[irq]++;
 190         action->handler(irq, regs);
 191 }
 192 
 193 /*
 194  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 195  * stuff - the handler is also running with interrupts disabled unless
 196  * it explicitly enables them later.
 197  */
 198 asmlinkage void do_fast_IRQ(int irq)
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 199 {
 200         struct irqaction * action = irq + irq_action;
 201 
 202         kstat.interrupts[irq]++;
 203         action->handler(irq, NULL);
 204 }
 205 
 206 #define SA_PROBE SA_ONESHOT
 207 
 208 int request_irq(unsigned int irq, void (*handler)(int, struct pt_regs *),
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 209         unsigned long irqflags, const char * devname)
 210 {
 211         struct irqaction * action;
 212         unsigned long flags;
 213 
 214         if (irq > 15)
 215                 return -EINVAL;
 216         action = irq + irq_action;
 217         if (action->handler)
 218                 return -EBUSY;
 219         if (!handler)
 220                 return -EINVAL;
 221         save_flags(flags);
 222         cli();
 223         action->handler = handler;
 224         action->flags = irqflags;
 225         action->mask = 0;
 226         action->name = devname;
 227         if (!(action->flags & SA_PROBE)) { /* SA_ONESHOT is used by probing */
 228                 if (action->flags & SA_INTERRUPT)
 229                         set_intr_gate(0x20+irq,fast_interrupt[irq]);
 230                 else
 231                         set_intr_gate(0x20+irq,interrupt[irq]);
 232         }
 233         if (irq < 8) {
 234                 cache_21 &= ~(1<<irq);
 235                 outb(cache_21,0x21);
 236         } else {
 237                 cache_21 &= ~(1<<2);
 238                 cache_A1 &= ~(1<<(irq-8));
 239                 outb(cache_21,0x21);
 240                 outb(cache_A1,0xA1);
 241         }
 242         restore_flags(flags);
 243         return 0;
 244 }
 245                 
 246 void free_irq(unsigned int irq)
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 247 {
 248         struct irqaction * action = irq + irq_action;
 249         unsigned long flags;
 250 
 251         if (irq > 15) {
 252                 printk("Trying to free IRQ%d\n",irq);
 253                 return;
 254         }
 255         if (!action->handler) {
 256                 printk("Trying to free free IRQ%d\n",irq);
 257                 return;
 258         }
 259         save_flags(flags);
 260         cli();
 261         if (irq < 8) {
 262                 cache_21 |= 1 << irq;
 263                 outb(cache_21,0x21);
 264         } else {
 265                 cache_A1 |= 1 << (irq-8);
 266                 outb(cache_A1,0xA1);
 267         }
 268         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 269         action->handler = NULL;
 270         action->flags = 0;
 271         action->mask = 0;
 272         action->name = NULL;
 273         restore_flags(flags);
 274 }
 275 
 276 /*
 277  * Note that on a 486, we don't want to do a SIGFPE on a irq13
 278  * as the irq is unreliable, and exception 16 works correctly
 279  * (ie as explained in the intel literature). On a 386, you
 280  * can't use exception 16 due to bad IBM design, so we have to
 281  * rely on the less exact irq13.
 282  *
 283  * Careful.. Not only is IRQ13 unreliable, but it is also
 284  * leads to races. IBM designers who came up with it should
 285  * be shot.
 286  */
 287 static void math_error_irq(int cpl, struct pt_regs *regs)
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 288 {
 289         outb(0,0xF0);
 290         if (ignore_irq13 || !hard_math)
 291                 return;
 292         math_error();
 293 }
 294 
 295 static void no_action(int cpl, struct pt_regs * regs) { }
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 296 
 297 unsigned int probe_irq_on (void)
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 298 {
 299         unsigned int i, irqs = 0, irqmask;
 300         unsigned long delay;
 301 
 302         /* first, snaffle up any unassigned irqs */
 303         for (i = 15; i > 0; i--) {
 304                 if (!request_irq(i, no_action, SA_PROBE, "probe")) {
 305                         enable_irq(i);
 306                         irqs |= (1 << i);
 307                 }
 308         }
 309 
 310         /* wait for spurious interrupts to mask themselves out again */
 311         for (delay = jiffies + 2; delay > jiffies; );   /* min 10ms delay */
 312 
 313         /* now filter out any obviously spurious interrupts */
 314         irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
 315         for (i = 15; i > 0; i--) {
 316                 if (irqs & (1 << i) & irqmask) {
 317                         irqs ^= (1 << i);
 318                         free_irq(i);
 319                 }
 320         }
 321 #ifdef DEBUG
 322         printk("probe_irq_on:  irqs=0x%04x irqmask=0x%04x\n", irqs, irqmask);
 323 #endif
 324         return irqs;
 325 }
 326 
 327 int probe_irq_off (unsigned int irqs)
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 328 {
 329         unsigned int i, irqmask;
 330 
 331         irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
 332         for (i = 15; i > 0; i--) {
 333                 if (irqs & (1 << i)) {
 334                         free_irq(i);
 335                 }
 336         }
 337 #ifdef DEBUG
 338         printk("probe_irq_off: irqs=0x%04x irqmask=0x%04x\n", irqs, irqmask);
 339 #endif
 340         irqs &= irqmask;
 341         if (!irqs)
 342                 return 0;
 343         i = ffz(~irqs);
 344         if (irqs != (irqs & (1 << i)))
 345                 i = -i;
 346         return i;
 347 }
 348 
 349 void init_IRQ(void)
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 350 {
 351         int i;
 352 
 353         /* set the clock to 100 Hz */
 354         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 355         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 356         outb(LATCH >> 8 , 0x40);        /* MSB */
 357         for (i = 0; i < 16 ; i++)
 358                 set_intr_gate(0x20+i,bad_interrupt[i]);
 359         if (request_irq(2, no_action, SA_INTERRUPT, "cascade"))
 360                 printk("Unable to get IRQ2 for cascade\n");
 361         if (request_irq(13,math_error_irq, 0, "math error"))
 362                 printk("Unable to get IRQ13 for math-error handler\n");
 363 }

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