arch/i386/kernel/irq.c

/* */
This source file includes following definitions.
disable_irq
enable_irq
get_irq_list
do_IRQ
do_fast_IRQ
request_irq
free_irq
math_error_irq
no_action
probe_irq_on
probe_irq_off
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/ioport.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/timex.h>
  26 #include <linux/random.h>
  27 
  28 #include <asm/system.h>
  29 #include <asm/io.h>
  30 #include <asm/irq.h>
  31 #include <asm/bitops.h>
  32 #include <asm/smp.h>
  33 
  34 #define CR0_NE 32
  35 
  36 static unsigned char cache_21 = 0xff;
  37 static unsigned char cache_A1 = 0xff;
  38 
  39 void disable_irq(unsigned int irq_nr)
     /*  */
  40 {
  41         unsigned long flags;
  42         unsigned char mask;
  43 
  44         mask = 1 << (irq_nr & 7);
  45         save_flags(flags);
  46         if (irq_nr < 8) {
  47                 cli();
  48                 cache_21 |= mask;
  49                 outb(cache_21,0x21);
  50                 restore_flags(flags);
  51                 return;
  52         }
  53         cli();
  54         cache_A1 |= mask;
  55         outb(cache_A1,0xA1);
  56         restore_flags(flags);
  57 }
  58 
  59 void enable_irq(unsigned int irq_nr)
     /*  */
  60 {
  61         unsigned long flags;
  62         unsigned char mask;
  63 
  64         mask = ~(1 << (irq_nr & 7));
  65         save_flags(flags);
  66         if (irq_nr < 8) {
  67                 cli();
  68                 cache_21 &= mask;
  69                 outb(cache_21,0x21);
  70                 restore_flags(flags);
  71                 return;
  72         }
  73         cli();
  74         cache_A1 &= mask;
  75         outb(cache_A1,0xA1);
  76         restore_flags(flags);
  77 }
  78 
  79 /*
  80  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  81  *
  82  * These macros create the low-level assembly IRQ routines that do all
  83  * the operations that are needed to keep the AT interrupt-controller
  84  * happy. They are also written to be fast - and to disable interrupts
  85  * as little as humanly possible.
  86  *
  87  * NOTE! These macros expand to three different handlers for each line: one
  88  * complete handler that does all the fancy stuff (including signal handling),
  89  * and one fast handler that is meant for simple IRQ's that want to be
  90  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
  91  * flag when installing a handler. Finally, one "bad interrupt" handler, that
  92  * is used when no handler is present.
  93  */
  94 BUILD_IRQ(FIRST,0,0x01)
  95 BUILD_IRQ(FIRST,1,0x02)
  96 BUILD_IRQ(FIRST,2,0x04)
  97 BUILD_IRQ(FIRST,3,0x08)
  98 BUILD_IRQ(FIRST,4,0x10)
  99 BUILD_IRQ(FIRST,5,0x20)
 100 BUILD_IRQ(FIRST,6,0x40)
 101 BUILD_IRQ(FIRST,7,0x80)
 102 BUILD_IRQ(SECOND,8,0x01)
 103 BUILD_IRQ(SECOND,9,0x02)
 104 BUILD_IRQ(SECOND,10,0x04)
 105 BUILD_IRQ(SECOND,11,0x08)
 106 BUILD_IRQ(SECOND,12,0x10)
 107 #ifdef __SMP__
 108 BUILD_MSGIRQ(SECOND,13,0x20)
 109 #else
 110 BUILD_IRQ(SECOND,13,0x20)
 111 #endif
 112 BUILD_IRQ(SECOND,14,0x40)
 113 BUILD_IRQ(SECOND,15,0x80)
 114 #ifdef __SMP__
 115 BUILD_RESCHEDIRQ(16)
 116 #endif
 117 
 118 /*
 119  * Pointers to the low-level handlers: first the general ones, then the
 120  * fast ones, then the bad ones.
 121  */
 122 static void (*interrupt[17])(void) = {
 123         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 124         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 125         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 126         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt      
 127 #ifdef __SMP__  
 128         ,IRQ16_interrupt
 129 #endif
 130 };
 131 
 132 static void (*fast_interrupt[16])(void) = {
 133         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 134         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 135         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 136         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 137         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 138         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 139         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 140         fast_IRQ14_interrupt, fast_IRQ15_interrupt
 141 };
 142 
 143 static void (*bad_interrupt[16])(void) = {
 144         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 145         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 146         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 147         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 148         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 149         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 150         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 151         bad_IRQ14_interrupt, bad_IRQ15_interrupt
 152 };
 153 
 154 /*
 155  * Initial irq handlers.
 156  */
 157 struct irqaction {
 158         void (*handler)(int, struct pt_regs *);
 159         unsigned long flags;
 160         unsigned long mask;
 161         const char *name;
 162 };
 163 
 164 static struct irqaction irq_action[16] = {
 165         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 166         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 167         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 168         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 169         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 170         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 171         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 172         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 173 };
 174 
 175 int get_irq_list(char *buf)
     /*  */
 176 {
 177         int i, len = 0;
 178         struct irqaction * action = irq_action;
 179 
 180         for (i = 0 ; i < 16 ; i++, action++) {
 181                 if (!action->handler)
 182                         continue;
 183                 len += sprintf(buf+len, "%3d: %8d %c %s\n",
 184                         i, kstat.interrupts[i],
 185                         (action->flags & SA_INTERRUPT) ? '+' : ' ',
 186                         action->name);
 187         }
 188 /*
 189  *      Linus - should you add NMI counts here ?????
 190  */
 191 #ifdef __SMP__
 192         len+=sprintf(buf+len, "IPI: %8lu received\n",
 193                 ipi_count);
 194         len+=sprintf(buf+len, "LCK: %8lu spins\n",
 195                 smp_spins);
 196 #endif          
 197         return len;
 198 }
 199 
 200 /*
 201  * do_IRQ handles IRQ's that have been installed without the
 202  * SA_INTERRUPT flag: it uses the full signal-handling return
 203  * and runs with other interrupts enabled. All relatively slow
 204  * IRQ's should use this format: notably the keyboard/timer
 205  * routines.
 206  */
 207 asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
     /*  */
 208 {
 209         struct irqaction * action = irq + irq_action;
 210 #ifdef __SMP__
 211         if(smp_threads_ready && active_kernel_processor!=smp_processor_id())
 212                 panic("IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
 213 #endif
 214 
 215         kstat.interrupts[irq]++;
 216         if (action->flags & SA_SAMPLE_RANDOM)
 217                 add_interrupt_randomness(irq);
 218         action->handler(irq, regs);
 219 }
 220 
 221 /*
 222  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 223  * stuff - the handler is also running with interrupts disabled unless
 224  * it explicitly enables them later.
 225  */
 226 asmlinkage void do_fast_IRQ(int irq)
     /*  */
 227 {
 228         struct irqaction * action = irq + irq_action;
 229 #ifdef __SMP__
 230         /* IRQ 13 is allowed - thats an invalidate */
 231         if(smp_threads_ready && active_kernel_processor!=smp_processor_id() && irq!=13)
 232                 panic("fast_IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
 233 #endif
 234 
 235         kstat.interrupts[irq]++;
 236         if (action->flags & SA_SAMPLE_RANDOM)
 237                 add_interrupt_randomness(irq);
 238         action->handler(irq, NULL);
 239 }
 240 
 241 #define SA_PROBE SA_ONESHOT
 242 
 243 int request_irq(unsigned int irq, void (*handler)(int, struct pt_regs *),
     /*  */
 244         unsigned long irqflags, const char * devname)
 245 {
 246         struct irqaction * action;
 247         unsigned long flags;
 248 
 249         if (irq > 15)
 250                 return -EINVAL;
 251         action = irq + irq_action;
 252         if (action->handler)
 253                 return -EBUSY;
 254         if (!handler)
 255                 return -EINVAL;
 256         if (irqflags & SA_SAMPLE_RANDOM)
 257                 rand_initialize_irq(irq);
 258         save_flags(flags);
 259         cli();
 260         action->handler = handler;
 261         action->flags = irqflags;
 262         action->mask = 0;
 263         action->name = devname;
 264         if (!(action->flags & SA_PROBE)) { /* SA_ONESHOT is used by probing */
 265                 if (action->flags & SA_INTERRUPT)
 266                         set_intr_gate(0x20+irq,fast_interrupt[irq]);
 267                 else
 268                         set_intr_gate(0x20+irq,interrupt[irq]);
 269         }
 270         if (irq < 8) {
 271                 cache_21 &= ~(1<<irq);
 272                 outb(cache_21,0x21);
 273         } else {
 274                 cache_21 &= ~(1<<2);
 275                 cache_A1 &= ~(1<<(irq-8));
 276                 outb(cache_21,0x21);
 277                 outb(cache_A1,0xA1);
 278         }
 279         restore_flags(flags);
 280         return 0;
 281 }
 282                 
 283 void free_irq(unsigned int irq)
     /*  */
 284 {
 285         struct irqaction * action = irq + irq_action;
 286         unsigned long flags;
 287 
 288         if (irq > 15) {
 289                 printk("Trying to free IRQ%d\n",irq);
 290                 return;
 291         }
 292         if (!action->handler) {
 293                 printk("Trying to free free IRQ%d\n",irq);
 294                 return;
 295         }
 296         save_flags(flags);
 297         cli();
 298         if (irq < 8) {
 299                 cache_21 |= 1 << irq;
 300                 outb(cache_21,0x21);
 301         } else {
 302                 cache_A1 |= 1 << (irq-8);
 303                 outb(cache_A1,0xA1);
 304         }
 305         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 306         action->handler = NULL;
 307         action->flags = 0;
 308         action->mask = 0;
 309         action->name = NULL;
 310         restore_flags(flags);
 311 }
 312 
 313 #ifndef __SMP__
 314 
 315 /*
 316  * Note that on a 486, we don't want to do a SIGFPE on a irq13
 317  * as the irq is unreliable, and exception 16 works correctly
 318  * (ie as explained in the intel literature). On a 386, you
 319  * can't use exception 16 due to bad IBM design, so we have to
 320  * rely on the less exact irq13.
 321  *
 322  * Careful.. Not only is IRQ13 unreliable, but it is also
 323  * leads to races. IBM designers who came up with it should
 324  * be shot.
 325  */
 326  
 327 
 328 static void math_error_irq(int cpl, struct pt_regs *regs)
     /*  */
 329 {
 330         outb(0,0xF0);
 331         if (ignore_irq13 || !hard_math)
 332                 return;
 333         math_error();
 334 }
 335 
 336 #endif
 337 
 338 static void no_action(int cpl, struct pt_regs * regs) { }
     /*  */
 339 
 340 unsigned long probe_irq_on (void)
     /*  */
 341 {
 342         unsigned int i, irqs = 0, irqmask;
 343         unsigned long delay;
 344 
 345         /* first, snaffle up any unassigned irqs */
 346         for (i = 15; i > 0; i--) {
 347                 if (!request_irq(i, no_action, SA_PROBE, "probe")) {
 348                         enable_irq(i);
 349                         irqs |= (1 << i);
 350                 }
 351         }
 352 
 353         /* wait for spurious interrupts to mask themselves out again */
 354         for (delay = jiffies + 2; delay > jiffies; );   /* min 10ms delay */
 355 
 356         /* now filter out any obviously spurious interrupts */
 357         irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
 358         for (i = 15; i > 0; i--) {
 359                 if (irqs & (1 << i) & irqmask) {
 360                         irqs ^= (1 << i);
 361                         free_irq(i);
 362                 }
 363         }
 364 #ifdef DEBUG
 365         printk("probe_irq_on:  irqs=0x%04x irqmask=0x%04x\n", irqs, irqmask);
 366 #endif
 367         return irqs;
 368 }
 369 
 370 int probe_irq_off (unsigned long irqs)
     /*  */
 371 {
 372         unsigned int i, irqmask;
 373 
 374         irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
 375         for (i = 15; i > 0; i--) {
 376                 if (irqs & (1 << i)) {
 377                         free_irq(i);
 378                 }
 379         }
 380 #ifdef DEBUG
 381         printk("probe_irq_off: irqs=0x%04x irqmask=0x%04x\n", irqs, irqmask);
 382 #endif
 383         irqs &= irqmask;
 384         if (!irqs)
 385                 return 0;
 386         i = ffz(~irqs);
 387         if (irqs != (irqs & (1 << i)))
 388                 i = -i;
 389         return i;
 390 }
 391 
 392 void init_IRQ(void)
     /*  */
 393 {
 394         int i;
 395         static unsigned char smptrap=0;
 396         if(smptrap)
 397                 return;
 398         smptrap=1;
 399 
 400         /* set the clock to 100 Hz */
 401         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 402         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 403         outb(LATCH >> 8 , 0x40);        /* MSB */
 404         for (i = 0; i < 16 ; i++)
 405                 set_intr_gate(0x20+i,bad_interrupt[i]);
 406         /* This bit is a hack because we don't send timer messages to all processors yet */
 407         /* It has to here .. it doesnt work if you put it down the bottom - assembler explodes 8) */
 408 #ifdef __SMP__  
 409         set_intr_gate(0x20+i, interrupt[i]);    /* IRQ '16' - IPI for rescheduling */
 410 #endif  
 411         if (request_irq(2, no_action, SA_INTERRUPT, "cascade"))
 412                 printk("Unable to get IRQ2 for cascade.\n");
 413 #ifndef __SMP__         
 414         if (request_irq(13,math_error_irq, 0, "math error"))
 415                 printk("Unable to get IRQ13 for math-error handler.\n");
 416 #else
 417         if (request_irq(13, smp_message_irq, SA_INTERRUPT, "IPI"))
 418                 printk("Unable to get IRQ13 for IPI.\n");
 419 #endif                          
 420         request_region(0x20,0x20,"pic1");
 421         request_region(0xa0,0x20,"pic2");
 422 }
/* */
root/arch/i386/kernel/irq.c

DEFINITIONS
