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/config.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/errno.h>
  21 #include <linux/kernel_stat.h>
  22 #include <linux/signal.h>
  23 #include <linux/sched.h>
  24 #include <linux/ioport.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/timex.h>
  27 #include <linux/random.h>
  28 
  29 #include <asm/system.h>
  30 #include <asm/io.h>
  31 #include <asm/irq.h>
  32 #include <asm/bitops.h>
  33 #include <asm/smp.h>
  34 
  35 #define CR0_NE 32
  36 
  37 static unsigned char cache_21 = 0xff;
  38 static unsigned char cache_A1 = 0xff;
  39 
  40 void disable_irq(unsigned int irq_nr)
     /*  */
  41 {
  42         unsigned long flags;
  43         unsigned char mask;
  44 
  45         mask = 1 << (irq_nr & 7);
  46         save_flags(flags);
  47         if (irq_nr < 8) {
  48                 cli();
  49                 cache_21 |= mask;
  50                 outb(cache_21,0x21);
  51                 restore_flags(flags);
  52                 return;
  53         }
  54         cli();
  55         cache_A1 |= mask;
  56         outb(cache_A1,0xA1);
  57         restore_flags(flags);
  58 }
  59 
  60 void enable_irq(unsigned int irq_nr)
     /*  */
  61 {
  62         unsigned long flags;
  63         unsigned char mask;
  64 
  65         mask = ~(1 << (irq_nr & 7));
  66         save_flags(flags);
  67         if (irq_nr < 8) {
  68                 cli();
  69                 cache_21 &= mask;
  70                 outb(cache_21,0x21);
  71                 restore_flags(flags);
  72                 return;
  73         }
  74         cli();
  75         cache_A1 &= mask;
  76         outb(cache_A1,0xA1);
  77         restore_flags(flags);
  78 }
  79 
  80 /*
  81  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  82  *
  83  * These macros create the low-level assembly IRQ routines that do all
  84  * the operations that are needed to keep the AT interrupt-controller
  85  * happy. They are also written to be fast - and to disable interrupts
  86  * as little as humanly possible.
  87  *
  88  * NOTE! These macros expand to three different handlers for each line: one
  89  * complete handler that does all the fancy stuff (including signal handling),
  90  * and one fast handler that is meant for simple IRQ's that want to be
  91  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
  92  * flag when installing a handler. Finally, one "bad interrupt" handler, that
  93  * is used when no handler is present.
  94  */
  95 BUILD_IRQ(FIRST,0,0x01)
  96 BUILD_IRQ(FIRST,1,0x02)
  97 BUILD_IRQ(FIRST,2,0x04)
  98 BUILD_IRQ(FIRST,3,0x08)
  99 BUILD_IRQ(FIRST,4,0x10)
 100 BUILD_IRQ(FIRST,5,0x20)
 101 BUILD_IRQ(FIRST,6,0x40)
 102 BUILD_IRQ(FIRST,7,0x80)
 103 BUILD_IRQ(SECOND,8,0x01)
 104 BUILD_IRQ(SECOND,9,0x02)
 105 BUILD_IRQ(SECOND,10,0x04)
 106 BUILD_IRQ(SECOND,11,0x08)
 107 BUILD_IRQ(SECOND,12,0x10)
 108 #ifdef CONFIG_SMP
 109 BUILD_MSGIRQ(SECOND,13,0x20)
 110 #else
 111 BUILD_IRQ(SECOND,13,0x20)
 112 #endif
 113 BUILD_IRQ(SECOND,14,0x40)
 114 BUILD_IRQ(SECOND,15,0x80)
 115 #ifdef CONFIG_SMP
 116 BUILD_RESCHEDIRQ(16)
 117 #endif
 118 
 119 /*
 120  * Pointers to the low-level handlers: first the general ones, then the
 121  * fast ones, then the bad ones.
 122  */
 123 static void (*interrupt[17])(void) = {
 124         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 125         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 126         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 127         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt      
 128 #ifdef CONFIG_SMP       
 129         ,IRQ16_interrupt
 130 #endif
 131 };
 132 
 133 static void (*fast_interrupt[16])(void) = {
 134         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 135         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 136         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 137         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 138         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 139         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 140         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 141         fast_IRQ14_interrupt, fast_IRQ15_interrupt
 142 };
 143 
 144 static void (*bad_interrupt[16])(void) = {
 145         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 146         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 147         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 148         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 149         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 150         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 151         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 152         bad_IRQ14_interrupt, bad_IRQ15_interrupt
 153 };
 154 
 155 /*
 156  * Initial irq handlers.
 157  */
 158 struct irqaction {
 159         void (*handler)(int, struct pt_regs *);
 160         unsigned long flags;
 161         unsigned long mask;
 162         const char *name;
 163 };
 164 
 165 static struct irqaction irq_action[16] = {
 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         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 174 };
 175 
 176 int get_irq_list(char *buf)
     /*  */
 177 {
 178         int i, len = 0;
 179         struct irqaction * action = irq_action;
 180 
 181         for (i = 0 ; i < 16 ; i++, action++) {
 182                 if (!action->handler)
 183                         continue;
 184                 len += sprintf(buf+len, "%3d: %8d %c %s\n",
 185                         i, kstat.interrupts[i],
 186                         (action->flags & SA_INTERRUPT) ? '+' : ' ',
 187                         action->name);
 188         }
 189 /*
 190  *      Linus - should you add NMI counts here ?????
 191  */
 192 #ifdef CONFIG_SMP
 193         len+=sprintf(buf+len, "IPI: %8lu received\n",
 194                 ipi_count);
 195         len+=sprintf(buf+len, "LCK: %8lu spins\n",
 196                 smp_spins);
 197 #endif          
 198         return len;
 199 }
 200 
 201 /*
 202  * do_IRQ handles IRQ's that have been installed without the
 203  * SA_INTERRUPT flag: it uses the full signal-handling return
 204  * and runs with other interrupts enabled. All relatively slow
 205  * IRQ's should use this format: notably the keyboard/timer
 206  * routines.
 207  */
 208 asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
     /*  */
 209 {
 210         struct irqaction * action = irq + irq_action;
 211 #ifdef CONFIG_SMP
 212         if(smp_threads_ready && active_kernel_processor!=smp_processor_id())
 213                 panic("IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
 214 #endif
 215 
 216         kstat.interrupts[irq]++;
 217         if (action->flags & SA_SAMPLE_RANDOM)
 218                 add_interrupt_randomness(irq);
 219         action->handler(irq, regs);
 220 }
 221 
 222 /*
 223  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 224  * stuff - the handler is also running with interrupts disabled unless
 225  * it explicitly enables them later.
 226  */
 227 asmlinkage void do_fast_IRQ(int irq)
     /*  */
 228 {
 229         struct irqaction * action = irq + irq_action;
 230 #ifdef CONFIG_SMP
 231         /* IRQ 13 is allowed - thats an invalidate */
 232         if(smp_threads_ready && active_kernel_processor!=smp_processor_id() && irq!=13)
 233                 panic("fast_IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
 234 #endif
 235 
 236         kstat.interrupts[irq]++;
 237         if (action->flags & SA_SAMPLE_RANDOM)
 238                 add_interrupt_randomness(irq);
 239         action->handler(irq, NULL);
 240 }
 241 
 242 #define SA_PROBE SA_ONESHOT
 243 
 244 int request_irq(unsigned int irq, void (*handler)(int, struct pt_regs *),
     /*  */
 245         unsigned long irqflags, const char * devname)
 246 {
 247         struct irqaction * action;
 248         unsigned long flags;
 249 
 250         if (irq > 15)
 251                 return -EINVAL;
 252         action = irq + irq_action;
 253         if (action->handler)
 254                 return -EBUSY;
 255         if (!handler)
 256                 return -EINVAL;
 257         if (irqflags & SA_SAMPLE_RANDOM)
 258                 rand_initialize_irq(irq);
 259         save_flags(flags);
 260         cli();
 261         action->handler = handler;
 262         action->flags = irqflags;
 263         action->mask = 0;
 264         action->name = devname;
 265         if (!(action->flags & SA_PROBE)) { /* SA_ONESHOT is used by probing */
 266                 if (action->flags & SA_INTERRUPT)
 267                         set_intr_gate(0x20+irq,fast_interrupt[irq]);
 268                 else
 269                         set_intr_gate(0x20+irq,interrupt[irq]);
 270         }
 271         if (irq < 8) {
 272                 cache_21 &= ~(1<<irq);
 273                 outb(cache_21,0x21);
 274         } else {
 275                 cache_21 &= ~(1<<2);
 276                 cache_A1 &= ~(1<<(irq-8));
 277                 outb(cache_21,0x21);
 278                 outb(cache_A1,0xA1);
 279         }
 280         restore_flags(flags);
 281         return 0;
 282 }
 283                 
 284 void free_irq(unsigned int irq)
     /*  */
 285 {
 286         struct irqaction * action = irq + irq_action;
 287         unsigned long flags;
 288 
 289         if (irq > 15) {
 290                 printk("Trying to free IRQ%d\n",irq);
 291                 return;
 292         }
 293         if (!action->handler) {
 294                 printk("Trying to free free IRQ%d\n",irq);
 295                 return;
 296         }
 297         save_flags(flags);
 298         cli();
 299         if (irq < 8) {
 300                 cache_21 |= 1 << irq;
 301                 outb(cache_21,0x21);
 302         } else {
 303                 cache_A1 |= 1 << (irq-8);
 304                 outb(cache_A1,0xA1);
 305         }
 306         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 307         action->handler = NULL;
 308         action->flags = 0;
 309         action->mask = 0;
 310         action->name = NULL;
 311         restore_flags(flags);
 312 }
 313 
 314 #ifndef CONFIG_SMP
 315 
 316 /*
 317  * Note that on a 486, we don't want to do a SIGFPE on a irq13
 318  * as the irq is unreliable, and exception 16 works correctly
 319  * (ie as explained in the intel literature). On a 386, you
 320  * can't use exception 16 due to bad IBM design, so we have to
 321  * rely on the less exact irq13.
 322  *
 323  * Careful.. Not only is IRQ13 unreliable, but it is also
 324  * leads to races. IBM designers who came up with it should
 325  * be shot.
 326  */
 327  
 328 
 329 static void math_error_irq(int cpl, struct pt_regs *regs)
     /*  */
 330 {
 331         outb(0,0xF0);
 332         if (ignore_irq13 || !hard_math)
 333                 return;
 334         math_error();
 335 }
 336 
 337 #endif
 338 
 339 static void no_action(int cpl, struct pt_regs * regs) { }
     /*  */
 340 
 341 unsigned long probe_irq_on (void)
     /*  */
 342 {
 343         unsigned int i, irqs = 0, irqmask;
 344         unsigned long delay;
 345 
 346         /* first, snaffle up any unassigned irqs */
 347         for (i = 15; i > 0; i--) {
 348                 if (!request_irq(i, no_action, SA_PROBE, "probe")) {
 349                         enable_irq(i);
 350                         irqs |= (1 << i);
 351                 }
 352         }
 353 
 354         /* wait for spurious interrupts to mask themselves out again */
 355         for (delay = jiffies + 2; delay > jiffies; );   /* min 10ms delay */
 356 
 357         /* now filter out any obviously spurious interrupts */
 358         irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
 359         for (i = 15; i > 0; i--) {
 360                 if (irqs & (1 << i) & irqmask) {
 361                         irqs ^= (1 << i);
 362                         free_irq(i);
 363                 }
 364         }
 365 #ifdef DEBUG
 366         printk("probe_irq_on:  irqs=0x%04x irqmask=0x%04x\n", irqs, irqmask);
 367 #endif
 368         return irqs;
 369 }
 370 
 371 int probe_irq_off (unsigned long irqs)
     /*  */
 372 {
 373         unsigned int i, irqmask;
 374 
 375         irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
 376         for (i = 15; i > 0; i--) {
 377                 if (irqs & (1 << i)) {
 378                         free_irq(i);
 379                 }
 380         }
 381 #ifdef DEBUG
 382         printk("probe_irq_off: irqs=0x%04x irqmask=0x%04x\n", irqs, irqmask);
 383 #endif
 384         irqs &= irqmask;
 385         if (!irqs)
 386                 return 0;
 387         i = ffz(~irqs);
 388         if (irqs != (irqs & (1 << i)))
 389                 i = -i;
 390         return i;
 391 }
 392 
 393 void init_IRQ(void)
     /*  */
 394 {
 395         int i;
 396         static unsigned char smptrap=0;
 397         if(smptrap)
 398                 return;
 399         smptrap=1;
 400 
 401         /* set the clock to 100 Hz */
 402         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 403         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 404         outb(LATCH >> 8 , 0x40);        /* MSB */
 405         for (i = 0; i < 16 ; i++)
 406                 set_intr_gate(0x20+i,bad_interrupt[i]);
 407         /* This bit is a hack because we don't send timer messages to all processors yet */
 408         /* It has to here .. it doesnt work if you put it down the bottom - assembler explodes 8) */
 409 #ifdef CONFIG_SMP       
 410         set_intr_gate(0x20+i, interrupt[i]);    /* IRQ '16' - IPI for rescheduling */
 411 #endif  
 412         if (request_irq(2, no_action, SA_INTERRUPT, "cascade"))
 413                 printk("Unable to get IRQ2 for cascade.\n");
 414 #ifndef CONFIG_SMP              
 415         if (request_irq(13,math_error_irq, 0, "math error"))
 416                 printk("Unable to get IRQ13 for math-error handler.\n");
 417 #else
 418         if (request_irq(13, smp_message_irq, SA_INTERRUPT, "IPI"))
 419                 printk("Unable to get IRQ13 for IPI.\n");
 420 #endif                          
 421         request_region(0x20,0x20,"pic1");
 422         request_region(0xa0,0x20,"pic2");
 423 }
/* */
root/arch/i386/kernel/irq.c

DEFINITIONS
