arch/i386/kernel/irq.c

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

DEFINITIONS
