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

DEFINITIONS
