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

DEFINITIONS
