kernel/irq.c

/* */
This source file includes following definitions.
disable_irq
enable_irq
do_bottom_half
get_irq_list
do_IRQ
do_fast_IRQ
irqaction
request_irq
free_irq
math_error_irq
no_action
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 
  36 #define CR0_NE 32
  37 
  38 static unsigned char cache_21 = 0xff;
  39 static unsigned char cache_A1 = 0xff;
  40 
  41 unsigned long intr_count = 0;
  42 unsigned long bh_active = 0;
  43 unsigned long bh_mask = 0xFFFFFFFF;
  44 struct bh_struct bh_base[32]; 
  45 
  46 void disable_irq(unsigned int irq_nr)
     /*  */
  47 {
  48         unsigned long flags;
  49         unsigned char mask;
  50 
  51         mask = 1 << (irq_nr & 7);
  52         save_flags(flags);
  53         if (irq_nr < 8) {
  54                 cli();
  55                 cache_21 |= mask;
  56                 outb(cache_21,0x21);
  57                 restore_flags(flags);
  58                 return;
  59         }
  60         cli();
  61         cache_A1 |= mask;
  62         outb(cache_A1,0xA1);
  63         restore_flags(flags);
  64 }
  65 
  66 void enable_irq(unsigned int irq_nr)
     /*  */
  67 {
  68         unsigned long flags;
  69         unsigned char mask;
  70 
  71         mask = ~(1 << (irq_nr & 7));
  72         save_flags(flags);
  73         if (irq_nr < 8) {
  74                 cli();
  75                 cache_21 &= mask;
  76                 outb(cache_21,0x21);
  77                 restore_flags(flags);
  78                 return;
  79         }
  80         cli();
  81         cache_A1 &= mask;
  82         outb(cache_A1,0xA1);
  83         restore_flags(flags);
  84 }
  85 
  86 /*
  87  * do_bottom_half() runs at normal kernel priority: all interrupts
  88  * enabled.  do_bottom_half() is atomic with respect to itself: a
  89  * bottom_half handler need not be re-entrant.
  90  */
  91 asmlinkage void do_bottom_half(void)
     /*  */
  92 {
  93         unsigned long active;
  94         unsigned long mask, left;
  95         struct bh_struct *bh;
  96 
  97         bh = bh_base;
  98         active = bh_active & bh_mask;
  99         for (mask = 1, left = ~0 ; left & active ; bh++,mask += mask,left += left) {
 100                 if (mask & active) {
 101                         void (*fn)(void *);
 102                         bh_active &= ~mask;
 103                         fn = bh->routine;
 104                         if (!fn)
 105                                 goto bad_bh;
 106                         fn(bh->data);
 107                 }
 108         }
 109         return;
 110 bad_bh:
 111         printk ("irq.c:bad bottom half entry\n");
 112 }
 113 
 114 /*
 115  * This builds up the IRQ handler stubs using some ugly macros in irq.h
 116  *
 117  * These macros create the low-level assembly IRQ routines that do all
 118  * the operations that are needed to keep the AT interrupt-controller
 119  * happy. They are also written to be fast - and to disable interrupts
 120  * as little as humanly possible.
 121  *
 122  * NOTE! These macros expand to three different handlers for each line: one
 123  * complete handler that does all the fancy stuff (including signal handling),
 124  * and one fast handler that is meant for simple IRQ's that want to be
 125  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
 126  * flag when installing a handler. Finally, one "bad interrupt" handler, that
 127  * is used when no handler is present.
 128  */
 129 BUILD_IRQ(FIRST,0,0x01)
 130 BUILD_IRQ(FIRST,1,0x02)
 131 BUILD_IRQ(FIRST,2,0x04)
 132 BUILD_IRQ(FIRST,3,0x08)
 133 BUILD_IRQ(FIRST,4,0x10)
 134 BUILD_IRQ(FIRST,5,0x20)
 135 BUILD_IRQ(FIRST,6,0x40)
 136 BUILD_IRQ(FIRST,7,0x80)
 137 BUILD_IRQ(SECOND,8,0x01)
 138 BUILD_IRQ(SECOND,9,0x02)
 139 BUILD_IRQ(SECOND,10,0x04)
 140 BUILD_IRQ(SECOND,11,0x08)
 141 BUILD_IRQ(SECOND,12,0x10)
 142 BUILD_IRQ(SECOND,13,0x20)
 143 BUILD_IRQ(SECOND,14,0x40)
 144 BUILD_IRQ(SECOND,15,0x80)
 145 
 146 /*
 147  * Pointers to the low-level handlers: first the general ones, then the
 148  * fast ones, then the bad ones.
 149  */
 150 static void (*interrupt[16])(void) = {
 151         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 152         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 153         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 154         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
 155 };
 156 
 157 static void (*fast_interrupt[16])(void) = {
 158         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 159         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 160         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 161         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 162         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 163         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 164         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 165         fast_IRQ14_interrupt, fast_IRQ15_interrupt
 166 };
 167 
 168 static void (*bad_interrupt[16])(void) = {
 169         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 170         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 171         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 172         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 173         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 174         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 175         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 176         bad_IRQ14_interrupt, bad_IRQ15_interrupt
 177 };
 178 
 179 /*
 180  * Initial irq handlers.
 181  */
 182 static struct sigaction irq_sigaction[16] = {
 183         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 184         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 185         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 186         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 187         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 188         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 189         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 190         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 191 };
 192 
 193 int get_irq_list(char *buf)
     /*  */
 194 {
 195         int i, len = 0;
 196         struct sigaction * sa = irq_sigaction;
 197 
 198         for (i = 0 ; i < 16 ; i++, sa++) {
 199                 if (!sa->sa_handler)
 200                         continue;
 201                 len += sprintf(buf+len, "%2d: %8d %c %s\n",
 202                         i, kstat.interrupts[i],
 203                         (sa->sa_flags & SA_INTERRUPT) ? '+' : ' ',
 204                         (char *) sa->sa_mask);
 205         }
 206         return len;
 207 }
 208 
 209 /*
 210  * do_IRQ handles IRQ's that have been installed without the
 211  * SA_INTERRUPT flag: it uses the full signal-handling return
 212  * and runs with other interrupts enabled. All relatively slow
 213  * IRQ's should use this format: notably the keyboard/timer
 214  * routines.
 215  */
 216 asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
     /*  */
 217 {
 218         struct sigaction * sa = irq + irq_sigaction;
 219 
 220         kstat.interrupts[irq]++;
 221         sa->sa_handler((int) regs);
 222 }
 223 
 224 /*
 225  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 226  * stuff - the handler is also running with interrupts disabled unless
 227  * it explicitly enables them later.
 228  */
 229 asmlinkage void do_fast_IRQ(int irq)
     /*  */
 230 {
 231         struct sigaction * sa = irq + irq_sigaction;
 232 
 233         kstat.interrupts[irq]++;
 234         sa->sa_handler(irq);
 235 }
 236 
 237 /*
 238  * Using "struct sigaction" is slightly silly, but there
 239  * are historical reasons and it works well, so..
 240  */
 241 static int irqaction(unsigned int irq, struct sigaction * new_sa)
     /*  */
 242 {
 243         struct sigaction * sa;
 244         unsigned long flags;
 245 
 246         if (irq > 15)
 247                 return -EINVAL;
 248         sa = irq + irq_sigaction;
 249         if (sa->sa_handler)
 250                 return -EBUSY;
 251         if (!new_sa->sa_handler)
 252                 return -EINVAL;
 253         save_flags(flags);
 254         cli();
 255         *sa = *new_sa;
 256         if (sa->sa_flags & SA_INTERRUPT)
 257                 set_intr_gate(0x20+irq,fast_interrupt[irq]);
 258         else
 259                 set_intr_gate(0x20+irq,interrupt[irq]);
 260         if (irq < 8) {
 261                 cache_21 &= ~(1<<irq);
 262                 outb(cache_21,0x21);
 263         } else {
 264                 cache_21 &= ~(1<<2);
 265                 cache_A1 &= ~(1<<(irq-8));
 266                 outb(cache_21,0x21);
 267                 outb(cache_A1,0xA1);
 268         }
 269         restore_flags(flags);
 270         return 0;
 271 }
 272                 
 273 int request_irq(unsigned int irq, void (*handler)(int),
     /*  */
 274         unsigned long flags, const char * devname)
 275 {
 276         struct sigaction sa;
 277 
 278         sa.sa_handler = handler;
 279         sa.sa_flags = flags;
 280         sa.sa_mask = (unsigned long) devname;
 281         sa.sa_restorer = NULL;
 282         return irqaction(irq,&sa);
 283 }
 284 
 285 void free_irq(unsigned int irq)
     /*  */
 286 {
 287         struct sigaction * sa = irq + irq_sigaction;
 288         unsigned long flags;
 289 
 290         if (irq > 15) {
 291                 printk("Trying to free IRQ%d\n",irq);
 292                 return;
 293         }
 294         if (!sa->sa_handler) {
 295                 printk("Trying to free free IRQ%d\n",irq);
 296                 return;
 297         }
 298         save_flags(flags);
 299         cli();
 300         if (irq < 8) {
 301                 cache_21 |= 1 << irq;
 302                 outb(cache_21,0x21);
 303         } else {
 304                 cache_A1 |= 1 << (irq-8);
 305                 outb(cache_A1,0xA1);
 306         }
 307         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 308         sa->sa_handler = NULL;
 309         sa->sa_flags = 0;
 310         sa->sa_mask = 0;
 311         sa->sa_restorer = NULL;
 312         restore_flags(flags);
 313 }
 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 static void math_error_irq(int cpl)
     /*  */
 327 {
 328         outb(0,0xF0);
 329         if (ignore_irq13 || !hard_math)
 330                 return;
 331         math_error();
 332 }
 333 
 334 static void no_action(int cpl) { }
     /*  */
 335 
 336 void init_IRQ(void)
     /*  */
 337 {
 338         int i;
 339 
 340         for (i = 0; i < 16 ; i++)
 341                 set_intr_gate(0x20+i,bad_interrupt[i]);
 342         if (request_irq(2, no_action, SA_INTERRUPT, "cascade"))
 343                 printk("Unable to get IRQ2 for cascade\n");
 344         if (request_irq(13,math_error_irq, 0, "math error"))
 345                 printk("Unable to get IRQ13 for math-error handler\n");
 346 
 347         /* initialize the bottom half routines. */
 348         for (i = 0; i < 32; i++) {
 349                 bh_base[i].routine = NULL;
 350                 bh_base[i].data = NULL;
 351         }
 352         bh_active = 0;
 353         intr_count = 0;
 354 }
/* */
root/kernel/irq.c

DEFINITIONS
