kernel/irq.c

/* */
This source file includes following definitions.
do_bottom_half
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.
  20  * sa_mask is 0 if nothing uses this IRQ
  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/signal.h>
  28 #include <linux/sched.h>
  29 #include <linux/interrupt.h>
  30 
  31 #include <asm/system.h>
  32 #include <asm/io.h>
  33 #include <asm/irq.h>
  34 
  35 
  36 void irq13(void);
  37 
  38 static unsigned long intr_count=0;
  39 
  40 /* I'll use an array for speed. and bitmap for speed. */
  41 int bh_active=0;
  42 struct bh_struct bh_base[32]; 
  43 
  44 /* interrupts should be on at the interrupt priority controller level. */
  45 /* returns with interrupts off at the processor level. */
  46 
  47 void do_bottom_half(void)
     /*  */
  48 {
  49         struct bh_struct *bh;
  50         int mask;
  51         int count;
  52         static int in_bh = 0;
  53 
  54         cli();
  55         if (intr_count > 1) {
  56                 intr_count--;
  57                 return;
  58         }
  59   /* don't just decrement it in case it is already 0 */
  60 
  61         intr_count = 0;
  62 
  63   /* any sort of real time test should go here. */
  64         if (in_bh != 0) {
  65                 return;
  66         }
  67 
  68         in_bh = 1;
  69         do {
  70                 count = 0;
  71                 for (mask = 1, bh = bh_base; mask ; bh++, mask = mask << 1) {
  72                         if (mask > bh_active)
  73                                 break;
  74                         if (!(mask & bh_active))
  75                                 continue;
  76 
  77                         count++;
  78                         bh_active &= ~mask;
  79 
  80                         /* turn the interrupts back on. */
  81                         sti();
  82 
  83                         if (bh->routine != NULL)
  84                                 bh->routine(bh->data);
  85                         else
  86                                 printk ("irq.c:bad bottom half entry.\n");
  87 
  88                 /* and back off. */
  89                         cli();
  90                 }
  91         } while (count > 0);
  92         in_bh = 0;
  93 }
  94 
  95 /*
  96  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  97  *
  98  * These macros create the low-level assembly IRQ routines that do all
  99  * the operations that are needed to keep the AT interrupt-controller
 100  * happy. They are also written to be fast - and to disable interrupts
 101  * as little as humanly possible.
 102  *
 103  * NOTE! These macros expand to three different handlers for each line: one
 104  * complete handler that does all the fancy stuff (including signal handling),
 105  * and one fast handler that is meant for simple IRQ's that want to be
 106  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
 107  * flag when installing a handler. Finally, one "bad interrupt" handler, that
 108  * is used when no handler is present.
 109  */
 110 BUILD_IRQ(FIRST,0,0x01)
 111 BUILD_IRQ(FIRST,1,0x02)
 112 BUILD_IRQ(FIRST,2,0x04)
 113 BUILD_IRQ(FIRST,3,0x08)
 114 BUILD_IRQ(FIRST,4,0x10)
 115 BUILD_IRQ(FIRST,5,0x20)
 116 BUILD_IRQ(FIRST,6,0x40)
 117 BUILD_IRQ(FIRST,7,0x80)
 118 BUILD_IRQ(SECOND,8,0x01)
 119 BUILD_IRQ(SECOND,9,0x02)
 120 BUILD_IRQ(SECOND,10,0x04)
 121 BUILD_IRQ(SECOND,11,0x08)
 122 BUILD_IRQ(SECOND,12,0x10)
 123 BUILD_IRQ(SECOND,13,0x20)
 124 BUILD_IRQ(SECOND,14,0x40)
 125 BUILD_IRQ(SECOND,15,0x80)
 126 
 127 /*
 128  * Pointers to the low-level handlers: first the general ones, then the
 129  * fast ones, then the bad ones.
 130  */
 131 static void (*interrupt[16])(void) = {
 132         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 133         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 134         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 135         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
 136 };
 137 
 138 static void (*fast_interrupt[16])(void) = {
 139         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 140         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 141         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 142         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 143         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 144         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 145         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 146         fast_IRQ14_interrupt, fast_IRQ15_interrupt
 147 };
 148 
 149 static void (*bad_interrupt[16])(void) = {
 150         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 151         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 152         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 153         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 154         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 155         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 156         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 157         bad_IRQ14_interrupt, bad_IRQ15_interrupt
 158 };
 159 
 160 /*
 161  * Initial irq handlers.
 162  */
 163 static struct sigaction irq_sigaction[16] = {
 164         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 165         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 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 };
 173 
 174 /*
 175  * do_IRQ handles IRQ's that have been installed without the
 176  * SA_INTERRUPT flag: it uses the full signal-handling return
 177  * and runs with other interrupts enabled. All relatively slow
 178  * IRQ's should use this format: notably the keyboard/timer
 179  * routines.
 180  */
 181 void do_IRQ(int irq, struct pt_regs * regs)
     /*  */
 182 {
 183         struct sigaction * sa = irq + irq_sigaction;
 184 
 185         sa->sa_handler((int) regs);
 186 }
 187 
 188 /*
 189  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 190  * stuff - the handler is also running with interrupts disabled unless
 191  * it explicitly enables them later.
 192  */
 193 void do_fast_IRQ(int irq)
     /*  */
 194 {
 195         struct sigaction * sa = irq + irq_sigaction;
 196 
 197         sa->sa_handler(irq);
 198 }
 199 
 200 int irqaction(unsigned int irq, struct sigaction * new)
     /*  */
 201 {
 202         struct sigaction * sa;
 203         unsigned long flags;
 204 
 205         if (irq > 15)
 206                 return -EINVAL;
 207         sa = irq + irq_sigaction;
 208         if (sa->sa_mask)
 209                 return -EBUSY;
 210         if (!new->sa_handler)
 211                 return -EINVAL;
 212         save_flags(flags);
 213         cli();
 214         *sa = *new;
 215         sa->sa_mask = 1;
 216         if (sa->sa_flags & SA_INTERRUPT)
 217                 set_intr_gate(0x20+irq,fast_interrupt[irq]);
 218         else
 219                 set_intr_gate(0x20+irq,interrupt[irq]);
 220         if (irq < 8)
 221                 outb(inb_p(0x21) & ~(1<<irq),0x21);
 222         else {
 223                 outb(inb_p(0x21) & ~(1<<2),0x21);
 224                 outb(inb_p(0xA1) & ~(1<<(irq-8)),0xA1);
 225         }
 226         restore_flags(flags);
 227         return 0;
 228 }
 229                 
 230 int request_irq(unsigned int irq, void (*handler)(int))
     /*  */
 231 {
 232         struct sigaction sa;
 233 
 234         sa.sa_handler = handler;
 235         sa.sa_flags = 0;
 236         sa.sa_mask = 0;
 237         sa.sa_restorer = NULL;
 238         return irqaction(irq,&sa);
 239 }
 240 
 241 void free_irq(unsigned int irq)
     /*  */
 242 {
 243         struct sigaction * sa = irq + irq_sigaction;
 244         unsigned long flags;
 245 
 246         if (irq > 15) {
 247                 printk("Trying to free IRQ%d\n",irq);
 248                 return;
 249         }
 250         if (!sa->sa_mask) {
 251                 printk("Trying to free free IRQ%d\n",irq);
 252                 return;
 253         }
 254         save_flags(flags);
 255         cli();
 256         if (irq < 8)
 257                 outb(inb_p(0x21) | (1<<irq),0x21);
 258         else
 259                 outb(inb_p(0xA1) | (1<<(irq-8)),0xA1);
 260         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 261         sa->sa_handler = NULL;
 262         sa->sa_flags = 0;
 263         sa->sa_mask = 0;
 264         sa->sa_restorer = NULL;
 265         restore_flags(flags);
 266 }
 267 
 268 extern void do_coprocessor_error(long,long);
 269 
 270 static void math_error_irq(int cpl)
     /*  */
 271 {
 272         outb(0,0xF0);
 273         do_coprocessor_error(0,0);
 274 }
 275 
 276 static void no_action(int cpl) { }
     /*  */
 277 
 278 static struct sigaction ignore_IRQ = {
 279         no_action,
 280         0,
 281         SA_INTERRUPT,
 282         NULL
 283 };
 284 
 285 void init_IRQ(void)
     /*  */
 286 {
 287         int i;
 288 
 289         for (i = 0; i < 16 ; i++)
 290                 set_intr_gate(0x20+i,bad_interrupt[i]);
 291         if (irqaction(2,&ignore_IRQ))
 292                 printk("Unable to get IRQ2 for cascade\n");
 293         if (request_irq(13,math_error_irq))
 294                 printk("Unable to get IRQ13 for math-error handler\n");
 295 
 296         /* intialize the bottom half routines. */
 297         for (i = 0; i < 32; i++)
 298           {
 299             bh_base[i].routine = NULL;
 300             bh_base[i].data = NULL;
 301           }
 302         bh_active = 0;
 303 
 304 }
/* */
root/kernel/irq.c

DEFINITIONS
