kernel/irq.c

/* */
This source file includes following definitions.
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 
  30 #include <asm/system.h>
  31 #include <asm/io.h>
  32 #include <asm/irq.h>
  33 
  34 void irq13(void);
  35 
  36 /*
  37  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  38  *
  39  * These macros create the low-level assembly IRQ routines that do all
  40  * the operations that are needed to keep the AT interrupt-controller
  41  * happy. They are also written to be fast - and to disable interrupts
  42  * as little as humanly possible.
  43  *
  44  * NOTE! These macros expand to three different handlers for each line: one
  45  * complete handler that does all the fancy stuff (including signal handling),
  46  * and one fast handler that is meant for simple IRQ's that want to be
  47  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
  48  * flag when installing a handler. Finally, one "bad interrupt" handler, that
  49  * is used when no handler is present.
  50  */
  51 BUILD_IRQ(FIRST,0,0x01)
  52 BUILD_IRQ(FIRST,1,0x02)
  53 BUILD_IRQ(FIRST,2,0x04)
  54 BUILD_IRQ(FIRST,3,0x08)
  55 BUILD_IRQ(FIRST,4,0x10)
  56 BUILD_IRQ(FIRST,5,0x20)
  57 BUILD_IRQ(FIRST,6,0x40)
  58 BUILD_IRQ(FIRST,7,0x80)
  59 BUILD_IRQ(SECOND,8,0x01)
  60 BUILD_IRQ(SECOND,9,0x02)
  61 BUILD_IRQ(SECOND,10,0x04)
  62 BUILD_IRQ(SECOND,11,0x08)
  63 BUILD_IRQ(SECOND,12,0x10)
  64 BUILD_IRQ(SECOND,13,0x20)
  65 BUILD_IRQ(SECOND,14,0x40)
  66 BUILD_IRQ(SECOND,15,0x80)
  67 
  68 /*
  69  * Pointers to the low-level handlers: first the general ones, then the
  70  * fast ones, then the bad ones.
  71  */
  72 static void (*interrupt[16])(void) = {
  73         IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
  74         IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
  75         IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
  76         IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
  77 };
  78 
  79 static void (*fast_interrupt[16])(void) = {
  80         fast_IRQ0_interrupt, fast_IRQ1_interrupt,
  81         fast_IRQ2_interrupt, fast_IRQ3_interrupt,
  82         fast_IRQ4_interrupt, fast_IRQ5_interrupt,
  83         fast_IRQ6_interrupt, fast_IRQ7_interrupt,
  84         fast_IRQ8_interrupt, fast_IRQ9_interrupt,
  85         fast_IRQ10_interrupt, fast_IRQ11_interrupt,
  86         fast_IRQ12_interrupt, fast_IRQ13_interrupt,
  87         fast_IRQ14_interrupt, fast_IRQ15_interrupt
  88 };
  89 
  90 static void (*bad_interrupt[16])(void) = {
  91         bad_IRQ0_interrupt, bad_IRQ1_interrupt,
  92         bad_IRQ2_interrupt, bad_IRQ3_interrupt,
  93         bad_IRQ4_interrupt, bad_IRQ5_interrupt,
  94         bad_IRQ6_interrupt, bad_IRQ7_interrupt,
  95         bad_IRQ8_interrupt, bad_IRQ9_interrupt,
  96         bad_IRQ10_interrupt, bad_IRQ11_interrupt,
  97         bad_IRQ12_interrupt, bad_IRQ13_interrupt,
  98         bad_IRQ14_interrupt, bad_IRQ15_interrupt
  99 };
 100 
 101 /*
 102  * Initial irq handlers.
 103  */
 104 static struct sigaction irq_sigaction[16] = {
 105         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 106         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 107         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 108         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 109         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 110         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 111         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 112         { NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 113 };
 114 
 115 /*
 116  * do_IRQ handles IRQ's that have been installed without the
 117  * SA_INTERRUPT flag: it uses the full signal-handling return
 118  * and runs with other interrupts disabled. All relatively slow
 119  * IRQ's should use this format: notably the keyboard/timer
 120  * routines.
 121  */
 122 int do_IRQ(int irq, struct pt_regs * regs)
     /*  */
 123 {
 124         struct sigaction * sa = irq + irq_sigaction;
 125 
 126         sa->sa_handler((int) regs);
 127         return 0;               /* re-enable the irq when returning */
 128 }
 129 
 130 /*
 131  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
 132  * stuff - the handler is also running with interrupts disabled unless
 133  * it explicitly enables them later.
 134  */
 135 int do_fast_IRQ(int irq)
     /*  */
 136 {
 137         struct sigaction * sa = irq + irq_sigaction;
 138 
 139         sa->sa_handler(0);
 140         return 0;               /* re-enable the irq when returning */
 141 }
 142 
 143 int irqaction(unsigned int irq, struct sigaction * new)
     /*  */
 144 {
 145         struct sigaction * sa;
 146         unsigned long flags;
 147 
 148         if (irq > 15)
 149                 return -EINVAL;
 150         sa = irq + irq_sigaction;
 151         if (sa->sa_mask)
 152                 return -EBUSY;
 153         if (!new->sa_handler)
 154                 return -EINVAL;
 155         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 156         *sa = *new;
 157         sa->sa_mask = 1;
 158         if (sa->sa_flags & SA_INTERRUPT)
 159                 set_intr_gate(0x20+irq,fast_interrupt[irq]);
 160         else
 161                 set_intr_gate(0x20+irq,interrupt[irq]);
 162         if (irq < 8)
 163                 outb(inb_p(0x21) & ~(1<<irq),0x21);
 164         else {
 165                 outb(inb_p(0x21) & ~(1<<2),0x21);
 166                 outb(inb_p(0xA1) & ~(1<<(irq-8)),0xA1);
 167         }
 168         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 169         return 0;
 170 }
 171                 
 172 int request_irq(unsigned int irq, void (*handler)(int))
     /*  */
 173 {
 174         struct sigaction sa;
 175 
 176         sa.sa_handler = handler;
 177         sa.sa_flags = 0;
 178         sa.sa_mask = 0;
 179         sa.sa_restorer = NULL;
 180         return irqaction(irq,&sa);
 181 }
 182 
 183 void free_irq(unsigned int irq)
     /*  */
 184 {
 185         struct sigaction * sa = irq + irq_sigaction;
 186         unsigned long flags;
 187 
 188         if (irq > 15) {
 189                 printk("Trying to free IRQ%d\n",irq);
 190                 return;
 191         }
 192         if (!sa->sa_mask) {
 193                 printk("Trying to free free IRQ%d\n",irq);
 194                 return;
 195         }
 196         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 197         if (irq < 8)
 198                 outb(inb_p(0x21) | (1<<irq),0x21);
 199         else
 200                 outb(inb_p(0xA1) | (1<<(irq-8)),0xA1);
 201         set_intr_gate(0x20+irq,bad_interrupt[irq]);
 202         sa->sa_handler = NULL;
 203         sa->sa_flags = 0;
 204         sa->sa_mask = 0;
 205         sa->sa_restorer = NULL;
 206         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 207 }
 208 
 209 extern void do_coprocessor_error(long,long);
 210 
 211 static void math_error_irq(int cpl)
     /*  */
 212 {
 213         outb(0,0xF0);
 214         do_coprocessor_error(0,0);
 215 }
 216 
 217 static void no_action(int cpl) { }
     /*  */
 218 
 219 static struct sigaction ignore_IRQ = {
 220         no_action,
 221         0,
 222         SA_INTERRUPT,
 223         NULL
 224 };
 225 
 226 void init_IRQ(void)
     /*  */
 227 {
 228         int i;
 229 
 230         for (i = 0; i < 16 ; i++)
 231                 set_intr_gate(0x20+i,bad_interrupt[i]);
 232         if (irqaction(2,&ignore_IRQ))
 233                 printk("Unable to get IRQ2 for cascade\n");
 234         if (request_irq(13,math_error_irq))
 235                 printk("Unable to get IRQ13 for math-error handler\n");
 236 }
/* */
root/kernel/irq.c

DEFINITIONS
