kernel/irq.c - pub/scm/linux/kernel/git/nico/archive - Git at Google

 /*
  *	linux/kernel/irq.c
  *
  *	Copyright (C) 1992 Linus Torvalds
  *
  * This file contains the code used by various IRQ handling routines:
  * asking for different IRQ's should be done through these routines
  * instead of just grabbing them. Thus setups with different IRQ numbers
  * shouldn't result in any weird surprises, and installing new handlers
  * should be easier.
  */

 /*
  * IRQ's are in fact implemented a bit like signal handlers for the kernel.
  * The same sigaction struct is used, and with similar semantics (ie there
  * is a SA_INTERRUPT flag etc). Naturally it's not a 1:1 relation, but there
  * are similarities.
  *
  * sa_handler(int irq_NR) is the default function called.
  * sa_mask is 0 if nothing uses this IRQ
  * sa_flags contains various info: SA_INTERRUPT etc
  * sa_restorer is the unused
  */

 #include <linux/ptrace.h>
 #include <linux/errno.h>
 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>

 #include <asm/system.h>
 #include <asm/io.h>
 #include <asm/irq.h>

 #define CR0_NE 32

 static unsigned char cache_21 = 0xff;
 static unsigned char cache_A1 = 0xff;

 unsigned long intr_count = 0;
 unsigned long bh_active = 0;
 unsigned long bh_mask = 0xFFFFFFFF;
 struct bh_struct bh_base[32];

 void disable_irq(unsigned int irq_nr)
 {
 	unsigned long flags;
 	unsigned char mask;

 	mask = 1 << (irq_nr & 7);
 	save_flags(flags);
 	if (irq_nr < 8) {
 		cli();
 		cache_21 |= mask;
 		outb(cache_21,0x21);
 		restore_flags(flags);
 		return;
 	}
 	cli();
 	cache_A1 |= mask;
 	outb(cache_A1,0xA1);
 	restore_flags(flags);
 }

 void enable_irq(unsigned int irq_nr)
 {
 	unsigned long flags;
 	unsigned char mask;

 	mask = ~(1 << (irq_nr & 7));
 	save_flags(flags);
 	if (irq_nr < 8) {
 		cli();
 		cache_21 &= mask;
 		outb(cache_21,0x21);
 		restore_flags(flags);
 		return;
 	}
 	cli();
 	cache_A1 &= mask;
 	outb(cache_A1,0xA1);
 	restore_flags(flags);
 }

 /*
  * do_bottom_half() runs at normal kernel priority: all interrupts
  * enabled.  do_bottom_half() is atomic with respect to itself: a
  * bottom_half handler need not be re-entrant.
  */
 asmlinkage void do_bottom_half(void)
 {
 	unsigned long active;
 	unsigned long mask, left;
 	struct bh_struct *bh;

 	bh = bh_base;
 	active = bh_active & bh_mask;
 	for (mask = 1, left = ~0 ; left & active ; bh++,mask += mask,left += left) {
 		if (mask & active) {
 			void (*fn)(void *);
 			bh_active &= ~mask;
 			fn = bh->routine;
 			if (!fn)
 				goto bad_bh;
 			fn(bh->data);
 		}
 	}
 	return;
 bad_bh:
 	printk ("irq.c:bad bottom half entry\n");
 }

 /*
  * This builds up the IRQ handler stubs using some ugly macros in irq.h
  *
  * These macros create the low-level assembly IRQ routines that do all
  * the operations that are needed to keep the AT interrupt-controller
  * happy. They are also written to be fast - and to disable interrupts
  * as little as humanly possible.
  *
  * NOTE! These macros expand to three different handlers for each line: one
  * complete handler that does all the fancy stuff (including signal handling),
  * and one fast handler that is meant for simple IRQ's that want to be
  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
  * flag when installing a handler. Finally, one "bad interrupt" handler, that
  * is used when no handler is present.
  */
 BUILD_IRQ(FIRST,0,0x01)
 BUILD_IRQ(FIRST,1,0x02)
 BUILD_IRQ(FIRST,2,0x04)
 BUILD_IRQ(FIRST,3,0x08)
 BUILD_IRQ(FIRST,4,0x10)
 BUILD_IRQ(FIRST,5,0x20)
 BUILD_IRQ(FIRST,6,0x40)
 BUILD_IRQ(FIRST,7,0x80)
 BUILD_IRQ(SECOND,8,0x01)
 BUILD_IRQ(SECOND,9,0x02)
 BUILD_IRQ(SECOND,10,0x04)
 BUILD_IRQ(SECOND,11,0x08)
 BUILD_IRQ(SECOND,12,0x10)
 BUILD_IRQ(SECOND,13,0x20)
 BUILD_IRQ(SECOND,14,0x40)
 BUILD_IRQ(SECOND,15,0x80)

 /*
  * Pointers to the low-level handlers: first the general ones, then the
  * fast ones, then the bad ones.
  */
 static void (*interrupt[16])(void) = {
 	IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
 	IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
 	IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
 	IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
 };

 static void (*fast_interrupt[16])(void) = {
 	fast_IRQ0_interrupt, fast_IRQ1_interrupt,
 	fast_IRQ2_interrupt, fast_IRQ3_interrupt,
 	fast_IRQ4_interrupt, fast_IRQ5_interrupt,
 	fast_IRQ6_interrupt, fast_IRQ7_interrupt,
 	fast_IRQ8_interrupt, fast_IRQ9_interrupt,
 	fast_IRQ10_interrupt, fast_IRQ11_interrupt,
 	fast_IRQ12_interrupt, fast_IRQ13_interrupt,
 	fast_IRQ14_interrupt, fast_IRQ15_interrupt
 };

 static void (*bad_interrupt[16])(void) = {
 	bad_IRQ0_interrupt, bad_IRQ1_interrupt,
 	bad_IRQ2_interrupt, bad_IRQ3_interrupt,
 	bad_IRQ4_interrupt, bad_IRQ5_interrupt,
 	bad_IRQ6_interrupt, bad_IRQ7_interrupt,
 	bad_IRQ8_interrupt, bad_IRQ9_interrupt,
 	bad_IRQ10_interrupt, bad_IRQ11_interrupt,
 	bad_IRQ12_interrupt, bad_IRQ13_interrupt,
 	bad_IRQ14_interrupt, bad_IRQ15_interrupt
 };

 /*
  * Initial irq handlers.
  */
 static struct sigaction irq_sigaction[16] = {
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
 	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
 };

 /*
  * do_IRQ handles IRQ's that have been installed without the
  * SA_INTERRUPT flag: it uses the full signal-handling return
  * and runs with other interrupts enabled. All relatively slow
  * IRQ's should use this format: notably the keyboard/timer
  * routines.
  */
 asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
 {
 	struct sigaction * sa = irq + irq_sigaction;

 	sa->sa_handler((int) regs);
 }

 /*
  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
  * stuff - the handler is also running with interrupts disabled unless
  * it explicitly enables them later.
  */
 asmlinkage void do_fast_IRQ(int irq)
 {
 	struct sigaction * sa = irq + irq_sigaction;

 	sa->sa_handler(irq);
 }

 int irqaction(unsigned int irq, struct sigaction * new_sa)
 {
 	struct sigaction * sa;
 	unsigned long flags;

 	if (irq > 15)
 		return -EINVAL;
 	sa = irq + irq_sigaction;
 	if (sa->sa_mask)
 		return -EBUSY;
 	if (!new_sa->sa_handler)
 		return -EINVAL;
 	save_flags(flags);
 	cli();
 	*sa = *new_sa;
 	sa->sa_mask = 1;
 	if (sa->sa_flags & SA_INTERRUPT)
 		set_intr_gate(0x20+irq,fast_interrupt[irq]);
 	else
 		set_intr_gate(0x20+irq,interrupt[irq]);
 	if (irq < 8) {
 		cache_21 &= ~(1<<irq);
 		outb(cache_21,0x21);
 	} else {
 		cache_21 &= ~(1<<2);
 		cache_A1 &= ~(1<<(irq-8));
 		outb(cache_21,0x21);
 		outb(cache_A1,0xA1);
 	}
 	restore_flags(flags);
 	return 0;
 }

 int request_irq(unsigned int irq, void (*handler)(int))
 {
 	struct sigaction sa;

 	sa.sa_handler = handler;
 	sa.sa_flags = 0;
 	sa.sa_mask = 0;
 	sa.sa_restorer = NULL;
 	return irqaction(irq,&sa);
 }

 void free_irq(unsigned int irq)
 {
 	struct sigaction * sa = irq + irq_sigaction;
 	unsigned long flags;

 	if (irq > 15) {
 		printk("Trying to free IRQ%d\n",irq);
 		return;
 	}
 	if (!sa->sa_mask) {
 		printk("Trying to free free IRQ%d\n",irq);
 		return;
 	}
 	save_flags(flags);
 	cli();
 	if (irq < 8) {
 		cache_21 |= 1 << irq;
 		outb(cache_21,0x21);
 	} else {
 		cache_A1 |= 1 << (irq-8);
 		outb(cache_A1,0xA1);
 	}
 	set_intr_gate(0x20+irq,bad_interrupt[irq]);
 	sa->sa_handler = NULL;
 	sa->sa_flags = 0;
 	sa->sa_mask = 0;
 	sa->sa_restorer = NULL;
 	restore_flags(flags);
 }

 /*
  * Note that on a 486, we don't want to do a SIGFPE on a irq13
  * as the irq is unreliable, and exception 16 works correctly
  * (ie as explained in the intel litterature). On a 386, you
  * can't use exception 16 due to bad IBM design, so we have to
  * rely on the less exact irq13.
  *
  * Careful.. Not only is IRQ13 unreliable, but it is also
  * leads to races. IBM designers who came up with it should
  * be shot.
  */
 static void math_error_irq(int cpl)
 {
 	outb(0,0xF0);
 	if (ignore_irq13)
 		return;
 	math_error();
 }

 static void no_action(int cpl) { }

 static struct sigaction ignore_IRQ = {
 	no_action,
 	0,
 	SA_INTERRUPT,
 	NULL
 };

 void init_IRQ(void)
 {
 	int i;

 	for (i = 0; i < 16 ; i++)
 		set_intr_gate(0x20+i,bad_interrupt[i]);
 	if (irqaction(2,&ignore_IRQ))
 		printk("Unable to get IRQ2 for cascade\n");
 	if (request_irq(13,math_error_irq))
 		printk("Unable to get IRQ13 for math-error handler\n");

 	/* intialize the bottom half routines. */
 	for (i = 0; i < 32; i++) {
 		bh_base[i].routine = NULL;
 		bh_base[i].data = NULL;
 	}
 	bh_active = 0;
 	intr_count = 0;
 }
	/*
	* linux/kernel/irq.c
	*
	* Copyright (C) 1992 Linus Torvalds
	*
	* This file contains the code used by various IRQ handling routines:
	* asking for different IRQ's should be done through these routines
	* instead of just grabbing them. Thus setups with different IRQ numbers
	* shouldn't result in any weird surprises, and installing new handlers
	* should be easier.
	*/

	/*
	* IRQ's are in fact implemented a bit like signal handlers for the kernel.
	* The same sigaction struct is used, and with similar semantics (ie there
	* is a SA_INTERRUPT flag etc). Naturally it's not a 1:1 relation, but there
	* are similarities.
	*
	* sa_handler(int irq_NR) is the default function called.
	* sa_mask is 0 if nothing uses this IRQ
	* sa_flags contains various info: SA_INTERRUPT etc
	* sa_restorer is the unused
	*/

	#include <linux/ptrace.h>
	#include <linux/errno.h>
	#include <linux/signal.h>
	#include <linux/sched.h>
	#include <linux/interrupt.h>

	#include <asm/system.h>
	#include <asm/io.h>
	#include <asm/irq.h>

	#define CR0_NE 32

	static unsigned char cache_21 = 0xff;
	static unsigned char cache_A1 = 0xff;

	unsigned long intr_count = 0;
	unsigned long bh_active = 0;
	unsigned long bh_mask = 0xFFFFFFFF;
	struct bh_struct bh_base[32];

	void disable_irq(unsigned int irq_nr)
	{
	unsigned long flags;
	unsigned char mask;

	mask = 1 << (irq_nr & 7);
	save_flags(flags);
	if (irq_nr < 8) {
	cli();
	cache_21 \|= mask;
	outb(cache_21,0x21);
	restore_flags(flags);
	return;
	}
	cli();
	cache_A1 \|= mask;
	outb(cache_A1,0xA1);
	restore_flags(flags);
	}

	void enable_irq(unsigned int irq_nr)
	{
	unsigned long flags;
	unsigned char mask;

	mask = ~(1 << (irq_nr & 7));
	save_flags(flags);
	if (irq_nr < 8) {
	cli();
	cache_21 &= mask;
	outb(cache_21,0x21);
	restore_flags(flags);
	return;
	}
	cli();
	cache_A1 &= mask;
	outb(cache_A1,0xA1);
	restore_flags(flags);
	}

	/*
	* do_bottom_half() runs at normal kernel priority: all interrupts
	* enabled. do_bottom_half() is atomic with respect to itself: a
	* bottom_half handler need not be re-entrant.
	*/
	asmlinkage void do_bottom_half(void)
	{
	unsigned long active;
	unsigned long mask, left;
	struct bh_struct *bh;

	bh = bh_base;
	active = bh_active & bh_mask;
	for (mask = 1, left = ~0 ; left & active ; bh++,mask += mask,left += left) {
	if (mask & active) {
	void (fn)(void );
	bh_active &= ~mask;
	fn = bh->routine;
	if (!fn)
	goto bad_bh;
	fn(bh->data);
	}
	}
	return;
	bad_bh:
	printk ("irq.c:bad bottom half entry\n");
	}

	/*
	* This builds up the IRQ handler stubs using some ugly macros in irq.h
	*
	* These macros create the low-level assembly IRQ routines that do all
	* the operations that are needed to keep the AT interrupt-controller
	* happy. They are also written to be fast - and to disable interrupts
	* as little as humanly possible.
	*
	* NOTE! These macros expand to three different handlers for each line: one
	* complete handler that does all the fancy stuff (including signal handling),
	* and one fast handler that is meant for simple IRQ's that want to be
	* atomic. The specific handler is chosen depending on the SA_INTERRUPT
	* flag when installing a handler. Finally, one "bad interrupt" handler, that
	* is used when no handler is present.
	*/
	BUILD_IRQ(FIRST,0,0x01)
	BUILD_IRQ(FIRST,1,0x02)
	BUILD_IRQ(FIRST,2,0x04)
	BUILD_IRQ(FIRST,3,0x08)
	BUILD_IRQ(FIRST,4,0x10)
	BUILD_IRQ(FIRST,5,0x20)
	BUILD_IRQ(FIRST,6,0x40)
	BUILD_IRQ(FIRST,7,0x80)
	BUILD_IRQ(SECOND,8,0x01)
	BUILD_IRQ(SECOND,9,0x02)
	BUILD_IRQ(SECOND,10,0x04)
	BUILD_IRQ(SECOND,11,0x08)
	BUILD_IRQ(SECOND,12,0x10)
	BUILD_IRQ(SECOND,13,0x20)
	BUILD_IRQ(SECOND,14,0x40)
	BUILD_IRQ(SECOND,15,0x80)

	/*
	* Pointers to the low-level handlers: first the general ones, then the
	* fast ones, then the bad ones.
	*/
	static void (*interrupt[16])(void) = {
	IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
	IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
	IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
	IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
	};

	static void (*fast_interrupt[16])(void) = {
	fast_IRQ0_interrupt, fast_IRQ1_interrupt,
	fast_IRQ2_interrupt, fast_IRQ3_interrupt,
	fast_IRQ4_interrupt, fast_IRQ5_interrupt,
	fast_IRQ6_interrupt, fast_IRQ7_interrupt,
	fast_IRQ8_interrupt, fast_IRQ9_interrupt,
	fast_IRQ10_interrupt, fast_IRQ11_interrupt,
	fast_IRQ12_interrupt, fast_IRQ13_interrupt,
	fast_IRQ14_interrupt, fast_IRQ15_interrupt
	};

	static void (*bad_interrupt[16])(void) = {
	bad_IRQ0_interrupt, bad_IRQ1_interrupt,
	bad_IRQ2_interrupt, bad_IRQ3_interrupt,
	bad_IRQ4_interrupt, bad_IRQ5_interrupt,
	bad_IRQ6_interrupt, bad_IRQ7_interrupt,
	bad_IRQ8_interrupt, bad_IRQ9_interrupt,
	bad_IRQ10_interrupt, bad_IRQ11_interrupt,
	bad_IRQ12_interrupt, bad_IRQ13_interrupt,
	bad_IRQ14_interrupt, bad_IRQ15_interrupt
	};

	/*
	* Initial irq handlers.
	*/
	static struct sigaction irq_sigaction[16] = {
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
	{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
	};

	/*
	* do_IRQ handles IRQ's that have been installed without the
	* SA_INTERRUPT flag: it uses the full signal-handling return
	* and runs with other interrupts enabled. All relatively slow
	* IRQ's should use this format: notably the keyboard/timer
	* routines.
	*/
	asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
	{
	struct sigaction * sa = irq + irq_sigaction;

	sa->sa_handler((int) regs);
	}

	/*
	* do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
	* stuff - the handler is also running with interrupts disabled unless
	* it explicitly enables them later.
	*/
	asmlinkage void do_fast_IRQ(int irq)
	{
	struct sigaction * sa = irq + irq_sigaction;

	sa->sa_handler(irq);
	}

	int irqaction(unsigned int irq, struct sigaction * new_sa)
	{
	struct sigaction * sa;
	unsigned long flags;

	if (irq > 15)
	return -EINVAL;
	sa = irq + irq_sigaction;
	if (sa->sa_mask)
	return -EBUSY;
	if (!new_sa->sa_handler)
	return -EINVAL;
	save_flags(flags);
	cli();
	sa = new_sa;
	sa->sa_mask = 1;
	if (sa->sa_flags & SA_INTERRUPT)
	set_intr_gate(0x20+irq,fast_interrupt[irq]);
	else
	set_intr_gate(0x20+irq,interrupt[irq]);
	if (irq < 8) {
	cache_21 &= ~(1<<irq);
	outb(cache_21,0x21);
	} else {
	cache_21 &= ~(1<<2);
	cache_A1 &= ~(1<<(irq-8));
	outb(cache_21,0x21);
	outb(cache_A1,0xA1);
	}
	restore_flags(flags);
	return 0;
	}

	int request_irq(unsigned int irq, void (*handler)(int))
	{
	struct sigaction sa;

	sa.sa_handler = handler;
	sa.sa_flags = 0;
	sa.sa_mask = 0;
	sa.sa_restorer = NULL;
	return irqaction(irq,&sa);
	}

	void free_irq(unsigned int irq)
	{
	struct sigaction * sa = irq + irq_sigaction;
	unsigned long flags;

	if (irq > 15) {
	printk("Trying to free IRQ%d\n",irq);
	return;
	}
	if (!sa->sa_mask) {
	printk("Trying to free free IRQ%d\n",irq);
	return;
	}
	save_flags(flags);
	cli();
	if (irq < 8) {
	cache_21 \|= 1 << irq;
	outb(cache_21,0x21);
	} else {
	cache_A1 \|= 1 << (irq-8);
	outb(cache_A1,0xA1);
	}
	set_intr_gate(0x20+irq,bad_interrupt[irq]);
	sa->sa_handler = NULL;
	sa->sa_flags = 0;
	sa->sa_mask = 0;
	sa->sa_restorer = NULL;
	restore_flags(flags);
	}

	/*
	* Note that on a 486, we don't want to do a SIGFPE on a irq13
	* as the irq is unreliable, and exception 16 works correctly
	* (ie as explained in the intel litterature). On a 386, you
	* can't use exception 16 due to bad IBM design, so we have to
	* rely on the less exact irq13.
	*
	* Careful.. Not only is IRQ13 unreliable, but it is also
	* leads to races. IBM designers who came up with it should
	* be shot.
	*/
	static void math_error_irq(int cpl)
	{
	outb(0,0xF0);
	if (ignore_irq13)
	return;
	math_error();
	}

	static void no_action(int cpl) { }

	static struct sigaction ignore_IRQ = {
	no_action,
	0,
	SA_INTERRUPT,
	NULL
	};

	void init_IRQ(void)
	{
	int i;

	for (i = 0; i < 16 ; i++)
	set_intr_gate(0x20+i,bad_interrupt[i]);
	if (irqaction(2,&ignore_IRQ))
	printk("Unable to get IRQ2 for cascade\n");
	if (request_irq(13,math_error_irq))
	printk("Unable to get IRQ13 for math-error handler\n");

	/* intialize the bottom half routines. */
	for (i = 0; i < 32; i++) {
	bh_base[i].routine = NULL;
	bh_base[i].data = NULL;
	}
	bh_active = 0;
	intr_count = 0;
	}