irq.c

讲述linux的初始化过程

	__save_flags(flags);

	if ((flags & PSR_PIL) != PSR_PIL)
		local_enabled = 1;

	/* default to local */
	retval = 2 + local_enabled;

	/* check for global flags if we're not in an interrupt */
	if (!local_irq_count(smp_processor_id())) {
		if (local_enabled)
			retval = 1;
		if (global_irq_holder == (unsigned char) smp_processor_id())
			retval = 0;
	}
	return retval;
}

void __global_restore_flags(unsigned long flags)
{
	switch (flags) {
	case 0:
		__global_cli();
		break;
	case 1:
		__global_sti();
		break;
	case 2:
		__cli();
		break;
	case 3:
		__sti();
		break;
	default:
	{
		unsigned long pc;
		__asm__ __volatile__("mov %%i7, %0" : "=r" (pc));
		printk("global_restore_flags: Bogon flags(%08lx) caller %08lx\n", flags, pc);
	}
	}
}

#endif /* CONFIG_SMP */

void unexpected_irq(int irq, void *dev_id, struct pt_regs * regs)
{
        int i;
	struct irqaction * action;
	unsigned int cpu_irq;
	
	cpu_irq = irq & NR_IRQS;
	action = *(cpu_irq + irq_action);

        printk("IO device interrupt, irq = %d\n", irq);
        printk("PC = %08lx NPC = %08lx FP=%08lx\n", regs->pc, 
		    regs->npc, regs->u_regs[14]);
	if (action) {
		printk("Expecting: ");
        	for (i = 0; i < 16; i++)
                	if (action->handler)
                        	prom_printf("[%s:%d:0x%x] ", action->name,
				    (int) i, (unsigned int) action->handler);
	}
        printk("AIEEE\n");
	panic("bogus interrupt received");
}

void handler_irq(int irq, struct pt_regs * regs)
{
	struct irqaction * action;
	int cpu = smp_processor_id();
#ifdef CONFIG_SMP
	extern void smp4m_irq_rotate(int cpu);
#endif

	irq_enter(cpu, irq);
	disable_pil_irq(irq);
#ifdef CONFIG_SMP
	/* Only rotate on lower priority IRQ's (scsi, ethernet, etc.). */
	if(irq < 10)
		smp4m_irq_rotate(cpu);
#endif
	action = *(irq + irq_action);
	kstat.irqs[cpu][irq]++;
	do {
		if (!action || !action->handler)
			unexpected_irq(irq, 0, regs);
		action->handler(irq, action->dev_id, regs);
		action = action->next;
	} while (action);
	enable_pil_irq(irq);
	irq_exit(cpu, irq);
}

#ifdef CONFIG_BLK_DEV_FD
extern void floppy_interrupt(int irq, void *dev_id, struct pt_regs *regs);

void sparc_floppy_irq(int irq, void *dev_id, struct pt_regs *regs)
{
	int cpu = smp_processor_id();

	disable_pil_irq(irq);
	irq_enter(cpu, irq);
	kstat.irqs[cpu][irq]++;
	floppy_interrupt(irq, dev_id, regs);
	irq_exit(cpu, irq);
	enable_pil_irq(irq);
}
#endif

/* Fast IRQ's on the Sparc can only have one routine attached to them,
 * thus no sharing possible.
 */
int request_fast_irq(unsigned int irq,
		     void (*handler)(int, void *, struct pt_regs *),
		     unsigned long irqflags, const char *devname)
{
	struct irqaction *action;
	unsigned long flags;
	unsigned int cpu_irq;
#ifdef CONFIG_SMP
	struct tt_entry *trap_table;
	extern struct tt_entry trapbase_cpu1, trapbase_cpu2, trapbase_cpu3;
#endif
	
	cpu_irq = irq & NR_IRQS;
	if(cpu_irq > 14)
		return -EINVAL;
	if(!handler)
		return -EINVAL;
	action = *(cpu_irq + irq_action);
	if(action) {
		if(action->flags & SA_SHIRQ)
			panic("Trying to register fast irq when already shared.\n");
		if(irqflags & SA_SHIRQ)
			panic("Trying to register fast irq as shared.\n");

		/* Anyway, someone already owns it so cannot be made fast. */
		printk("request_fast_irq: Trying to register yet already owned.\n");
		return -EBUSY;
	}

	save_and_cli(flags);

	/* If this is flagged as statically allocated then we use our
	 * private struct which is never freed.
	 */
	if (irqflags & SA_STATIC_ALLOC) {
	    if (static_irq_count < MAX_STATIC_ALLOC)
		action = &static_irqaction[static_irq_count++];
	    else
		printk("Fast IRQ%d (%s) SA_STATIC_ALLOC failed using kmalloc\n",
		       irq, devname);
	}
	
	if (action == NULL)
	    action = (struct irqaction *)kmalloc(sizeof(struct irqaction),
						 GFP_KERNEL);
	
	if (!action) { 
		restore_flags(flags);
		return -ENOMEM;
	}

	/* Dork with trap table if we get this far. */
#define INSTANTIATE(table) \
	table[SP_TRAP_IRQ1+(cpu_irq-1)].inst_one = SPARC_RD_PSR_L0; \
	table[SP_TRAP_IRQ1+(cpu_irq-1)].inst_two = \
		SPARC_BRANCH((unsigned long) handler, \
			     (unsigned long) &table[SP_TRAP_IRQ1+(cpu_irq-1)].inst_two);\
	table[SP_TRAP_IRQ1+(cpu_irq-1)].inst_three = SPARC_RD_WIM_L3; \
	table[SP_TRAP_IRQ1+(cpu_irq-1)].inst_four = SPARC_NOP;

	INSTANTIATE(sparc_ttable)
#ifdef CONFIG_SMP
	trap_table = &trapbase_cpu1; INSTANTIATE(trap_table)
	trap_table = &trapbase_cpu2; INSTANTIATE(trap_table)
	trap_table = &trapbase_cpu3; INSTANTIATE(trap_table)
#endif
#undef INSTANTIATE
	/*
	 * XXX Correct thing whould be to flush only I- and D-cache lines
	 * which contain the handler in question. But as of time of the
	 * writing we have no CPU-neutral interface to fine-grained flushes.
	 */
	flush_cache_all();

	action->handler = handler;
	action->flags = irqflags;
	action->mask = 0;
	action->name = devname;
	action->dev_id = NULL;
	action->next = NULL;

	*(cpu_irq + irq_action) = action;

	enable_irq(irq);
	restore_flags(flags);
	return 0;
}

int request_irq(unsigned int irq,
		void (*handler)(int, void *, struct pt_regs *),
		unsigned long irqflags, const char * devname, void *dev_id)
{
	struct irqaction * action, *tmp = NULL;
	unsigned long flags;
	unsigned int cpu_irq;
	
	if (sparc_cpu_model == sun4d) {
		extern int sun4d_request_irq(unsigned int, 
					     void (*)(int, void *, struct pt_regs *),
					     unsigned long, const char *, void *);
		return sun4d_request_irq(irq, handler, irqflags, devname, dev_id);
	}
	cpu_irq = irq & NR_IRQS;
	if(cpu_irq > 14)
		return -EINVAL;

	if (!handler)
	    return -EINVAL;
	    
	action = *(cpu_irq + irq_action);
	if (action) {
		if ((action->flags & SA_SHIRQ) && (irqflags & SA_SHIRQ)) {
			for (tmp = action; tmp->next; tmp = tmp->next);
		} else {
			return -EBUSY;
		}
		if ((action->flags & SA_INTERRUPT) ^ (irqflags & SA_INTERRUPT)) {
			printk("Attempt to mix fast and slow interrupts on IRQ%d denied\n", irq);
			return -EBUSY;
		}   
		action = NULL;		/* Or else! */
	}

	save_and_cli(flags);

	/* If this is flagged as statically allocated then we use our
	 * private struct which is never freed.
	 */
	if (irqflags & SA_STATIC_ALLOC) {
	    if (static_irq_count < MAX_STATIC_ALLOC)
		action = &static_irqaction[static_irq_count++];
	    else
		printk("Request for IRQ%d (%s) SA_STATIC_ALLOC failed using kmalloc\n",irq, devname);
	}
	
	if (action == NULL)
	    action = (struct irqaction *)kmalloc(sizeof(struct irqaction),
						 GFP_KERNEL);
	
	if (!action) { 
		restore_flags(flags);
		return -ENOMEM;
	}

	action->handler = handler;
	action->flags = irqflags;
	action->mask = 0;
	action->name = devname;
	action->next = NULL;
	action->dev_id = dev_id;

	if (tmp)
		tmp->next = action;
	else
		*(cpu_irq + irq_action) = action;

	enable_irq(irq);
	restore_flags(flags);
	return 0;
}

/* We really don't need these at all on the Sparc.  We only have
 * stubs here because they are exported to modules.
 */
unsigned long probe_irq_on(void)
{
	return 0;
}

int probe_irq_off(unsigned long mask)
{
	return 0;
}

/* djhr
 * This could probably be made indirect too and assigned in the CPU
 * bits of the code. That would be much nicer I think and would also
 * fit in with the idea of being able to tune your kernel for your machine
 * by removing unrequired machine and device support.
 *
 */

void __init init_IRQ(void)
{
	extern void sun4c_init_IRQ( void );
	extern void sun4m_init_IRQ( void );
	extern void sun4d_init_IRQ( void );
    
	switch(sparc_cpu_model) {
	case sun4c:
	case sun4:
		sun4c_init_IRQ();
		break;

	case sun4m:
#ifdef CONFIG_PCI
		pcic_probe();
		if (pcic_present()) {
			sun4m_pci_init_IRQ();
			break;
		}
#endif
		sun4m_init_IRQ();
		break;
		
	case sun4d:
		sun4d_init_IRQ();
		break;

	default:
		prom_printf("Cannot initialize IRQ's on this Sun machine...");
		break;
	}
	btfixup();
}

void init_irq_proc(void)
{
	/* For now, nothing... */
}