irq.c

linux-2.4.29操作系统的源码

			spin_unlock_irqrestore(&desc->lock,flags);
			return -EBUSY;
		}

		/* add new interrupt at end of irq queue */
		do {
			p = &old->next;
			old = *p;
		} while (old);
		shared = 1;
	}

	*p = new;

	if (!shared) {
		desc->depth = 0;
		desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING);
		unmask_irq(irq);
	}
	spin_unlock_irqrestore(&desc->lock,flags);

	register_irq_proc(irq);
	return 0;
}

/* This could be promoted to a real free_irq() ... */
static int
do_free_irq(int irq, void* dev_id)
{
	irq_desc_t *desc = irqdesc(irq);
	struct irqaction **p;
	unsigned long flags;

	spin_lock_irqsave(&desc->lock,flags);
	p = &desc->action;
	for (;;) {
		struct irqaction * action = *p;
		if (action) {
			struct irqaction **pp = p;
			p = &action->next;
			if (action->dev_id != dev_id)
				continue;

			/* Found it - now remove it from the list of entries */
			*pp = action->next;
			if (!desc->action) {
				desc->status |= IRQ_DISABLED;
				mask_irq(irq);
			}
			spin_unlock_irqrestore(&desc->lock,flags);

#ifdef CONFIG_SMP
			/* Wait to make sure it's not being used on another CPU */
			while (desc->status & IRQ_INPROGRESS)
				barrier();
#endif
			irq_kfree(action);
			return 0;
		}
		printk("Trying to free free IRQ%d\n",irq);
		spin_unlock_irqrestore(&desc->lock,flags);
		break;
	}
	return -ENOENT;
}

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;
	int retval;

	if (irq >= MAX_IRQS)
		return -EINVAL;

	if (!handler)
		/* We could implement really free_irq() instead of that... */
		return do_free_irq(irq, dev_id);
	
	action = (struct irqaction *)
		irq_kmalloc(sizeof(struct irqaction), GFP_KERNEL);
	if (!action) {
		printk(KERN_ERR "irq_kmalloc() failed for irq %d !\n", irq);
		return -ENOMEM;
	}
	
	action->handler = handler;
	action->flags = irqflags;					
	action->mask = 0;
	action->name = devname;
	action->dev_id = dev_id;
	action->next = NULL;
	
	retval = setup_irq(irq, action);
	if (retval)
		kfree(action);
		
	return 0;
}

void free_irq(unsigned int irq, void *dev_id)
{
	request_irq(irq, NULL, 0, NULL, dev_id);
}

/*
 * Generic enable/disable code: this just calls
 * down into the PIC-specific version for the actual
 * hardware disable after having gotten the irq
 * controller lock. 
 */
 
/**
 *	disable_irq_nosync - disable an irq without waiting
 *	@irq: Interrupt to disable
 *
 *	Disable the selected interrupt line. Disables of an interrupt
 *	stack. Unlike disable_irq(), this function does not ensure existing
 *	instances of the IRQ handler have completed before returning.
 *
 *	This function may be called from IRQ context.
 */
 
 void disable_irq_nosync(unsigned int irq)
{
	irq_desc_t *desc = irqdesc(irq);
	unsigned long flags;

	spin_lock_irqsave(&desc->lock, flags);
	if (!desc->depth++) {
		if (!(desc->status & IRQ_PER_CPU))
			desc->status |= IRQ_DISABLED;
		mask_irq(irq);
	}
	spin_unlock_irqrestore(&desc->lock, flags);
}

/**
 *	disable_irq - disable an irq and wait for completion
 *	@irq: Interrupt to disable
 *
 *	Disable the selected interrupt line. Disables of an interrupt
 *	stack. That is for two disables you need two enables. This
 *	function waits for any pending IRQ handlers for this interrupt
 *	to complete before returning. If you use this function while
 *	holding a resource the IRQ handler may need you will deadlock.
 *
 *	This function may be called - with care - from IRQ context.
 */
 
void disable_irq(unsigned int irq)
{
	disable_irq_nosync(irq);

	if (!local_irq_count(smp_processor_id())) {
		do {
			barrier();
		} while (irqdesc(irq)->status & IRQ_INPROGRESS);
	}
}

/**
 *	enable_irq - enable interrupt handling on an irq
 *	@irq: Interrupt to enable
 *
 *	Re-enables the processing of interrupts on this IRQ line
 *	providing no disable_irq calls are now in effect.
 *
 *	This function may be called from IRQ context.
 */
 
void enable_irq(unsigned int irq)
{
	irq_desc_t *desc = irqdesc(irq);
	unsigned long flags;

	spin_lock_irqsave(&desc->lock, flags);
	switch (desc->depth) {
	case 1: {
		unsigned int status = desc->status & ~IRQ_DISABLED;
		desc->status = status;
		if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
			desc->status = status | IRQ_REPLAY;
			hw_resend_irq(desc->handler,irq);
		}
		unmask_irq(irq);
		/* fall-through */
	}
	default:
		desc->depth--;
		break;
	case 0:
		printk("enable_irq(%u) unbalanced\n", irq);
	}
	spin_unlock_irqrestore(&desc->lock, flags);
}

/* This function as implemented was a potential source of data
 * corruption.  I pulled it for now, until it can be properly
 * implemented. DRENG
 */
int get_irq_list(char *buf)
{
	return(0);
}

int show_interrupts(struct seq_file *p, void *v)
{
	int i, j;
	struct irqaction * action;
	irq_desc_t *desc;
	struct hw_irq_stat *hwstat;
	unsigned long *per_cpus;
	unsigned long flags;

	seq_printf(p, "           ");
	for (j=0; j<smp_num_cpus; j++)
		seq_printf(p, "CPU%d       ",j);
	seq_putc(p, '\n');

	for_each_irq(i) {
		desc = irqdesc(i);
		spin_lock_irqsave(&desc->lock, flags);
		action = desc->action;

		if (!action || !action->handler)
			goto skip;
		seq_printf(p, "%3d: ", i);
		hwstat = get_irq_stat(desc);
		per_cpus = get_irq_per_cpu(hwstat);
		if (per_cpus) {
		for (j = 0; j < smp_num_cpus; j++)
				seq_printf(p, "%10lu ", per_cpus[j]);
		} else {
			seq_printf(p, "%10lu ", hwstat->irqs);
		}

		if (irqdesc(i)->handler)
			seq_printf(p, " %s ", irqdesc(i)->handler->typename );
		else
			seq_printf(p, "  None      ");
		seq_printf(p, "%s", (irqdesc(i)->status & IRQ_LEVEL) ? "Level " : "Edge  ");
		seq_printf(p, "    %s",action->name);
		for (action=action->next; action; action = action->next)
			seq_printf(p, ", %s", action->name);
		seq_putc(p, '\n');
skip:
		spin_unlock_irqrestore(&desc->lock, flags);
	}
#ifdef CONFIG_SMP
	/* should this be per processor send/receive? */
	seq_printf(p, "IPI (recv/sent): %10u/%u\n",
		       atomic_read(&ipi_recv), atomic_read(&ipi_sent));
#endif		
	seq_printf(p, "BAD: %10u\n", ppc_spurious_interrupts);
	return 0;
}

static inline void
handle_irq_event(int irq, struct pt_regs *regs, struct irqaction *action)
{
	int status = 0;

	if (!(action->flags & SA_INTERRUPT))
		__sti();

	do {
		status |= action->flags;
		action->handler(irq, action->dev_id, regs);
		action = action->next;
	} while (action);
	if (status & SA_SAMPLE_RANDOM)
		add_interrupt_randomness(irq);
	__cli();
}

/*
 * Eventually, this should take an array of interrupts and an array size
 * so it can dispatch multiple interrupts.
 */
void ppc_irq_dispatch_handler(struct pt_regs *regs, int irq)
{
	int status;
	struct irqaction *action;
	int cpu = smp_processor_id();
	irq_desc_t *desc = irqdesc(irq);
	struct hw_irq_stat *hwstat;
	unsigned long *per_cpus;

	/* Statistics. */
	hwstat = get_irq_stat(desc);	/* same cache line as desc */
	hwstat->irqs++;
	per_cpus = get_irq_per_cpu(hwstat); /* same cache line for < 8 cpus */
	if (per_cpus)
		per_cpus[cpu]++;

	if(irq < NR_IRQS) {
	kstat.irqs[cpu][irq]++;
	} else {
		kstat.irqs[cpu][NR_IRQS-1]++;
	}


	spin_lock(&desc->lock);
	ack_irq(irq);	
	/*
	   REPLAY is when Linux resends an IRQ that was dropped earlier
	   WAITING is used by probe to mark irqs that are being tested
	   */
	status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
	if (!(status & IRQ_PER_CPU))
		status |= IRQ_PENDING; /* we _want_ to handle it */

	/*
	 * If the IRQ is disabled for whatever reason, we cannot
	 * use the action we have.
	 */
	action = NULL;
	if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
		action = desc->action;
		if (!action || !action->handler) {
			ppc_spurious_interrupts++;
			printk(KERN_DEBUG "Unhandled interrupt %x, disabled\n", irq);
			/* We can't call disable_irq here, it would deadlock */
			if (!desc->depth)
				desc->depth = 1;
			desc->status |= IRQ_DISABLED;
			/* This is not a real spurrious interrupt, we
			 * have to eoi it, so we jump to out
			 */
			mask_irq(irq);
			goto out;
		}
		status &= ~IRQ_PENDING; /* we commit to handling */
		if (!(status & IRQ_PER_CPU))
			status |= IRQ_INPROGRESS; /* we are handling it */
	}
	desc->status = status;

	/*
	 * If there is no IRQ handler or it was disabled, exit early.
	   Since we set PENDING, if another processor is handling
	   a different instance of this same irq, the other processor
	   will take care of it.
	 */
	if (!action)
		goto out;


	/*
	 * Edge triggered interrupts need to remember
	 * pending events.
	 * This applies to any hw interrupts that allow a second
	 * instance of the same irq to arrive while we are in do_IRQ
	 * or in the handler. But the code here only handles the _second_
	 * instance of the irq, not the third or fourth. So it is mostly
	 * useful for irq hardware that does not mask cleanly in an
	 * SMP environment.
	 */
	for (;;) {
		spin_unlock(&desc->lock);
		handle_irq_event(irq, regs, action);
		spin_lock(&desc->lock);
		
		if (!(desc->status & IRQ_PENDING))
			break;
		desc->status &= ~IRQ_PENDING;
	}
	desc->status &= ~IRQ_INPROGRESS;
out:
	/*
	 * The ->end() handler has to deal with interrupts which got
	 * disabled while the handler was running.
	 */
	if (desc->handler) {
		if (desc->handler->end)
			desc->handler->end(irq);
		else if (desc->handler->enable)
			desc->handler->enable(irq);
	}
	spin_unlock(&desc->lock);
}

int do_IRQ(struct pt_regs *regs)
{
	int cpu = smp_processor_id();
	int irq, first = 1;
#ifdef CONFIG_PPC_ISERIES
	struct paca_struct *lpaca;
	struct ItLpQueue *lpq;
#endif

	irq_enter(cpu);

#ifdef CONFIG_PPC_ISERIES
	lpaca = get_paca();
#ifdef CONFIG_SMP
	if (lpaca->xLpPaca.xIntDword.xFields.xIpiCnt) {
		lpaca->xLpPaca.xIntDword.xFields.xIpiCnt = 0;
		iSeries_smp_message_recv(regs);
	}
#endif /* CONFIG_SMP */
	lpq = lpaca->lpQueuePtr;
	if (lpq && ItLpQueue_isLpIntPending(lpq))
		lpEvent_count += ItLpQueue_process(lpq, regs);
#else
	/*
	 * Every arch is required to implement ppc_md.get_irq.
	 * This function will either return an irq number or -1 to
	 * indicate there are no more pending.  But the first time
	 * through the loop this means there wasn't an IRQ pending.
	 * The value -2 is for buggy hardware and means that this IRQ
	 * has already been handled. -- Tom
	 */
	while ((irq = ppc_md.get_irq(regs)) >= 0) {
		ppc_irq_dispatch_handler(regs, irq);
		first = 0;
	}