参照元†
- unsigned int irq
- struct irq_desc *desc
- struct irqaction *new
返り値†
/*
* Internal function to register an irqaction - typically used to
* allocate special interrupts that are part of the architecture.
*/
static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
struct irqaction *old, **old_ptr;
const char *old_name = NULL;
unsigned long flags;
int nested, shared = 0;
int ret;
if (!desc)
return -EINVAL;
if (desc->chip == &no_irq_chip)
return -ENOSYS;
/*
* Some drivers like serial.c use request_irq() heavily,
* so we have to be careful not to interfere with a
* running system.
*/
if (new->flags & IRQF_SAMPLE_RANDOM) {
/*
* This function might sleep, we want to call it first,
* outside of the atomic block.
* Yes, this might clear the entropy pool if the wrong
* driver is attempted to be loaded, without actually
* installing a new handler, but is this really a problem,
* only the sysadmin is able to do this.
*/
rand_initialize_irq(irq);
}
/* Oneshot interrupts are not allowed with shared */
if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
return -EINVAL;
/*
* Check whether the interrupt nests into another interrupt
* thread.
*/
nested = desc->status & IRQ_NESTED_THREAD;
if (nested) {
if (!new->thread_fn)
return -EINVAL;
/*
* Replace the primary handler which was provided from
* the driver for non nested interrupt handling by the
* dummy function which warns when called.
*/
new->handler = irq_nested_primary_handler;
}
/*
* Create a handler thread when a thread function is supplied
* and the interrupt does not nest into another interrupt
* thread.
*/
if (new->thread_fn && !nested) {
struct task_struct *t;
t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
new->name);
if (IS_ERR(t))
return PTR_ERR(t);
/*
* We keep the reference to the task struct even if
* the thread dies to avoid that the interrupt code
* references an already freed task_struct.
*/
get_task_struct(t);
new->thread = t;
}
/*
* The following block of code has to be executed atomically
*/
raw_spin_lock_irqsave(&desc->lock, flags);
old_ptr = &desc->action;
old = *old_ptr;
if (old) {
/*
* Can't share interrupts unless both agree to and are
* the same type (level, edge, polarity). So both flag
* fields must have IRQF_SHARED set and the bits which
* set the trigger type must match.
*/
if (!((old->flags & new->flags) & IRQF_SHARED) ||
((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
old_name = old->name;
goto mismatch;
}
#if defined(CONFIG_IRQ_PER_CPU)
/* All handlers must agree on per-cpuness */
if ((old->flags & IRQF_PERCPU) !=
(new->flags & IRQF_PERCPU))
goto mismatch;
#endif
/* add new interrupt at end of irq queue */
do {
old_ptr = &old->next;
old = *old_ptr;
} while (old);
shared = 1;
}
if (!shared) {
irq_chip_set_defaults(desc->chip);
init_waitqueue_head(&desc->wait_for_threads);
/* Setup the type (level, edge polarity) if configured: */
if (new->flags & IRQF_TRIGGER_MASK) {
ret = __irq_set_trigger(desc, irq,
new->flags & IRQF_TRIGGER_MASK);
if (ret)
goto out_thread;
} else
compat_irq_chip_set_default_handler(desc);
#if defined(CONFIG_IRQ_PER_CPU)
if (new->flags & IRQF_PERCPU)
desc->status |= IRQ_PER_CPU;
#endif
desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
if (new->flags & IRQF_ONESHOT)
desc->status |= IRQ_ONESHOT;
if (!(desc->status & IRQ_NOAUTOEN)) {
desc->depth = 0;
desc->status &= ~IRQ_DISABLED;
desc->chip->startup(irq);
} else
/* Undo nested disables: */
desc->depth = 1;
/* Exclude IRQ from balancing if requested */
if (new->flags & IRQF_NOBALANCING)
desc->status |= IRQ_NO_BALANCING;
/* Set default affinity mask once everything is setup */
setup_affinity(irq, desc);
} else if ((new->flags & IRQF_TRIGGER_MASK)
&& (new->flags & IRQF_TRIGGER_MASK)
!= (desc->status & IRQ_TYPE_SENSE_MASK)) {
/* hope the handler works with the actual trigger mode... */
pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
(int)(new->flags & IRQF_TRIGGER_MASK));
}
new->irq = irq;
*old_ptr = new;
/* Reset broken irq detection when installing new handler */
desc->irq_count = 0;
desc->irqs_unhandled = 0;
/*
* Check whether we disabled the irq via the spurious handler
* before. Reenable it and give it another chance.
*/
if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
desc->status &= ~IRQ_SPURIOUS_DISABLED;
__enable_irq(desc, irq, false);
}
raw_spin_unlock_irqrestore(&desc->lock, flags);
/*
* Strictly no need to wake it up, but hung_task complains
* when no hard interrupt wakes the thread up.
*/
if (new->thread)
wake_up_process(new->thread);
register_irq_proc(irq, desc);
new->dir = NULL;
register_handler_proc(irq, new);
return 0;
mismatch:
#ifdef CONFIG_DEBUG_SHIRQ
if (!(new->flags & IRQF_PROBE_SHARED)) {
printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
if (old_name)
printk(KERN_ERR "current handler: %s\n", old_name);
dump_stack();
}
#endif
ret = -EBUSY;
out_thread:
raw_spin_unlock_irqrestore(&desc->lock, flags);
if (new->thread) {
struct task_struct *t = new->thread;
new->thread = NULL;
if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
kthread_stop(t);
put_task_struct(t);
}
return ret;
}
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