中断注册
request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn,
unsigned long flags, const char *name, void *dev);
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
{
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
在驱动程序中，要想使设备能够产生中断，则首先需要调用request_irq()来分配中断线。在通过request_irq()函数注册中断服务程序的时候，将会把设备中断处理程序添加进系统，以在中断发生的时候调用相应的中断处理程序。用户驱动程序通过request_irq函数向内核注册中断处理函数，request_irq函数根据中断号找到irq_desc数组项，然后在它的 action链表添加一个表项。
在kernel/irq/manage.c中
/**
*request_threaded_irq - allocate an interrupt line
*@irq: Interrupt line to allocate
*@handler: Function to be called when the IRQ occurs.
* Primary handler for threaded interrupts
* If NULL and thread_fn != NULL the default
* primary handler is installed
*@thread_fn: Function called from the irq handler thread
* If NULL, no irq thread is created
*@irqflags: Interrupt type flags
*@devname: An ascii name for the claiming device
*@dev_id: A cookie passed back to the handler function
*
*This call allocates interrupt resources and enables the
*interrupt line and IRQ handling. From the point this
*call is made your handler function may be invoked. Since
*your handler function must clear any interrupt the board
*raises, you must take care both to initialise your hardware
*and to set up the interrupt handler in the right order.
*
*If you want to set up a threaded irq handler for your device
*then you need to supply @handler and @thread_fn. @handler ist
*still called in hard interrupt context and has to check
*whether the interrupt originates from the device. If yes it
*needs to disable the interrupt on the device and return
*IRQ_WAKE_THREAD which will wake up the handler thread and run
*@thread_fn. This split handler design is necessary to support
*shared interrupts.
*
*Dev_id must be globally unique. Normally the address of the
*device data structure is used as the cookie. Since the handler
*receives this value it makes sense to use it.
*
*If your interrupt is shared you must pass a non NULL dev_id
*as this is required when freeing the interrupt.
*
*Flags:
*
*IRQF_SHAREDInterrupt is shared
*IRQF_SAMPLE_RANDOMThe interrupt can be used for entropy
*IRQF_TRIGGER_*Specify active edge(s) or level
*
*/
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id)
{
struct irqaction *action;
struct irq_desc *desc;
int retval;
/*
* Sanity-check: shared interrupts must pass in a real dev-ID,
* otherwise we'll have trouble later trying to figure out
* which interrupt is which (messes up the interrupt freeing
* logic etc).
*/
if ((irqflags & IRQF_SHARED) && !dev_id)
return -EINVAL;
desc = irq_to_desc(irq);
if (!desc)
return -EINVAL;
if (desc->status & IRQ_NOREQUEST)
return -EINVAL;
if (!handler) {
if (!thread_fn)
return -EINVAL;
handler = irq_default_primary_handler;
}
action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
if (!action)
return -ENOMEM;
action->handler = handler;
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
chip_bus_lock(irq, desc);
retval = __setup_irq(irq, desc, action);
chip_bus_sync_unlock(irq, desc);
if (retval)
kfree(action);
#ifdef CONFIG_DEBUG_SHIRQ
if (!retval && (irqflags & IRQF_SHARED)) {
/*
* It's a shared IRQ -- the driver ought to be prepared for it
* to happen immediately, so let's make sure....
* We disable the irq to make sure that a 'real' IRQ doesn't
* run in parallel with our fake.
*/
unsigned long flags;
disable_irq(irq);
local_irq_save(flags);
handler(irq, dev_id);
local_irq_restore(flags);
enable_irq(irq);
}
#endif
return retval;
}
EXPORT_SYMBOL(request_threaded_irq);
申请的中毒在这里分配
retval = __setup_irq(irq, desc, action);将分配的struct irqaction *action;加入链表
也在该文件中,
/*
* 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;
}
中断的顶半部和底半部
顶半部即
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
底半部分为:
1.tasklet
实例:
02 |
void test_tasklet_action(unsigned long t);
|
03 |
DECLARE_TASKLET(test_tasklet, test_tasklet_action, 0);
|
05 |
void test_tasklet_action(unsigned long t)
|
07 |
printk("tasklet is executing\n");
|
12 |
static irqreturn_t xxx_interrupt(int irq, void *dev_id)
|
15 |
tasklet_schedule(&test_tasklet);
|
21 |
int __init xxx_init(void)
|
24 |
request_irq(IRQ_EINT0,xxx_interrupt, IRQ_TYPE_LEVEL_LOW, "xxx", NULL);
|
30 |
void __exit xxx_exit(void)
|
2.work queue
实例:
01 |
struct work_struct my_wq;
|
03 |
void my_wq_func(unsigned long);
|
06 |
void my_wq_func(unsigned long t)
|
13 |
static irqreturn_t xxx_interrupt(int irq, void *dev_id)
|
16 |
schedule_work(& my_wq);
|
23 |
int __init xxx_init(void)
|
26 |
request_irq(IRQ_EINT0,xxx_interrupt, IRQ_TYPE_LEVEL_LOW, "xxx", NULL);
|
27 |
INIT_WORK(&my_wq,(void (*)(void*))my_wq_func,NULL);
|
33 |
void __exit xxx_exit(void)
|
