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genirq: Add oneshot support

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For threaded interrupt handlers we expect the hard interrupt handler
part to mask the interrupt on the originating device. The interrupt
line itself is reenabled after the hard interrupt handler has
executed.

This requires access to the originating device from hard interrupt
context which is not always possible. There are devices which can only
be accessed via a bus (i2c, spi, ...). The bus access requires thread
context. For such devices we need to keep the interrupt line masked
until the threaded handler has executed.

Add a new flag IRQF_ONESHOT which allows drivers to request that the
interrupt is not unmasked after the hard interrupt context handler has
been executed and the thread has been woken. The interrupt line is
unmasked after the thread handler function has been executed.

Note that for now IRQF_ONESHOT cannot be used with IRQF_SHARED to
avoid complex accounting mechanisms.

For oneshot interrupts the primary handler simply returns
IRQ_WAKE_THREAD and does nothing else. A generic implementation
irq_default_primary_handler() is provided to avoid useless copies all
over the place. It is automatically installed when
request_threaded_irq() is called with handler=NULL and
thread_fn!=NULL.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Trilok Soni <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: Brian Swetland <[email protected]>
Cc: Joonyoung Shim <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected],
Cc: David Brownell <[email protected]>
Cc: Daniel Ribeiro <[email protected]>
Cc: [email protected]
Cc: Barry Song <[email protected]>
This commit is contained in:
Thomas Gleixner 2009-08-13 12:17:22 +02:00
commit b25c340c19
4 changed files with 61 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

14
kernel/irq/chip.c
View file

@ -382,7 +382,10 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc)
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
if (unlikely(desc->status & IRQ_ONESHOT))
desc->status |= IRQ_MASKED;
else if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
out_unlock:
spin_unlock(&desc->lock);
@ -478,8 +481,13 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
kstat_incr_irqs_this_cpu(irq, desc);
/* Start handling the irq */
if (desc->chip->ack)
desc->chip->ack(irq);
if (unlikely(desc->status & IRQ_ONESHOT)) {
desc->status |= IRQ_MASKED;
mask_ack_irq(desc, irq);
} else {
if (desc->chip->ack)
desc->chip->ack(irq);
}
/* Mark the IRQ currently in progress.*/
desc->status |= IRQ_INPROGRESS;

49
kernel/irq/manage.c
View file

@ -436,6 +436,16 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
return ret;
}
/*
* Default primary interrupt handler for threaded interrupts. Is
* assigned as primary handler when request_threaded_irq is called
* with handler == NULL. Useful for oneshot interrupts.
*/
static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
{
return IRQ_WAKE_THREAD;
}
static int irq_wait_for_interrupt(struct irqaction *action)
{
while (!kthread_should_stop()) {
@ -451,6 +461,21 @@ static int irq_wait_for_interrupt(struct irqaction *action)
return -1;
}
/*
* Oneshot interrupts keep the irq line masked until the threaded
* handler finished. unmask if the interrupt has not been disabled and
* is marked MASKED.
*/
static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
{
spin_lock_irq(&desc->lock);
if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
desc->status &= ~IRQ_MASKED;
desc->chip->unmask(irq);
}
spin_unlock_irq(&desc->lock);
}
#ifdef CONFIG_SMP
/*
* Check whether we need to change the affinity of the interrupt thread.
@ -492,7 +517,7 @@ static int irq_thread(void *data)
struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
struct irqaction *action = data;
struct irq_desc *desc = irq_to_desc(action->irq);
int wake;
int wake, oneshot = desc->status & IRQ_ONESHOT;
sched_setscheduler(current, SCHED_FIFO, &param);
current->irqaction = action;
@ -518,6 +543,9 @@ static int irq_thread(void *data)
spin_unlock_irq(&desc->lock);
action->thread_fn(action->irq, action->dev_id);
if (oneshot)
irq_finalize_oneshot(action->irq, desc);
}
wake = atomic_dec_and_test(&desc->threads_active);
@ -590,6 +618,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
rand_initialize_irq(irq);
}
/* Oneshot interrupts are not allowed with shared */
if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
return -EINVAL;
/*
* Threaded handler ?
*/
@ -663,9 +695,12 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
desc->status |= IRQ_PER_CPU;
#endif
desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
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;
@ -878,6 +913,8 @@ EXPORT_SYMBOL(free_irq);
* @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
@ -957,8 +994,12 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
if (desc->status & IRQ_NOREQUEST)
return -EINVAL;
if (!handler)
return -EINVAL;
if (!handler) {
if (!thread_fn)
return -EINVAL;
handler = irq_default_primary_handler;
}
action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
if (!action)