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authorThomas Gleixner <tglx@linutronix.de>2009-08-13 07:21:38 -0400
committerThomas Gleixner <tglx@linutronix.de>2009-08-17 04:54:05 -0400
commit399b5da29b9f851eb7b96e2882097127f003e87c (patch)
tree0264a7ae22988e8a298407c611b5b639c9315ff7 /kernel/irq
parent70aedd24d20e75198f5a0b11750faabbb56924e2 (diff)
genirq: Support nested threaded irq handling
Interrupt chips which are behind a slow bus (i2c, spi ...) and demultiplex other interrupt sources need to run their interrupt handler in a thread. The demultiplexed interrupt handlers need to run in thread context as well and need to finish before the demux handler thread can reenable the interrupt line. So the easiest way is to run the sub device handlers in the context of the demultiplexing handler thread. To avoid that a separate thread is created for the subdevices the function set_nested_irq_thread() is provided which sets the IRQ_NESTED_THREAD flag in the interrupt descriptor. A driver which calls request_threaded_irq() must not be aware of the fact that the threaded handler is called in the context of the demultiplexing handler thread. The setup code checks the IRQ_NESTED_THREAD flag which was set from the irq chip setup code and does not setup a separate thread for the interrupt. The primary function which is provided by the device driver is replaced by an internal dummy function which warns when it is called. For the demultiplexing handler a helper function handle_nested_irq() is provided which calls the demux interrupt thread function in the context of the caller and does the proper interrupt accounting and takes the interrupt disabled status of the demultiplexed subdevice into account. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Trilok Soni <soni.trilok@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: Brian Swetland <swetland@google.com> Cc: Joonyoung Shim <jy0922.shim@samsung.com> Cc: m.szyprowski@samsung.com Cc: t.fujak@samsung.com Cc: kyungmin.park@samsung.com, Cc: David Brownell <david-b@pacbell.net> Cc: Daniel Ribeiro <drwyrm@gmail.com> Cc: arve@android.com Cc: Barry Song <21cnbao@gmail.com>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/chip.c67
-rw-r--r--kernel/irq/manage.c34
2 files changed, 98 insertions, 3 deletions
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index f856330e684a..5765aad94998 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -222,6 +222,34 @@ int set_irq_chip_data(unsigned int irq, void *data)
222} 222}
223EXPORT_SYMBOL(set_irq_chip_data); 223EXPORT_SYMBOL(set_irq_chip_data);
224 224
225/**
226 * set_irq_nested_thread - Set/Reset the IRQ_NESTED_THREAD flag of an irq
227 *
228 * @irq: Interrupt number
229 * @nest: 0 to clear / 1 to set the IRQ_NESTED_THREAD flag
230 *
231 * The IRQ_NESTED_THREAD flag indicates that on
232 * request_threaded_irq() no separate interrupt thread should be
233 * created for the irq as the handler are called nested in the
234 * context of a demultiplexing interrupt handler thread.
235 */
236void set_irq_nested_thread(unsigned int irq, int nest)
237{
238 struct irq_desc *desc = irq_to_desc(irq);
239 unsigned long flags;
240
241 if (!desc)
242 return;
243
244 spin_lock_irqsave(&desc->lock, flags);
245 if (nest)
246 desc->status |= IRQ_NESTED_THREAD;
247 else
248 desc->status &= ~IRQ_NESTED_THREAD;
249 spin_unlock_irqrestore(&desc->lock, flags);
250}
251EXPORT_SYMBOL_GPL(set_irq_nested_thread);
252
225/* 253/*
226 * default enable function 254 * default enable function
227 */ 255 */
@@ -299,6 +327,45 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
299 } 327 }
300} 328}
301 329
330/*
331 * handle_nested_irq - Handle a nested irq from a irq thread
332 * @irq: the interrupt number
333 *
334 * Handle interrupts which are nested into a threaded interrupt
335 * handler. The handler function is called inside the calling
336 * threads context.
337 */
338void handle_nested_irq(unsigned int irq)
339{
340 struct irq_desc *desc = irq_to_desc(irq);
341 struct irqaction *action;
342 irqreturn_t action_ret;
343
344 might_sleep();
345
346 spin_lock_irq(&desc->lock);
347
348 kstat_incr_irqs_this_cpu(irq, desc);
349
350 action = desc->action;
351 if (unlikely(!action || (desc->status & IRQ_DISABLED)))
352 goto out_unlock;
353
354 desc->status |= IRQ_INPROGRESS;
355 spin_unlock_irq(&desc->lock);
356
357 action_ret = action->thread_fn(action->irq, action->dev_id);
358 if (!noirqdebug)
359 note_interrupt(irq, desc, action_ret);
360
361 spin_lock_irq(&desc->lock);
362 desc->status &= ~IRQ_INPROGRESS;
363
364out_unlock:
365 spin_unlock_irq(&desc->lock);
366}
367EXPORT_SYMBOL_GPL(handle_nested_irq);
368
302/** 369/**
303 * handle_simple_irq - Simple and software-decoded IRQs. 370 * handle_simple_irq - Simple and software-decoded IRQs.
304 * @irq: the interrupt number 371 * @irq: the interrupt number
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0a3fd5b524c9..e485cea04bf1 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -451,6 +451,16 @@ static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
451 return IRQ_WAKE_THREAD; 451 return IRQ_WAKE_THREAD;
452} 452}
453 453
454/*
455 * Primary handler for nested threaded interrupts. Should never be
456 * called.
457 */
458static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
459{
460 WARN(1, "Primary handler called for nested irq %d\n", irq);
461 return IRQ_NONE;
462}
463
454static int irq_wait_for_interrupt(struct irqaction *action) 464static int irq_wait_for_interrupt(struct irqaction *action)
455{ 465{
456 while (!kthread_should_stop()) { 466 while (!kthread_should_stop()) {
@@ -600,7 +610,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
600 struct irqaction *old, **old_ptr; 610 struct irqaction *old, **old_ptr;
601 const char *old_name = NULL; 611 const char *old_name = NULL;
602 unsigned long flags; 612 unsigned long flags;
603 int shared = 0; 613 int nested, shared = 0;
604 int ret; 614 int ret;
605 615
606 if (!desc) 616 if (!desc)
@@ -630,9 +640,27 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
630 return -EINVAL; 640 return -EINVAL;
631 641
632 /* 642 /*
633 * Threaded handler ? 643 * Check whether the interrupt nests into another interrupt
644 * thread.
645 */
646 nested = desc->status & IRQ_NESTED_THREAD;
647 if (nested) {
648 if (!new->thread_fn)
649 return -EINVAL;
650 /*
651 * Replace the primary handler which was provided from
652 * the driver for non nested interrupt handling by the
653 * dummy function which warns when called.
654 */
655 new->handler = irq_nested_primary_handler;
656 }
657
658 /*
659 * Create a handler thread when a thread function is supplied
660 * and the interrupt does not nest into another interrupt
661 * thread.
634 */ 662 */
635 if (new->thread_fn) { 663 if (new->thread_fn && !nested) {
636 struct task_struct *t; 664 struct task_struct *t;
637 665
638 t = kthread_create(irq_thread, new, "irq/%d-%s", irq, 666 t = kthread_create(irq_thread, new, "irq/%d-%s", irq,