Merge branch 'rt/head' into rt/2.6.31-rc6

drivers/char/tty_ldisc.c

@@ -69,7 +69,7 @@ static void put_ldisc(struct tty_ldisc *ld)
 	 * We really want an "atomic_dec_and_lock_irqsave()",
 	 * but we don't have it, so this does it by hand.
 	 */
-	local_irq_save(flags);
+	local_irq_save_nort(flags);
 	if (atomic_dec_and_lock(&ld->users, &tty_ldisc_lock)) {
 		struct tty_ldisc_ops *ldo = ld->ops;
 
@@ -80,7 +80,7 @@ static void put_ldisc(struct tty_ldisc *ld)
 		kfree(ld);
 		return;
 	}
-	local_irq_restore(flags);
+	local_irq_restore_nort(flags);
 }
 
 /**

include/linux/interrupt.h

@@ -50,6 +50,9 @@
  * IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
  *                registered first in an shared interrupt is considered for
  *                performance reasons)
+ * IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
+ *                Used by threaded interrupts which need to keep the
+ *                irq line disabled until the threaded handler has been run.
  * IRQF_NODELAY - Interrupt is not force threaded
  */
 #define IRQF_DISABLED		0x00000020
@@ -60,7 +63,8 @@
 #define IRQF_PERCPU		0x00000400
 #define IRQF_NOBALANCING	0x00000800
 #define IRQF_IRQPOLL		0x00001000
-#define IRQF_NODELAY		0x00002000
+#define IRQF_ONESHOT		0x00002000
+#define IRQF_NODELAY		0x00004000
 
 #define IRQF_TIMER		(__IRQF_TIMER | IRQF_NODELAY)
 

include/linux/irq.h

@@ -69,6 +69,8 @@ typedef	void (*irq_flow_handler_t)(unsigned int irq,
 #define IRQ_MOVE_PCNTXT		0x01000000	/* IRQ migration from process context */
 #define IRQ_AFFINITY_SET	0x02000000	/* IRQ affinity was set from userspace*/
 #define IRQ_SUSPENDED		0x04000000	/* IRQ has gone through suspend sequence */
+#define IRQ_ONESHOT		0x08000000	/* IRQ is not unmasked after hardirq */
+#define IRQ_NESTED_THREAD	0x10000000	/* IRQ is nested into another, no own handler thread */
 
 #ifdef CONFIG_IRQ_PER_CPU
 # define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU)
@@ -100,6 +102,9 @@ struct msi_desc;
  * @set_type:		set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ
  * @set_wake:		enable/disable power-management wake-on of an IRQ
  *
+ * @bus_lock:		function to lock access to slow bus (i2c) chips
+ * @bus_sync_unlock:	function to sync and unlock slow bus (i2c) chips
+ *
  * @release:		release function solely used by UML
  * @typename:		obsoleted by name, kept as migration helper
  */
@@ -123,6 +128,9 @@ struct irq_chip {
 	int		(*set_type)(unsigned int irq, unsigned int flow_type);
 	int		(*set_wake)(unsigned int irq, unsigned int on);
 
+	void		(*bus_lock)(unsigned int irq);
+	void		(*bus_sync_unlock)(unsigned int irq);
+
 	/* Currently used only by UML, might disappear one day.*/
 #ifdef CONFIG_IRQ_RELEASE_METHOD
 	void		(*release)(unsigned int irq, void *dev_id);
@@ -380,6 +388,8 @@ set_irq_chained_handler(unsigned int irq,
 	__set_irq_handler(irq, handle, 1, NULL);
 }
 
+extern void set_irq_nested_thread(unsigned int irq, int nest);
+
 extern void set_irq_noprobe(unsigned int irq);
 extern void set_irq_probe(unsigned int irq);
 

kernel/irq/chip.c

@@ -222,6 +222,34 @@ int set_irq_chip_data(unsigned int irq, void *data)
 }
 EXPORT_SYMBOL(set_irq_chip_data);
 
+/**
+ *	set_irq_nested_thread - Set/Reset the IRQ_NESTED_THREAD flag of an irq
+ *
+ *	@irq:	Interrupt number
+ *	@nest:	0 to clear / 1 to set the IRQ_NESTED_THREAD flag
+ *
+ *	The IRQ_NESTED_THREAD flag indicates that on
+ *	request_threaded_irq() no separate interrupt thread should be
+ *	created for the irq as the handler are called nested in the
+ *	context of a demultiplexing interrupt handler thread.
+ */
+void set_irq_nested_thread(unsigned int irq, int nest)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	unsigned long flags;
+
+	if (!desc)
+		return;
+
+	atomic_spin_lock_irqsave(&desc->lock, flags);
+	if (nest)
+		desc->status |= IRQ_NESTED_THREAD;
+	else
+		desc->status &= ~IRQ_NESTED_THREAD;
+	atomic_spin_unlock_irqrestore(&desc->lock, flags);
+}
+EXPORT_SYMBOL_GPL(set_irq_nested_thread);
+
 /*
  * default enable function
  */
@@ -300,6 +328,45 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
 	}
 }
 
+/*
+ *	handle_nested_irq - Handle a nested irq from a irq thread
+ *	@irq:	the interrupt number
+ *
+ *	Handle interrupts which are nested into a threaded interrupt
+ *	handler. The handler function is called inside the calling
+ *	threads context.
+ */
+void handle_nested_irq(unsigned int irq)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irqaction *action;
+	irqreturn_t action_ret;
+
+	might_sleep();
+
+	atomic_spin_lock_irq(&desc->lock);
+
+	kstat_incr_irqs_this_cpu(irq, desc);
+
+	action = desc->action;
+	if (unlikely(!action || (desc->status & IRQ_DISABLED)))
+		goto out_unlock;
+
+	desc->status |= IRQ_INPROGRESS;
+	atomic_spin_unlock_irq(&desc->lock);
+
+	action_ret = action->thread_fn(action->irq, action->dev_id);
+	if (!noirqdebug)
+		note_interrupt(irq, desc, action_ret);
+
+	atomic_spin_lock_irq(&desc->lock);
+	desc->status &= ~IRQ_INPROGRESS;
+
+out_unlock:
+	atomic_spin_unlock_irq(&desc->lock);
+}
+EXPORT_SYMBOL_GPL(handle_nested_irq);
+
 /**
  *	handle_simple_irq - Simple and software-decoded IRQs.
  *	@irq:	the interrupt number
@@ -383,8 +450,10 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc)
 
 	atomic_spin_lock(&desc->lock);
 	desc->status &= ~IRQ_INPROGRESS;
-	if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask &&
-	    !desc->forced_threads_active)
+
+	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:
 	atomic_spin_unlock(&desc->lock);
@@ -427,6 +496,9 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
 		goto out;
 	}
 
+	if ((desc->status & IRQ_ONESHOT) && desc->chip->mask)
+		desc->chip->mask(irq);
+
 	desc->status |= IRQ_INPROGRESS;
 	desc->status &= ~IRQ_PENDING;
 	atomic_spin_unlock(&desc->lock);
@@ -480,8 +552,13 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
 	kstat_incr_irqs_this_cpu(irq, desc);
 
 	/* Start handling the 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;
@@ -574,6 +651,7 @@ __set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
 		desc->chip = &dummy_irq_chip;
 	}
 
+	chip_bus_lock(irq, desc);
 	atomic_spin_lock_irqsave(&desc->lock, flags);
 
 	/* Uninstall? */
@@ -592,7 +670,9 @@ __set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
 		desc->depth = 0;
 		desc->chip->startup(irq);
 	}
+
 	atomic_spin_unlock_irqrestore(&desc->lock, flags);
+	chip_bus_sync_unlock(irq, desc);
 }
 EXPORT_SYMBOL_GPL(__set_irq_handler);
 

kernel/irq/handle.c

@@ -356,6 +356,25 @@ static void warn_no_thread(unsigned int irq, struct irqaction *action)
 	       "but no thread function available.", irq, action->name);
 }
 
+/*
+ * Momentary workaround until I have a brighter idea how to handle the
+ * accounting of forced threaded (shared) handlers.
+ */
+irqreturn_t handle_irq_action(unsigned int irq, struct irqaction *action)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (desc->status & IRQ_ONESHOT) {
+		unsigned long flags;
+
+		atomic_spin_lock_irqsave(&desc->lock, flags);
+		desc->forced_threads_active |= action->thread_mask;
+		atomic_spin_unlock_irqrestore(&desc->lock, flags);
+		return IRQ_WAKE_THREAD;
+	}
+	return action->handler(irq, action->dev_id);
+}
+
 /**
  * handle_IRQ_event - irq action chain handler
  * @irq:	the interrupt number

kernel/irq/internals.h

@@ -44,15 +44,18 @@ extern int irq_select_affinity_usr(unsigned int irq);
 
 extern void irq_set_thread_affinity(struct irq_desc *desc);
 
-#ifdef CONFIG_PREEMPT_HARDIRQS
-extern irqreturn_t handle_irq_action(unsigned int irq,struct irqaction *action);
-#else
-static inline irqreturn_t
-handle_irq_action(unsigned int irq, struct irqaction *action)
+/* Inline functions for support of irq chips on slow busses */
+static inline void chip_bus_lock(unsigned int irq, struct irq_desc *desc)
 {
-	return action->handler(irq, action->dev_id);
+	if (unlikely(desc->chip->bus_lock))
+		desc->chip->bus_lock(irq);
+}
+
+static inline void chip_bus_sync_unlock(unsigned int irq, struct irq_desc *desc)
+{
+	if (unlikely(desc->chip->bus_sync_unlock))
+		desc->chip->bus_sync_unlock(irq);
 }
-#endif
 
 /*
  * Debugging printout:

kernel/irq/manage.c

@@ -230,9 +230,11 @@ void disable_irq_nosync(unsigned int irq)
 	if (!desc)
 		return;
 
+	chip_bus_lock(irq, desc);
 	atomic_spin_lock_irqsave(&desc->lock, flags);
 	__disable_irq(desc, irq, false);
 	atomic_spin_unlock_irqrestore(&desc->lock, flags);
+	chip_bus_sync_unlock(irq, desc);
 }
 EXPORT_SYMBOL(disable_irq_nosync);
 
@@ -295,7 +297,8 @@ void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
  *	matches the last disable, processing of interrupts on this
  *	IRQ line is re-enabled.
  *
- *	This function may be called from IRQ context.
+ *	This function may be called from IRQ context only when
+ *	desc->chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
  */
 void enable_irq(unsigned int irq)
 {
@@ -305,9 +308,11 @@ void enable_irq(unsigned int irq)
 	if (!desc)
 		return;
 
+	chip_bus_lock(irq, desc);
 	atomic_spin_lock_irqsave(&desc->lock, flags);
 	__enable_irq(desc, irq, false);
 	atomic_spin_unlock_irqrestore(&desc->lock, flags);
+	chip_bus_sync_unlock(irq, desc);
 }
 EXPORT_SYMBOL(enable_irq);
 
@@ -437,40 +442,46 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 	return ret;
 }
 
-#ifdef CONFIG_PREEMPT_HARDIRQS
 /*
- * handler function for forced irq threading. Dummy code. See
- * handle_irq_action() below.
+ * 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 preempt_hardirq_handler(int irq, void *dev_id)
+static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
 {
 	return IRQ_WAKE_THREAD;
 }
 
 /*
- * Momentary workaround until I have a brighter idea how to handle the
- * accounting of forced thread handlers.
+ * Primary handler for nested threaded interrupts. Should never be
+ * called.
  */
-irqreturn_t handle_irq_action(unsigned int irq, struct irqaction *action)
+static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
 {
-	if (action->handler == preempt_hardirq_handler) {
-		struct irq_desc *desc = irq_to_desc(irq);
-		unsigned long flags;
+	WARN(1, "Primary handler called for nested irq %d\n", irq);
+	return IRQ_NONE;
+}
 
-		atomic_spin_lock_irqsave(&desc->lock, flags);
+#ifdef CONFIG_PREEMPT_HARDIRQS
+/*
+ * If the caller does not request irq threading then the handler
+ * becomes the thread function and we use the above handler as the
+ * primary hardirq context handler.
+ */
+static void preempt_hardirq_setup(struct irqaction *new)
+{
+	if (new->thread_fn || (new->flags & IRQF_NODELAY))
+		return;
 
-		/* FIXME: use some flag to do that */
-		if (desc->handle_irq == handle_fasteoi_irq) {
-			if (desc->chip->mask)
-				desc->chip->mask(irq);
-		}
-		desc->forced_threads_active |= action->thread_mask;
-		atomic_spin_unlock_irqrestore(&desc->lock, flags);
-		return IRQ_WAKE_THREAD;
-	}
-	return action->handler(irq, action->dev_id);
+	new->flags |= IRQF_ONESHOT;
+	new->thread_fn = new->handler;
+	new->handler = irq_default_primary_handler;
 }
 
+#else
+static inline void preempt_hardirq_setup(struct irqaction *new) { }
+#endif
+
 /*
  * forced threaded interrupts need to unmask the interrupt line
  */
@@ -479,7 +490,7 @@ static int preempt_hardirq_thread_done(struct irq_desc *desc,
 {
 	unsigned long masked;
 
-	if (action->handler != preempt_hardirq_handler)
+	if (!(desc->status & IRQ_ONESHOT))
 		return 0;
 again:
 	atomic_spin_lock_irq(&desc->lock);
@@ -524,20 +535,6 @@ again:
 	return 0;
 }
 
-/*
- * If the caller does not request irq threading then the handler
- * becomes the thread function and we use the above handler as the
- * primary hardirq context handler.
- */
-static void preempt_hardirq_setup(struct irqaction *new)
-{
-	if (new->thread_fn || (new->flags & IRQF_NODELAY))
-		return;
-
-	new->thread_fn = new->handler;
-	new->handler = preempt_hardirq_handler;
-}
-
 static inline void
 preempt_hardirq_cleanup(struct irq_desc *desc, struct irqaction *action)
 {
@@ -545,17 +542,6 @@ preempt_hardirq_cleanup(struct irq_desc *desc, struct irqaction *action)
 	preempt_hardirq_thread_done(desc, action);
 }
 
-#else
-static inline void preempt_hardirq_setup(struct irqaction *new) { }
-static inline int
-preempt_hardirq_thread_done(struct irq_desc *d, struct irqaction *a)
-{
-	return 0;
-}
-static inline void
-preempt_hardirq_cleanup(struct irq_desc *d, struct irqaction *a) { }
-#endif
-
 static int
 irq_wait_for_interrupt(struct irq_desc *desc, struct irqaction *action)
 {
@@ -690,7 +676,7 @@ __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, thread_mask = 0;
-	int shared = 0;
+	int nested, shared = 0;
 	int ret;
 
 	if (!desc)
@@ -715,13 +701,32 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 		rand_initialize_irq(irq);
 	}
 
+
 	/* Preempt-RT setup for forced threading */
 	preempt_hardirq_setup(new);
 
 	/*
-	 * Threaded handler ?
+	 * 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.
 		 */
-	if (new->thread_fn) {
+		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,
@@ -798,9 +803,12 @@ __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;
@@ -825,6 +833,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 				(int)(new->flags & IRQF_TRIGGER_MASK));
 	}
 
+	new->irq = irq;
 	*old_ptr = new;
 
 	/* Reset broken irq detection when installing new handler */
@@ -842,14 +851,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 
 	atomic_spin_unlock_irqrestore(&desc->lock, flags);
 
-	new->irq = irq;
 	register_irq_proc(irq, desc);
 	new->dir = NULL;
 	register_handler_proc(irq, new);
 
-	if (new->thread)
-		wake_up_process(new->thread);
-
 	return 0;
 
 mismatch:
@@ -1007,7 +1012,14 @@ EXPORT_SYMBOL_GPL(remove_irq);
  */
 void free_irq(unsigned int irq, void *dev_id)
 {
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (!desc)
+		return;
+
+	chip_bus_lock(irq, desc);
 	kfree(__free_irq(irq, dev_id));
+	chip_bus_sync_unlock(irq, desc);
 }
 EXPORT_SYMBOL(free_irq);
 
@@ -1016,6 +1028,8 @@ 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
@@ -1095,8 +1109,12 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
 
 	if (desc->status & IRQ_NOREQUEST)
 		return -EINVAL;
-	if (!handler)
+
+	if (!handler) {
+		if (!thread_fn)
 			return -EINVAL;
+		handler = irq_default_primary_handler;
+	}
 
 	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
 	if (!action)
@@ -1108,7 +1126,10 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
 	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);