genirq: Introduce request_any_context_irq()

Now that we enjoy threaded interrupts, we're starting to see irq_chip implementations (wm831x, pca953x) that make use of threaded interrupts for the controller, and nested interrupts for the client interrupt. It all works very well, with one drawback: Drivers requesting an IRQ must now know whether the handler will run in a thread context or not, and call request_threaded_irq() or request_irq() accordingly. The problem is that the requesting driver sometimes doesn't know about the nature of the interrupt, specially when the interrupt controller is a discrete chip (typically a GPIO expander connected over I2C) that can be connected to a wide variety of otherwise perfectly supported hardware. This patch introduces the request_any_context_irq() function that mostly mimics the usual request_irq(), except that it checks whether the irq level is configured as nested or not, and calls the right backend. On success, it also returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED. [ tglx: Made return value an enum, simplified code and made the export of request_any_context_irq GPL ] Signed-off-by: Marc Zyngier <maz@misterjones.org> Cc: <joachim.eastwood@jotron.com> LKML-Reference: <927ea285bd0c68934ddae1a47e44a9ba@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

genirq: Introduce request_any_context_irq()
Now that we enjoy threaded interrupts, we're starting to see irq_chip implementations (wm831x, pca953x) that make use of threaded interrupts for the controller, and nested interrupts for the client interrupt. It all works very well, with one drawback: Drivers requesting an IRQ must now know whether the handler will run in a thread context or not, and call request_threaded_irq() or request_irq() accordingly. The problem is that the requesting driver sometimes doesn't know about the nature of the interrupt, specially when the interrupt controller is a discrete chip (typically a GPIO expander connected over I2C) that can be connected to a wide variety of otherwise perfectly supported hardware. This patch introduces the request_any_context_irq() function that mostly mimics the usual request_irq(), except that it checks whether the irq level is configured as nested or not, and calls the right backend. On success, it also returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED. [ tglx: Made return value an enum, simplified code and made the export of request_any_context_irq GPL ] Signed-off-by: Marc Zyngier <maz@misterjones.org> Cc: <joachim.eastwood@jotron.com> LKML-Reference: <927ea285bd0c68934ddae1a47e44a9ba@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Marc Zyngier · Thomas Gleixner
1 parent 7c7145f6ac
Showing 2 changed files with 60 additions and 0 deletions Side-by-side Diff
include/linux/interrupt.h
kernel/irq/manage.c
@@ -77,6 +77,18 @@
 	IRQTF_AFFINITY,
 };
  
+/**
+ * These values can be returned by request_any_context_irq() and
+ * describe the context the interrupt will be run in.
+ *
+ * IRQC_IS_HARDIRQ - interrupt runs in hardirq context
+ * IRQC_IS_NESTED - interrupt runs in a nested threaded context
+ */
+enum {
+	IRQC_IS_HARDIRQ	= 0,
+	IRQC_IS_NESTED,
+};
+
 typedef irqreturn_t (*irq_handler_t)(int, void *);
  
 /**
@@ -120,6 +132,10 @@
 	return request_threaded_irq(irq, handler, NULL, flags, name, dev);
 }
  
+extern int __must_check
+request_any_context_irq(unsigned int irq, irq_handler_t handler,
+			unsigned long flags, const char *name, void *dev_id);
+
 extern void exit_irq_thread(void);
 #else
  
@@ -139,6 +155,13 @@
 		     unsigned long flags, const char *name, void *dev)
 {
 	return request_irq(irq, handler, flags, name, dev);
+}
+
+static inline int __must_check
+request_any_context_irq(unsigned int irq, irq_handler_t handler,
+			unsigned long flags, const char *name, void *dev_id)
+{
+	return request_irq(irq, handler, flags, name, dev_id);
 }
  
 static inline void exit_irq_thread(void) { }
@@ -1120,4 +1120,41 @@
 	return retval;
 }
 EXPORT_SYMBOL(request_threaded_irq);
+
+/**
+ *	request_any_context_irq - allocate an interrupt line
+ *	@irq: Interrupt line to allocate
+ *	@handler: Function to be called when the IRQ occurs.
+ *		  Threaded handler for threaded interrupts.
+ *	@flags: Interrupt type flags
+ *	@name: 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. It selects either a
+ *	hardirq or threaded handling method depending on the
+ *	context.
+ *
+ *	On failure, it returns a negative value. On success,
+ *	it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
+ */
+int request_any_context_irq(unsigned int irq, irq_handler_t handler,
+			    unsigned long flags, const char *name, void *dev_id)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	int ret;
+
+	if (!desc)
+		return -EINVAL;
+
+	if (desc->status & IRQ_NESTED_THREAD) {
+		ret = request_threaded_irq(irq, NULL, handler,
+					   flags, name, dev_id);
+		return !ret ? IRQC_IS_NESTED : ret;
+	}
+
+	ret = request_irq(irq, handler, flags, name, dev_id);
+	return !ret ? IRQC_IS_HARDIRQ : ret;
+}
+EXPORT_SYMBOL_GPL(request_any_context_irq);
...	...	@@ -77,6 +77,18 @@
77	77	IRQTF_AFFINITY,
78	78	};
79	79
	80	+/**
	81	+ * These values can be returned by request_any_context_irq() and
	82	+ * describe the context the interrupt will be run in.
	83	+ *
	84	+ * IRQC_IS_HARDIRQ - interrupt runs in hardirq context
	85	+ * IRQC_IS_NESTED - interrupt runs in a nested threaded context
	86	+ */
	87	+enum {
	88	+ IRQC_IS_HARDIRQ = 0,
	89	+ IRQC_IS_NESTED,
	90	+};
	91	+
80	92	typedef irqreturn_t (irq_handler_t)(int, void );
81	93
82	94	/**
...	...	@@ -120,6 +132,10 @@
120	132	return request_threaded_irq(irq, handler, NULL, flags, name, dev);
121	133	}
122	134
	135	+extern int __must_check
	136	+request_any_context_irq(unsigned int irq, irq_handler_t handler,
	137	+ unsigned long flags, const char name, void dev_id);
	138	+
123	139	extern void exit_irq_thread(void);
124	140	#else
125	141
...	...	@@ -139,6 +155,13 @@
139	155	unsigned long flags, const char name, void dev)
140	156	{
141	157	return request_irq(irq, handler, flags, name, dev);
	158	+}
	159	+
	160	+static inline int __must_check
	161	+request_any_context_irq(unsigned int irq, irq_handler_t handler,
	162	+ unsigned long flags, const char name, void dev_id)
	163	+{
	164	+ return request_irq(irq, handler, flags, name, dev_id);
142	165	}
143	166
144	167	static inline void exit_irq_thread(void) { }
...	...	@@ -1120,4 +1120,41 @@
1120	1120	return retval;
1121	1121	}
1122	1122	EXPORT_SYMBOL(request_threaded_irq);
	1123	+
	1124	+/**
	1125	+ * request_any_context_irq - allocate an interrupt line
	1126	+ * @irq: Interrupt line to allocate
	1127	+ * @handler: Function to be called when the IRQ occurs.
	1128	+ * Threaded handler for threaded interrupts.
	1129	+ * @flags: Interrupt type flags
	1130	+ * @name: An ascii name for the claiming device
	1131	+ * @dev_id: A cookie passed back to the handler function
	1132	+ *
	1133	+ * This call allocates interrupt resources and enables the
	1134	+ * interrupt line and IRQ handling. It selects either a
	1135	+ * hardirq or threaded handling method depending on the
	1136	+ * context.
	1137	+ *
	1138	+ * On failure, it returns a negative value. On success,
	1139	+ * it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
	1140	+ */
	1141	+int request_any_context_irq(unsigned int irq, irq_handler_t handler,
	1142	+ unsigned long flags, const char name, void dev_id)
	1143	+{
	1144	+ struct irq_desc *desc = irq_to_desc(irq);
	1145	+ int ret;
	1146	+
	1147	+ if (!desc)
	1148	+ return -EINVAL;
	1149	+
	1150	+ if (desc->status & IRQ_NESTED_THREAD) {
	1151	+ ret = request_threaded_irq(irq, NULL, handler,
	1152	+ flags, name, dev_id);
	1153	+ return !ret ? IRQC_IS_NESTED : ret;
	1154	+ }
	1155	+
	1156	+ ret = request_irq(irq, handler, flags, name, dev_id);
	1157	+ return !ret ? IRQC_IS_HARDIRQ : ret;
	1158	+}
	1159	+EXPORT_SYMBOL_GPL(request_any_context_irq);