[PATCH v2 1/4] genirq: Introduce driver-readable IRQ status word

[Jan Kiszka]

From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>

This associates a status word with every IRQ descriptor. Drivers can obtain
its content via get_irq_status(irq). First use case will be propagating the
interrupt sharing state.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 include/linux/interrupt.h |    2 ++
 include/linux/irq.h       |    2 ++
 kernel/irq/manage.c       |   15 +++++++++++++++
 3 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 79d0c4f..16cdbbf 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -126,6 +126,8 @@ struct irqaction {
 
 extern irqreturn_t no_action(int cpl, void *dev_id);
 
+extern unsigned long get_irq_status(unsigned long irq);
+
 #ifdef CONFIG_GENERIC_HARDIRQS
 extern int __must_check
 request_threaded_irq(unsigned int irq, irq_handler_t handler,
diff --git a/include/linux/irq.h b/include/linux/irq.h
index abde252..5554203 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -96,6 +96,7 @@ struct msi_desc;
  *			methods, to allow shared chip implementations
  * @msi_desc:		MSI descriptor
  * @affinity:		IRQ affinity on SMP
+ * @status:		driver-readable status flags (IRQS_*)
  *
  * The fields here need to overlay the ones in irq_desc until we
  * cleaned up the direct references and switched everything over to
@@ -108,6 +109,7 @@ struct irq_data {
 	void			*handler_data;
 	void			*chip_data;
 	struct msi_desc		*msi_desc;
+	unsigned long		status;
 #ifdef CONFIG_SMP
 	cpumask_var_t		affinity;
 #endif
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5f92acc..df51284 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1157,3 +1157,18 @@ int request_any_context_irq(unsigned int irq, irq_handler_t handler,
 	return !ret ? IRQC_IS_HARDIRQ : ret;
 }
 EXPORT_SYMBOL_GPL(request_any_context_irq);
+
+/**
+ *	get_irq_status - read interrupt line status word
+ *	@irq: Interrupt line of the status word
+ *
+ *	This returns the current content of the status word associated with
+ *	the given interrupt line. See IRQS_* flags for details.
+ */
+unsigned long get_irq_status(unsigned long irq)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	return desc ? desc->irq_data.status : 0;
+}
+EXPORT_SYMBOL_GPL(get_irq_status);
-- 
1.7.1

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