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Subject[PATCH v3 1/4] genirq: Introduce driver-readable IRQ status word
Date
From: Jan Kiszka <jan.kiszka@siemens.com>

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@siemens.com>
---
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..4c1aa72 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 int 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..8bdb421 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
+ * @drv_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
@@ -111,6 +112,7 @@ struct irq_data {
#ifdef CONFIG_SMP
cpumask_var_t affinity;
#endif
+ unsigned long drv_status;
};

/**
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5f92acc..2ea0d30 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 int irq)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+
+ return desc ? desc->irq_data.drv_status : 0;
+}
+EXPORT_SYMBOL_GPL(get_irq_status);
--
1.7.1


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