genirq: Add preflow handler support

sparc64 needs to call a preflow handler on certain interrupts befor
calling the action chain. Integrate it into handle_fasteoi_irq. Must
be enabled via CONFIG_IRQ_FASTEOI_PREFLOW. No impact when disabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David S. Miller <davem@davemloft.net>

4 files changed, 30 insertions, 1 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 3e29e2f42e04..36390970693c 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -29,9 +29,10 @@
 #include <asm/irq_regs.h>
 
 struct irq_desc;
+struct irq_data;
 typedef void (*irq_flow_handler_t)(unsigned int irq,
                                             struct irq_desc *desc);
-
+typedef void (*irq_preflow_handler_t)(struct irq_data *data);
 
 /*
  * IRQ line status.
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 36c95f08023d..2f87d6441302 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -63,6 +63,9 @@ struct irq_desc {
         struct timer_rand_state *timer_rand_state;
         unsigned int __percpu   *kstat_irqs;
         irq_flow_handler_t      handle_irq;
+#ifdef CONFIG_IRQ_PREFLOW_FASTEOI
+        irq_preflow_handler_t   preflow_handler;
+#endif
         struct irqaction        *action;        /* IRQ action list */
 #ifdef CONFIG_GENERIC_HARDIRQS_NO_COMPAT
         unsigned int            status_use_accessors;
@@ -187,6 +190,17 @@ static inline void __set_irq_handler_unlocked(int irq,
         desc = irq_to_desc(irq);
         desc->handle_irq = handler;
 }
+
+#ifdef CONFIG_IRQ_PREFLOW_FASTEOI
+static inline void
+__irq_set_preflow_handler(unsigned int irq, irq_preflow_handler_t handler)
+{
+        struct irq_desc *desc;
+
+        desc = irq_to_desc(irq);
+        desc->preflow_handler = handler;
+}
+#endif
 #endif
 
 #endif
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 48ad25f5fa59..9149be729e45 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -35,6 +35,9 @@ config AUTO_IRQ_AFFINITY
 config HARDIRQS_SW_RESEND
        def_bool n
 
+config IRQ_PREFLOW_FASTEOI
+       def_bool n
+
 config SPARSE_IRQ
         bool "Support sparse irq numbering"
         depends on HAVE_SPARSE_IRQ
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 2a36038b8f59..08be5d182be3 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -471,6 +471,16 @@ out_unlock:
 }
 EXPORT_SYMBOL_GPL(handle_level_irq);
 
+#ifdef CONFIG_IRQ_PREFLOW_FASTEOI
+static inline void preflow_handler(struct irq_desc *desc)
+{
+        if (desc->preflow_handler)
+                desc->preflow_handler(&desc->irq_data);
+}
+#else
+static inline void preflow_handler(struct irq_desc *desc) { }
+#endif
+
 /**
  *      handle_fasteoi_irq - irq handler for transparent controllers
  *      @irq:   the interrupt number
@@ -503,6 +513,7 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
                 mask_irq(desc);
                 goto out;
         }
+        preflow_handler(desc);
         handle_irq_event(desc);
 out:
         desc->irq_data.chip->irq_eoi(&desc->irq_data);