[PATCH] genirq: add genirq sw IRQ-retrigger

Enable platforms that do not have a hardware-assisted hardirq-resend mechanism
to resend them via a softirq-driven IRQ emulation mechanism.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index b2688157b51bff9ebe71cd0dabf37649a8564e09..9a39756bfd31162f3891932d055b67d6c987bd72 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -246,6 +246,9 @@ extern void note_interrupt(unsigned int irq, struct irq_desc *desc,
                           int action_ret, struct pt_regs *regs);
 extern int can_request_irq(unsigned int irq, unsigned long irqflags);
 
+/* Resending of interrupts :*/
+void check_irq_resend(struct irq_desc *desc, unsigned int irq);
+
 extern void init_irq_proc(void);
 
 #endif /* CONFIG_GENERIC_HARDIRQS */

diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile
index 9f77f50d814317409f1ed02ce73372bfb428c99f..627ace98d4a2426f79254c43e72bec6af8b746c9 100644 (file)
--- a/kernel/irq/Makefile
+++ b/kernel/irq/Makefile
@@ -1,5 +1,5 @@
 
-obj-y := handle.o manage.o spurious.o
+obj-y := handle.o manage.o spurious.o resend.o
 obj-$(CONFIG_GENERIC_IRQ_PROBE) += autoprobe.o
 obj-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_GENERIC_PENDING_IRQ) += migration.o

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 19b438e09f1243ee6693b175544ba96d1b8a129d..cffde48438971c13b8b1f9b14bb84dc7fb3f7b1a 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -118,15 +118,7 @@ void enable_irq(unsigned int irq)
                WARN_ON(1);
                break;
        case 1: {
-               unsigned int status = desc->status & ~IRQ_DISABLED;
-
-               desc->status = status;
-               if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
-                       desc->status = status | IRQ_REPLAY;
-                       if (desc->chip && desc->chip->retrigger)
-                               desc->chip->retrigger(irq);
-               }
-               desc->chip->enable(irq);
+               check_irq_resend(desc, irq);
                /* fall-through */
        }
        default:

diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
new file mode 100644 (file)
index 0000000..096b102
--- /dev/null
+++ b/kernel/irq/resend.c
@@ -0,0 +1,78 @@
+/*
+ * linux/kernel/irq/resend.c
+ *
+ * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
+ * Copyright (C) 2005-2006, Thomas Gleixner
+ *
+ * This file contains the IRQ-resend code
+ *
+ * If the interrupt is waiting to be processed, we try to re-run it.
+ * We can't directly run it from here since the caller might be in an
+ * interrupt-protected region. Not all irq controller chips can
+ * retrigger interrupts at the hardware level, so in those cases
+ * we allow the resending of IRQs via a tasklet.
+ */
+
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/interrupt.h>
+
+#include "internals.h"
+
+#ifdef CONFIG_HARDIRQS_SW_RESEND
+
+/* Bitmap to handle software resend of interrupts: */
+static DECLARE_BITMAP(irqs_resend, NR_IRQS);
+
+/*
+ * Run software resends of IRQ's
+ */
+static void resend_irqs(unsigned long arg)
+{
+       struct irq_desc *desc;
+       int irq;
+
+       while (!bitmap_empty(irqs_resend, NR_IRQS)) {
+               irq = find_first_bit(irqs_resend, NR_IRQS);
+               clear_bit(irq, irqs_resend);
+               desc = irq_desc + irq;
+               spin_lock_irqsave(&desc->lock, flags);
+               desc->handle_irq(irq, desc, NULL);
+               spin_unlock_irqrestore(&desc->lock, flags);
+       }
+}
+
+/* Tasklet to handle resend: */
+static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
+
+#endif
+
+/*
+ * IRQ resend
+ *
+ * Is called with interrupts disabled and desc->lock held.
+ */
+void check_irq_resend(struct irq_desc *desc, unsigned int irq)
+{
+       unsigned int status = desc->status;
+
+       /*
+        * Make sure the interrupt is enabled, before resending it:
+        */
+       desc->chip->enable(irq);
+
+       if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
+               desc->status &= ~IRQ_PENDING;
+               desc->status = status | IRQ_REPLAY;
+
+               if (!desc->chip || !desc->chip->retrigger ||
+                                       !desc->chip->retrigger(irq)) {
+#ifdef CONFIG_HARDIRQS_SW_RESEND
+                       /* Set it pending and activate the softirq: */
+                       set_bit(irq, irqs_resend);
+                       tasklet_schedule(&resend_tasklet);
+#endif
+               }
+       }
+}