genirq: Add IRQF_FORCE_RESUME

Xen needs to reenable interrupts which are marked IRQF_NO_SUSPEND in the
resume path. Add a flag to force the reenabling in the resume code.

Tested-and-acked-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/interrupt.h

@@ -55,7 +55,7 @@
  *                Used by threaded interrupts which need to keep the
  *                irq line disabled until the threaded handler has been run.
  * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend
- *
+ * IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND is set
  */
 #define IRQF_DISABLED		0x00000020
 #define IRQF_SAMPLE_RANDOM	0x00000040
@@ -67,6 +67,7 @@
 #define IRQF_IRQPOLL		0x00001000
 #define IRQF_ONESHOT		0x00002000
 #define IRQF_NO_SUSPEND		0x00004000
+#define IRQF_FORCE_RESUME	0x00008000
 
 #define IRQF_TIMER		(__IRQF_TIMER | IRQF_NO_SUSPEND)
 

kernel/irq/manage.c

@@ -282,8 +282,17 @@ EXPORT_SYMBOL(disable_irq);
 
 void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
 {
-	if (resume)
+	if (resume) {
+		if (!(desc->status & IRQ_SUSPENDED)) {
+			if (!desc->action)
+				return;
+			if (!(desc->action->flags & IRQF_FORCE_RESUME))
+				return;
+			/* Pretend that it got disabled ! */
+			desc->depth++;
+		}
 		desc->status &= ~IRQ_SUSPENDED;
+	}
 
 	switch (desc->depth) {
 	case 0:

kernel/irq/pm.c

@@ -53,9 +53,6 @@ void resume_device_irqs(void)
 	for_each_irq_desc(irq, desc) {
 		unsigned long flags;
 
-		if (!(desc->status & IRQ_SUSPENDED))
-			continue;
-
 		raw_spin_lock_irqsave(&desc->lock, flags);
 		__enable_irq(desc, irq, true);
 		raw_spin_unlock_irqrestore(&desc->lock, flags);