genirq: Add IRQCHIP_SET_TYPE_MASKED flag

irq_chips, which require to mask the chip before changing the trigger
type should set this flag. So the core takes care of it and the
requirement for looking into desc->status in the chip goes away.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>

include/linux/irq.h

@@ -308,6 +308,15 @@ struct irq_chip {
 #endif
 };
 
+/*
+ * irq_chip specific flags
+ *
+ * IRQCHIP_SET_TYPE_MASKED:		Mask before calling chip.irq_set_type()
+ */
+enum {
+	IRQCHIP_SET_TYPE_MASKED		= (1 <<  0),
+};
+
 /* This include will go away once we isolated irq_desc usage to core code */
 #include <linux/irqdesc.h>
 

kernel/irq/chip.c

@@ -367,7 +367,7 @@ static inline void mask_ack_irq(struct irq_desc *desc)
 	irq_state_set_masked(desc);
 }
 
-static inline void mask_irq(struct irq_desc *desc)
+void mask_irq(struct irq_desc *desc)
 {
 	if (desc->irq_data.chip->irq_mask) {
 		desc->irq_data.chip->irq_mask(&desc->irq_data);
@@ -375,7 +375,7 @@ static inline void mask_irq(struct irq_desc *desc)
 	}
 }
 
-static inline void unmask_irq(struct irq_desc *desc)
+void unmask_irq(struct irq_desc *desc)
 {
 	if (desc->irq_data.chip->irq_unmask) {
 		desc->irq_data.chip->irq_unmask(&desc->irq_data);

kernel/irq/internals.h

@@ -84,6 +84,8 @@ extern int irq_startup(struct irq_desc *desc);
 extern void irq_shutdown(struct irq_desc *desc);
 extern void irq_enable(struct irq_desc *desc);
 extern void irq_disable(struct irq_desc *desc);
+extern void mask_irq(struct irq_desc *desc);
+extern void unmask_irq(struct irq_desc *desc);
 
 extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr);
 

kernel/irq/manage.c

@@ -554,8 +554,8 @@ void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 		      unsigned long flags)
 {
-	int ret;
 	struct irq_chip *chip = desc->irq_data.chip;
+	int ret, unmask = 0;
 
 	if (!chip || !chip->irq_set_type) {
 		/*
@@ -568,6 +568,14 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 	}
 
 	flags &= IRQ_TYPE_SENSE_MASK;
+
+	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
+		if (!(desc->istate & IRQS_MASKED))
+			mask_irq(desc);
+		if (!(desc->istate & IRQS_DISABLED))
+			unmask = 1;
+	}
+
 	/* caller masked out all except trigger mode flags */
 	ret = chip->irq_set_type(&desc->irq_data, flags);
 
@@ -588,11 +596,13 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 
 		if (chip != desc->irq_data.chip)
 			irq_chip_set_defaults(desc->irq_data.chip);
-		return 0;
+		ret = 0;
 	default:
 		pr_err("setting trigger mode %lu for irq %u failed (%pF)\n",
 		       flags, irq, chip->irq_set_type);
 	}
+	if (unmask)
+		unmask_irq(desc);
 	return ret;
 }
 
@@ -669,7 +679,7 @@ static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
 
 #ifdef CONFIG_SMP
 /*
- * Check whether we need to change the affinity of the interrupt thread.
+ * Check whether we need to chasnge the affinity of the interrupt thread.
  */
 static void
 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)