genirq: Avoid unnecessary low level irq function calls

Check irq state in enable/disable/unmask/mask_irq to avoid unnecessary
low level irq function calls.

This has two advantages:
    - Conditionals are faster than hardware access

    - Solves issues with the underlying refcounting of the pinctrl
      infrastructure
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: tfiga@chromium.org
Cc: briannorris@chromium.org
Cc: dianders@chromium.org
Link: http://lkml.kernel.org/r/1498476814-12563-2-git-send-email-jeffy.chen@rock-chips.com

kernel/irq/chip.c

@@ -314,16 +314,25 @@ void irq_shutdown(struct irq_desc *desc)
 
 void irq_enable(struct irq_desc *desc)
 {
+	if (!irqd_irq_disabled(&desc->irq_data)) {
+		unmask_irq(desc);
+	} else {
 		irq_state_clr_disabled(desc);
-	if (desc->irq_data.chip->irq_enable)
+		if (desc->irq_data.chip->irq_enable) {
 			desc->irq_data.chip->irq_enable(&desc->irq_data);
-	else
-		desc->irq_data.chip->irq_unmask(&desc->irq_data);
 			irq_state_clr_masked(desc);
+		} else {
+			unmask_irq(desc);
+		}
+	}
 }
 
 static void __irq_disable(struct irq_desc *desc, bool mask)
 {
+	if (irqd_irq_disabled(&desc->irq_data)) {
+		if (mask)
+			mask_irq(desc);
+	} else {
 		irq_state_set_disabled(desc);
 		if (desc->irq_data.chip->irq_disable) {
 			desc->irq_data.chip->irq_disable(&desc->irq_data);
@@ -331,6 +340,7 @@ static void __irq_disable(struct irq_desc *desc, bool mask)
 		} else if (mask) {
 			mask_irq(desc);
 		}
+	}
 }
 
 /**
@@ -378,18 +388,21 @@ void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu)
 
 static inline void mask_ack_irq(struct irq_desc *desc)
 {
-	if (desc->irq_data.chip->irq_mask_ack)
+	if (desc->irq_data.chip->irq_mask_ack) {
 		desc->irq_data.chip->irq_mask_ack(&desc->irq_data);
-	else {
-		desc->irq_data.chip->irq_mask(&desc->irq_data);
+		irq_state_set_masked(desc);
+	} else {
+		mask_irq(desc);
 		if (desc->irq_data.chip->irq_ack)
 			desc->irq_data.chip->irq_ack(&desc->irq_data);
 	}
-	irq_state_set_masked(desc);
 }
 
 void mask_irq(struct irq_desc *desc)
 {
+	if (irqd_irq_masked(&desc->irq_data))
+		return;
+
 	if (desc->irq_data.chip->irq_mask) {
 		desc->irq_data.chip->irq_mask(&desc->irq_data);
 		irq_state_set_masked(desc);
@@ -398,6 +411,9 @@ void mask_irq(struct irq_desc *desc)
 
 void unmask_irq(struct irq_desc *desc)
 {
+	if (!irqd_irq_masked(&desc->irq_data))
+		return;
+
 	if (desc->irq_data.chip->irq_unmask) {
 		desc->irq_data.chip->irq_unmask(&desc->irq_data);
 		irq_state_clr_masked(desc);
@@ -411,10 +427,7 @@ void unmask_threaded_irq(struct irq_desc *desc)
 	if (chip->flags & IRQCHIP_EOI_THREADED)
 		chip->irq_eoi(&desc->irq_data);
 
-	if (chip->irq_unmask) {
-		chip->irq_unmask(&desc->irq_data);
-		irq_state_clr_masked(desc);
-	}
+	unmask_irq(desc);
 }
 
 /*