irqchip/gic: Cleanup Franken-GIC handling

Introduce a static key identifying Samsung's unique creation, allowing
to replace the indirect call to compute the base addresses with
a simple test on the static key.

Faster, cheaper, negative diffstat.
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

drivers/irqchip/irq-gic.c

@@ -83,9 +83,6 @@ struct gic_chip_data {
 #endif
 	struct irq_domain *domain;
 	unsigned int gic_irqs;
-#ifdef CONFIG_GIC_NON_BANKED
-	void __iomem *(*get_base)(union gic_base *);
-#endif
 };
 
 #ifdef CONFIG_BL_SWITCHER
@@ -127,35 +124,27 @@ static struct gic_kvm_info gic_v2_kvm_info;
 static DEFINE_PER_CPU(u32, sgi_intid);
 
 #ifdef CONFIG_GIC_NON_BANKED
-static void __iomem *gic_get_percpu_base(union gic_base *base)
-{
-	return raw_cpu_read(*base->percpu_base);
-}
+static DEFINE_STATIC_KEY_FALSE(frankengic_key);
 
-static void __iomem *gic_get_common_base(union gic_base *base)
+static void enable_frankengic(void)
 {
-	return base->common_base;
+	static_branch_enable(&frankengic_key);
 }
 
-static inline void __iomem *gic_data_dist_base(struct gic_chip_data *data)
+static inline void __iomem *__get_base(union gic_base *base)
 {
-	return data->get_base(&data->dist_base);
-}
+	if (static_branch_unlikely(&frankengic_key))
+		return raw_cpu_read(*base->percpu_base);
 
-static inline void __iomem *gic_data_cpu_base(struct gic_chip_data *data)
-{
-	return data->get_base(&data->cpu_base);
+	return base->common_base;
 }
 
-static inline void gic_set_base_accessor(struct gic_chip_data *data,
-					 void __iomem *(*f)(union gic_base *))
-{
-	data->get_base = f;
-}
+#define gic_data_dist_base(d)	__get_base(&(d)->dist_base)
+#define gic_data_cpu_base(d)	__get_base(&(d)->cpu_base)
 #else
 #define gic_data_dist_base(d)	((d)->dist_base.common_base)
 #define gic_data_cpu_base(d)	((d)->cpu_base.common_base)
-#define gic_set_base_accessor(d, f)
+#define enable_frankengic()	do { } while(0)
 #endif
 
 static inline void __iomem *gic_dist_base(struct irq_data *d)
@@ -307,7 +296,7 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
 
 	/* Interrupt configuration for SGIs can't be changed */
 	if (gicirq < 16)
-		return type == IRQ_TYPE_EDGE_RISING ? 0 : -EINVAL;
+		return type != IRQ_TYPE_EDGE_RISING ? -EINVAL : 0;
 
 	/* SPIs have restrictions on the supported types */
 	if (gicirq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
@@ -720,11 +709,6 @@ static int gic_notifier(struct notifier_block *self, unsigned long cmd,	void *v)
 	int i;
 
 	for (i = 0; i < CONFIG_ARM_GIC_MAX_NR; i++) {
-#ifdef CONFIG_GIC_NON_BANKED
-		/* Skip over unused GICs */
-		if (!gic_data[i].get_base)
-			continue;
-#endif
 		switch (cmd) {
 		case CPU_PM_ENTER:
 			gic_cpu_save(&gic_data[i]);
@@ -1165,7 +1149,7 @@ static int gic_init_bases(struct gic_chip_data *gic,
 				gic->raw_cpu_base + offset;
 		}
 
-		gic_set_base_accessor(gic, gic_get_percpu_base);
+		enable_frankengic();
 	} else {
 		/* Normal, sane GIC... */
 		WARN(gic->percpu_offset,
@@ -1173,7 +1157,6 @@ static int gic_init_bases(struct gic_chip_data *gic,
 		     gic->percpu_offset);
 		gic->dist_base.common_base = gic->raw_dist_base;
 		gic->cpu_base.common_base = gic->raw_cpu_base;
-		gic_set_base_accessor(gic, gic_get_common_base);
 	}
 
 	/*