irqchip/xilinx: Switch to GENERIC_IRQ_MULTI_HANDLER

Register the Xilinx driver as the root interrupt controller using
the GENERIC_IRQ_MULTI_HANDLER API, instead of the arch-specific hack.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Stefan Asserhall <stefan.asserhall@xilinx.com>
[maz: repainted commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/e6c6595a81f662bf839cee3109d0fa58a596ea47.1646380284.git.michal.simek@xilinx.com

Author: Michal Simek

arch/microblaze/Kconfig

@@ -45,6 +45,8 @@ config MICROBLAZE
 	select SET_FS
 	select ZONE_DMA
 	select TRACE_IRQFLAGS_SUPPORT
+	select GENERIC_IRQ_MULTI_HANDLER
+	select HANDLE_DOMAIN_IRQ
 
 # Endianness selection
 choice

arch/microblaze/include/asm/irq.h

@@ -11,7 +11,4 @@
 struct pt_regs;
 extern void do_IRQ(struct pt_regs *regs);
 
-/* should be defined in each interrupt controller driver */
-extern unsigned int xintc_get_irq(void);
-
 #endif /* _ASM_MICROBLAZE_IRQ_H */

arch/microblaze/kernel/irq.c

@@ -20,27 +20,13 @@
 #include <linux/irqchip.h>
 #include <linux/of_irq.h>
 
-static u32 concurrent_irq;
-
 void __irq_entry do_IRQ(struct pt_regs *regs)
 {
-	unsigned int irq;
 	struct pt_regs *old_regs = set_irq_regs(regs);
 	trace_hardirqs_off();
 
 	irq_enter();
-	irq = xintc_get_irq();
-next_irq:
-	BUG_ON(!irq);
-	generic_handle_irq(irq);
-
-	irq = xintc_get_irq();
-	if (irq != -1U) {
-		pr_debug("next irq: %d\n", irq);
-		++concurrent_irq;
-		goto next_irq;
-	}
-
+	handle_arch_irq(regs);
 	irq_exit();
 	set_irq_regs(old_regs);
 	trace_hardirqs_on();

drivers/irqchip/irq-xilinx-intc.c

@@ -32,6 +32,8 @@
 #define MER_ME (1<<0)
 #define MER_HIE (1<<1)
 
+#define SPURIOUS_IRQ	(-1U)
+
 static DEFINE_STATIC_KEY_FALSE(xintc_is_be);
 
 struct xintc_irq_chip {
@@ -110,20 +112,6 @@ static struct irq_chip intc_dev = {
 	.irq_mask_ack = intc_mask_ack,
 };
 
-unsigned int xintc_get_irq(void)
-{
-	unsigned int irq = -1;
-	u32 hwirq;
-
-	hwirq = xintc_read(primary_intc, IVR);
-	if (hwirq != -1U)
-		irq = irq_find_mapping(primary_intc->root_domain, hwirq);
-
-	pr_debug("irq-xilinx: hwirq=%d, irq=%d\n", hwirq, irq);
-
-	return irq;
-}
-
 static int xintc_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
 {
 	struct xintc_irq_chip *irqc = d->host_data;
@@ -164,6 +152,19 @@ static void xil_intc_irq_handler(struct irq_desc *desc)
 	chained_irq_exit(chip, desc);
 }
 
+static void xil_intc_handle_irq(struct pt_regs *regs)
+{
+	u32 hwirq;
+
+	do {
+		hwirq = xintc_read(primary_intc, IVR);
+		if (unlikely(hwirq == SPURIOUS_IRQ))
+			break;
+
+		generic_handle_domain_irq(primary_intc->root_domain, hwirq);
+	} while (true);
+}
+
 static int __init xilinx_intc_of_init(struct device_node *intc,
 					     struct device_node *parent)
 {
@@ -233,6 +234,7 @@ static int __init xilinx_intc_of_init(struct device_node *intc,
 	} else {
 		primary_intc = irqc;
 		irq_set_default_host(primary_intc->root_domain);
+		set_handle_irq(xil_intc_handle_irq);
 	}
 
 	return 0;