Revert "irqchip/xilinx: Enable generic irq multi handler"

This reverts commit a0789993bf, which
breaks a number of PPC platforms.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/44b64be7-9240-fd52-af90-e0245220f38b@xilinx.com

arch/microblaze/Kconfig

@@ -47,8 +47,6 @@ config MICROBLAZE
 	select CPU_NO_EFFICIENT_FFS
 	select MMU_GATHER_NO_RANGE if MMU
 	select SPARSE_IRQ
-	select GENERIC_IRQ_MULTI_HANDLER
-	select HANDLE_DOMAIN_IRQ
 
 # Endianness selection
 choice

arch/microblaze/include/asm/irq.h

@@ -14,4 +14,7 @@
 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

@@ -20,10 +20,29 @@
 #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();
-	handle_arch_irq(regs);
+
+	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;
+	}
+
+	irq_exit();
+	set_irq_regs(old_regs);
 	trace_hardirqs_on();
 }
 

drivers/irqchip/irq-xilinx-intc.c

@@ -124,6 +124,20 @@ static unsigned int xintc_get_irq_local(struct xintc_irq_chip *irqc)
 	return irq;
 }
 
+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;
@@ -163,25 +177,6 @@ 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;
-	struct xintc_irq_chip *irqc = primary_intc;
-
-	do {
-		hwirq = xintc_read(irqc, IVR);
-		if (likely(hwirq != -1U)) {
-			int ret;
-
-			ret = handle_domain_irq(irqc->root_domain, hwirq, regs);
-			WARN_ONCE(ret, "Unhandled HWIRQ %d\n", hwirq);
-			continue;
-		}
-
-		break;
-	} while (1);
-}
-
 static int __init xilinx_intc_of_init(struct device_node *intc,
 					     struct device_node *parent)
 {
@@ -251,7 +246,6 @@ 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;