[tip: irq/core] irqchip/versatile-fpga: Handle chained IRQs properly

[tip-bot2 for Sungbo Eo]

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     486562da598c59e9f835b551d7cf19507de2d681
Gitweb:        https://git.kernel.org/tip/486562da598c59e9f835b551d7cf19507de2d681
Author:        Sungbo Eo <mans0n@xxxxxxxxxx>
AuthorDate:    Thu, 19 Mar 2020 11:34:48 +09:00
Committer:     Marc Zyngier <maz@xxxxxxxxxx>
CommitterDate: Thu, 19 Mar 2020 08:37:44 

irqchip/versatile-fpga: Handle chained IRQs properly

Enclose the chained handler with chained_irq_{enter,exit}(), so that the
muxed interrupts get properly acked.

This patch also fixes a reboot bug on OX820 SoC, where the jiffies timer
interrupt is never acked. The kernel waits a clock tick forever in
calibrate_delay_converge(), which leads to a boot hang.

Fixes: c41b16f8c9d9 ("ARM: integrator/versatile: consolidate FPGA IRQ handling code")
Signed-off-by: Sungbo Eo <mans0n@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200319023448.1479701-1-mans0n@xxxxxxxxxx
---
 drivers/irqchip/irq-versatile-fpga.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-versatile-fpga.c b/drivers/irqchip/irq-versatile-fpga.c
index 928858d..70e2cff 100644
--- a/drivers/irqchip/irq-versatile-fpga.c
+++ b/drivers/irqchip/irq-versatile-fpga.c
@@ -6,6 +6,7 @@
 #include <linux/irq.h>
 #include <linux/io.h>
 #include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/irqchip/versatile-fpga.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
@@ -68,12 +69,16 @@ static void fpga_irq_unmask(struct irq_data *d)
 
 static void fpga_irq_handle(struct irq_desc *desc)
 {
+	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
-	u32 status = readl(f->base + IRQ_STATUS);
+	u32 status;
+
+	chained_irq_enter(chip, desc);
 
+	status = readl(f->base + IRQ_STATUS);
 	if (status == 0) {
 		do_bad_IRQ(desc);
-		return;
+		goto out;
 	}
 
 	do {
@@ -82,6 +87,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
 		status &= ~(1 << irq);
 		generic_handle_irq(irq_find_mapping(f->domain, irq));
 	} while (status);
+
+out:
+	chained_irq_exit(chip, desc);
 }
 
 /*