[PATCH] selftest: drivers: Add support to check duplicate hwirq

[Joseph Jang <jjang@nvidia.com>]

Validate there are no duplicate hwirq from the irq debug
file system /sys/kernel/debug/irq/irqs/* per chip name.

One example log show 2 duplicated hwirq in the irq debug
file system.

$ sudo cat /sys/kernel/debug/irq/irqs/163
handler:  handle_fasteoi_irq
device:   0019:00:00.0
     <SNIP>
node:     1
affinity: 72-143
effectiv: 76
domain:  irqchip@0x0000100022040000-3
 hwirq:   0xc8000000
 chip:    ITS-MSI
  flags:   0x20

$ sudo cat /sys/kernel/debug/irq/irqs/174
handler:  handle_fasteoi_irq
device:   0039:00:00.0
    <SNIP>
node:     3
affinity: 216-287
effectiv: 221
domain:  irqchip@0x0000300022040000-3
 hwirq:   0xc8000000
 chip:    ITS-MSI
  flags:   0x20

The irq-check.sh can help to collect hwirq and chip name from
/sys/kernel/debug/irq/irqs/* and print error log when find duplicate
hwirq per chip name.

Kernel patch ("PCI/MSI: Fix MSI hwirq truncation") [1] fix above issue.
[1]: https://lore.kernel.org/all/20240115135649.708536-1-vidyas@nvidia.com/

Signed-off-by: Joseph Jang <jjang@nvidia.com>
Reviewed-by: Matthew R. Ochs <mochs@nvidia.com>
---
 tools/testing/selftests/drivers/irq/Makefile  |  5 +++
 tools/testing/selftests/drivers/irq/config    |  2 +
 .../selftests/drivers/irq/irq-check.sh        | 39 +++++++++++++++++++
 3 files changed, 46 insertions(+)
 create mode 100644 tools/testing/selftests/drivers/irq/Makefile
 create mode 100644 tools/testing/selftests/drivers/irq/config
 create mode 100755 tools/testing/selftests/drivers/irq/irq-check.sh

diff --git a/tools/testing/selftests/drivers/irq/Makefile b/tools/testing/selftests/drivers/irq/Makefile
new file mode 100644
index 000000000000..d6998017c861
--- /dev/null
+++ b/tools/testing/selftests/drivers/irq/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_PROGS := irq-check.sh
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/drivers/irq/config b/tools/testing/selftests/drivers/irq/config
new file mode 100644
index 000000000000..a53d3b713728
--- /dev/null
+++ b/tools/testing/selftests/drivers/irq/config
@@ -0,0 +1,2 @@
+CONFIG_GENERIC_IRQ_DEBUGFS=y
+CONFIG_GENERIC_IRQ_INJECTION=y
diff --git a/tools/testing/selftests/drivers/irq/irq-check.sh b/tools/testing/selftests/drivers/irq/irq-check.sh
new file mode 100755
index 000000000000..e784777043a1
--- /dev/null
+++ b/tools/testing/selftests/drivers/irq/irq-check.sh
@@ -0,0 +1,39 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This script need root permission
+uid=$(id -u)
+if [ $uid -ne 0 ]; then
+	echo "SKIP: Must be run as root"
+	exit 4
+fi
+
+# Ensure debugfs is mounted
+mount -t debugfs nodev /sys/kernel/debug 2>/dev/null
+if [ ! -d "/sys/kernel/debug/irq/irqs" ]; then
+	echo "SKIP: irq debugfs not found"
+	exit 4
+fi
+
+# Traverse the irq debug file system directory to collect chip_name and hwirq
+hwirq_list=$(for irq_file in /sys/kernel/debug/irq/irqs/*; do
+	# Read chip name and hwirq from the irq_file
+	chip_name=$(cat "$irq_file" | grep -m 1 'chip:' | awk '{print $2}')
+	hwirq=$(cat "$irq_file" | grep -m 1 'hwirq:' | awk '{print $2}' )
+
+	if [ -z "$chip_name" ] || [ -z "$hwirq" ]; then
+		continue
+	fi
+
+	echo "$chip_name $hwirq"
+done)
+
+dup_hwirq_list=$(echo "$hwirq_list" | sort | uniq -cd)
+
+if [ -n "$dup_hwirq_list" ]; then
+	echo "ERROR: Found duplicate hwirq"
+	echo "$dup_hwirq_list"
+	exit 1
+fi
+
+exit 0
-- 
2.34.1