From fd439cfa6fe542cd71a2f664fb01b62ad3a9d566 Mon Sep 17 00:00:00 2001
From: Jason Tang <jtang@umbc.edu>
Date: Sat, 18 Aug 2018 19:12:41 -0400
Subject: [PATCH 3/3] x86: Add handler for CS421 HW1

This creates a new platform driver with an IRQ handler. It does nothing else.

Signed-off-by: Jason Tang <jtang@umbc.edu>
---
 drivers/platform/x86/Kconfig     |  8 ++++++++
 drivers/platform/x86/Makefile    |  1 +
 drivers/platform/x86/cs421_hw1.c | 34 ++++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+)
 create mode 100644 drivers/platform/x86/cs421_hw1.c

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 566644bb496a..874b7c96fe43 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -15,6 +15,14 @@ menuconfig X86_PLATFORM_DEVICES
 
 if X86_PLATFORM_DEVICES
 
+config CS421_HW1
+	tristate "CS421 Homework 1 Interrupt Handler"
+	default y
+	---help---
+	  This driver adds a new interrupt handler to the kernel. When this
+	  driver is installed, note the new line added to /proc/interrupts. In
+	  your Part 4 response, say which IRQ corresponds to that new line.
+
 config ACER_WMI
 	tristate "Acer WMI Laptop Extras"
 	depends on ACPI
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 2ba6cb795338..d4d332610942 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -3,6 +3,7 @@
 # Makefile for linux/drivers/platform/x86
 # x86 Platform-Specific Drivers
 #
+obj-$(CONFIG_CS421_HW1)		+= cs421_hw1.o
 obj-$(CONFIG_ASUS_LAPTOP)	+= asus-laptop.o
 obj-$(CONFIG_ASUS_WMI)		+= asus-wmi.o
 obj-$(CONFIG_ASUS_NB_WMI)	+= asus-nb-wmi.o
diff --git a/drivers/platform/x86/cs421_hw1.c b/drivers/platform/x86/cs421_hw1.c
new file mode 100644
index 000000000000..b5a4d4e44453
--- /dev/null
+++ b/drivers/platform/x86/cs421_hw1.c
@@ -0,0 +1,34 @@
+/*
+ * Copyright(c) 2016 Jason Tang <jtang@umbc.edu>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+
+#define HW1_IRQ 3
+
+static irqreturn_t hw1_handler(int irq, void *dev)
+{
+	return IRQ_HANDLED;
+}
+
+static int __init hw1_init(void)
+{
+	return request_irq(HW1_IRQ, hw1_handler, 0, "CS421 HW1", NULL);
+}
+
+static void __exit hw1_exit(void)
+{
+	free_irq(HW1_IRQ, NULL);
+}
+
+module_init(hw1_init);
+module_exit(hw1_exit);
+
+MODULE_DESCRIPTION("CS421 HW1");
+MODULE_LICENSE("GPL");
-- 
2.17.1