From 391f8bee7ef5a2e92d24d73f0072915b7cb12b6b Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Thu, 3 May 2018 12:52:32 +0200
Subject: Create basic char device

---
 char.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 char.c

(limited to 'char.c')

diff --git a/char.c b/char.c
new file mode 100644
index 0000000..7fe7652
--- /dev/null
+++ b/char.c
@@ -0,0 +1,92 @@
+#include "char.h"
+
+#include "linux/cdev.h"
+#include "linux/device.h"
+#include "linux/fs.h"
+
+#include "util.h"
+
+#define DOOMDEV_COUNT 256
+#define DOOMDEV_NAME "doom"
+
+dev_t first;
+int major;
+int next_minor = 0;
+
+long doom_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	return -1;
+}
+
+int doom_open(struct inode *inode, struct file *filp)
+{
+	return -1;
+}
+
+struct file_operations doomdev_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = doom_ioctl,
+	.compat_ioctl = doom_ioctl,
+	.open = doom_open
+};
+	
+struct class *doom_class;
+
+int new_doomdev(void)
+{
+	int err = 0;
+	int minor;
+	dev_t devt;
+	struct cdev *doom_cdev;
+	struct device *doomdev;
+	if (next_minor >= DOOMDEV_COUNT) {
+		return -ENOMEM;
+	}
+
+	doom_cdev = cdev_alloc();
+	if (doom_cdev == NULL) {
+		return -ENOMEM;
+	}
+
+	doom_cdev->ops = &doomdev_fops;
+	ORFAIL(cdev_add(doom_cdev, first, 1), error_add);
+	minor = next_minor++;
+	devt = MKDEV(major, minor);
+	ORFAIL_PTR(device_create(doom_class, NULL, devt, NULL,
+				"doom%d", minor),
+			doomdev, error_create);
+
+error_create:
+	cdev_del(doom_cdev);
+error_add:
+	return err;
+}
+
+void destroy_doomdev(void)
+{
+	device_destroy(doom_class, first);
+}
+
+int char_init(void)
+{
+	int err = 0;
+	ORFAIL(alloc_chrdev_region(&first, 0, DOOMDEV_COUNT, DOOMDEV_NAME),
+			error_region);
+	major = MAJOR(first);
+	doom_class = class_create(THIS_MODULE, "doom");
+	if (IS_ERR(doom_class)) {
+		err = PTR_ERR(doom_class);
+		goto error_create;
+	}
+
+error_create:
+	unregister_chrdev_region(first, DOOMDEV_COUNT);
+error_region:
+	return err;
+}
+
+void char_cleanup(void)
+{
+	unregister_chrdev_region(first, DOOMDEV_COUNT);
+	class_unregister(doom_class);
+}
-- 
cgit v1.2.3