From bfb105b36e902ffc1aec9424a38245db693eea02 Mon Sep 17 00:00:00 2001
From: lonkaars <loek@pipeframe.xyz>
Date: Thu, 18 Apr 2024 17:34:40 +0200
Subject: dynamically get major:minor numbers + register /dev node + /sys/class
 node

---
 1/main.c | 42 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 7 deletions(-)

(limited to '1/main.c')

diff --git a/1/main.c b/1/main.c
index 66ceac4..101f675 100644
--- a/1/main.c
+++ b/1/main.c
@@ -6,6 +6,9 @@
 #include "config.h"
 
 struct cdev *cdev;
+struct device *dev;
+struct class *class;
+dev_t node;
 struct file_operations fops = {
 	.read = fop_read,
 	.write = fop_write,
@@ -15,38 +18,63 @@ struct file_operations fops = {
 
 static int mod_init(void) {
 	int err;
-	cdev = cdev_alloc();
-	dev_t node = MKDEV(NODE_MAJOR, NODE_MINOR);
 
+	err = alloc_chrdev_region(&node, 0, 1, DRV_NAME);
+	if (err < 0) {
+		printk(KERN_ERR "alloc_chrdev_region error %d\n", err);
+		goto return_err;
+	}
+
+	class = class_create(DRV_NAME);
+	if (IS_ERR_OR_NULL(class)) {
+		err = PTR_ERR(class);
+		printk(KERN_ERR "class_create error %d\n", err);
+		goto free_class;
+	}
+
+	cdev = cdev_alloc();
 	if (!cdev) {
 		err = ENOMEM;
 		goto free_cdev;
 	}
 
 	cdev->ops = &fops;
-
+	cdev_init(cdev, &fops);
 	err = cdev_add(cdev, node, 1);
 	if (err < 0) {
-		printk(KERN_ERR "cdev_add failed w/ error code %d\n", err);
+		printk(KERN_ERR "cdev_add error %d\n", err);
 		goto free_cdev;
 	}
 
-	printk("%s\n", __PRETTY_FUNCTION__);
+	dev = device_create(class, NULL, node, NULL, DRV_NAME);
+	if (IS_ERR_OR_NULL(dev)) {
+		err = PTR_ERR(dev);
+		printk(KERN_ERR "device_create error %d\n", err);
+		goto free_device;
+	}
+
+	printk("%s %d:%d\n", __PRETTY_FUNCTION__, MAJOR(node), MINOR(node));
 	return 0;
 
+free_device:
+	device_destroy(class, node);
 free_cdev:
 	cdev_del(cdev);
-
+free_class:
+	class_destroy(class);
+return_err:
 	printk("%s: %d\n", __PRETTY_FUNCTION__, err);
 	return err;
 }
 
 static void mod_exit(void) {
+	device_destroy(class, node);
 	cdev_del(cdev);
+	class_destroy(class);
 	printk("%s\n", __PRETTY_FUNCTION__);
 }
 
 module_init(mod_init);
 module_exit(mod_exit);
-MODULE_LICENSE("MIT");
+MODULE_LICENSE("Dual MIT/GPL");
 
-- 
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