Create basic char device

6 files changed, 142 insertions, 18 deletions

diff --git a/Kbuild b/Kbuild
index d4a3e64..0214343 100644
--- a/Kbuild
+++ b/Kbuild
@@ -1,2 +1,2 @@
 obj-m := harddoom.o
-harddoom-objs := harddoom_main.o pci.o
+harddoom-objs := harddoom_main.o pci.o char.o
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);
+}
diff --git a/char.h b/char.h
new file mode 100644
index 0000000..503ba04
--- /dev/null
+++ b/char.h
@@ -0,0 +1,9 @@
+#ifndef CHAR_H
+#define CHAR_H
+
+int new_doomdev(void);
+void destroy_doomdev(void);
+int char_init(void);
+void char_cleanup(void);
+
+#endif
diff --git a/harddoom_main.c b/harddoom_main.c
index 9ffe62f..300c910 100644
--- a/harddoom_main.c
+++ b/harddoom_main.c
@@ -1,29 +1,31 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 
+#include "char.h"
 #include "pci.h"
+#include "util.h"
 
 MODULE_LICENSE("GPL");
 
 int harddoom_init(void)
 {
 	int err = 0;
-	printk(KERN_INFO "Initializing harddoom\n");
-	err = pci_init();
-	if (err < 0) {
-		goto error;
-	}
+
+	ORFAIL(char_init(), error_char) ;
+	ORFAIL(pci_init(), error_pci);
 
 	return 0;
 
-error:
+error_pci:
+	char_cleanup();
+error_char:
 	return err;
 }
 
 void harddoom_cleanup(void)
 {
-	printk(KERN_INFO "Removing harddoom\n");
 	pci_cleanup();
+	char_cleanup();
 }
 
 module_init(harddoom_init);
diff --git a/pci.c b/pci.c
index 36f1ad8..3850633 100644
--- a/pci.c
+++ b/pci.c
@@ -3,46 +3,47 @@
 #include <linux/kernel.h>
 #include <linux/pci.h>
 
+#include "char.h"
 #include "harddoom.h"
+#include "pci.h"
+#include "util.h"
 
 int doom_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
-	printk(KERN_INFO "In probe\n");
-	return 0;
+	int err = 0;
+	ORFAIL(new_doomdev(), error_doomdev);
+
+error_doomdev:
+	return err;
 }
 
 void doom_remove (struct pci_dev *dev)
 {
-	printk(KERN_INFO "In remove\n");
+	destroy_doomdev();
 }
 
 int doom_suspend (struct pci_dev *dev, pm_message_t state)
 {
-	printk(KERN_INFO "In suspend\n");
 	return 0;
 }
 
 int doom_suspend_late (struct pci_dev *dev, pm_message_t state)
 {
-	printk(KERN_INFO "In suspend_late\n");
 	return 0;
 }
 
 int doom_resume_early (struct pci_dev *dev)
 {
-	printk(KERN_INFO "In resume_early\n");
 	return 0;
 }
 
 int doom_resume (struct pci_dev *dev)
 {
-	printk(KERN_INFO "In resume\n");
 	return 0;
 }
 
 void doom_shutdown (struct pci_dev *dev)
 {
-	printk(KERN_INFO "In shutdown\n");
 }
 
 struct pci_device_id device_ids[1] = {
@@ -63,12 +64,10 @@ struct pci_driver driver = {
 
 int pci_init(void)
 {
-	printk(KERN_INFO "In pci init\n");
 	return pci_register_driver(&driver);
 }
 
 void pci_cleanup(void)
 {
-	printk(KERN_INFO "In pci cleanup\n");
 	pci_unregister_driver(&driver);
 }
diff --git a/util.h b/util.h
new file mode 100644
index 0000000..bd9bcc3
--- /dev/null
+++ b/util.h
@@ -0,0 +1,22 @@
+#ifndef UTIL_H
+#define UTIL_H
+
+#define ORFAIL(cond, label) \
+({ \
+	err = (cond); \
+	if (err < 0) { \
+		goto label; \
+	} \
+})
+
+#define ORFAIL_PTR(cond, lvalue, label) \
+({ \
+	lvalue = (cond); \
+	if (IS_ERR(lvalue)) { \
+		err = PTR_ERR(lvalue); \
+		goto label; \
+	} \
+})
+	
+
+#endif