Beispiel-Treiber von Merlin Klaßen

examples/20150518/Makefile

+
+obj-m += mydriver2.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

examples/20150518/README

+From: Merlin Klaßen <merlin.klassen@hs-bochum.de>
+To: Peter Gerwinski <peter.gerwinski@hs-bochum.de>
+Subject: code für Treiber-Entwicklung
+
+Hi.
+Hier der Link den ich verwendet habe:
+http://sysplay.in/blog/tag/character-device-files/
+
+... und mein Quellcode (mit Makefile) im Anhang.
+Gruß Merlin

examples/20150518/mydriver2.c

+/* see http://www.tldp.org/LDP/lkmpg/2.6/html/x569.html */
+#include <linux/kernel.h>	/* Needed for KERN_INFO */
+#include <linux/module.h>	/* Needed by all modules */
+#include <linux/init.h>		/* Needed for the macros */
+#include <linux/fs.h>
+#include <asm/uaccess.h>	/* for put_user */
+#include <linux/device.h>
+#include <linux/cdev.h>
+
+//#define _BSD_SOURCE
+//#include <sys/types.h>
+//#include <sys/stat.h>
+//#include <fcntl.h>
+//#include <unistd.h>
+
+#define DRIVER_AUTHOR  "Merlin Klaszen"
+#define DRIVER_DESC    "My first own driver"
+#define DRIVER_LICENSE "Dual BSD/GPL"
+#define SUCCESS 0
+#define DEVICE_NAME "mydriver2"	/* Dev name as it appears in /proc/devices   */
+#define DEVICE_COUNT 1
+#define BUF_LEN 80
+
+static int device_open(struct inode *, struct file *);
+static int device_release(struct inode *, struct file *);
+static ssize_t device_read(struct file *, char *, size_t, loff_t *);
+static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
+
+static int Device_Open = 0;
+static char msg [ BUF_LEN ];
+static char *msg_Ptr;
+static dev_t dev;              /* a basic device struct, contains Major and Minor(-offset) */
+static struct cdev    chardev; /* will be bound to dev, to add special fields for character devices */
+static struct class  *cdc;     /* the 'class' of the device(s) */
+static struct device *myDev;   /* the struct, that represents the actual thing, which we will see in the file system  */
+
+static struct file_operations fops =
+{
+	.read = device_read,
+	.write = device_write,
+	.open = device_open,
+	.release = device_release
+};
+
+static int __init mydriver1_init ( void )
+{
+	int e = alloc_chrdev_region ( &dev, 0, DEVICE_COUNT, DEVICE_NAME );
+	if ( e < 0 )
+	{
+		printk ( KERN_ALERT "Registering %s failed with %d\n", DEVICE_NAME, e );
+		return e;
+	}
+	cdev_init ( &chardev, &fops );
+	chardev.owner = THIS_MODULE;
+	chardev.ops = &	fops;
+	e = cdev_add ( &chardev, dev, 1 );
+	if ( e )
+	{
+		printk ( KERN_INFO "%s: Error %d adding device", DEVICE_NAME, e );
+		return e;
+	}
+	cdc = class_create ( THIS_MODULE, "myCharDevClass" );
+	myDev = device_create ( cdc, NULL, dev, NULL, "myCharDev-%d-%d", MAJOR(dev), MINOR(dev) );
+
+	printk ( KERN_INFO "%s: Hello, world\n", DEVICE_NAME );
+	printk ( KERN_INFO "%s: Major: %d, Minor %d.\n", DEVICE_NAME, MAJOR(dev), MINOR(dev) );
+	
+	sprintf ( msg, "Try to write into this file\n" );
+	
+	return SUCCESS;
+}
+
+static void __exit mydriver1_exit ( void )
+{
+	printk ( KERN_INFO "%s: Goodbye, world\n", DEVICE_NAME );
+	
+	device_destroy ( cdc, dev );
+	class_destroy ( cdc );
+	cdev_del ( &chardev );
+	unregister_chrdev_region ( dev, DEVICE_COUNT );
+}
+
+static int device_open ( struct inode *inode, struct file *file )
+{
+	if ( Device_Open )
+	{
+		return -EBUSY;
+	}
+
+	Device_Open++;
+	msg_Ptr = msg;
+	try_module_get ( THIS_MODULE );
+	printk ( KERN_INFO "%s was opened.\n", DEVICE_NAME );
+
+	return SUCCESS;
+}
+
+static int device_release ( struct inode *inode, struct file *file )
+{
+	Device_Open--;
+
+	module_put(THIS_MODULE);
+	printk ( KERN_INFO "%s was closed.\n", DEVICE_NAME );
+
+	return 0;
+}
+
+static ssize_t device_read ( struct file *fp, char *buf, size_t len, loff_t * off )
+{
+	int bytes_read = 0;
+
+	/* At the end of the message, return 0 signifying end of file */
+	if (*msg_Ptr == 0)
+	{
+		return 0;
+	}
+
+	/* Actually put the data into the buffer */
+	while ( len && *msg_Ptr )
+	{
+		put_user(*(msg_Ptr++), buf++);
+		len--;
+		bytes_read++;
+	}
+	
+	printk ( KERN_INFO "%s: Someone read.\n", DEVICE_NAME );
+
+	/* return the number of bytes put into the buffer */
+	return bytes_read;
+}
+
+static ssize_t device_write ( struct file *fp, const char *buf, size_t len, loff_t * off )
+{
+	int bytes_written = 0;
+	char c = ' ';
+	msg_Ptr = msg;
+	if ( len >= BUF_LEN )
+	{
+		len = 79;
+	}
+	while ( len && c )
+	{
+		get_user ( c, buf );
+		if ( (c>='a') && (c<='z') )
+		{
+			c = c & ~0x20;
+		}
+		*msg_Ptr = c;
+		msg_Ptr++;
+		len--;
+		bytes_written++;
+		buf++;
+	}
+	if ( *(msg_Ptr - 1) ) /* make sure the string is terminated */
+	{
+		*msg_Ptr = '\0';
+	}
+	msg_Ptr = msg;
+	printk ( KERN_INFO "%s: Someone wrote.\n", DEVICE_NAME );
+	
+	return bytes_written;
+}
+
+module_init(mydriver1_init);
+module_exit(mydriver1_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);	/* Who wrote this module? */
+MODULE_DESCRIPTION(DRIVER_DESC);	/* What does this module do */
+MODULE_LICENSE(DRIVER_LICENSE);
+
+/*  
+  MODULE_SUPPORTED_DEVICE("testdevice");
+ * This module may use /dev/testdevice. The MODULE_SUPPORTED_DEVICE macro might
+ * be used in the future to help automatic configuration of modules, but is 
+ * currently unused other than for documentation purposes.
+ */
+