list2.c

/***************************************************************************//**
*  \file       driver.c
*
*  \details    Simple Linux device driver (Kernel Linked List)
*
*  \author     EmbeTronicX
*
* *******************************************************************************/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kdev_t.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include<linux/slab.h>                 //kmalloc()
#include<linux/uaccess.h>              //copy_to/from_user()
#include<linux/sysfs.h> 
#include<linux/kobject.h> 
#include <linux/interrupt.h>
#include <asm/io.h>
#include <linux/workqueue.h>            // Required for workqueues
 
 
#define IRQ_NO 11
 
volatile int etx_value = 0;
 
dev_t dev = 0;
static struct class *dev_class;
static struct cdev etx_cdev;
struct kobject *kobj_ref;
 
static int __init etx_driver_init(void);
static void __exit etx_driver_exit(void);
 
static struct workqueue_struct *own_workqueue;
 
 
static void workqueue_fn(struct work_struct *work); 
 
static DECLARE_WORK(work, workqueue_fn);
 
/*Linked List Node*/
struct my_list{
     struct list_head list;     //linux kernel list implementation
     int data;
};
 
/*Declare and init the head node of the linked list*/
LIST_HEAD(Head_Node);
 
/*
** Function Prototypes
*/ 
/*************** Driver Fuctions **********************/
static int etx_open(struct inode *inode, struct file *file);
static int etx_release(struct inode *inode, struct file *file);
static ssize_t etx_read(struct file *filp, 
                char __user *buf, size_t len,loff_t * off);
static ssize_t etx_write(struct file *filp, 
                const char *buf, size_t len, loff_t * off);
 
/*************** Sysfs Fuctions **********************/
static ssize_t sysfs_show(struct kobject *kobj, 
                struct kobj_attribute *attr, char *buf);
static ssize_t sysfs_store(struct kobject *kobj, 
                struct kobj_attribute *attr,const char *buf, size_t count);
 
struct kobj_attribute etx_attr = __ATTR(etx_value, 0660, sysfs_show, sysfs_store);
/******************************************************/
 
 
/*Workqueue Function*/
static void workqueue_fn(struct work_struct *work)
{
        struct my_list *temp_node = NULL;
 
        printk(KERN_INFO "Executing Workqueue Function\n");
        
        /*Creating Node*/
        temp_node = kmalloc(sizeof(struct my_list), GFP_KERNEL);
 
        /*Assgin the data that is received*/
        temp_node->data = etx_value;
 
        /*Init the list within the struct*/
        INIT_LIST_HEAD(&temp_node->list);
 
        /*Add Node to Linked List*/
        list_add_tail(&temp_node->list, &Head_Node);
}
 
 
//Interrupt handler for IRQ 11. 
static irqreturn_t irq_handler(int irq,void *dev_id) {
        printk(KERN_INFO "Shared IRQ: Interrupt Occurred\n");
        /*Allocating work to queue*/
        queue_work(own_workqueue, &work);
        
        return IRQ_HANDLED;
}

/*
** File operation sturcture
*/ 
static struct file_operations fops =
{
        .owner          = THIS_MODULE,
        .read           = etx_read,
        .write          = etx_write,
        .open           = etx_open,
        .release        = etx_release,
};

/*
** This fuction will be called when we read the sysfs file
*/  
static ssize_t sysfs_show(struct kobject *kobj, 
                struct kobj_attribute *attr, char *buf)
{
        printk(KERN_INFO "Sysfs - Read!!!\n");
        return sprintf(buf, "%d", etx_value);
}

/*
** This fuction will be called when we write the sysfsfs file
*/  
static ssize_t sysfs_store(struct kobject *kobj, 
                struct kobj_attribute *attr,const char *buf, size_t count)
{
        printk(KERN_INFO "Sysfs - Write!!!\n");
        return count;
}

/*
** This fuction will be called when we open the Device file
*/ 
static int etx_open(struct inode *inode, struct file *file)
{
        printk(KERN_INFO "Device File Opened...!!!\n");
        return 0;
}

/*
** This fuction will be called when we close the Device file
*/   
static int etx_release(struct inode *inode, struct file *file)
{
        printk(KERN_INFO "Device File Closed...!!!\n");
        return 0;
}

/*
** This fuction will be called when we read the Device file
*/ 
static ssize_t etx_read(struct file *filp, 
                char __user *buf, size_t len, loff_t *off)
{
        struct my_list *temp;
        int count = 0;
        printk(KERN_INFO "Read function\n");
 
        /*Traversing Linked List and Print its Members*/
        list_for_each_entry(temp, &Head_Node, list) {
            printk(KERN_INFO "Node %d data = %d\n", count++, temp->data);
        }
 
        printk(KERN_INFO "Total Nodes = %d\n", count);
        return 0;
}

/*
** This fuction will be called when we write the Device file
*/
static ssize_t etx_write(struct file *filp, 
                const char __user *buf, size_t len, loff_t *off)
{
        printk(KERN_INFO "Write Function\n");
        /*Copying data from user space*/
        sscanf(buf,"%d",&etx_value);
        /* Triggering Interrupt */
        asm("int $0x3B");  // Corresponding to irq 11
        return len;
}
 
/*
** Module Init function
*/  
static int __init etx_driver_init(void)
{
        /*Allocating Major number*/
        if((alloc_chrdev_region(&dev, 0, 1, "etx_Dev")) <0){
                printk(KERN_INFO "Cannot allocate major number\n");
                return -1;
        }
        printk(KERN_INFO "Major = %d Minor = %d n",MAJOR(dev), MINOR(dev));
 
        /*Creating cdev structure*/
        cdev_init(&etx_cdev,&fops);
 
        /*Adding character device to the system*/
        if((cdev_add(&etx_cdev,dev,1)) < 0){
            printk(KERN_INFO "Cannot add the device to the system\n");
            goto r_class;
        }
 
        /*Creating struct class*/
        if((dev_class = class_create(THIS_MODULE,"etx_class")) == NULL){
            printk(KERN_INFO "Cannot create the struct class\n");
            goto r_class;
        }
 
        /*Creating device*/
        if((device_create(dev_class,NULL,dev,NULL,"etx_device")) == NULL){
            printk(KERN_INFO "Cannot create the Device \n");
            goto r_device;
        }
 
        /*Creating a directory in /sys/kernel/ */
        kobj_ref = kobject_create_and_add("etx_sysfs",kernel_kobj);
 
        /*Creating sysfs file*/
        if(sysfs_create_file(kobj_ref,&etx_attr.attr)){
                printk(KERN_INFO"Cannot create sysfs file......\n");
                goto r_sysfs;
        }
        if (request_irq(IRQ_NO, irq_handler, IRQF_SHARED, "etx_device", (void *)(irq_handler))) {
            printk(KERN_INFO "my_device: cannot register IRQ \n");
                    goto irq;
        }
 
        /*Creating workqueue */
        own_workqueue = create_workqueue("own_wq");
        
        printk(KERN_INFO "Device Driver Insert...Done!!!\n");
        return 0;
 
irq:
        free_irq(IRQ_NO,(void *)(irq_handler));
 
r_sysfs:
        kobject_put(kobj_ref); 
        sysfs_remove_file(kernel_kobj, &etx_attr.attr);
 
r_device:
        class_destroy(dev_class);
r_class:
        unregister_chrdev_region(dev,1);
        cdev_del(&etx_cdev);
        return -1;
}

/*
** Module Exit function
*/ 
static void __exit etx_driver_exit(void)
{
 
        /* Go through the list and free the memory. */
        struct my_list *cursor, *temp;
        list_for_each_entry_safe(cursor, temp, &Head_Node, list) {
            list_del(&cursor->list);
            kfree(cursor);
        }
 
        /* Delete workqueue */
        destroy_workqueue(own_workqueue);
        free_irq(IRQ_NO,(void *)(irq_handler));
        kobject_put(kobj_ref); 
        sysfs_remove_file(kernel_kobj, &etx_attr.attr);
        device_destroy(dev_class,dev);
        class_destroy(dev_class);
        cdev_del(&etx_cdev);
        unregister_chrdev_region(dev, 1);
        printk(KERN_INFO "Device Driver Remove...Done!!\n");
}
 
module_init(etx_driver_init);
module_exit(etx_driver_exit);
 
MODULE_LICENSE("GPL");
MODULE_AUTHOR("EmbeTronicX <embetronicx@gmail.com>");
MODULE_DESCRIPTION("A simple device driver - Kernel Linked List");
MODULE_VERSION("1.13");