设备驱动之一 - 最简单的可运行的scull模块

/**********************************************
* Author: lewiyon@hotmail.com
* File name: scull.h
* Description: define scull
* Date: 2012-07-4
*********************************************/
#ifndef __SCULL_H
#define __SCULL_H

#include <linux/semaphore.h>
#include <linux/cdev.h>
#include <linux/fs.h>           /* register      */

#ifndef SCULL_MAJOR
#define SCULL_MAJOR     0
#endif

#ifndef SCULL_NR_DEVS
#define SCULL_NR_DEVS   1
#endif

#ifndef SCULL_QUANTUM
#define SCULL_QUANTUM   5000
#endif

#ifndef SCULL_QSET
#define SCULL_QSET      1000
#endif

/*
* parameters of module
*/
int scull_major;
int scull_quantum;
int scull_qset;

struct scull_qset {
void **data;
struct scull_qset *next;
};

/*
* define scull_dev struct
*/
struct scull_dev {
struct scull_qset *data; /* point first child set */
int quantum;             /* size of current set   */
int qset;                /* size of array         */
unsigned long size;      /* save total quantity   */
unsigned int access_key; /* used by scullid and scullpriv */
struct semaphore sem;    /* mutex                 */
struct cdev cdev;        /* character device      */
};

struct file_operations scull_fops;

int scull_trim(struct scull_dev *dev);

#endif

/**********************************************
* Author: lewiyon@hotmail.com
* File name: initialize and release function for scull
* Description: scull
* Date: 2012-07-4
*********************************************/

#include <linux/init.h>         /* module        */
#include <linux/module.h>       /* module        */
#include <linux/moduleparam.h>  /* module        */
#include <linux/errno.h>        /* error codes   */
#include <linux/kernel.h>       /* printk        */
#include <linux/slab.h>         /* kmalloc kfree */
#include <linux/types.h>        /* dev_t         */

/* local head files */
#include "scull.h"

/* default parameters of module */
int scull_major = SCULL_MAJOR;
int scull_minor = 0;
int scull_nr_devs = SCULL_NR_DEVS;
int scull_quantum = SCULL_QUANTUM;
int scull_qset = SCULL_QSET;

/* input parameters of module */
module_param(scull_major, int, S_IRUGO);
module_param(scull_minor, int, S_IRUGO);
module_param(scull_nr_devs, int, S_IRUGO);
module_param(scull_quantum, int, S_IRUGO);
module_param(scull_qset, int, S_IRUGO);

struct scull_dev *scull_devices;

/*
* scull_trim -  遍历链表，并释放所有找到的量子和量子集
*/
int scull_trim(struct scull_dev *dev)
{
int i, qset;
struct scull_qset *next, *dptr;

qset = dev->qset;
for (dptr = dev->data; dptr; dptr = next) {
if (dptr->data) {
for (i = 0; i < qset; i++)
kfree(dptr->data[i]);
kfree(dptr->data);
dptr->data = NULL;
}
next = dptr->next;
kfree(dptr);
}
dev->size = 0;
dev->quantum = scull_quantum;
dev->qset = scull_qset;
dev->data = NULL;

return 0;
}

static void scull_setup_cdev(struct scull_dev *dev, int index)
{
int err;
int devno;

devno = MKDEV(scull_major, scull_minor + index);
cdev_init(&dev->cdev, &scull_fops);
dev->cdev.owner = THIS_MODULE;
//dev->cdev.ops = &scull_fops;

err = cdev_add(&dev->cdev, devno, 1);
if (err)
printk(KERN_NOTICE "Error %d adding scull%d", err, index);

}

/*
* initialze scull module
*/
void scull_cleanup_module(void)
{
int i;
dev_t devno;

devno = MKDEV(scull_major, scull_minor);
/* delete each entry */
if (scull_devices) {
for (i = 0; i < scull_nr_devs; i++) {
scull_trim(scull_devices + i);
cdev_del(&scull_devices[i].cdev);
}
kfree(scull_devices);
}

/* unregister */
unregister_chrdev_region(devno, scull_nr_devs);
printk(KERN_WARNING "scull: Bye!\n");
}

/*
* initialze scull module
*/
int scull_init_module(void)
{
int i, res;
dev_t dev = 0;

if (scull_major) {
dev = MKDEV(scull_major, scull_minor);
res = register_chrdev_region(dev, scull_nr_devs, "scull");
} else {
res = alloc_chrdev_region(&dev, scull_minor,
scull_nr_devs, "scull");
scull_major = MAJOR(dev);
}
if (res < 0) {
printk(KERN_WARNING "scull: can't get major %d\n", scull_major);
return res;
}

/*
* allocate the device struct cache
*/
scull_devices = kmalloc(scull_nr_devs * sizeof(struct scull_dev),
GFP_KERNEL);
if (NULL == scull_devices) {
res = -ENOMEM;
printk(KERN_WARNING "scull: NOMEM for scull!\n");
goto fail;
}
memset(scull_devices, 0, scull_nr_devs * sizeof(struct scull_dev));
/* initialize each device */
for (i = 0; i < scull_nr_devs; i++) {
scull_devices[i].quantum = scull_quantum;
scull_devices[i].qset = scull_qset;
sema_init(&scull_devices[i].sem, 1);
scull_setup_cdev(&scull_devices[i], i);
}
printk(KERN_INFO "scull: OK!\n");
return 0;
fail:
scull_cleanup_module();
return res;
}

module_init(scull_init_module);
module_exit(scull_cleanup_module);

MODULE_AUTHOR("lewiyon@hotmail.com");
MODULE_LICENSE("GPL");

obj-m := scull.o
KERNELBUILD := /lib/modules/$(shell uname -r)/build
default:
$(MAKE) -C $(KERNELBUILD) M=$(shell pwd) modules
clean:
-rm -rf *.o .*.cmd *.ko* *.mod.c .tmp_versions
-rm -rf  modules.order Module.symvers