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linux驅動開發--字符設備：創建一組設備節點
cdev改進為設備驅動支持多個設備個體做準備，針對cdev進行改進
將代表字符設備的cdev對象包含在設備驅動定義的私有數據結構體中
對設備驅動私有數據結構體采用內核內存分配方式為其分配內存
將為每個設備添加cdev對象和創建設備節點封裝為一個獨立函數
支持多個設備個體
為設備驅動支持多個設備個體對驅動進行改進
循環調用為每個設備添加cdev對象和創建設備節點而封裝的獨立函數實現在係統中添加對多個設備個體的支持
/**
*Copyright (c) 2013.TianYuan
*All rights reserved.
*
*文件名稱: char_device_driver06.c
*文件標識: 支持多設備:創建10個設備節點文件,操作函數還需修改
*#測試： cat /dev/cdd0
*當前版本：1.0
*作者：wuyq
*
*取代版本：xxx
*原作者：xxx
*完成日期：2013-11-26
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/slab.h>
MODULE_LICENSE("GPL");
#define CDD_MAJOR 200//cat /proc/devices找一個尚未使用的
#define CDD_MINOR 0
#define CDD_COUNT 10
dev_t dev = 0;
u32 cdd_major = 0;
u32 cdd_minor = 0;
struct class *dev_class = NULL;
struct cdd_cdev{
struct cdev cdev;
struct device *dev_device;
u8 led;
};
struct cdd_cdev *cdd_cdevp = NULL;
int cdd_open(struct inode* inode, struct file *filp)
{
struct cdd_cdev *pcdevp = NULL;
printk("enter cdd_open!\n");
pcdevp = container_of(inode->i_cdev, struct cdd_cdev, cdev);
printk("led = %d\n", pcdevp->led);
return 0;
}
int cdd_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
{
printk("enter cdd_read!\n");
return 0;
}
int cdd_write(struct file *filp, const char __user *buf, size_t count, loff_t *offset)
{
printk("enter cdd_write!\n");
return 0;
}
int cdd_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long data)
{
printk("enter cdd_ioctl!\n");
return 0;
}
int cdd_release(struct inode *inode, struct file *filp)
{
printk("enter cdd_release!\n");
return 0;
}
struct file_operations cdd_fops = {
.owner = THIS_MODULE,
.open = cdd_open,
.read = cdd_read,
.write = cdd_write,
.ioctl = cdd_ioctl,
.release = cdd_release,
};
int __init cdd_init(void)
{
int ret = 0;
int i = 0;
if(cdd_major){
dev = MKDEV(CDD_MAJOR, CDD_MINOR);//生成設備號
//注冊設備號;1、要注冊的起始設備號2、連續注冊的設備號個數3、名字
ret = register_chrdev_region(dev, CDD_COUNT, "cdd_demo");
}else{
// 動態分配設備號
ret = alloc_chrdev_region(&dev, cdd_minor, CDD_COUNT, "cdd_demo02");
}
if(ret < 0){
printk("register_chrdev_region failed!\n");
goto failure_register_chrdev;
}
//獲取主設備號
cdd_major = MAJOR(dev);
printk("cdd_major = %d\n", cdd_major);
cdd_cdevp = kzalloc(sizeof(struct cdd_cdev)*CDD_COUNT, GFP_KERNEL);
if(IS_ERR(cdd_cdevp)){
printk("kzalloc failed!\n");
goto failure_kzalloc;
}
/*創建設備類*/
dev_class = class_create(THIS_MODULE, "cdd_class");
if(IS_ERR(dev_class)){
printk("class_create failed!\n");
goto failure_dev_class;
}
for(i=0; i<CDD_COUNT; i++){
/*初始化cdev*/
cdev_init(&(cdd_cdevp[i].cdev), &cdd_fops);
/*添加cdev到內核*/
cdev_add(&(cdd_cdevp[i].cdev), dev+i, 1);
/* “/dev/xxx” */
device_create(dev_class, NULL, dev+i, NULL, "cdd%d", i);
cdd_cdevp[i].led = i;
}
return 0;
failure_dev_class:
kfree(cdd_cdevp);
failure_kzalloc:
unregister_chrdev_region(dev, CDD_COUNT);
failure_register_chrdev:
return ret;
}
void __exit cdd_exit(void)
{
/*逆序消除*/
int i = 0;
for(; i < CDD_COUNT; i++){
device_destroy(dev_class, dev+i);
cdev_del(&(cdd_cdevp[i].cdev));
//cdev_del(&((cdd_cdevp+i)->cdev));
}
class_destroy(dev_class);
kfree(cdd_cdevp);
unregister_chrdev_region(dev, CDD_COUNT);
}
module_init(cdd_init);
module_exit(cdd_exit);
最後更新：2017-04-03 12:53:59