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作者:晏渭川
随着Linux2.6的发布,由于2.6内核做了新的改动,各个设备的驱动程序在不同程度上要进行改写。为了方便各位Linux爱好者我把自己整理的这分 文档share出来。该文当列举了2.6内核同以前版本的绝大多数变化,可惜的是由于时间和精力有限没有详细列出各个函数的用法。

1、 使用新的入口
必须包含 <linux/init.h>
module_init(your_init_func);
module_exit(your_exit_func);
老版本:int init_module(void);
void cleanup_module(voi);
2.4中两种都可以用,对如后面的入口函数不必要显示包含任何头文件。

2、 GPL
MODULE_LICENSE("Dual BSD/GPL");
老版本:MODULE_LICENSE("GPL");

3、 模块参数
必须显式包含<linux/moduleparam.h>
module_param(name, type, perm);
module_param_named(name, value, type, perm);
参数定义
module_param_string(name, string, len, perm);
module_param_array(name, type, num, perm);
老版本:MODULE_PARM(variable,type);
MODULE_PARM_DESC(variable,type);

4、 模块别名
MODULE_ALIAS("alias-name");
这是新增的,在老版本中需在/etc/modules.conf配置,现在在代码中就可以实现。

5、 模块计数
int try_module_get(&module);
module_put();
老版本:MOD_INC_USE_COUNT 和 MOD_DEC_USE_COUNT

http://www.fsl.cs.sunysb.edu/~sean/parser.cgi?modules

In 2.4 modules, the MOD_INC_USE_COUNT macro is used to prevent unloading of the module while there is an open file. The 2.6 kernel, however, knows not to unload a module that owns a character device that's currently open.
However, this requires that the module be explicit in specifying ownership of character devices, using the THIS_MODULE macro.

You also have to take out all calls to MOD_INC_USE_COUNT and MOD_DEC_USE_COUNT.
       
    static struct file_operations fops =
{
         .owner = THIS_MODULE,
         .read = device_read,
         .write = device_write,
         .open = device_open,
         .release = device_release
}    
       

The 2.6 kernel considers modules that use the deprecated facility to be unsafe, and does not permit their unloading, even with rmmod -f.

2.6,2.5的kbuild不需要到处加上MOD_INC_USE_COUNT来消除模块卸载竞争(module unload race)

6、 符号导出
只有显示的导出符号才能被其他模块使用,默认不导出所有的符号,不必使用EXPORT_NO_SYMBOLS
老板本:默认导出所有的符号,除非使用EXPORT_NO_SYMBOLS

7、 内核版本检查
需要在多个文件中包含<linux/module.h>时,不必定义__NO_VERSION__
老版本:在多个文件中包含<linux/module.h>时,除在主文件外的其他文件中必须定义__NO_VERSION__,防止版本重复定义。

8、 设备号
kdev_t被废除不可用,新的dev_t拓展到了32位,12位主设备号,20位次设备号。
unsigned int iminor(struct inode *inode);
unsigned int imajor(struct inode *inode);
老版本:8位主设备号,8位次设备号
int MAJOR(kdev_t dev);
int MINOR(kdev_t dev);

9、 内存分配头文件变更
所有的内存分配函数包含在头文件<linux/slab.h>,而原来的<linux/malloc.h>不存在
老版本:内存分配函数包含在头文件<linux/malloc.h>

10、 结构体的初试化
gcc开始采用ANSI C的struct结构体的初始化形式:
static struct some_structure = {
.field1 = value,
.field2 = value,
..
};
老版本:非标准的初试化形式
static struct some_structure = {
field1: value,
field2: value,
..
};

11、 用户模式帮助器
int call_usermodehelper(char *path, char **argv, char **envp, int wait);
新增wait参数

12、 request_module()
request_module("foo-device-%d", number);
老版本:
char module_name[32];
printf(module_name, "foo-device-%d", number);
request_module(module_name);

13、 dev_t引发的字符设备的变化
1、取主次设备号为
unsigned iminor(struct inode *inode);
unsigned imajor(struct inode *inode);
2、老的register_chrdev()用法没变,保持向后兼容,但不能访问设备号大于256的设备。
3、新的接口为
a)注册字符设备范围
int register_chrdev_region(dev_t from, unsigned count, char *name);
b)动态申请主设备号
int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, char *name);
看了这两个函数郁闷吧^_^!怎么和file_operations结构联系起来啊?别急!
c)包含 <linux/cdev.h>,利用struct cdev和file_operations连接
struct cdev *cdev_alloc(void);
void cdev_init(struct cdev *cdev, struct file_operations *fops);
int cdev_add(struct cdev *cdev, dev_t dev, unsigned count);
(分别为,申请cdev结构,和fops连接,将设备加入到系统中!好复杂啊!)
d)void cdev_del(struct cdev *cdev);
只有在cdev_add执行成功才可运行。
e)辅助函数
kobject_put(&cdev->kobj);
struct kobject *cdev_get(struct cdev *cdev);
void cdev_put(struct cdev *cdev);
这一部分变化和新增的/sys/dev有一定的关联。

14、 新增对/proc的访问操作
<linux/seq_file.h>
以前的/proc中只能得到string, seq_file操作能得到如long等多种数据。
相关函数:
static struct seq_operations 必须实现这个类似file_operations得数据中得各个成员函数。
seq_printf();
int seq_putc(struct seq_file *m, char c);
int seq_puts(struct seq_file *m, const char *s);
int seq_escape(struct seq_file *m, const char *s, const char *esc);
int seq_path(struct seq_file *m, struct vfsmount *mnt,
struct dentry *dentry, char *esc);
seq_open(file, &ct_seq_ops);
等等

15、 底层内存分配
1、<linux/malloc.h>头文件改为<linux/slab.h>
2、分配标志GFP_BUFFER被取消,取而代之的是GFP_NOIO 和 GFP_NOFS
3、新增__GFP_REPEAT,__GFP_NOFAIL,__GFP_NORETRY分配标志
4、页面分配函数alloc_pages(),get_free_page()被包含在<linux/gfp.h>中
5、对NUMA系统新增了几个函数:
a) struct page *alloc_pages_node(int node_id, unsigned int gfp_mask, unsigned int order);
b) void free_hot_page(struct page *page);
c) void free_cold_page(struct page *page);
6、 新增Memory pools
<linux/mempool.h>
mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn, mempool_free_t *free_fn, void *pool_data);
void *mempool_alloc(mempool_t *pool, int gfp_mask);
void mempool_free(void *element, mempool_t *pool);
int mempool_resize(mempool_t *pool, int new_min_nr, int gfp_mask);

16、 per-CPU变量
get_cpu_var();
put_cpu_var();
void *alloc_percpu(type);
void free_percpu(const void *);
per_cpu_ptr(void *ptr, int cpu)
get_cpu_ptr(ptr)
put_cpu_ptr(ptr)
老版本使用
DEFINE_PER_CPU(type, name);
EXPORT_PER_CPU_SYMBOL(name);
EXPORT_PER_CPU_SYMBOL_GPL(name);
DECLARE_PER_CPU(type, name);
DEFINE_PER_CPU(int, mypcint);
2.6内核采用了可剥夺得调度方式这些宏都不安全。

17、 内核时间变化
1、现在的各个平台的HZ为
Alpha: 1024/1200; ARM: 100/128/200/1000; CRIS: 100; i386: 1000; IA-64: 1024; M68K: 100; M68K-nommu: 50-1000; MIPS: 100/128/1000; MIPS64: 100; PA-RISC: 100/1000; PowerPC32: 100; PowerPC64: 1000; S/390: 100; SPARC32: 100; SPARC64: 100; SuperH: 100/1000; UML: 100; v850: 24-100; x86-64: 1000.
2、由于HZ的变化,原来的jiffies计数器很快就溢出了,引入了新的计数器jiffies_64
3、#include <linux/jiffies.h>
u64 my_time = get_jiffies_64();
4、新的时间结构增加了纳秒成员变量
struct timespec current_kernel_time(void);
5、他的timer函数没变,新增
void add_timer_on(struct timer_list *timer, int cpu);
6、新增纳秒级延时函数
ndelay();
7、POSIX clocks 参考kernel/posix-timers.c

18、 工作队列(workqueue)
1、任务队列(task queue )接口函数都被取消,新增了workqueue接口函数
struct workqueue_struct *create_workqueue(const char *name);
DECLARE_WORK(name, void (*function)(void *), void *data);
INIT_WORK(struct work_struct *work,
void (*function)(void *), void *data);
PREPARE_WORK(struct work_struct *work,
void (*function)(void *), void *data);
2、申明struct work_struct结构
int queue_work(struct workqueue_struct *queue, struct work_struct *work);
int queue_delayed_work(struct workqueue_struct *queue, struct work_struct *work,
unsigned long delay);
int cancel_delayed_work(struct work_struct *work);
void flush_workqueue(struct workqueue_struct *queue);
void destroy_workqueue(struct workqueue_struct *queue);
int schedule_work(struct work_struct *work);
int schedule_delayed_work(struct work_struct *work, unsigned long delay);

19、 新增创建VFS的"libfs"
libfs给创建一个新的文件系统提供了大量的API.
主要是对struct file_system_type的实现。
参考源代码:
drivers/hotplug/pci_hotplug_core.c
drivers/usb/core/inode.c
drivers/oprofile/oprofilefs.c
fs/ramfs/inode.c
fs/nfsd/nfsctl.c (simple_fill_super() example)

20、 DMA的变化
未变化的有:
void *pci_alloc_consistent(struct pci_dev *dev, size_t size, dma_addr_t *dma_handle);
void pci_free_consistent(struct pci_dev *dev, size_t size, void *cpu_addr, dma_addr_t dma_handle);
变化的有:
1、 void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, int flag);
void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_handle);
2、列举了映射方向:
enum dma_data_direction {
DMA_BIDIRECTIONAL = 0,
DMA_TO_DEVICE = 1,
DMA_FROM_DEVICE = 2,
DMA_NONE = 3,
};
3、单映射
dma_addr_t dma_map_single(struct device *dev, void *addr, size_t size, enum dma_data_direction direction);
void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction direction);
4、页面映射
dma_addr_t dma_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction direction);
void dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction direction);
5、有关scatter/gather的函数:
int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction direction);
void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nhwentries, enum dma_data_direction direction);
6、非一致性映射(Noncoherent DMA mappings)
void *dma_alloc_noncoherent(struct device *dev, size_t size, dma_addr_t *dma_handle, int flag);
void dma_sync_single_range(struct device *dev, dma_addr_t dma_handle, unsigned long offset, size_t size,
enum dma_data_direction direction);
void dma_free_noncoherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_handle);
7、DAC (double address cycle)
int pci_dac_set_dma_mask(struct pci_dev *dev, u64 mask);
void pci_dac_dma_sync_single(struct pci_dev *dev, dma64_addr_t dma_addr, size_t len, int direction);

21、 互斥
新增seqlock主要用于:
1、少量的数据保护
2、数据比较简单(没有指针),并且使用频率很高
3、对不产生任何副作用的数据的访问
4、访问时写者不被饿死
<linux/seqlock.h>
初始化
seqlock_t lock1 = SEQLOCK_UNLOCKED;
或seqlock_t lock2; seqlock_init(&lock2);
void write_seqlock(seqlock_t *sl);
void write_sequnlock(seqlock_t *sl);
int write_tryseqlock(seqlock_t *sl);
void write_seqlock_irqsave(seqlock_t *sl, long flags);
void write_sequnlock_irqrestore(seqlock_t *sl, long flags);
void write_seqlock_irq(seqlock_t *sl);
void write_sequnlock_irq(seqlock_t *sl);
void write_seqlock_bh(seqlock_t *sl);
void write_sequnlock_bh(seqlock_t *sl);
unsigned int read_seqbegin(seqlock_t *sl);
int read_seqretry(seqlock_t *sl, unsigned int iv);
unsigned int read_seqbegin_irqsave(seqlock_t *sl, long flags);
int read_seqretry_irqrestore(seqlock_t *sl, unsigned int iv, long flags);

22、 内核可剥夺
<linux/preempt.h>
preempt_disable();
preempt_enable_no_resched();
preempt_enable_noresched();
preempt_check_resched();

23、 眠和唤醒
1、原来的函数可用,新增下列函数:
prepare_to_wait_exclusive();
prepare_to_wait();
2、等待队列的变化
typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int sync);
void init_waitqueue_func_entry(wait_queue_t *queue, wait_queue_func_t func);

24、 新增完成事件(completion events)
<linux/completion.h>
init_completion(&my_comp);
void wait_for_completion(struct completion *comp);
void complete(struct completion *comp);
void complete_all(struct completion *comp);

25、 RCU(Read-copy-update)
rcu_read_lock();
void call_rcu(struct rcu_head *head, void (*func)(void *arg),
void *arg);

26、 中断处理
1、中断处理有返回值了。
IRQ_RETVAL(handled);
2、cli(), sti(), save_flags(), 和 restore_flags()不再有效,应该使用local_save
_flags() 或local_irq_disable()。
3、synchronize_irq()函数有改动
4、新增int can_request_irq(unsigned int irq, unsigned long flags);
5、 request_irq() 和free_irq() 从 <linux/sched.h>改到了 <linux/interrupt.h>

27、 异步I/O(AIO)
<linux/aio.h>
ssize_t (*aio_read) (struct kiocb *iocb, char __user *buffer, size_t count, loff_t pos);
ssize_t (*aio_write) (struct kiocb *iocb, const char __user *buffer, size_t count, loff_t pos);
int (*aio_fsync) (struct kiocb *, int datasync);
新增到了file_operation结构中。
is_sync_kiocb(struct kiocb *iocb);
int aio_complete(struct kiocb *iocb, long res, long res2);

28、 网络驱动
1、struct net_device *alloc_netdev(int sizeof_priv, const char *name, void (*setup)(struct net_device *));
struct net_device *alloc_etherdev(int sizeof_priv);
2、新增NAPI(New API)
void netif_rx_schedule(struct net_device *dev);
void netif_rx_complete(struct net_device *dev);
int netif_rx_ni(struct sk_buff *skb);
(老版本为netif_rx())

29、 USB驱动
老版本struct usb_driver取消了,新的结构体为
struct usb_class_driver {
char *name;
struct file_operations *fops;
mode_t mode;
int minor_base;
};
int usb_submit_urb(struct urb *urb, int mem_flags);
int (*probe) (struct usb_interface *intf,
const struct usb_device_id *id);

30、 block I/O 层
这一部分做的改动最大。不祥叙。

31、 mmap()
int remap_page_range(struct vm_area_struct *vma, unsigned long from, unsigned long to, unsigned long size, pgprot_t prot);
int io_remap_page_range(struct vm_area_struct *vma, unsigned long from, unsigned long to, unsigned long size, pgprot_t prot);
struct page *(*nopage)(struct vm_area_struct *area, unsigned long address, int *type);
int (*populate)(struct vm_area_struct *area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock);
int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot);
struct page *vmalloc_to_page(void *address);

32、 零拷贝块I/O(Zero-copy block I/O)
struct bio *bio_map_user(struct block_device *bdev, unsigned long uaddr, unsigned int len, int write_to_vm);
void bio_unmap_user(struct bio *bio, int write_to_vm);
int get_user_pages(struct task_struct *task, struct mm_struct *mm, unsigned long start, int len, int write, int force, struct page **pages, struct vm_area_struct **vmas);

33、 高端内存操作kmaps
void *kmap_atomic(struct page *page, enum km_type type);
void kunmap_atomic(void *address, enum km_type type);
struct page *kmap_atomic_to_page(void *address);
老版本:kmap() 和 kunmap()。

34、 驱动模型
主要用于设备管理。
1、 sysfs
2、 Kobjects

推荐文章:
http:/www-900.ibm.com/developerWorks/cn/linux/kernel/l-kernel26/index.shtml
http:/www-900.ibm.com/developerWorks/cn/linux/l-inside/index.shtml

2.6里不需要再定义“__KERNEL__”和“MODULE”了。
用下面的Makefile文件编译:

代码:

    obj-m   := hello.o

    KDIR   := /lib/modules/$(shell uname -r)/build
    PWD      := $(shell pwd)
    default:
              $(MAKE) -C $(KDIR) M=$(PWD) modules


评论

# 请求帮忙写个linux2.6内核的模块化的字符设备驱动程序  回复  更多评论   

2009-05-26 09:56 by 晴天
请求帮忙写个linux2.6内核的模块化的字符设备驱动程序

我写了个可以运行于linux2.4内核的但是不会改成可以运行在linux2.6内核上的

请帮忙
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>

#define DEMO_MAJOR 125
#define COMMAND1 1
#define COMMAND2 2

static int demo_init(void);
static int demo_open(struct inode *inode,struct file *file);
static int demo_close(struct inode *inode,struct file *file);
static ssize_t demo_read(struct file *file,char *buf,size_t count,loff_t *offset);
static int demo_ioctl(struct inode *inode,struct file *file,unsigned int cmd,unsigned long arg);
static void demo_cleanup(void);

int demo_param = 9;
static int demo_initialized = 0;
static volatile int demo_flag = 0;
static struct file_operations demo_fops = {
owner:THIS_MODULE,
llseek:NULL,
read:demo_read,
write:NULL,
ioctl:demo_ioctl,
open:demo_open,
release:demo_close,
};

static int demo_init(void)
{
int i;
if(demo_initialized == 1)
return 0;
i = register_chrdev(DEMO_MAJOR,"demo_drv",&demo_fops);
if(i<0)
{
printk(KERN_CRIT"DEMO:i=%d\n",i);
return -EIO;
}
printk(KERN_CRIT"DEMO:demo_drv registerred successfully:)=\n");

demo_initialized = 1;
return 0;
}

static int demo_open(struct inode *inode,struct file *file)
{
if(demo_flag==1)
{
return -1;
}
printk(KERN_CRIT"DEMO:demo device open \n");
MOD_INC_USE_COUNT;
demo_flag = 1;
return 0;
}

static int demo_close(struct inode *inode,struct file *file)
{
if(demo_flag==0)
return 0;
printk(KERN_CRIT "DEMO:demo device close\n");
MOD_DEC_USE_COUNT;
demo_flag = 0;
return 0;
}

static ssize_t demo_read(struct file *file,char *buf,size_t count,loff_t *offset)
{
printk(KERN_CRIT "DEMO:demo is reading,demo_parm=%d\n",demo_param);
return 0;
}

static int demo_ioctl(struct inode *inode,struct file *file,unsigned int cmd,unsigned long arg)
{
if(cmd==COMMAND1)
{
printk(KERN_CRIT "DEMO:set command COMMAND1\n");
return 0;
}
if(cmd==COMMAND2)
{
printk(KERN_CRIT "DEMO:set command COMMAND2\n");
return 0;
}
printk(KERN_CRIT "DEMO:set command WRONG\n");
return 0;
}

static void demo_cleanup(void)
{
if(demo_initialized==1)
{
unregister_chrdev(DEMO_MAJOR,"demo_drv");
demo_initialized = 0;
printk(KERN_CRIT "DEMO:demo device is cleanup\n");
}
return;
}

#ifdef MODULE
MODULE_AUTHOR("DEPART 901");
MODULE_DESCRIPTION("DEMO driver");
MODULE_PARM(demo_param,"i");
MODULE_PARM_DESC(demo_param,"parameter send to driver");
int init_module(void)
{
return demo_init();
}
void cleanup_module(void)
{
demo_cleanup();
}
#endif
谢谢了

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