scull内存驱动

最新推荐文章于 2025-08-20 22:17:23 发布

yuweixian

最新推荐文章于 2025-08-20 22:17:23 发布

阅读量579

点赞数

分类专栏： LDD学习笔记文章标签： ioc pointers module io user list

LDD学习笔记专栏收录该内容

27 篇文章

订阅专栏

来自 http://dev.firnow.com/course/6_system/linux/Linuxjs/2008108/149162.html

/* * scull.h -- definitions for the char module * * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet * Copyright (C) 2001 O'Reilly & Associates * * The source code in this file can be freely used, adapted, * and redistributed in source or binary form, so long as an * acknowledgment appears in derived source files. The citation * should list that the code comes from the book "Linux Device * Drivers" by Alessandro Rubini and Jonathan Corbet, published * by O'Reilly & Associates. No warranty is attached; * we cannot take responsibility for errors or fitness for use. * * $Id: scull.h,v 1.15 2004/11/04 17:51:18 rubini Exp $ */

# ifndef _SCULL_H_ # define _SCULL_H_ # include < linux/ ioctl. h> /* 为了使用_IOW/ /* * 定义一些宏来帮助调试 */ # undef PDEBUG /* 取消对PDEBUG的定义，防止重复定义*/ # ifdef SCULL_DEBUG /*开启调试*/ # ifdef __KERNEL__ /*在内核空间下，将调试信息用printk打印*/ # define PDEBUG( fmt, args. . . ) printk( KERN_DEBUG "scull: " fmt, # # args) # else /*在用户空间下，将信息打印到stderr*/ # define PDEBUG( fmt, args. . . ) fprintf ( stderr , fmt, # # args) # endif # else # define PDEBUG( fmt, args. . . ) /* 调试没开启，PDEBUG定义为什么都不做 */ # endif # undef PDEBUGG # define PDEBUGG( fmt, args. . . ) /* PDEBUGG不做任何事，充当占位符 */ # ifndef SCULL_MAJOR # define SCULL_MAJOR 0 /* 默认使用动态分配主设备号 */ # endif /*这里将SCULL_MAJOR(主设备号)初始化为0，是为了在 scull_init_module()中动态分配设备号，在scull.c中，有一全局变量 int scull_major = SCULL_MAJOR; 用来代表设备号。在scull_init_module中有以下： if (scull_major) regidter_chrdev_region -----静态 else alloc_chrdev_region --------动态 */ # ifndef SCULL_NR_DEVS # define SCULL_NR_DEVS 4 /* 设备数目或设备序号，从scull0到scull3 */ # endif /* * The bare device is a variable-length region of memory. * Use a linked list of indirect blocks. * "scull_dev->data" points to an array of pointers, each * pointer refers to a memory area of SCULL_QUANTUM bytes. * The array (quantum-set) is SCULL_QSET long. scull_dev->data指向一组指针，其中每一个指针指向一个SCULL_QUANTUM字节的内存空间. */ # ifndef SCULL_QUANTUM # define SCULL_QUANTUM 4000 /*量子的大小,4000字节.指的是数据区域中的指针所引用的内存大小*/ # endif # ifndef SCULL_QSET # define SCULL_QSET 1000 /*量

子集大小，1000 个，指的是共有 1000 个指针，或者指针数组的长度。每一个指针用来应用 4000 字节的小的空间 */
# endif

/*
* Representation of scull quantum sets.
   scull设备的 quantum 的实现如下
*/
struct scull_qset {      /*设备的实现为一个简单的链表结点。 data 作为一个指向 4000 字节的区域 */
     void ** data ;
     struct scull_qset * next ;
};

struct scull_dev {      /*设备的结构 */
     struct scull_qset * data ; /* 指向第一个量子集 */
     int quantum ; /* 当前量子的大小 */
     int qset ; /* 当前数组的大小 */
     unsigned long size ; /* 保存在其中的数据总量 */
     unsigned int access_key ; /* 由 sculluid 和 scullpriv 使用 */
     struct semaphore sem ; /* 互斥信号量 */
     struct cdev cdev ;       /* 字符设备结构 */
};
/* 对于字符设备的实现，一般要定义自己的设备类型的结构。 scull_dev 就是该设备类型。
   一般要把信号量，锁之类的保护措施和struct cdev 放在其中
*/

/*
* Split minors in two parts
*/
# define TYPE ( minor )      ((( minor ) >> 4 ) & 0xf )      /* high nibble */
# define NUM ( minor )      (( minor ) & 0xf )          /* low nibble */
/*这两个东西不知道有什么作用 */

/*
* The different configurable parameters
   一些外部声明
*/
extern int scull_major ; /* main.c */
extern int scull_nr_devs ;
extern int scull_quantum ;
extern int scull_qset ;

/*函数声明 */
int scull_trim ( struct scull_dev * dev );

ssize_t scull_read ( struct file * filp , char __user * buf , size_t count , loff_t * f_pos );

ssize_t scull_write ( struct file * filp , const char __user * buf , size_t count , loff_t * f_pos );

loff_t scull_llseek ( struct file

ssize_t scull_read ( struct file * filp , char __user * buf , size_t count , loff_t * f_pos );

ssize_t scull_write ( struct file * filp , const char __user * buf , size_t count , loff_t * f_pos );

loff_t scull_llseek ( struct file yle="color: rgb(0, 0, 204);">*filp , loff_t off , int whence );

int scull_ioctl ( struct inode * inode , struct file * filp , unsigned int cmd , unsigned long arg );

/*
* Ioctl definitions
IO控制的定义
*/

/* Use 'k' as magic number
使用k 作为幻数 */
# define SCULL_IOC_MAGIC 'k'
/* Please use a different 8-bit number in your code */

# define SCULL_IOCRESET _IO ( SCULL_IOC_MAGIC , 0 )

/*
* S means 通过指针 “ 设置 ”
* T means 直接用参数值通知
* G means 表示 “ 获取 ” ，通过设置指针来应答
* Q means 表示 “ 查询 ” ，通过返回值应答
* X means 表示 “ 交换 ” ，原子地交换 G S
* H means 表示 “ 切换 ” ，原子地交换 T Q
*/
# define SCULL_IOCSQUANTUM _IOW ( SCULL_IOC_MAGIC , 1 , int )
# define SCULL_IOCSQSET _IOW ( SCULL_IOC_MAGIC , 2 , int )
# define SCULL_IOCTQUANTUM _IO ( SCULL_IOC_MAGIC , 3 )
# define SCULL_IOCTQSET _IO ( SCULL_IOC_MAGIC , 4 )
# define SCULL_IOCGQUANTUM _IOR ( SCULL_IOC_MAGIC , 5 , int )
# define SCULL_IOCGQSET _IOR ( SCULL_IOC_MAGIC , 6 , int )
# define SCULL_IOCQQUANTUM _IO ( SCULL_IOC_MAGIC , 7 )
# define SCULL_IOCQQSET _IO ( SCULL_IOC_MAGIC , 8 )
# define SCULL_IOCXQUANTUM _IOWR ( SCULL_IOC_MAGIC , 9 , int )
# define SCULL_IOCXQSET _IOWR ( SCULL_IOC_MAGIC , 10 , int )
# define SCULL_IOCHQUANTUM _IO ( SCULL_IOC_MAGIC , 11 )
# define SCULL_IOCHQSET _IO ( SCULL_IOC_MAGIC , 12 )

/*
* The other entities only have "Tell" and "Query", because they're
* not printed in the book, and there's no need to have all six.
* (The previous stuff was only there to show different ways to do it.
*/

# define SCULL_IOC_MAXNR 12

# endif /* _SCULL_H_ */