/*
* 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 $
*/
/* scull: Sample Character Utility for Loading Localities */
#ifndef _SCULL_H_
#define _SCULL_H_
#include <linux/ioctl.h> /* needed for the _IOW etc stuff used later */
/*
* Macros to help debugging
*/
// #undef 是在后面取消以前定义的宏定义
// 下面是如何处理打印信息的宏定义
#undef PDEBUG /* undef it, just in case */
#ifdef SCULL_DEBUG
# ifdef __KERNEL__
/* This one if debugging is on, and kernel space */
# define PDEBUG(fmt, args...) printk( KERN_DEBUG &quot;scull: &quot; fmt, ## args)
# else
/* This one for user space */
# define PDEBUG(fmt, args...) fprintf(stderr, fmt, ## args)
# endif
#else
# define PDEBUG(fmt, args...) /* not debugging: nothing */
#endif
#undef PDEBUGG
#define PDEBUGG(fmt, args...) /* nothing: it's a placeholder */
// 主设备号
#ifndef SCULL_MAJOR
#define SCULL_MAJOR 0 /* dynamic major by default */
#endif
// scull 字符设备总数
#ifndef SCULL_NR_DEVS
#define SCULL_NR_DEVS 4 /* scull0 through scull3 */
#endif
// scull_pipe 字符设备总数
#ifndef SCULL_P_NR_DEVS
#define SCULL_P_NR_DEVS 4 /* scullpipe0 through scullpipe3 */
#endif
/*
* The bare device is a variable-length region of memory.
* Use a linked list of indirect blocks.
*
* &quot;scull_dev->data&quot; 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.
*/
// 量子大小（字节）
#ifndef SCULL_QUANTUM
#define SCULL_QUANTUM 4000
#endif
// 量子集大小（包含的量子数目）
#ifndef SCULL_QSET
#define SCULL_QSET 1000
#endif
/*
* The pipe device is a simple circular buffer. Here its default size
*/
// scull_pipe 默认缓冲大小
#ifndef SCULL_P_BUFFER
#define SCULL_P_BUFFER 4000
#endif
/*
* Representation of scull quantum sets.
*/
struct scull_qset {
void **data;// 当前量子集首地址
struct scull_qset *next;// 下一个量子集地址
};
struct scull_dev {
// 第一个量子集
struct scull_qset *data; /* Pointer to first quantum set */
// 每一个量子所占字节数
int quantum; /* the current quantum size */
// 每一个量子集所含量子数
int qset; /* the current array size */
// 存储的数据量
unsigned long size; /* amount of data stored here */
unsigned int access_key; /* used by sculluid and scullpriv */
// 信号量
struct semaphore sem; /* mutual exclusion semaphore */
// 字符设备结构
struct cdev cdev; /* Char device structure */
};
/*
* Split minors in two parts
*/
// 取指定参数的高、低半字
#define TYPE(minor) (((minor) >> 4) & 0xf) /* high nibble */
#define NUM(minor) ((minor) & 0xf) /* low nibble */
/*
* The different configurable parameters
*/
extern int scull_major; /* main.c */
extern int scull_nr_devs;
extern int scull_quantum;
extern int scull_qset;
extern int scull_p_buffer; /* pipe.c */
/*
* Prototypes for shared functions
*/
int scull_p_init(dev_t dev);
void scull_p_cleanup(void);
int scull_access_init(dev_t dev);
void scull_access_cleanup(void);
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 *filp, loff_t off, int whence);
int scull_ioctl(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg);
/*
* Ioctl definitions
*/
/* Use 'k' as magic number */
// 魔数
#define SCULL_IOC_MAGIC 'k'
/* Please use a different 8-bit number in your code */
// ioctl 方法的命令
#define SCULL_IOCRESET _IO(SCULL_IOC_MAGIC, 0)
/*
* S means &quot;Set&quot; through a ptr,
* T means &quot;Tell&quot; directly with the argument value
* G means &quot;Get&quot;: reply by setting through a pointer
* Q means &quot;Query&quot;: response is on the return value
* X means &quot;eXchange&quot;: switch G and S atomically
* H means &quot;sHift&quot;: switch T and Q atomically
*/
#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 &quot;Tell&quot; and &quot;Query&quot;, 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_P_IOCTSIZE _IO(SCULL_IOC_MAGIC, 13)
#define SCULL_P_IOCQSIZE _IO(SCULL_IOC_MAGIC, 14)
/* ... more to come */
#define SCULL_IOC_MAXNR 14
#endif /* _SCULL_H_ */
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