关于/proc文件系统及seq_file实现，求解惑！！
第一：/proc文件系统是什么 ？这个网上很多，说的很细，我也就不说了。但是他是做什么用的，网上也很多，但是我不解，就我目前了解的，简单的说，/proc是驱动程序的一种调式方法（如有不对可以指出），那么怎样让我的/proc文件系统与我的驱动程序建立联系！！？？如下面最简单的一个/proc文件系统例子：// include kernel head files#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
// licensed under BSD/GPL
MODULE_LICENSE("Dual BSD/GPL");
static struct proc_dir_entry *prwd_dir = NULL;
static struct proc_dir_entry *prwd_rdonly = NULL;
static struct proc_dir_entry *prwd_rdwr = NULL;
static char sbufr[ 100 ] = "One test string from reading only !\n";
static char sbufrw[ 1000 ] = "";
// read-only function
static int prwd_rdonly_read(char *page, char **start, off_t off, int count, int *eof, void *data)
{
sprintf( page, "%s", sbufr );
*eof = 1;
return strlen( sbufr );
}
// read function for read-write
static int prwd_rdwr_read(char *page, char **start, off_t off, int count, int *eof, void *data)
{
int len;
len = strlen( sbufrw );
if( len <= off ) {
printk(KERN_ALERT "File pointer at end of file or no data for reading in read-write buffer !\n");
return -EINVAL;
}
if( ( len - off ) < count ) {
count = len - off;
}
memcpy( page, ( sbufrw + off ), count );
if( len <= ( off + count ) ) {
*eof = 1;
}
return count;
}
// write function for read-write
static int prwd_rdwr_write(struct file *file, const char __user *buffer, unsigned long count, void *data)
{
unsigned long cnt = count;
if( cnt >= sizeof( sbufrw ) ) {
cnt = sizeof( sbufrw ) - 1;
}
if( copy_from_user( sbufrw, buffer, cnt ) ) {
printk(KERN_ALERT "Failure to copy data from user space !\n");
return -EFAULT;
}
sbufrw[ cnt ] = '\0';
return cnt;
}
// initialize module function
static int __init procreadwritedemo_init(void)
{
printk(KERN_ALERT "Entry procreadwritedemo_init !\n");
// create directory: procreadwritedemo in /proc
prwd_dir = proc_mkdir( "procreadwritedemo", NULL );
if( NULL == prwd_dir ) {
printk(KERN_ALERT "Cann't create directory: /proc/procreadwritedemo !\n");
goto failure_create_dir;
}
printk(KERN_ALERT "Success to create directory: /proc/procreadwritedemo !\n");
// create read-only file: rdonly in /proc/procreadwritedemo
prwd_rdonly = create_proc_read_entry( "rdonly", 0400, prwd_dir, prwd_rdonly_read, NULL );
if( NULL == prwd_rdonly ) {
printk(KERN_ALERT "Cann't create read-only file: /proc/procreadwritedemo/rdonly !\n");
goto failure_create_rdonly;
}
printk(KERN_ALERT "Success to create read-only file: /proc/procreadwritedemo/rdonly !\n");
// create read-write file: rdwr in /proc/procreadwritedemo
prwd_rdwr = create_proc_entry( "rdwr", 0666, prwd_dir );
if( NULL == prwd_rdwr ) {
printk(KERN_ALERT "Cann't create read-write file: /proc/procreadwritedemo/rdwr !\n");
goto failure_create_rdwr;
}
prwd_rdwr->read_proc = prwd_rdwr_read;
prwd_rdwr->write_proc = prwd_rdwr_write;
printk(KERN_ALERT "Success to create read-write file: /proc/procreadwritedemo/rdwr !\n");
return 0;
failure_create_rdwr:
remove_proc_entry( "rdonly", prwd_dir );
failure_create_rdonly:
remove_proc_entry( "procreadwritedemo", NULL );
failure_create_dir:
return -EFAULT;
}
// clean up module function
static void __exit procreadwritedemo_exit(void)
{
printk(KERN_ALERT "Entry procreadwritedemo_exit !\n");
// remove files and directory created in /proc
remove_proc_entry( "rdwr", prwd_dir );
remove_proc_entry( "rdonly", prwd_dir );
remove_proc_entry( "procreadwritedemo", NULL );
}
// the declarations of initilization and cleaning up module funcitons
module_init( procreadwritedemo_init );
module_exit( procreadwritedemo_exit );
// module information
MODULE_AUTHOR("wensheng");
MODULE_DESCRIPTION("Proc filesystem read/write demo");
MODULE_VERSION("0.0.1");
MODULE_ALIAS("ProcReadWriteDemo");
上面的一例，完全是一个独立/proc系统代码的实现，问题是：他是那怎与我想调试的驱动（如一个块设备）程序建立关系了，如是不能跟我的相关驱动建联系，那/proc文件系统存在意义是什么 （简单说就是做什么用的，最好可以举个易懂的例子）？？
第二：关于seq_file机制
有如下代码#include <linux/fs.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
struct proc_dir_entry proc_root;
void * our_seq_start(struct seq_file *m, loff_t *pos)
{
//printk("<0>""in our_seq_start/n");
if(*pos == 0)
return pos;
return NULL;
}
void * our_seq_stop(struct seq_file *m, void *v)
{
//printk("/nDO NOTHING/n");
}
int our_seq_show(struct seq_file *m, loff_t *pos)
{
static unsigned long counter = 0;
int i;
for(i=0;i<10;i++)
seq_printf(m,"the counter is %d/n",i);
return 0;
}
void *our_seq_next(struct seq_file *m, loff_t *pos)
{
static unsigned long counter_next = 0;
if(pos < 1)
{
counter_next++;
pos++;
return pos;
}
else
{
*pos = 0;
return NULL;
}
}
static const struct seq_operations our_seq_ops = {
.start = our_seq_start,
.next= our_seq_next,
.stop= our_seq_stop,
.show= our_seq_show
};
static int our_seq_open(struct inode *inode, struct file *filp)
{
printk("<0>""in our_seq_open/n");
return seq_open(filp, &our_seq_ops);
}
int our_ioctl()
{
printk("<0>""in our_seq_ioctl/n");
return 0;
}
int our_write()
{
printk("<0>""in our_seq_write/n");
return 5;
}
struct file_operations our_proc_ops = {
.open = our_seq_open,
.read = seq_read,
.write = our_write,
.llseek= seq_lseek,
.ioctl = our_ioctl,
.release = seq_release
};
int our_init()
{
proc_create("hehe", 0, NULL, &our_proc_ops);
return 0;
}
void our_exit()
{
remove_proc_entry("hehe",NULL);
}
module_init(our_init);
module_exit(our_exit);上面代码是目前我在网上查到的/proc文件系统实现中唯一个涉及到ioctl操作（此处不关心代码是否有错，关心功能码是否以实现），因为之前所有相关seq_file机制建立/proc，中struct file_operations，只有如下操作struct file_operations our_proc_ops = {
.open = our_seq_open,
.read = seq_read,
.llseek= seq_lseek,
.release = seq_release
};而且我们只用实现open（），而read，lseek，release，都是seq_file内部实现，我们可不管。问题是没有write（），没有ioctl（）（为什么没有，我们可以暂不讨论），我想问的是，我们可否像上面那个代码一样添加自己的write与ioctl功能。
以上都是自己跟据现有资做出的理解，如有不对，请您不吝指出，还有我的一些不解之处，求大神解惑！！
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