nvram.c

上传代码是ARM嵌入式系统下的NVRAM的驱动源程序

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/hardware.h>
#include <asm/mach-types.h>
#include <linux/version.h>
#include <asm-arm/arch-iop33x/iop33x.h>
unsigned char *nvram_remap_address;

#define nvram_NAME "nvram_driver"
#define nvram_MAJOR 127
#define nvram_SIZE 0x8000

typedef struct{
	int openflag;
	char buf[nvram_SIZE];
}nvram_dev;

static nvram_dev df_dev;

static int
nvram_open(struct inode *inode,struct file *filp);  
static int
nvram_release(struct inode *inode,struct file *filp);  

static loff_t 
nvram_llseek(struct file *file, loff_t offset, int origin);
static ssize_t 
read_nvram(struct file *file, char __user *buf, size_t count, loff_t *ppos);
static ssize_t 
write_nvram(struct file *file, const char __user *buf, size_t count, loff_t *ppos);
static int
nvram_init(void); 
static void
nvram_exit(void); 
 
struct file_operations nvram_fops = {
       owner:         THIS_MODULE,
       llseek:        nvram_llseek,
       read:          read_nvram,
       write:         write_nvram,
       open:	 nvram_open,
    	release: nvram_release,

};


static int 
nvram_open(struct inode *inode,struct file *filp)  /* open device */
{
	nvram_dev	*dev;	
	dev=&df_dev;	
nvram_remap_address =ioremap(0xce870000, 0x8000);
	if(dev->openflag !=0)
	{	
	return -EBUSY;
	}
	dev->openflag =1;
	filp->private_data =dev;
//	MOD_INC_USE_COUNT;
	return 0;
}
static int 
nvram_release(struct inode *inode,struct file *filp)  /* close device */
{
	nvram_dev	*dev=(nvram_dev *)filp->private_data;
//	MOD_DEC_USE_COUNT;
	dev->openflag = 0;
	return 0;	
}
static int __init nvram_init(void)

{      

  int result = register_chrdev(nvram_MAJOR,nvram_NAME,&nvram_fops);
	if(result<0)
	{
	  printk(KERN_ALERT"nvram: can't get major %d\n",nvram_MAJOR);
	  return result;
	}	
	return 0;


}
 

static void __exit nvram_exit(void)

{
  unregister_chrdev(nvram_MAJOR,nvram_NAME);
	iounmap((void *)nvram_remap_address);   

}

static unsigned char read_byte_nvram(int addr)

{
       return inb(nvram_remap_address + addr + 1);
}

static void write_byte_nvram(unsigned char val, int addr)

{
       outb(val, nvram_remap_address + addr + 1);
}

static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)

{
       lock_kernel();

       switch (origin) {
       case 1:                                       
              offset += file->f_pos;
              break;
       case 2:                                          
              offset += 0x8000 - 1;                 
              break;
       }
       if (offset < 0) {
              unlock_kernel();
              return -EINVAL;
       }
       file->f_pos = offset;                   
       unlock_kernel();
       return file->f_pos;
}

static ssize_t read_nvram(struct file *file, char __user *buf, size_t count, loff_t *ppos)

{
       unsigned int i;

       char __user *p = buf;
       if (!access_ok(VERIFY_WRITE, buf, count))
              return -EFAULT;
       if (*ppos >= 0x8000 - 1)                  
              return 0;
       for (i = *ppos; count > 0 && i < 0x8000 - 1; ++i, ++p, --count)
              if (__put_user(read_byte_nvram(i), p))
                     return -EFAULT;
       *ppos = i;
       return p - buf;
}

static ssize_t write_nvram(struct file *file, const char *buf, size_t count, loff_t *ppos)

{
  unsigned int i;

  nvram_dev *dev=(nvram_dev *)filp->private_data;                      
	if(count==0)
	return 0;		
    if(copy_from_user(dev->buf,buf,count))     
      {
         printk(KERN_ALERT"copy from user erro!!\n");
         return -EFAULT;
      }
  //     const char  *p = buf;
       unsigned char c;
  //     if (!access_ok(VERIFY_READ, buf, count))
  //            return -EFAULT;
       if (*ppos >= 0x8000 - 1)
              return 0;
  //     for (i = *ppos; count > 0 && i < 0x8000 - 1; ++i, ++p, --count) {
  //            if (__get_user(c, p))
  //                   return -EFAULT;
           for (i=0;i<count;i++)
             { 
              write_byte_nvram(dev->buf[i],i)
            }
       }
}
module_init(nvram_init);
module_exit(nvram_exit);

//MODULE_ALIAS("nvram"); 
//MODULE_DESCRIPTION("nvram Driver For EM104-MINI2410");
//MODULE_LICENSE("GPL");     
//MODULE_AUTHOR("jjj. <[e-mail]>");