头文件：

//+++++add by Jay for proc sysfs debug
#define DEBUG_ENABLE	1
#ifdef	DEBUG_ENABLE
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>
#include <linux/proc_fs.h>
#include <asm/io.h>
#define MAX_CHAR_LENGTH	PAGE_SIZE
struct proc_dir_entry *procfile;
static char proc_cmd[20], proc_reg[10], proc_data[10];
static char *globalmem;
static struct i2c_client *proc_client;
#endif

static int __init mma8451_init(void)
{
	/* register driver */
	int res;

	res = i2c_add_driver(&mma8451_driver);
	if (res < 0) {
		printk(KERN_INFO "add mma8451 i2c driver failed\n");
		return -ENODEV;
	}
	//++++++setup our proc debug sysfs
#ifdef	DEBUG_ENABLE
	globalmem = (char *)vmalloc(MAX_CHAR_LENGTH);
	if(!globalmem)
		printk(KERN_INFO "allocate memory error!\n");
	memset(globalmem, 0, MAX_CHAR_LENGTH);
	procfile = create_proc_entry("mma8451",0401,NULL);
	if(procfile == NULL) {
		res = -ENOMEM;
		vfree(globalmem);
		printk(KERN_INFO "create procfile error!\n");
	} else {
		procfile->read_proc = mma_proc_read;
		procfile->write_proc = mma_proc_write;
	}
#endif
	return res;
}

#ifdef	DEBUG_ENABLE
ssize_t mma_proc_write( struct file *filp, const char __user *buff,
                        unsigned long len, void *data )
{
	int reg_index = 0;
	int reg_data = 0;
	int reg, result;
		
	printk(KERN_INFO "--MMA_PROC---%s----\n",__func__);
	if(copy_from_user(globalmem, buff, len))
		return -EFAULT;
	globalmem[len-1] = '\0';
	sscanf(globalmem, "%s%s%s", proc_cmd, proc_reg, proc_data);
	if(strcmp(proc_cmd, "write") == 0) {
		reg_index = simple_strtol(proc_reg, NULL, 16);
		reg_data = simple_strtol(proc_data, NULL, 16);
		reg = i2c_smbus_read_byte_data(proc_client, MMA8451_CTRL_REG1);
		reg &= ~0x01;
		result = i2c_smbus_write_byte_data(proc_client, MMA8451_CTRL_REG1, reg);
		if (result < 0)
			goto out;
		printk(KERN_INFO "index: %x, data:%x \n",reg_index,reg_data);

		result = i2c_smbus_write_byte_data(proc_client, reg_index, reg_data);
		if (result < 0)
			goto out;

		reg |= 0x01;
		result = i2c_smbus_write_byte_data(proc_client, MMA8451_CTRL_REG1,
					   reg);
		if (result < 0)
			goto out;
	}
	return len;
out:
	dev_err(&proc_client->dev, "error when init mma8451:(%d)", result);
	return len;
}

int mma_proc_read( char *page, char **start, off_t off,
                   int count, int *eof, void *data )
{
	int len = 0;
	int reg_index, reg_data;
	printk(KERN_INFO "--MMA_PROC---%s----\n",__func__);
	if(off > 0) {
		*eof = 1;
		return 0;
	}

//	if(strcmp(proc_cmd, "dump") == 0)
	{
//		reg_index = simple_strtol(proc_reg, NULL, 16);
//		printk("reg1: %x\n",i2c_smbus_read_byte_data(client, MMA8451_CTRL_REG1));
//		printk("reg2: %x\n",i2c_smbus_read_byte_data(client, MMA8451_CTRL_REG2));
//		printk("reg3: %x\n",i2c_smbus_read_byte_data(client, MMA8451_CTRL_REG3));
//		printk("reg4: %x\n",i2c_smbus_read_byte_data(client, MMA8451_CTRL_REG4));
//		printk("reg5: %x\n",i2c_smbus_read_byte_data(client, MMA8451_CTRL_REG5));
		len = sprintf(page, "==========MMA REG==========\n");
		reg_data = i2c_smbus_read_byte_data(proc_client, MMA8451_CTRL_REG1);
		len += sprintf(page + len, "REG1: 0x%x\n", reg_data);
		reg_data = i2c_smbus_read_byte_data(proc_client, MMA8451_CTRL_REG2);
		len += sprintf(page + len, "REG2: 0x%x\n", reg_data);
		reg_data = i2c_smbus_read_byte_data(proc_client, MMA8451_CTRL_REG3);
		len += sprintf(page + len, "REG3: 0x%x\n", reg_data);
		reg_data = i2c_smbus_read_byte_data(proc_client, MMA8451_CTRL_REG4);
		len += sprintf(page + len, "REG4: 0x