IOCTL call not working with driver - c

Question

I wrote a IOCTL driver and a corresponding ioctl app with a header file containing commands.
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kdev_t.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>
#include "myioctl.h"
#include <linux/ioctl.h>
#define NAME MyCharDevice
//Function Prototypes
int NAME_open(struct inode *inode, struct file *filp);
int NAME_release(struct inode *indoe, struct file *filp);
ssize_t NAME_write(struct file *filp, char __user *Ubuff, size_t count, loff_t *offp);
ssize_t NAME_read(struct file *filp, char __user *Ubuff, size_t count, loff_t *offp);
int NAME_flush (struct file *filp);
int NAME_IOCTL (struct inode *inode, struct file *filp, unsigned long cmd, unsigned long val);
//Structure that defines the operations that the driver provides
struct file_operations fops =
{
.owner = THIS_MODULE,
.open = NAME_open,
.read = NAME_read,
.write = NAME_write,
.unlocked_ioctl = NAME_IOCTL,
.release = NAME_release,
.flush = NAME_flush,
};
//Structure for a character driver
struct cdev *my_cdev;
//Init Module
static int __init CharDevice_init(void)
{
int result;
int MAJOR,MINOR;
dev_t Mydev;
Mydev = MKDEV(255,0);//Create a device number
MAJOR=MAJOR(Mydev);
MINOR=MINOR(Mydev);
printk("\nThe Major Number is %d...THe Minor Number is %d\n",MAJOR,MINOR);
result=register_chrdev_region(Mydev,1,"MyCharDevice");//register device region.....
if(result<0)
{
printk(KERN_ALERT "\nThe Region requested for is not obtainable\n");
return(-1);
}
my_cdev = cdev_alloc();//allocate memory to Char Device structure
my_cdev->ops = &fops;//link our file operations to the char device
result=cdev_add(my_cdev,Mydev,1);//Notify the kernel abt the new device
if(result<0)
{
printk(KERN_ALERT "\nThe Char Devide has not been created......\n");
return (-1);
}
return 0;
}
//Cleanup Module
void __exit CharDevice_exit(void)
{
dev_t Mydev;
int MAJOR,MINOR;
Mydev=MKDEV(255,0);
MAJOR=MAJOR(Mydev);
MINOR=MINOR(Mydev);
printk("\nThe Major Number is %d...THe Minor Number is %d\n",MAJOR,MINOR);
unregister_chrdev_region(Mydev,1);//unregister the device numbers and the device created
cdev_del(my_cdev);
printk(KERN_ALERT "\nI have unregistered the stuff that was allocated.....Goodbye for ever.....\n");
return;
}
int NAME_IOCTL (struct inode *inode, struct file *filp, unsigned long cmd, unsigned long val)
{
int BAUD=0, STOP;
char PARITY, CONFIG;
printk ("In IOCTL\n");
printk("command = %d %d val = %d\n", cmd, SET_BAUD, val);
switch (cmd) {
case SET_BAUD:
get_user (BAUD, (int *)val);
printk ("The baud is %d", BAUD);
case SET_PARITY:
case SET_STOP:
case READ_CONFIG:
default:
return -1;
}
return 0;
}
//Open System Call
int NAME_open(struct inode *inode, struct file *filp)
{
printk(KERN_ALERT "\nThis is the Kernel....Open Call.....I have nothing to do.....but YOU ALL HAVE....HAHAHAHA...\n");
return 0;
}
//Close System Call
int NAME_release(struct inode *indoe, struct file *filp)
{
printk(KERN_ALERT "\nThis is the release method of my Character Driver......Bye Dudes......\n");
return 0;
}
//Write Functionality
ssize_t NAME_write(struct file *filp, char __user *Ubuff, size_t count, loff_t *offp)
{
char Kbuff[80];
unsigned long result;
ssize_t retval;
//strcpy(Kbuff,Ubuff);
result=copy_from_user((char *)Kbuff,(char *)Ubuff,count); //get user data
if(result==0)
{
printk(KERN_ALERT "\nMessage from the user......\n>>>> %s <<<<\n",Kbuff);
printk(KERN_ALERT "\n Data Successfully Written.....\n");
retval=count;
return retval;
}
else
{
printk(KERN_ALERT "\n Error Writing Data\n");
retval=-EFAULT;
return retval;
}
}
//read Functionality
ssize_t NAME_read(struct file *filp, char __user *Ubuff, size_t count, loff_t *offp)
{
char Kbuff[]="THis is some date from the kernel to the user....User,ENJOY......";
unsigned long result;
ssize_t retval;
//strcpy(Kbuff,Ubuff);
result=copy_to_user((char *)Ubuff,(char *)Kbuff,sizeof(Kbuff)); //copy to user
if(result==0)
{
//printk("\nMessage from the user......\n>>>> %s <<<<\n");
printk(KERN_ALERT "\n Data Successfully read.....\n");
retval=count;
return retval;
}
else
{
printk(KERN_ALERT"\n Error Writing Data to User\n");
retval=-EFAULT;
return retval;
}
}
int NAME_flush (struct file *filp)
{
printk("\n This is the close function of the file....");
return 0;
}
//Module over ride functions
module_init(CharDevice_init);
module_exit(CharDevice_exit);
header file
#define MAGIC 'x'
#define SET_BAUD _IOW(MAGIC,0, int)
#define SET_PARITY _IOW(MAGIC, 1, char)
#define SET_STOP _IOW(MAGIC, 2, int)
#define READ_CONFIG _IOR(MAGIC, 3, int)
c file
#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <linux/ioctl.h>
#include "myioctl.h"
int main()
{
int FileDesc, Baud=9600;
// char Ubuff[]="THis is the User Buffer......Sending Data to the Kernel....";
// char Kbuff[100];
FileDesc=open("/dev/MyCharDevice",O_RDWR);
if(FileDesc <0)
{
printf("\nError Opening Device\n");
exit(1);
}
ioctl (FileDesc, SET_BAUD, &Baud);
printf("%d %d \n", SET_BAUD, &Baud);
// write(FileDesc,Ubuff,sizeof(Ubuff));
// read(FileDesc,Kbuff,sizeof(Ubuff));
// printf("\n The Data read from the Kernel is\n>>>> %s <<<<\n",Kbuff);
close(FileDesc);
}
I am printing in driver what are the command and value of the argument that print like this
command = 1622004312 1074034688 val = 1622004312
So sent command is equal to the argument I sent. Why this is happening?

Answer 1

I used older IOCTL prototype in my driver.
it should be of this type
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,35))
static int my_ioctl(struct inode *i, struct file *f, unsigned int cmd, unsigned long arg)
#else
static long my_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
#endif
In my case against my kernel
static long my_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
is the correct type.