The contents of First_drv.c are as follows:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>
static struct class *firstdrv_class;
static struct class_device *firstdrv_class_devs;
volatile unsigned long *GPFCON = NULL;
volatile unsigned long *GPFDAT = NULL;
static int first_drv_open(struct inode *inode, struct file *file)
{
//printk("first_drv_open\n");
/*配置引脚GPF 4 5 6为输出*/
*GPFCON &= ~((3<< (4*2)) |(3<<(5*2)) |(3<< (6*2)));
*GPFCON |= ((1<< (4*2)) |(1<< (5*2)) |(1<< (6*2)));
return 0;
}
static ssize_t first_drv_write(struct file * file, const char __user *buf, size_t count, loff_t * ppos)
{
int val;
//printk("first_drv_write\n");
/*Data transfer between user space and kernel space cope_to_user*/
copy_from_user(&val, buf , count);
if(val == 1)
{
//light on
*GPFDAT &= ~((1<<5) |(1<<6)|(1<<4));
}else
{
//Off
*GPFDAT |= ((1<<5) |(1<<6)|(1<<4));
}
return 0;
}
/* This structure is the core of the character device driver
* The open, read, write and other functions called when the application operates the device file,
* will eventually call the corresponding function specified in this structure
*/
static struct file_operations first_drv_fops = {
.owner = THIS_MODULE, /* This is a macro, Push to the __this_module variable automatically created when the module is compiled*/
.open = first_drv_open, .write = first_drv_write, }; int major; /* * This function is called when the insmod command is executed */ int first_drv_init(void) { major = register_chrdev(0,"first_drv",&first_drv_fops); //Register, tell the kernel
firstdrv_class = class_create(THIS_MODULE, "firstdrv"); //Create a class //if (IS_ERR(firstdrv_class)) //return PTR_ERR(firstdrv_class); firstdrv_class_devs = class_device_create(firstdrv_class, NULL, MKDEV(major, 0), NULL, "xyz"); /* /dev/xyz */ //Create a device under the class // if (unlikely(IS_ERR(firstdrv_class_devs))) // return PTR_ERR(firstdrv_class_devs); GPFCON = (volatile unsigned long *)ioremap (0x56000050,16); GPFDAT = GPFCON+1; return 0; } /* * This function is called when the rmmod command is executed */ static void first_drv_exit(void) { unregister_chrdev(major,"first_drv"); //Uninstall the driver
class_device_unregister(firstdrv_class_devs);
class_destroy(firstdrv_class);
iounmap(GPFCON);
}
module_init(first_drv_init);
module_exit(first_drv_exit);
MODULE_LICENSE("GPL");
The test file firstdrvtest.c is as follows:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
/*
firstdrvtest on
firstdrvtest off
*/
int main(int argc , char **argv)
{
int fd;
int val = 1;
fd = open("/dev/xyz",O_RDWR);
if (fd < 0)
printf("cannt open!\n");
if(argc != 2)
{
printf("Usage :\n");
printf("%s <on/off>\n",argv[0]);
return 0;
}
if(strcmp(argv[1], "on") == 0)
{
val=1;
}
else
{
val=0;}
write(fd,&val,4);
return 0;
}
Note:
When compiling the led driver file, the directory of the header file must be specified. In the video of Wei Dongshan, the compiled kernel directory is specified in the makefile.