Drive application layer code
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include "head.h"
int main(int argc, char const *argv[])
{<!-- -->
int a, b;
char buf[128] = {<!-- -->0};
int fd_led1 = open("/dev/led0", O_RDWR); //corresponding key1 button
if (fd_led1 < 0)
{<!-- -->
printf("Failed to open LED1 device file\\
");
exit(-1);
}
while (1)
{<!-- -->
// read from terminal
printf("Please select KEY1 light function\\
");
printf("0(off) 1(on)>");
scanf("%d", &a);
printf("Please enter the key to be controlled\\
");
printf("1(KEY1) 2(KEY2) 3(KEY3)>");
scanf("%d", &b);
if (a == 1) // turn on the light
{<!-- -->
switch (b)
{<!-- -->
case 1:
while(1){<!-- -->
//ioctl(fd_led1, LED_ON, b);
//ioctl(fd_led1, LED_ON, b);
//memset(buf,0,sizeof(buf));//clear
read(fd_led1,buf,sizeof(buf));//read data
printf("number:%c\\
",buf[0]);
sleep(1);
}
break;
case 2:
//ioctl(fd_led2, LED_ON, b);
break;
case 3:
// ioctl(fd_led3, LED_ON, b);
break;
}
}
else if (a == 0) // turn off the light
{<!-- -->
switch (b)
{<!-- -->
case 1:
//ioctl(fd_led1, LED_OFF, b);
//ioctl(fd_led1, LED_ON, b);
break;
case 2:
//ioctl(fd_led2, LED_OFF, b);
break;
case 3:
//ioctl(fd_led3, LED_OFF, b);
break;
}
}
}
close(fd_led1);
// close(fd_led2);
// close(fd_led3);
return 0;
}
Driver code
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/timer.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include "head.h"
struct cdev *cdev; //first address of character device space
unsigned int major=500; //Static application device number
unsigned int minor=0;//The initial value of the minor device number
dev_t devno; //Dynamic application device number
struct class *cls; //Receive the address of the registration structure
struct device *dev; //device number
/*mykeys{
interrupt-parent=< & gpiof>;
interrupts=<9 0>,<7 0>,<8 0>; //9 indicates the index information when referencing the interrupted parent node 0 indicates the default setting
};*/
//unsigned int irqno;//a device
int irqno; //interrupt
struct gpio_desc *gpiono; //gpio
//struct gpio_desc *gpiono2;
//struct gpio_desc *gpiono3;
struct device_node *dnode;
char number = 0; //define number
char kbuf[128] = {<!-- -->0}; //The buffer in the driver
int mycdev_open(struct inode *inode, struct file *file)
{<!-- -->
// unsigned int aaa = MINOR(inode->i_rdev); // get the secondary device number aaa
// file->private_data = (void *)aaa;
printk("%s:%s:%d\\
", __FILE__, __func__, __LINE__);
return 0;
}
// interrupt handler
irqreturn_t myirq_handler(int irqno, void *dev_id)
{<!-- -->
printk("key1 interrupt\\
");
//Invert the state of the light
gpiod_set_value(gpiono, !gpiod_get_value(gpiono));
//Send the data of number to the kbuf buffer
number = !number;
/*
unsigned int arg = (unsigned int) dev_id;
switch(arg)
{
case 0:
printk("key1 interrupt\\
");
//Invert the state of the light
gpiod_set_value(gpiono, !gpiod_get_value(gpiono));
//Send the data of number to the kbuf buffer
number = !number;
break;
case 1:
printk("key2 interrupt\\
");
//Invert the state of the light
break;
case 2:
printk("key3 interrupt\\
");
//Invert the state of the light
break;
}*/
return IRQ_HANDLED;
}
//read of the application callback
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{<!-- -->
int ret;
if(sizeof(kbuf)<size)
size=sizeof(kbuf);
// wait_event_interruptible(wq_head,condition);//Switch the process to sleep
//
kbuf[0] = number;
printk("****************************************%c\\
", number);
ret=copy_to_user(ubuf,kbuf,size);
if(ret)
{<!-- -->
printk("copy_to_user filed\\
");
return -EIO;
}
printk("%s:%s:%d\\
", __FILE__, __func__, __LINE__);
// condition=0;//Indicates that the next hardware data is not ready
return 0;
}
/*
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
myirq_handler(irqno, NULL); // Button 1 soft interrupt
return 0;
}
*/
int mycdev_close(struct inode *inode, struct file *file)
{<!-- -->
printk("%s:%s:%d\\
", __FILE__, __func__, __LINE__);
return 0;
}
// Define the operation method structure variable and assign it
struct file_operations fops = {<!-- -->
.open = mycdev_open,
// .unlocked_ioctl = mycdev_ioctl,
.read = mycdev_read,
.release = mycdev_close,
};
static int __init mycdev_init(void) //register address mapping and initialization
{<!-- -->
int ret; //ret returns an error code
int ret1;
\t
//1. Allocate character device driver object space cdev_alloc
cdev=cdev_alloc(); //The first address of character device space
if(cdev==NULL)
{<!-- -->
printk("Failed to apply for character device driver object space\\
");
ret=-EFAULT;
goto out1;
}
printk("Character device driver object application is successful\\
");
//2. Partial initialization of the character device driver object cdev_init
cdev_init(cdev, & fops);
//3. Apply for device number register_chrdev_region/alloc_chrdev_region
if(major>0)//Static application device number
{<!-- -->
ret=register_chrdev_region(MKDEV(major,minor),1,"led0"); //The device number needs to be combined, the number of secondary devices, and the device file name
if(ret)
{<!-- -->
printk("**********Failed to statically specify the device number**********\\
");
goto out2;
}
}
else//Dynamic application device number
{<!-- -->
ret=alloc_chrdev_region( & amp;devno,minor,1,"led0"); //Dynamically apply for device number, minor device number, device quantity, file name
if(ret)
{<!-- -->
printk("Dynamic application for device number failed\\
");
goto out2;
}
major=MAJOR(devno); //Get the major device number according to the device number
minor=MINOR(devno); //Get the minor device number according to the device number
}
printk("Apply for device number successfully\\
");
//4. Register character device driver object cdev_add()
ret=cdev_add(cdev,MKDEV(major,minor),1); //Character device, device number, device quantity
if(ret)
{<!-- -->
printk("Failed to register character device driver object\\
");
goto out3;
}
printk("Register character device driver object successfully\\
");
//5. Submit directory up
cls=class_create(THIS_MODULE,"led0"); //Pointer to itself, file name
if(IS_ERR(cls))
{<!-- -->
printk("Failed to submit directory up\\
");
ret=-PTR_ERR(cls);
goto out4;
}
printk("submit directory successfully\\
");
//6. Submit the device node up
dev=device_create(cls,NULL,MKDEV(major,0),NULL,"led0"); //create device node
if(IS_ERR(dev))
{<!-- -->
printk("Failed to submit node information up\\
");
ret=-PTR_ERR(dev);
goto out5;
}
printk("Successful submission of device node information\\
");
//gpio subsystem
// 1. Parse the device tree node
dnode=of_find_node_by_name(NULL,"myleds");
if(dnode==NULL)
{<!-- -->
printk("Failed to parse device tree node\\
");
return -ENOMEM;
}
printk("parse device tree node successfully\\
");
// 2. Analyze the gpio number according to the device tree node and apply for the corresponding led
gpiono=gpiod_get_from_of_node(dnode,"led1",0,GPIOD_OUT_LOW,NULL);
if(IS_ERR(gpiono))
{<!-- -->
printk("Failed to parse the device number\\
");
return -PTR_ERR(gpiono);
}
printk("Apply for gpio number successfully\\
");
// 3. Turn on the light
gpiod_set_value(gpiono,1);
//soft interrupt
//Parse the device tree node
dnode=of_find_node_by_name(NULL,"mykeys");
if(dnode==NULL)
{<!-- -->
printk("Failed to parse device tree node\\
");
return -ENXIO;
}
printk("Device tree node parsed successfully\\
");
// Get soft interrupt number
irqno = irq_of_parse_and_map(dnode, 0);
if (!irqno)
{<!-- -->
printk("Soft interrupt number acquisition failed\\
");
return -ENOMEM;
}
printk("Soft interrupt number obtained successfully irqno=%d\\
", irqno);
// register interrupt
// ret1 = request_irq(irqno, myirq_handler, IRQF_TRIGGER_FALLING, "key", (void *)1);
ret1 = request_irq(irqno, myirq_handler, IRQF_TRIGGER_FALLING, "key", NULL);
if (ret1)
{<!-- -->
printk("Failed to register driver\\
");
return ret1;
}
printk("key1 interruption registration successful\\
");
return 0;
out5:
//Destroy the device information submitted above
device_destroy(cls,MKDEV(major,0));
class_destroy(cls);
out4:
cdev_del(cdev);
out3:
unregister_chrdev_region(MKDEV(major,minor),1);
out2:
kfree(cdev);
out1:
return ret;
}
static void __exit mycdev_exit(void)
{<!-- -->
//gpio subsystem
// 4. Turn off the lights
gpiod_set_value(gpiono,0);
// 5. Release the gpio number
gpiod_put(gpiono);
// logout interrupt
free_irq(irqno, NULL);
//1. Destroy device information device_destroy
device_destroy(cls,MKDEV(major,0));
//2. Destroy the directory class_destroy
class_destroy(cls);
//3. Logout object cdev_del()
cdev_del(cdev);
//4. Release the device number unregister_chrdev_region()
unregister_chrdev_region(MKDEV(major,minor),1);
//5. Release object space kfree()
kfree(cdev);
// Unregister the character device driver
unregister_chrdev(major, "led0");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
