디바이스 드라이버 GPIO 조이스틱 예제

조이스틱 모듈 예제.

---

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
    
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <linux/gpio.h>
 
 
//조이스틱 GPIO PIN번호
#define JOG_UP      5
#define JOG_DOWN    6
#define JOG_LEFT   16
#define JOG_RIGHT  20
#define JOG_CENTER 21
 
static ssize_t drv_hw_sw_read(struct file * file, char * buf, size_t length, loff_t * ofs)
{
    int ret;
    int stat[5];
 
    stat[0] = gpio_get_value(JOG_UP);
    stat[1] = gpio_get_value(JOG_DOWN);
    stat[2] = gpio_get_value(JOG_LEFT);
    stat[3] = gpio_get_value(JOG_RIGHT);
    stat[4] = gpio_get_value(JOG_CENTER);
 
    // 유저 영역에서 넘어온 buf포인터에 stat을 stat size만큼 복사.
    ret = copy_to_user(buf, stat, sizeof(stat));
 
    return 0;
}
 
static struct file_operations drv_hw_sw_fops = 
{
    .owner = THIS_MODULE,
    .read = drv_hw_sw_read,
};
 
static struct miscdevice drv_hw_sw_driver = 
{
    .minor = MISC_DYNAMIC_MINOR,
    .name = "drv_hw_sw",
    .fops = &drv_hw_sw_fops,
};
 
static int drv_hw_sw_init(void)
{
    int ret;
    ret = gpio_request(JOG_UP, "gpio sw");
    if(ret)
        printk("#### FAILED Request gpio %d. error : %d \n", JOG_UP, ret);
    else 
        gpio_direction_input(JOG_UP);
    
 
    ret = gpio_request(JOG_DOWN, "gpio sw");
    if(ret)
        printk("#### FAILED Request gpio %d. error : %d \n", JOG_DOWN, ret);
    else 
        gpio_direction_input(JOG_DOWN);
    
 
    ret = gpio_request(JOG_LEFT, "gpio sw");
    if(ret)
        printk("#### FAILED Request gpio %d. error : %d \n", JOG_LEFT, ret);
    else 
        gpio_direction_input(JOG_LEFT);
    
 
    ret = gpio_request(JOG_RIGHT, "gpio sw");
    if(ret)
        printk("#### FAILED Request gpio %d. error : %d \n", JOG_RIGHT, ret);
    else 
        gpio_direction_input(JOG_RIGHT);
    
 
    ret = gpio_request(JOG_CENTER, "gpio sw");
    if(ret)
        printk("#### FAILED Request gpio %d. error : %d \n", JOG_CENTER, ret);
    else 
        gpio_direction_input(JOG_CENTER);
    
    return misc_register(&drv_hw_sw_driver);
}
 
static void drv_hw_sw_exit(void)
{
    gpio_free(JOG_UP);
    gpio_free(JOG_DOWN);
    gpio_free(JOG_LEFT);
    gpio_free(JOG_RIGHT);
    gpio_free(JOG_CENTER);
    misc_deregister(&drv_hw_sw_driver);
}
 
module_init(drv_hw_sw_init);
module_exit(drv_hw_sw_exit);
 
MODULE_AUTHOR("PlanX Studio");
MODULE_DESCRIPTION("drv_hw_sw");
MODULE_LICENSE("Dual BSD/GPL");
 

조이스틱 어플리케이션 예제.

---

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
 
#include <sys/time.h>
#include <fcntl.h>
#include <pthread.h>
 
pthread_t thread;  /* User Thread */
 
int thread_start_flag = 1;
int thr_id;
 
#define NODE_NAME "/dev/drv_hw_sw"
 
void print_button_state(int i, int* before_state)
{
    if (i == 0)
        printf(" jog up botton\n");
    else if (i == 1)
        printf (" jog down botton\n");
    else if (i == 2)
        printf(" jog left botton\n");
    else if (i == 3)
        printf(" jog right botton\n");
    else if (i == 4)
        printf(" jog centor botton\n");
    else 
        printf("input scope is 0 ~ 4\n");
}
 
void *sw_thread(void * unuse) {
    int fd;
    int ret;
    int before_stat[5]={};
    int cur_stat[5];
    int cnt=0;
    int i;
    fd = open(NODE_NAME, O_RDONLY);
 
    while(thread_start_flag) {
        
        // 모듈에서의 처리결과 cur_stat에 조이스틱의 현재 값이 복사된다.
        ret = read(fd, cur_stat, sizeof(cur_stat));
        
        for (i=0; i<5; i++)
        {
            if (before_stat[i] != cur_stat[i]) {
                print_button_state(i, before_stat);
                before_stat[i] = cur_stat[i];
            }
            //usleep(100000); // 0.1sec
        }
    }
    close(fd);
 
    printf("#### Terminate thead...\n");
    pthread_exit((void *)fd);
}
 
int main(int argc, char * argv[]) 
{
    int status, i;
 
    thr_id = pthread_create(&thread, 0, sw_thread, 0);
    if (thr_id < 0) {
        printf("#### ERROR pthread_create\n");
        exit(0);
    }
 
 
    while (1)
        pause();
    thread_start_flag = 0;
    pthread_join(thread, (void **)&status);
    printf("#### Exit program, status = %d\n", status);
 
    exit(0);
}
 

출처 : 인지소프트웨어 기술포럼 ( 전유진 강사님 수업자료)