Linux驱动修炼之道-LCD背光与gpio控制

努力成为linux kernel hacker的人李万鹏原创作品，为梦而战。转载请标明出处

http://blog.csdn.net/woshixingaaa/archive/2011/05/16/6423462.aspx

下图是LCD的引脚截图，GPG4是复用引脚，可以发送电源使能信号。GPIO的程序很简单，这里不再赘述。

驱动程序：

#include <linux/init.h>  
#include <linux/module.h>  
#include <linux/fs.h>  
#include <mach/regs-gpio.h>  
#include <asm/io.h>  
#include <mach/hardware.h>  
#include <linux/device.h>  
#include <linux/cdev.h>  
#include <linux/delay.h>  
int MYGPIO_MAJOR = 0;  
int MYGPIO_MINOR = 0;  
#define MYGPIO_NAME "lwp-gpio"  
dev_t dev_num;  
struct cdev *gpio_cdev;  
struct class *gpio_class;  
int i;  
static unsigned long led_table[]={  
    S3C2410_GPF3,  
    S3C2410_GPF4,  
    S3C2410_GPF5,  
    S3C2410_GPF6,  
};  
static unsigned long led_cfg_table[]={  
    S3C2410_GPF3_OUTP,  
    S3C2410_GPF4_OUTP,  
    S3C2410_GPF5_OUTP,  
    S3C2410_GPF6_OUTP,  
};  
int gpio_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg){  
    switch(cmd){  
        case -1:                   
            s3c2410_gpio_cfgpin(S3C2410_GPG4, S3C2410_GPG4_OUTP);         //关闭LCD背光 
            s3c2410_gpio_setpin(S3C2410_GPG4, 0);  
            break;  
        case  1:                                                          //打开背光
            s3c2410_gpio_setpin(S3C2410_GPG4, 1);                        
            break;  
        case  2:                                                          //开启流水灯                                                  
            while(1){  
                for(i = 0; i < 4; i++)  
                    s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);     
                for(i = 0; i < 4; i++){  
                    s3c2410_gpio_setpin(led_table[i],0);  
                    msleep(1000);  
                    s3c2410_gpio_setpin(led_table[i],1);  
                }  
            }  
            break;  
        case -2:                                                          //关闭流水灯
            for(i = 0; i < 4; i++){  
                s3c2410_gpio_setpin(led_table[i],1);  
            }  
            break;  
        case  3:                                                          //开启蜂鸣器
            s3c2410_gpio_cfgpin(S3C2410_GPB0, S3C2410_GPB0_OUTP);  
            s3c2410_gpio_setpin(S3C2410_GPB0, 1);  
            break;  
        case -3:                                                          //关闭蜂鸣器
            s3c2410_gpio_setpin(S3C2410_GPB0, 0);  
            break;  
        default:  
            break;  
    }  
    return 0;  
}  
int gpio_open(struct inode *inode, struct file *file){  
    printk("gpio is opened success/n");  
    return 0;  
}  
int gpio_close(struct inode *inode, struct file *file){  
    printk("gpio is closed success/n");  
    return 0;  
}  
struct file_operations gpio_ops = {  
    .owner = THIS_MODULE,  
        .ioctl = gpio_ioctl,      
    .open = gpio_open,  
    .release = gpio_close,  
};  
static int __init my_gpio_init(void){  
    int ret;  
    ret = alloc_chrdev_region(&dev_num, MYGPIO_MINOR, 1, MYGPIO_NAME);          //分配设备号
    if(ret < 0)  
        printk("can't get major number/n");  
    gpio_cdev = kmalloc(sizeof(struct cdev),GFP_KERNEL);                        //分配字父设备  
    if(!gpio_cdev){  
        return -ENOMEM;  
        goto fail_malloc;  
    }  
    memset(gpio_cdev,0,sizeof(struct cdev));  
    cdev_init(gpio_cdev, &gpio_ops);                                            //初始化字父设备  
    cdev_add(gpio_cdev, dev_num, 1);                                            //字符设备注册到系统
    gpio_class = class_create(THIS_MODULE,MYGPIO_NAME);                         //在/sys下建立一个类
    if(IS_ERR(gpio_class)){  
        printk("ERROR: Fail to create gpio_class class/n");  
        return -1;  
    }  
    device_create(gpio_class,NULL,dev_num,NULL,MYGPIO_NAME);                    //创建设备节点
    printk("gpio_cdev is registered success/n");  
fail_malloc:  
    unregister_chrdev_region(dev_num, 1);  
    return 0;  
}  
static void __exit my_gpio_exit(void){  
    unregister_chrdev_region(dev_num, 1);  
    cdev_del(gpio_cdev);  
    kfree(gpio_cdev);  
    device_destroy(gpio_class,dev_num);  
    class_destroy(gpio_class);  
    printk("gpio_cdev is dereigstered success/n");  
}  
module_init(my_gpio_init);  
module_exit(my_gpio_exit);  
MODULE_LICENSE("GPL");  
MODULE_AUTHOR("liwanpeng");

测试程序：

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
int main(){
	int fd, cmd;
	cmd = 0;
	fd = open("/dev/lwp-gpio",O_RDWR);
	if(fd < 0){
		printf("cannot open /dev/lwp-gpio/n");
		exit(1);
	}
	while(1){
		scanf("%d", &cmd);
		printf("cmd is %d/n",cmd);
		ioctl(fd, cmd);
	}
	close(fd);
	return 0;
}