linux driver ------ GPIO的驱动编写和调用

判断哪些文件被编译进内核：

1、通过 make menuconfig 查看

2、比如查看gpio类型的文件，输入 ls drivers/gpio/*.o，有生成.o文件表示被编译进内核

在编写驱动程序之前要保证该GPIO口没有被其他程序占用，若被占用则需要取消编译那个驱动程序。

/arch/arm/mach-exynos/include/mach/gpio-exynos4.h

/drivers/gpio/gpio-exynos4.c

#include <linux/init.h>
#include <linux/module.h>

/*驱动注册的头文件，包含驱动的结构体和注册和卸载的函数*/
#include <linux/platform_device.h>
/*注册杂项设备头文件*/
#include <linux/miscdevice.h>
/*注册设备节点的文件结构体*/
#include <linux/fs.h>

/*Linux中申请GPIO的头文件*/
#include <linux/gpio.h>
/*三星平台的GPIO配置函数头文件*/
/*三星平台EXYNOS系列平台，GPIO配置参数宏定义头文件*/
#include <plat/gpio-cfg.h>
#include <mach/gpio.h>
/*三星平台4412平台，GPIO宏定义头文件*/
#include <mach/gpio-exynos4.h>

#define DRIVER_NAME "hello_ctl"
#define DEVICE_NAME "hello_ctl"


MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("TOPEET");

static long hello_ioctl( struct file *files, unsigned int cmd, unsigned long arg){
    printk("cmd is %d,arg is %d
",cmd,arg);
    
    if(cmd > 1){
        printk(KERN_EMERG "cmd is 0 or 1
");
    }
    if(arg > 1){
        printk(KERN_EMERG "arg is only 1
");
    }
    
    gpio_set_value(EXYNOS4_GPL2(0),cmd);
    
    return 0;
}

static int hello_release(struct inode *inode, struct file *file){
    printk(KERN_EMERG "hello release
");
    return 0;
}

static int hello_open(struct inode *inode, struct file *file){
    printk(KERN_EMERG "hello open
");
    return 0;
}

static struct file_operations hello_ops = {
    .owner = THIS_MODULE,
    .open = hello_open,
    .release = hello_release,
    .unlocked_ioctl = hello_ioctl,
};

static  struct miscdevice hello_dev = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &hello_ops,
};


static int hello_probe(struct platform_device *pdv){
    int ret;
    
    printk(KERN_EMERG "	initialized
");
    
    ret = gpio_request(EXYNOS4_GPL2(0),"LEDS");
    if(ret < 0){
        printk(KERN_EMERG "gpio_request EXYNOS4_GPL2(0) failed!
");
        return ret;
    }
    
    s3c_gpio_cfgpin(EXYNOS4_GPL2(0),S3C_GPIO_OUTPUT);
    
    gpio_set_value(EXYNOS4_GPL2(0),0);
    
    misc_register(&hello_dev);
    
    return 0;
}

static int hello_remove(struct platform_device *pdv){
    
    printk(KERN_EMERG "	remove
");
    misc_deregister(&hello_dev);
    return 0;
}

static void hello_shutdown(struct platform_device *pdv){
    
    ;
}

static int hello_suspend(struct platform_device *pdv,pm_message_t pmt){
    
    return 0;
}

static int hello_resume(struct platform_device *pdv){
    
    return 0;
}

struct platform_driver hello_driver = {
    .probe = hello_probe,
    .remove = hello_remove,
    .shutdown = hello_shutdown,
    .suspend = hello_suspend,
    .resume = hello_resume,
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
    }
};


static int hello_init(void)
{
    int DriverState;
    
    printk(KERN_EMERG "HELLO WORLD enter!
");
    DriverState = platform_driver_register(&hello_driver);
    
    printk(KERN_EMERG "	DriverState is %d
",DriverState);
    return 0;
}


static void hello_exit(void)
{
    printk(KERN_EMERG "HELLO WORLD exit!
");
    
    platform_driver_unregister(&hello_driver);    
}

module_init(hello_init);
module_exit(hello_exit);