杂项设备驱动之 申请IO口

ret = gpio_request(EXYNOS4_GPL2(0),"LEDS");

gpio_free(EXYNOS4_GPL2(0));

在probe 程序时，request 之后，记得需要在release 中释放。

#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"
#define DEVICE_NAME "hello"




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


static long hello_ioctl( struct file *files, unsigned int cmd, unsigned long arg){
printk("cmd is %d,arg is %ld\n",cmd,arg);

if(cmd < 1){
printk(KERN_EMERG " need the param \n");
return 0;
}



gpio_set_value(EXYNOS4_GPL2(0),arg);

return 0;
}


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


static int hello_open(struct inode *inode, struct file *file){
printk(KERN_EMERG "hello open\n");
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 "\tinitialized\n");
ret = gpio_request(EXYNOS4_GPL2(0),"LEDS");
if(ret < 0){
printk(KERN_EMERG "gpio_request EXYNOS4_GPL2(0) failed!\n");
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){

//gpio_free(EXYNOS4_GPL2(0));

/*

安装卸载后，重新安装，出现以下

[ 5073.916637] gpio_request EXYNOS4_GPL2(0) failed!
[ 5073.929300] hello: probe of hello failed with error -16

因为第一次安装模块时

ret = gpio_request(EXYNOS4_GPL2(0),"LEDS");

占用了该io 的资源

但是在卸载时，并没有释放，导致资源一直被占用。

*/

printk(KERN_EMERG "\tremove\n");
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!\n");
DriverState = platform_driver_register(&hello_driver);

printk(KERN_EMERG "\tDriverState is %d\n",DriverState);
return 0;
}




static void hello_exit(void)
{
printk(KERN_EMERG "HELLO WORLD exit!\n");

platform_driver_unregister(&hello_driver);
}


module_init(hello_init);
module_exit(hello_exit);