linux驱动–LED驱动

配置介绍

前面已经详细的介绍了关于设备注册、驱动注册以及设备节点的生成的相关问题，本文主要介绍如何写LED驱动程序。

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主要介绍GPIO的 调用、赋值以及配置的函数

（1）使用一个GPIO前必须对其进行申请，申请GPIO的函数在linux头文件include/linux/gpio.h下

GPIO_request函数有两个参数，第一个gpio为所需要申请的gpio，*label为gpio编号，是为了便于阅读。若该gpio被占用，则返回错误表示被占用。

与GPIO_request对应的是gpio_free函数，操作方法只需要传入gpio端口号即可。

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（2）配置完GPIO后，需要对其设置值，就需要使用gpio_set_value函数了

两个参数分别为
unsigned gpio，GPIO
int value，高电平 1 和低电平 0

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（3）GPIO输出方式配置
在平台文件中arch/arm/plat-samsung/include/plat/gpio-cfg.h中使用函数extern int s3c_gpio_cfgpin(unsigned int pin, unsigned int to)

参数 unsigned int pin，管脚

参数 unsigned int to，配置参数。

to参数可以取值如下
arch/arm/plat-samsung/include/plat/gpio-cfg.h中定义的to取值

#define S3C_GPIO_INPUT    (S3C_GPIO_SPECIAL(0))#define S3C_GPIO_OUTPUT   (S3C_GPIO_SPECIAL(1))#define S3C_GPIO_SFN(x)    (S3C_GPIO_SPECIAL(x))

LED驱动例程

    #include <linux/module.h>//与module相关的信息    #include <linux/kernel.h>    #include <linux/init.h>      //与init相关的函数    #include <linux/platform_device.h>    #include <linux/miscdevice.h>    #include <linux/fs.h>    /***gpio申请和释放***/    #include <linux/gpio.h>    /*******************/    #include <plat/gpio-cfg.h>    /*********************/    #include <mach/gpio-exynos4.h>    #include <mach/gpio.h>    /***************用到的函数与结构体******************    extern int platform_driver_register(struct platform_driver *);    extern void platform_driver_unregister(struct platform_driver *);            int (*probe)(struct platform_device *);            int (*remove)(struct platform_device *);            void (*shutdown)(struct platform_device *);            int (*suspend)(struct platform_device *, pm_message_t state);            int (*resume)(struct platform_device *);    杂项设备结构体    struct miscdevice  {            int minor;            const char *name;            const struct file_operations *fops;            struct list_head list;            struct device *parent;            struct device *this_device;            const char *nodename;            mode_t mode;    };    extern int misc_register(struct miscdevice * misc);    extern int misc_deregister(struct miscdevice *misc);    struct file_operations {            struct module *owner;             long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);            long (*compat_ioctl) (struct file *, unsigned int, unsigned long);            int (*mmap) (struct file *, struct vm_area_struct *);            int (*open) (struct inode *, struct file *);            int (*flush) (struct file *, fl_owner_t id);            int (*release) (struct inode *, struct file *);            int (*fsync) (struct file *, int datasync);            int (*aio_fsync) (struct kiocb *, int datasync);            int (*fasync) (int, struct file *, int);            int (*lock) (struct file *, int, struct file_lock *);    static inline int gpio_request(unsigned gpio, const char *label)    static inline void gpio_free(unsigned gpio)    static inline void gpio_set_value(unsigned gpio, int value)    EXYNOS4_GPIO_L2    s3c_gpio_cfgpin(unsigned int pin, unsigned int to);    S3C_GPIO_OUTPUT    **********************************/    MODULE_LICENSE("GPL");    MODULE_AUTHOR("zhangsan");    #define DRIVER_NAME "hello_ctl"    #define DEVICE_NAME "hello_ctl"    static long hello_ioctl(struct file *file, unsigned int cmd, unsigned long arg)    {        printk(KERN_INFO "The cmd is %d,arg is %d\n",cmd,arg);        if(cmd>1)        {           printk(KERN_INFO "cmd should be 0 or 1\n");        }        if(arg>1)           printk(KERN_INFO "arg must be 1\n");        gpio_set_value(EXYNOS4_GPL2(0), cmd);//关闭        return 0;    }    static int hello_release(struct inode *inode, struct file *file)    {        printk(KERN_INFO "hello_release\n");            return 0;    }    static int hello_open(struct inode *inode, struct file *file)    {        printk(KERN_INFO "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_INFO "program inited!\n");        ret=gpio_request(EXYNOS4_GPL2(0),"LED1");        if(ret<0)        {           printk(KERN_INFO "request gpio failed\n");           return ret;          }        s3c_gpio_cfgpin(EXYNOS4_GPL2(0),S3C_GPIO_OUTPUT);        gpio_set_value(EXYNOS4_GPL2(0), 0);//关闭        misc_register(&hello_dev);        return 0;    }    static int hello_remove(struct platform_device *pdv)    {        gpio_free(EXYNOS4_GPL2(0));        misc_deregister(&hello_dev);        return 0;    }    static void hello_shutdown(struct platform_device *pdv)    {        printk(KERN_INFO "hello_shutdown\n");       }    static int hello_suspend(struct platform_device *pdv)    {        printk(KERN_INFO "Hello_suspend\n");        return 0;    }    static int hello_resume(struct platform_device *pdv)    {        printk(KERN_INFO "Hello_resume\n");        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 hellodriver_init()    {        int Driverstate;        //printk(KERN_INFO "Hello_init\n");        Driverstate=platform_driver_register(&hello_driver);        printk(KERN_INFO "Driverstate is %d\n",Driverstate);        return 0;    }    static void hellodriver_exit()    {        printk(KERN_INFO "Hello_exit\n");        platform_driver_unregister(&hello_driver);    }    module_init(hellodriver_init);    module_exit(hellodriver_exit);

驱动调用程序

写简单的驱动调用程序测试驱动

    #include <stdio.h>    #include <sys/types.h>    #include <sys/stat.h>    #include <fcntl.h>    #include <unistd.h>    #include <sys/ioctl.h>    int main()    {        int fd;        char *hellonode="/dev/hello_ctl";        if((fd=open(hellonode,O_RDWR|O_NOCTTY|O_NDELAY))<0)        {            printf("open %s.failed",hellonode);        }        else        {            printf("APP open %s sucess!",hellonode);            ioctl(fd,0,1);            sleep(2);            ioctl(fd,1,1);            sleep(2);            ioctl(fd,0,1);            sleep(2);            ioctl(fd,1,1);            sleep(2);        }        close(fd);        return 0;    }