//1驱动框架
1.1静态注册设备
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#define LED_MAJOR		200		/* 主设备号 */
#define LED_NAME		"led" 	/* 设备名字 */

static int led_open(struct inode *inode, struct file *filp)
{
	return 0;
}

static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt)
{
	return 0;
}

static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{
	return 0;
}

static int led_release(struct inode *inode, struct file *filp)
{
	return 0;
}

static struct file_operations led_fops = {
	.owner = THIS_MODULE,
	.open = led_open,
	.read = led_read,
	.write = led_write,
	.release = led_release,
};


static int __init led_init(void)
{
	register_chrdev(LED_MAJOR, LED_NAME, &led_fops);
	return 0;
}

static void __exit led_exit(void)
{
	unregister_chrdev(LED_MAJOR, LED_NAME);
}

module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("sakura");

1.2新字符设备，引用了字符设备结构体
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>

/* newchrled设备结构体 */
struct newchrled_dev{
	dev_t devid;			/* 设备号 	 */
	struct cdev cdev;		/* cdev 	*/
	struct class *class;		/* 类 		*/
	struct device *device;	/* 设备 	 */
	int major;				/* 主设备号	  */
	int minor;				/* 次设备号   */
};

struct newchrled_dev newchrled;	/* led设备 */

static int led_open(struct inode *inode, struct file *filp)
{
	filp->private_data = &newchrled; /* 设置私有数据 */
	return 0;
}

static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt)
{
	return 0;
}

static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{
	return 0;
}

static int led_release(struct inode *inode, struct file *filp)
{
	return 0;
}

/* 设备操作函数 */
static struct file_operations newchrled_fops = {
	.owner = THIS_MODULE,
	.open = led_open,
	.read = led_read,
	.write = led_write,
	.release = 	led_release,
};

static int __init led_init(void)
{	
	if (newchrled.major) {		/*  定义了设备号 */
		newchrled.devid = MKDEV(newchrled.major, 0);
		register_chrdev_region(newchrled.devid, NEWCHRLED_CNT, NEWCHRLED_NAME);
	} else {						/* 没有定义设备号 */
		alloc_chrdev_region(&newchrled.devid, 0, NEWCHRLED_CNT, NEWCHRLED_NAME);	/* 申请设备号 */
		newchrled.major = MAJOR(newchrled.devid);	/* 获取分配号的主设备号 */
		newchrled.minor = MINOR(newchrled.devid);	/* 获取分配号的次设备号 */
	}	
	newchrled.cdev.owner = THIS_MODULE;
	cdev_init(&newchrled.cdev, &newchrled_fops);
	cdev_add(&newchrled.cdev, newchrled.devid, NEWCHRLED_CNT);
	newchrled.class = class_create(THIS_MODULE, NEWCHRLED_NAME);
	newchrled.device = device_create(newchrled.class, NULL, newchrled.devid, NULL, NEWCHRLED_NAME);
	
	return 0;
}

static void __exit led_exit(void)
{
	cdev_del(&newchrled.cdev);/*  删除cdev */
	unregister_chrdev_region(newchrled.devid, NEWCHRLED_CNT); /* 注销设备号 */
	device_destroy(newchrled.class, newchrled.devid);
	class_destroy(newchrled.class);
}

module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("zuozhongkai");

1.3platform驱动
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of_gpio.h>
#include <linux/semaphore.h>
#include <linux/timer.h>
#include <linux/irq.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/platform_device.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>

struct leddev_dev{
	dev_t devid;			/* 设备号	*/
	struct cdev cdev;		/* cdev		*/
	struct class *class;	/* 类 		*/
	struct device *device;	/* 设备		*/
	int major;				/* 主设备号	*/		
};

struct leddev_dev leddev; 	/* led设备 */

static int led_open(struct inode *inode, struct file *filp)
{
	filp->private_data = &leddev; /* 设置私有数据  */
	return 0;
}

static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{
	return 0;
}

static struct file_operations led_fops = {
	.owner = THIS_MODULE,
	.open = led_open,
	.write = led_write,
};

static int led_probe(struct platform_device *dev)
{	
	if (leddev.major) {		/*  定义了设备号 */
		leddev.devid = MKDEV(leddev.major, 0);
		register_chrdev_region(leddev.devid, LEDDEV_CNT, LEDDEV_NAME);
	} else {						/* 没有定义设备号 */
		alloc_chrdev_region(&leddev.devid, 0, LEDDEV_CNT, LEDDEV_NAME);	/* 申请设备号 */
		leddev.major = MAJOR(leddev.devid);	/* 获取分配号的主设备号 */
	}
	leddev.cdev.owner = THIS_MODULE;
	cdev_init(&leddev.cdev, &led_fops);
	cdev_add(&leddev.cdev, leddev.devid, LEDDEV_CNT);
	leddev.class = class_create(THIS_MODULE, LEDDEV_NAME);
	leddev.device = device_create(leddev.class, NULL, leddev.devid, NULL, LEDDEV_NAME);
	return 0;
}

static int led_remove(struct platform_device *dev)
{
	cdev_del(&leddev.cdev);/*  删除cdev */
	unregister_chrdev_region(leddev.devid, LEDDEV_CNT); /* 注销设备号 */
	device_destroy(leddev.class, leddev.devid);
	class_destroy(leddev.class);
	return 0;
}

static struct platform_driver led_driver = {
	.driver		= {
		.name	= "imx6ul-led",			/* 驱动名字，用于和设备匹配 */
	},
	.probe		= led_probe,
	.remove		= led_remove,
};
		
static int __init leddriver_init(void)
{
	return platform_driver_register(&led_driver);
}

static void __exit leddriver_exit(void)
{
	platform_driver_unregister(&led_driver);
}

module_init(leddriver_init);
module_exit(leddriver_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("zuozhongkai");

1.4dts的platform驱动
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of_gpio.h>
#include <linux/semaphore.h>
#include <linux/timer.h>
#include <linux/irq.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/platform_device.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>

struct leddev_dev{
	dev_t devid;				/* 设备号	*/
	struct cdev cdev;			/* cdev		*/
	struct class *class;		/* 类 		*/
	struct device *device;		/* 设备		*/
	int major;					/* 主设备号	*/	
	struct device_node *node;	/* LED设备节点 */
	int led0;					/* LED灯GPIO标号 */
};

struct leddev_dev leddev; 		/* led设备 */

static int led_open(struct inode *inode, struct file *filp)
{
	filp->private_data = &leddev; /* 设置私有数据  */
	return 0;
}

static struct file_operations led_fops = {
	.owner = THIS_MODULE,
	.open = led_open,
	.write = led_write,
};

static int led_probe(struct platform_device *dev)
{	
	if (leddev.major) {
		leddev.devid = MKDEV(leddev.major, 0);
		register_chrdev_region(leddev.devid, LEDDEV_CNT, LEDDEV_NAME);
	} else {
		alloc_chrdev_region(&leddev.devid, 0, LEDDEV_CNT, LEDDEV_NAME);
		leddev.major = MAJOR(leddev.devid);
	}
	cdev_init(&leddev.cdev, &led_fops);
	cdev_add(&leddev.cdev, leddev.devid, LEDDEV_CNT);
	leddev.class = class_create(THIS_MODULE, LEDDEV_NAME);
	leddev.device = device_create(leddev.class, NULL, leddev.devid, NULL, LEDDEV_NAME);
	leddev.node = of_find_node_by_path("/gpioled");
	of_get_named_gpio(leddev.node, "led-gpio", 0);
	return 0;
}

static int led_remove(struct platform_device *dev)
{
	cdev_del(&leddev.cdev);				/*  删除cdev */
	unregister_chrdev_region(leddev.devid, LEDDEV_CNT); /* 注销设备号 */
	device_destroy(leddev.class, leddev.devid);
	class_destroy(leddev.class);
	return 0;
}

static const struct of_device_id led_of_match[] = {
	{ .compatible = "atkalpha-gpioled" },
	{ /* Sentinel */ }
};

static struct platform_driver led_driver = {
	.driver		= {
		.name	= "imx6ul-led",			/* 驱动名字，用于和设备匹配 */
		.of_match_table	= led_of_match, /* 设备树匹配表 		 */
	},
	.probe		= led_probe,
	.remove		= led_remove,
};
		
static int __init leddriver_init(void)
{
	return platform_driver_register(&led_driver);
}

static void __exit leddriver_exit(void)
{
	platform_driver_unregister(&led_driver);
}

module_init(leddriver_init);
module_exit(leddriver_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("zuozhongkai");




//一些重要的函数
static inline int register_chrdev(unsigned int major, const char *name,const struct file_operations *fops)//要配合cat /proc/devices使用（先查看设备号）
static inline void unregister_chrdev(unsigned int major, const char *name)
MAJOR(dev) 
MINOR(dev) 
MKDEV(ma,mi)
int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count, const char *name)
void unregister_chrdev_region(dev_t from, unsigned count)
copy_from_user(void *to, const void __user *from, unsigned long n)
copy_to_user(void __user *to, const void *from, unsigned long n)
void writel (unsigned char data , unsigned short addr )   //4byte
unsigned char readl (unsigned int addr )                //4byte
void *memcpy(void *destin, void *source, unsigned n)
ioremap(cookie,size)
iounmap (volatile void __iomem *addr)
of_find_node_by_path("/alphaled")            //设备树常用函数，一定先找节点
of_find_property(dtsled.nd, "compatible", NULL)
ret = of_property_read_string(dtsled.nd, "status", &str);
of_property_read_u32_array(dtsled.nd, "reg", regdata, 10);

//shell
insmod chrdevbase.ko
modprobe chrdevbase.ko
mknod /dev/chrdevbase c 200 0  //创建设备节点文件
rmmod chrdevbase.ko

test：
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#define NEWCHRLED_CNT 1
#define NEWCHRLED_NAME "test"

/* newchrled设备结构体 */
struct newchrled_dev{
        dev_t devid;                    /* 设备号        */
        struct cdev cdev;               /* cdev         */
        struct class *class;            /* 类           */
        struct device *device;  /* 设备          */
        int major;                              /* 主设备号       */
        int minor;                              /* 次设备号   */
};

struct newchrled_dev newchrled; /* led设备 */

static int led_open(struct inode *inode, struct file *filp)
{
        filp->private_data = &newchrled; /* 设置私有数据 */
        return 0;
}

static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt)
{
        return 0;
}

static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{
        return 0;
}

static int led_release(struct inode *inode, struct file *filp)
{
        return 0;
}

/* 设备操作函数 */

static int led_release(struct inode *inode, struct file *filp)
{
        return 0;
}

/* 设备操作函数 */
static struct file_operations newchrled_fops = {
        .owner = THIS_MODULE,
        .open = led_open,
        .read = led_read,
        .write = led_write,
        .release =      led_release,
};

static int __init led_init(void)
{
        if (newchrled.major) {          /*  定义了设备号 */
                newchrled.devid = MKDEV(newchrled.major, 0);
                register_chrdev_region(newchrled.devid, NEWCHRLED_CNT, NEWCHRLED_NAME);
        } else {                                                /* 没有定义设备号 */
                alloc_chrdev_region(&newchrled.devid, 0, NEWCHRLED_CNT, NEWCHRLED_NAME);        /* 申请设备号 */
                newchrled.major = MAJOR(newchrled.devid);       /* 获取分配号的主设备号 */
                newchrled.minor = MINOR(newchrled.devid);       /* 获取分配号的次设备号 */
        }
        newchrled.cdev.owner = THIS_MODULE;
        cdev_init(&newchrled.cdev, &newchrled_fops);
        cdev_add(&newchrled.cdev, newchrled.devid, NEWCHRLED_CNT);
        newchrled.class = class_create(THIS_MODULE, NEWCHRLED_NAME);
        if (IS_ERR(newchrled.class)) {
                return PTR_ERR(newchrled.class);
        }
        newchrled.device = device_create(newchrled.class, NULL,newchrled.devid, NULL, NEWCHRLED_NAME);
        if (IS_ERR(newchrled.device)) {
                return PTR_ERR(newchrled.device);
        }
        printk(KERN_EMERG"init success\n");
        return 0;
}

static void __exit led_exit(void)
{
        cdev_del(&newchrled.cdev);/*  删除cdev */
        unregister_chrdev_region(newchrled.devid, NEWCHRLED_CNT); /* 注销设备号 */
        device_destroy(newchrled.class, newchrled.devid);
        class_destroy(newchrled.class);

        printk(KERN_EMERG"exit success\n");
}

module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("luozhikun");
/****************************************************************************/


/*makefile   */
KERNELDIR := /home/sakurar/linux/IMX6ULL/linux/alientek_linux/linux-imx-rel_imx_4.1.15_2.1.0_ga
CURRENT_PATH := $(shell pwd)
obj-m := chrdevbase.o

build: kernel_modules

kernel_modules:
	$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) modules
clean:
	$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) clean