Linux 编写一个 字符设备驱动

Linux-DEVICE_ATTR()介绍及使用示例

驱动中动态创建设备号、设备节点

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#include <linux/init.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/rockchip/common.h> #include <linux/kdev_t.h> #include <linux/device.h>   /** struct hello_test_data {     struct device *classdev;     int blue=456; }   static struct hello_test_data *hello_data; **/   static struct class  *hello_test_class; //定义设备类 static struct device *classdev; static  char mybuf[100]="123";   //执行cat会调用到此函数     show对应的是read static ssize_t hello_test_show(struct device *dev, struct device_attribute *attr, char *buf) {     return sprintf(buf, "%s\n", mybuf); } //执行echo 1 >  hello_test会执行到此函数   store 对应的是write static ssize_t hello_test_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) {     sprintf(mybuf, "%s", buf);     return count; }       //                  _name     _mode(权限)  (显示函数) （写入） static DEVICE_ATTR(hello_test, 0777, hello_test_show, hello_test_store);                 //设备属性文件 名                     // probe初始化函数                                 //cdev 分配设备对象空间 static int hello_test_probe(struct platform_device *pdev) {     printk("Gatsby  probe hello_test\n");           // 创建对应的节点file        //device_create_file(&pdev->dev, &dev_attr_hello_test);       classdev=device_create(hello_test_class, &pdev->dev, MKDEV(0, 0), NULL,"hello_test_device",0);       sysfs_create_file(&pdev->dev.kobj, &dev_attr_hello_test.attr);                 return 0; }   static const struct of_device_id hello_of_match[] = {         { .compatible = "rockchip,hello_test"},         { }, };   // platform_driver 的结构 static struct platform_driver hello_test_driver = {          .probe = hello_test_probe,                     .driver = {                      .name = "hello_test_class",                      .owner = THIS_MODULE,                      .of_match_table = hello_of_match, //需要再dts中做匹配                     } };       static int __init hello_init(void) {     printk("Gatsby hello_init\n");           /**     struct device *classdev;           classdev = device_create(hello_test, 0, MKDEV(0,0),NULL,"mytest_device");    //创建mytest_device设备     **/           hello_test_class = class_create(THIS_MODULE, "hello_test_class");//  在/sys/class目录下生成 hello_test目录           platform_driver_register(&hello_test_driver);           return 0; }   static void __exit hello_exit(void) {     printk("Gatsby hello_exit\n");     platform_driver_unregister(&hello_test_driver); }   module_init(hello_init); module_exit(hello_exit);   MODULE_AUTHOR("hello_test"); MODULE_DESCRIPTION("Gatsby"); MODULE_LICENSE("GPL");

makefile

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1	obj-$(CONFIG_HELLO_TEST)            += hello_test.o

kconfig

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config HELLO_TEST     tristate "Hello world for Gatsby"     help       Hello for Gatsby

上一级目录 makefile

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1	obj-y               += gatsby/

kconfig

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1	source "drivers/gatsby/Kconfig"