add 09_UART/07

IMX6ULL/doc_pic/09_UART/07_字符设备驱动程序的另一种注册方法.md

@@ -0,0 +1,115 @@
+## 字符设备驱动程序的另一种注册方法
+
+参考资料
+
+* 参考代码：`drivers\char\pc8736x_gpio.c`
+
+* 本节课程源码在GIT仓库里
+
+  ```shell
+  驱动大全:
+  doc_and_source_for_drivers\IMX6ULL\source\09_UART\
+  	03_char_dev_driver\
+  		01b_hello_drv
+  doc_and_source_for_drivers\STM32MP157\source\A7\09_UART\
+  	03_char_dev_driver\
+  		01b_hello_drv
+
+  快速入门:
+  01_all_series_quickstart\05_嵌入式Linux驱动开发基础知识\source\
+  	01b_hello_drv
+  ```
+  
+  
+
+### 1. 字符设备驱动程序框架
+
+![image-20210721184155242](pic/09_UART/22_chr_dev_driver.png)
+
+
+
+编写驱动程序的套路：
+* 确定主设备号，也可以让内核分配
+* 定义自己的file_operations结构体
+* 实现对应的drv_open/drv_read/drv_write等函数，填入file_operations结构体
+* 把file_operations结构体告诉内核：register_chrdev
+* 谁来注册驱动程序啊？得有一个入口函数：安装驱动程序时，就会去调用这个入口函数
+* 有入口函数就应该有出口函数：卸载驱动程序时，出口函数调用unregister_chrdev
+* 其他完善：提供设备信息，自动创建设备节点：class_create, device_create
+
+
+
+
+
+### 2. 新的注册方法
+
+参考代码：`drivers\char\pc8736x_gpio.c`
+
+* 注册字符设备区域
+  * 有主设备号：register_chrdev_region
+  * 无主设备号：alloc_chrdev_region
+* 分配/设置/注册cdev
+  * cdev_alloc
+  * cdev_init
+  * cdev_add
+
+
+
+
+
+### 3. 上机实验
+
+#### 3.1 IMX6ULL
+
+先设置工具链：
+
+```shell
+export ARCH=arm
+export CROSS_COMPILE=arm-buildroot-linux-gnueabihf-
+export PATH=$PATH:/home/book/100ask_imx6ull-sdk/ToolChain/arm-buildroot-linux-gnueabihf_sdk-buildroot/bin
+```
+
+
+
+编译、执行程序:
+
+```shell
+Ubuntu:
+cd 01_hello_drv\
+make
+
+开发板:
+insmod hello_drv.ko
+./hello_drv_test  -w abcd
+./hello_drv_test  -r
+```
+
+
+
+#### 3.2 STM32MP157
+
+先设置工具链：
+
+```shell
+export ARCH=arm
+export CROSS_COMPILE=arm-buildroot-linux-gnueabihf-
+export PATH=$PATH:/home/book/100ask_stm32mp157_pro-sdk/ToolChain/arm-buildroot-linux-gnueabihf_sdk-buildroot/bin
+```
+
+
+
+编译、执行程序:
+
+```shell
+Ubuntu:
+cd 01_hello_drv\
+make
+
+开发板:
+insmod hello_drv.ko
+./hello_drv_test  -w abcd
+./hello_drv_test  -r
+```
+
+
+

IMX6ULL/source/09_UART/03_char_dev_driver/01_hello_drv/Makefile

@@ -0,0 +1,21 @@
+
+# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
+# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
+# 2.1 ARCH,          比如: export ARCH=arm64
+# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
+# 2.3 PATH,          比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin 
+# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
+#       请参考各开发板的高级用户使用手册
+
+KERN_DIR = /home/book/100ask_imx6ull-sdk/Linux-4.9.88
+
+all:
+	make -C $(KERN_DIR) M=`pwd` modules 
+	$(CROSS_COMPILE)gcc -o hello_drv_test hello_drv_test.c 
+
+clean:
+	make -C $(KERN_DIR) M=`pwd` modules clean
+	rm -rf modules.order
+	rm -f hello_drv_test
+
+obj-m	+= hello_drv.o

IMX6ULL/source/09_UART/03_char_dev_driver/01_hello_drv/hello_drv.c

@@ -0,0 +1,104 @@
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/stat.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/tty.h>
+#include <linux/kmod.h>
+#include <linux/gfp.h>
+
+/* 1. 确定主设备号                                                                 */
+static int major = 0;
+static char kernel_buf[1024];
+static struct class *hello_class;
+
+
+#define MIN(a, b) (a < b ? a : b)
+
+/* 3. 实现对应的open/read/write等函数，填入file_operations结构体                   */
+static ssize_t hello_drv_read (struct file *file, char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_to_user(buf, kernel_buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static ssize_t hello_drv_write (struct file *file, const char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_from_user(kernel_buf, buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static int hello_drv_open (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+static int hello_drv_close (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+/* 2. 定义自己的file_operations结构体                                              */
+static struct file_operations hello_drv = {
+	.owner	 = THIS_MODULE,
+	.open    = hello_drv_open,
+	.read    = hello_drv_read,
+	.write   = hello_drv_write,
+	.release = hello_drv_close,
+};
+
+/* 4. 把file_operations结构体告诉内核：注册驱动程序                                */
+/* 5. 谁来注册驱动程序啊？得有一个入口函数：安装驱动程序时，就会去调用这个入口函数 */
+static int __init hello_init(void)
+{
+	int err;
+	
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	major = register_chrdev(0, "hello", &hello_drv);  /* /dev/hello */
+
+
+	hello_class = class_create(THIS_MODULE, "hello_class");
+	err = PTR_ERR(hello_class);
+	if (IS_ERR(hello_class)) {
+		printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+		unregister_chrdev(major, "hello");
+		return -1;
+	}
+	
+	device_create(hello_class, NULL, MKDEV(major, 0), NULL, "hello"); /* /dev/hello */
+	
+	return 0;
+}
+
+/* 6. 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数           */
+static void __exit hello_exit(void)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	device_destroy(hello_class, MKDEV(major, 0));
+	class_destroy(hello_class);
+	unregister_chrdev(major, "hello");
+}
+
+
+/* 7. 其他完善：提供设备信息，自动创建设备节点                                     */
+
+module_init(hello_init);
+module_exit(hello_exit);
+
+MODULE_LICENSE("GPL");
+
+

IMX6ULL/source/09_UART/03_char_dev_driver/01_hello_drv/hello_drv_test.c

@@ -0,0 +1,54 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * ./hello_drv_test -w abc
+ * ./hello_drv_test -r
+ */
+int main(int argc, char **argv)
+{
+	int fd;
+	char buf[1024];
+	int len;
+	
+	/* 1. 判断参数 */
+	if (argc < 2) 
+	{
+		printf("Usage: %s -w <string>\n", argv[0]);
+		printf("       %s -r\n", argv[0]);
+		return -1;
+	}
+
+	/* 2. 打开文件 */
+	fd = open("/dev/hello", O_RDWR);
+	if (fd == -1)
+	{
+		printf("can not open file /dev/hello\n");
+		return -1;
+	}
+
+	/* 3. 写文件或读文件 */
+	if ((0 == strcmp(argv[1], "-w")) && (argc == 3))
+	{
+		len = strlen(argv[2]) + 1;
+		len = len < 1024 ? len : 1024;
+		write(fd, argv[2], len);
+	}
+	else
+	{
+		len = read(fd, buf, 1024);		
+		buf[1023] = '\0';
+		printf("APP read : %s\n", buf);
+	}
+	
+	close(fd);
+	
+	return 0;
+}
+
+

IMX6ULL/source/09_UART/03_char_dev_driver/01b_hello_drv/Makefile

@@ -0,0 +1,21 @@
+
+# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
+# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
+# 2.1 ARCH,          比如: export ARCH=arm64
+# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
+# 2.3 PATH,          比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin 
+# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
+#       请参考各开发板的高级用户使用手册
+
+KERN_DIR = /home/book/100ask_imx6ull-sdk/Linux-4.9.88
+
+all:
+	make -C $(KERN_DIR) M=`pwd` modules 
+	$(CROSS_COMPILE)gcc -o hello_drv_test hello_drv_test.c 
+
+clean:
+	make -C $(KERN_DIR) M=`pwd` modules clean
+	rm -rf modules.order
+	rm -f hello_drv_test
+
+obj-m	+= hello_drv.o

IMX6ULL/source/09_UART/03_char_dev_driver/01b_hello_drv/hello_drv.c

@@ -0,0 +1,114 @@
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/stat.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/tty.h>
+#include <linux/kmod.h>
+#include <linux/gfp.h>
+
+/* 1. 确定主设备号                                                                 */
+static int major = 0;
+static struct cdev hello_cdev;
+
+static char kernel_buf[1024];
+static struct class *hello_class;
+
+
+#define MIN(a, b) (a < b ? a : b)
+
+/* 3. 实现对应的open/read/write等函数，填入file_operations结构体                   */
+static ssize_t hello_drv_read (struct file *file, char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_to_user(buf, kernel_buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static ssize_t hello_drv_write (struct file *file, const char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_from_user(kernel_buf, buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static int hello_drv_open (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+static int hello_drv_close (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+/* 2. 定义自己的file_operations结构体                                              */
+static struct file_operations hello_drv = {
+	.owner	 = THIS_MODULE,
+	.open    = hello_drv_open,
+	.read    = hello_drv_read,
+	.write   = hello_drv_write,
+	.release = hello_drv_close,
+};
+
+/* 4. 把file_operations结构体告诉内核：注册驱动程序                                */
+/* 5. 谁来注册驱动程序啊？得有一个入口函数：安装驱动程序时，就会去调用这个入口函数 */
+static int __init hello_init(void)
+{
+	int err;
+	int rc;
+	dev_t devid;
+	
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	//major = register_chrdev(0, "hello", &hello_drv);  /* /dev/hello */
+	rc = alloc_chrdev_region(&devid, 0, 1, "hello");
+	major = MAJOR(devid);
+	cdev_init(&hello_cdev, &hello_drv);
+	cdev_add(&hello_cdev, devid, 1);
+
+	hello_class = class_create(THIS_MODULE, "hello_class");
+	err = PTR_ERR(hello_class);
+	if (IS_ERR(hello_class)) {
+		printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+		unregister_chrdev(major, "hello");
+		return -1;
+	}
+	
+	device_create(hello_class, NULL, MKDEV(major, 0), NULL, "hello"); /* /dev/hello */
+	
+	return 0;
+}
+
+/* 6. 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数           */
+static void __exit hello_exit(void)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	device_destroy(hello_class, MKDEV(major, 0));
+	class_destroy(hello_class);
+	
+	//unregister_chrdev(major, "hello");
+	cdev_del(&hello_cdev);
+	unregister_chrdev_region(MKDEV(major,0), 1);	
+}
+
+
+/* 7. 其他完善：提供设备信息，自动创建设备节点                                     */
+
+module_init(hello_init);
+module_exit(hello_exit);
+
+MODULE_LICENSE("GPL");
+
+

IMX6ULL/source/09_UART/03_char_dev_driver/01b_hello_drv/hello_drv_test.c

@@ -0,0 +1,54 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * ./hello_drv_test -w abc
+ * ./hello_drv_test -r
+ */
+int main(int argc, char **argv)
+{
+	int fd;
+	char buf[1024];
+	int len;
+	
+	/* 1. 判断参数 */
+	if (argc < 2) 
+	{
+		printf("Usage: %s -w <string>\n", argv[0]);
+		printf("       %s -r\n", argv[0]);
+		return -1;
+	}
+
+	/* 2. 打开文件 */
+	fd = open("/dev/hello", O_RDWR);
+	if (fd == -1)
+	{
+		printf("can not open file /dev/hello\n");
+		return -1;
+	}
+
+	/* 3. 写文件或读文件 */
+	if ((0 == strcmp(argv[1], "-w")) && (argc == 3))
+	{
+		len = strlen(argv[2]) + 1;
+		len = len < 1024 ? len : 1024;
+		write(fd, argv[2], len);
+	}
+	else
+	{
+		len = read(fd, buf, 1024);		
+		buf[1023] = '\0';
+		printf("APP read : %s\n", buf);
+	}
+	
+	close(fd);
+	
+	return 0;
+}
+
+

README.md

@@ -334,6 +334,12 @@ git clone https://e.coding.net/weidongshan/linux/doc_and_source_for_drivers.git
   06_Linux串口应用编程_GPS
   ```
 
+* 2021.07.21 发布"UART子系统"
+
+  ```shell
+  07_字符设备驱动程序的另一种注册方法
+  ```
+
 ## 6. 联系方式
 
 * 官网：http://www.100ask.net

STM32MP157/doc_pic/09_UART/07_字符设备驱动程序的另一种注册方法.md

@@ -0,0 +1,115 @@
+## 字符设备驱动程序的另一种注册方法
+
+参考资料
+
+* 参考代码：`drivers\char\pc8736x_gpio.c`
+
+* 本节课程源码在GIT仓库里
+
+  ```shell
+  驱动大全:
+  doc_and_source_for_drivers\IMX6ULL\source\09_UART\
+  	03_char_dev_driver\
+  		01b_hello_drv
+  doc_and_source_for_drivers\STM32MP157\source\A7\09_UART\
+  	03_char_dev_driver\
+  		01b_hello_drv
+
+  快速入门:
+  01_all_series_quickstart\05_嵌入式Linux驱动开发基础知识\source\
+  	01b_hello_drv
+  ```
+  
+  
+
+### 1. 字符设备驱动程序框架
+
+![image-20210721184155242](pic/09_UART/22_chr_dev_driver.png)
+
+
+
+编写驱动程序的套路：
+* 确定主设备号，也可以让内核分配
+* 定义自己的file_operations结构体
+* 实现对应的drv_open/drv_read/drv_write等函数，填入file_operations结构体
+* 把file_operations结构体告诉内核：register_chrdev
+* 谁来注册驱动程序啊？得有一个入口函数：安装驱动程序时，就会去调用这个入口函数
+* 有入口函数就应该有出口函数：卸载驱动程序时，出口函数调用unregister_chrdev
+* 其他完善：提供设备信息，自动创建设备节点：class_create, device_create
+
+
+
+
+
+### 2. 新的注册方法
+
+参考代码：`drivers\char\pc8736x_gpio.c`
+
+* 注册字符设备区域
+  * 有主设备号：register_chrdev_region
+  * 无主设备号：alloc_chrdev_region
+* 分配/设置/注册cdev
+  * cdev_alloc
+  * cdev_init
+  * cdev_add
+
+
+
+
+
+### 3. 上机实验
+
+#### 3.1 IMX6ULL
+
+先设置工具链：
+
+```shell
+export ARCH=arm
+export CROSS_COMPILE=arm-buildroot-linux-gnueabihf-
+export PATH=$PATH:/home/book/100ask_imx6ull-sdk/ToolChain/arm-buildroot-linux-gnueabihf_sdk-buildroot/bin
+```
+
+
+
+编译、执行程序:
+
+```shell
+Ubuntu:
+cd 01_hello_drv\
+make
+
+开发板:
+insmod hello_drv.ko
+./hello_drv_test  -w abcd
+./hello_drv_test  -r
+```
+
+
+
+#### 3.2 STM32MP157
+
+先设置工具链：
+
+```shell
+export ARCH=arm
+export CROSS_COMPILE=arm-buildroot-linux-gnueabihf-
+export PATH=$PATH:/home/book/100ask_stm32mp157_pro-sdk/ToolChain/arm-buildroot-linux-gnueabihf_sdk-buildroot/bin
+```
+
+
+
+编译、执行程序:
+
+```shell
+Ubuntu:
+cd 01_hello_drv\
+make
+
+开发板:
+insmod hello_drv.ko
+./hello_drv_test  -w abcd
+./hello_drv_test  -r
+```
+
+
+

STM32MP157/source/A7/09_UART/03_char_dev_driver/01_hello_drv/Makefile

@@ -0,0 +1,21 @@
+
+# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
+# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
+# 2.1 ARCH,          比如: export ARCH=arm64
+# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
+# 2.3 PATH,          比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin 
+# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
+#       请参考各开发板的高级用户使用手册
+
+KERN_DIR = /home/book/100ask_stm32mp157_pro-sdk/Linux-5.4
+
+all:
+	make -C $(KERN_DIR) M=`pwd` modules 
+	$(CROSS_COMPILE)gcc -o hello_drv_test hello_drv_test.c 
+
+clean:
+	make -C $(KERN_DIR) M=`pwd` modules clean
+	rm -rf modules.order
+	rm -f hello_drv_test
+
+obj-m	+= hello_drv.o

STM32MP157/source/A7/09_UART/03_char_dev_driver/01_hello_drv/hello_drv.c

@@ -0,0 +1,104 @@
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/stat.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/tty.h>
+#include <linux/kmod.h>
+#include <linux/gfp.h>
+
+/* 1. 确定主设备号                                                                 */
+static int major = 0;
+static char kernel_buf[1024];
+static struct class *hello_class;
+
+
+#define MIN(a, b) (a < b ? a : b)
+
+/* 3. 实现对应的open/read/write等函数，填入file_operations结构体                   */
+static ssize_t hello_drv_read (struct file *file, char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_to_user(buf, kernel_buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static ssize_t hello_drv_write (struct file *file, const char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_from_user(kernel_buf, buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static int hello_drv_open (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+static int hello_drv_close (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+/* 2. 定义自己的file_operations结构体                                              */
+static struct file_operations hello_drv = {
+	.owner	 = THIS_MODULE,
+	.open    = hello_drv_open,
+	.read    = hello_drv_read,
+	.write   = hello_drv_write,
+	.release = hello_drv_close,
+};
+
+/* 4. 把file_operations结构体告诉内核：注册驱动程序                                */
+/* 5. 谁来注册驱动程序啊？得有一个入口函数：安装驱动程序时，就会去调用这个入口函数 */
+static int __init hello_init(void)
+{
+	int err;
+	
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	major = register_chrdev(0, "hello", &hello_drv);  /* /dev/hello */
+
+
+	hello_class = class_create(THIS_MODULE, "hello_class");
+	err = PTR_ERR(hello_class);
+	if (IS_ERR(hello_class)) {
+		printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+		unregister_chrdev(major, "hello");
+		return -1;
+	}
+	
+	device_create(hello_class, NULL, MKDEV(major, 0), NULL, "hello"); /* /dev/hello */
+	
+	return 0;
+}
+
+/* 6. 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数           */
+static void __exit hello_exit(void)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	device_destroy(hello_class, MKDEV(major, 0));
+	class_destroy(hello_class);
+	unregister_chrdev(major, "hello");
+}
+
+
+/* 7. 其他完善：提供设备信息，自动创建设备节点                                     */
+
+module_init(hello_init);
+module_exit(hello_exit);
+
+MODULE_LICENSE("GPL");
+
+

STM32MP157/source/A7/09_UART/03_char_dev_driver/01_hello_drv/hello_drv_test.c

@@ -0,0 +1,54 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * ./hello_drv_test -w abc
+ * ./hello_drv_test -r
+ */
+int main(int argc, char **argv)
+{
+	int fd;
+	char buf[1024];
+	int len;
+	
+	/* 1. 判断参数 */
+	if (argc < 2) 
+	{
+		printf("Usage: %s -w <string>\n", argv[0]);
+		printf("       %s -r\n", argv[0]);
+		return -1;
+	}
+
+	/* 2. 打开文件 */
+	fd = open("/dev/hello", O_RDWR);
+	if (fd == -1)
+	{
+		printf("can not open file /dev/hello\n");
+		return -1;
+	}
+
+	/* 3. 写文件或读文件 */
+	if ((0 == strcmp(argv[1], "-w")) && (argc == 3))
+	{
+		len = strlen(argv[2]) + 1;
+		len = len < 1024 ? len : 1024;
+		write(fd, argv[2], len);
+	}
+	else
+	{
+		len = read(fd, buf, 1024);		
+		buf[1023] = '\0';
+		printf("APP read : %s\n", buf);
+	}
+	
+	close(fd);
+	
+	return 0;
+}
+
+

STM32MP157/source/A7/09_UART/03_char_dev_driver/01b_hello_drv/Makefile

@@ -0,0 +1,21 @@
+
+# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
+# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
+# 2.1 ARCH,          比如: export ARCH=arm64
+# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
+# 2.3 PATH,          比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin 
+# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
+#       请参考各开发板的高级用户使用手册
+
+KERN_DIR = /home/book/100ask_stm32mp157_pro-sdk/Linux-5.4
+
+all:
+	make -C $(KERN_DIR) M=`pwd` modules 
+	$(CROSS_COMPILE)gcc -o hello_drv_test hello_drv_test.c 
+
+clean:
+	make -C $(KERN_DIR) M=`pwd` modules clean
+	rm -rf modules.order
+	rm -f hello_drv_test
+
+obj-m	+= hello_drv.o

STM32MP157/source/A7/09_UART/03_char_dev_driver/01b_hello_drv/hello_drv.c

@@ -0,0 +1,114 @@
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/stat.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/tty.h>
+#include <linux/kmod.h>
+#include <linux/gfp.h>
+
+/* 1. 确定主设备号                                                                 */
+static int major = 0;
+static struct cdev hello_cdev;
+
+static char kernel_buf[1024];
+static struct class *hello_class;
+
+
+#define MIN(a, b) (a < b ? a : b)
+
+/* 3. 实现对应的open/read/write等函数，填入file_operations结构体                   */
+static ssize_t hello_drv_read (struct file *file, char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_to_user(buf, kernel_buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static ssize_t hello_drv_write (struct file *file, const char __user *buf, size_t size, loff_t *offset)
+{
+	int err;
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	err = copy_from_user(kernel_buf, buf, MIN(1024, size));
+	return MIN(1024, size);
+}
+
+static int hello_drv_open (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+static int hello_drv_close (struct inode *node, struct file *file)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	return 0;
+}
+
+/* 2. 定义自己的file_operations结构体                                              */
+static struct file_operations hello_drv = {
+	.owner	 = THIS_MODULE,
+	.open    = hello_drv_open,
+	.read    = hello_drv_read,
+	.write   = hello_drv_write,
+	.release = hello_drv_close,
+};
+
+/* 4. 把file_operations结构体告诉内核：注册驱动程序                                */
+/* 5. 谁来注册驱动程序啊？得有一个入口函数：安装驱动程序时，就会去调用这个入口函数 */
+static int __init hello_init(void)
+{
+	int err;
+	int rc;
+	dev_t devid;
+	
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	//major = register_chrdev(0, "hello", &hello_drv);  /* /dev/hello */
+	rc = alloc_chrdev_region(&devid, 0, 1, "hello");
+	major = MAJOR(devid);
+	cdev_init(&hello_cdev, &hello_drv);
+	cdev_add(&hello_cdev, devid, 1);
+
+	hello_class = class_create(THIS_MODULE, "hello_class");
+	err = PTR_ERR(hello_class);
+	if (IS_ERR(hello_class)) {
+		printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+		unregister_chrdev(major, "hello");
+		return -1;
+	}
+	
+	device_create(hello_class, NULL, MKDEV(major, 0), NULL, "hello"); /* /dev/hello */
+	
+	return 0;
+}
+
+/* 6. 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数           */
+static void __exit hello_exit(void)
+{
+	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
+	device_destroy(hello_class, MKDEV(major, 0));
+	class_destroy(hello_class);
+	
+	//unregister_chrdev(major, "hello");
+	cdev_del(&hello_cdev);
+	unregister_chrdev_region(MKDEV(major,0), 1);	
+}
+
+
+/* 7. 其他完善：提供设备信息，自动创建设备节点                                     */
+
+module_init(hello_init);
+module_exit(hello_exit);
+
+MODULE_LICENSE("GPL");
+
+

STM32MP157/source/A7/09_UART/03_char_dev_driver/01b_hello_drv/hello_drv_test.c

@@ -0,0 +1,54 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * ./hello_drv_test -w abc
+ * ./hello_drv_test -r
+ */
+int main(int argc, char **argv)
+{
+	int fd;
+	char buf[1024];
+	int len;
+	
+	/* 1. 判断参数 */
+	if (argc < 2) 
+	{
+		printf("Usage: %s -w <string>\n", argv[0]);
+		printf("       %s -r\n", argv[0]);
+		return -1;
+	}
+
+	/* 2. 打开文件 */
+	fd = open("/dev/hello", O_RDWR);
+	if (fd == -1)
+	{
+		printf("can not open file /dev/hello\n");
+		return -1;
+	}
+
+	/* 3. 写文件或读文件 */
+	if ((0 == strcmp(argv[1], "-w")) && (argc == 3))
+	{
+		len = strlen(argv[2]) + 1;
+		len = len < 1024 ? len : 1024;
+		write(fd, argv[2], len);
+	}
+	else
+	{
+		len = read(fd, buf, 1024);		
+		buf[1023] = '\0';
+		printf("APP read : %s\n", buf);
+	}
+	
+	close(fd);
+	
+	return 0;
+}
+
+