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    【全志T113-S3_100ask】2-编写第一个驱动

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    • Y
      giao LV 6 最后由 yanmingjian 编辑

      （1）开发环境

      windows开发环境：VsCode
      linux 开发环境：Ubuntu 18.04 环境参考

      1、指定交叉编译

      在buildroot 目录下发现两个 arm-linux-gnueabi-gcc

      root@znh-ubuntu:/disk/buildroot-100ask_t113-pro/buildroot# find ./* -name "*gnueabi-gcc"
./output/host/opt/ext-toolchain/bin/arm-linux-gnueabi-gcc
./output/host/bin/arm-linux-gnueabi-gcc

      但 ./output/host/bin/arm-linux-gnueabi-gcc 是链接过去的

      c7a46f0a61d24d149466e43da584b784.png

      ./output/host/opt/ext-toolchain/bin/arm-linux-gnueabi-gcc 是原始的

      f577b95a46d9419dbbb2dc632ba6c0f1.png

      在这里我使用链接后的gcc
      加载环境变量：

      export PATH=$PATH:/disk/buildroot-100ask_t113-pro/buildroot/output/host/bin
export ARCH=arm
export CROSS_COMPILE=arm-linux-gnueabi-

      root@znh-ubuntu:~# export PATH=$PATH:/disk/buildroot-100ask_t113-pro/buildroot/output/host/bin
root@znh-ubuntu:~# export ARCH=arm
root@znh-ubuntu:~# export CROSS_COMPILE=arm-linux-gnueabi-
root@znh-ubuntu:~#
root@znh-ubuntu:~# arm-linux-gnueabi-gcc -v
使用内建 specs。
COLLECT_GCC=arm-linux-gnueabi-gcc
COLLECT_LTO_WRAPPER=/disk/t113GitHub/eLinuxCore_100ask-t113-pro/toolchain/gcc-linaro-7.2.1-2017.11-x86_64_arm-linux-gnueabi/bin/../libexec/gcc/arm-linux-gnueabi/7.2.1/lto-wrapper
目标：arm-linux-gnueabi
配置为：'/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/snapshots/gcc.git~linaro-7.2-2017.11/configure' SHELL=/bin/bash --with-mpc=/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/_build/builds/destdir/x86_64-unknown-linux-gnu --with-mpfr=/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/_build/builds/destdir/x86_64-unknown-linux-gnu --with-gmp=/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/_build/builds/destdir/x86_64-unknown-linux-gnu --with-gnu-as --with-gnu-ld --disable-libmudflap --enable-lto --enable-shared --without-included-gettext --enable-nls --disable-sjlj-exceptions --enable-gnu-unique-object --enable-linker-build-id --disable-libstdcxx-pch --enable-c99 --enable-clocale=gnu --enable-libstdcxx-debug --enable-long-long --with-cloog=no --with-ppl=no --with-isl=no --disable-multilib --with-float=soft --with-mode=thumb --with-tune=cortex-a9 --with-arch=armv7-a --enable-threads=posix --enable-multiarch --enable-libstdcxx-time=yes --enable-gnu-indirect-function --with-build-sysroot=/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/_build/sysroots/arm-linux-gnueabi --with-sysroot=/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/_build/builds/destdir/x86_64-unknown-linux-gnu/arm-linux-gnueabi/libc --enable-checking=release --disable-bootstrap --enable-languages=c,c++,fortran,lto --build=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu --target=arm-linux-gnueabi --prefix=/home/tcwg-buildslave/workspace/tcwg-make-release/builder_arch/amd64/label/tcwg-x86_64-build/target/arm-linux-gnueabi/_build/builds/destdir/x86_64-unknown-linux-gnu
线程模型：posix
gcc 版本 7.2.1 20171011 (Linaro GCC 7.2-2017.11)

      不想每次否加载可以写在自启动脚本

      vim ~/.bashrc

      f71d9f87bd1542bdb05759c4ee985910.png

      ##（2）编写驱动

      1、编写 helloword驱动 hello_drv.c

      #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");

      2、编写测试驱动文件 hello_drv_test.c

      #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;
}

      3、编写Makefile

      # 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 = /disk/buildroot-100ask_t113-pro/buildroot/output/build/linux-d96275805a67d54998123d36e59108cb1ed52ad5

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

      关于 KERN_DIR ，本环境使用的是 buildroot ，通过GitHub把kernel下载下来的，源码在./buildroot-100ask_t113-pro/buildroot/dl/linux/git 下，但是该源码未经过编译，而上一节已经编译过 buildroot 生成镜像img了，那就是已经编译过了，但是指定该目录编译不了

      82c44d9bc6af4be29e232d1fe8f53cd3.png

      真正的编译目录在
      ./buildroot-100ask_t113-pro/buildroot/output/build/linux-d96275805a67d54998123d36e59108cb1ed52ad5
      （我不确实后面的字母数字是不是每个人一样）

      f98a38e3af8544d090c968382aa25756.png

      （3）测试

      将生成的 hello_drv.ko、hello_drv_test 放到开发板上
      在这里使用 tftp 下载。（TFTP的搭建参考：链接）
      但第一次使用系统没有连接网络（现在已经插入网线）

      # ifconfig
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:6 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:603 (603.0 B)  TX bytes:603 (603.0 B)

      1、使用udhcpc 自动联网

      # udhcpc
udhcpc: started, v1.35.0
[ 3538.458305] libphy: 4500000.eth: probed
[ 3538.462913] sunxi-gmac 4500000.eth eth0: eth0: Type(7) PHY ID 001cc816 at 0 IRQ poll (4500000.eth-0:00)
udhcpc: broadcasting discover
[ 3541.673890] sunxi-gmac 4500000.eth eth0: Link is Up - 100Mbps/Full - flow control off
[ 3541.682714] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
udhcpc: broadcasting discover
udhcpc: broadcasting select for 192.168.3.45, server 192.168.3.1
udhcpc: lease of 192.168.3.45 obtained from 192.168.3.1, lease time 604800
deleting routers
adding dns 192.168.3.1

      2、通过 tftp 下载资源

      # tftp -g -r hello_drv.ko 192.168.3.44
# tftp -g -r hello_drv_test 192.168.3.44
#
# ls
hello_drv.ko    hello_drv_test

      3、测试驱动

      （1）加载驱动

      #  insmod hello_drv.ko
[ 3860.564181] hello_drv: loading out-of-tree module taints kernel.
[ 3860.571552] /disk/vsCode/01_hello/hello_drv.c hello_init line 70



（2）查看驱动是否加载
# ls /dev/hello*
/dev/hello
# lsmod
Module                  Size  Used by    Tainted: G
hello_drv              16384  0

（3）添加权限
# chmod 777 ./hello_drv_test


（4）向驱动写入数据
# ./hello_drv_test  -w abc
[ 3906.061995] /disk/vsCode/01_hello/hello_drv.c hello_drv_open line 45
[ 3906.069274] /disk/vsCode/01_hello/hello_drv.c hello_drv_write line 38
[ 3906.076579] /disk/vsCode/01_hello/hello_drv.c hello_drv_close line 51

（5）读取驱动数据
# ./hello_drv_test  -r
[ 3913.268282] /disk/vsCode/01_hello/hello_drv.c hello_drv_open line 45
[ 3913.275535] /disk/vsCode/01_hello/hello_drv.c hello_drv_read line 30
APP read : abc
[ 3913.283024] /disk/vsCode/01_hello/hello_drv.c hello_drv_close line 51

（6）卸载驱动
# rmmod hello_drv
[ 4304.419170] /disk/vsCode/01_hello/hello_drv.c hello_exit line 90
# lsmod
Module                  Size  Used by    Tainted: G
sunxi_ce               57344  0

      原文链接:https://blog.csdn.net/qq_46079439/article/details/125897482

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