飞凌嵌入式i.MX8MP开发板移植驱动，其实可以很简单
<p>各位工程师用户在对<strong>飞凌嵌入式OKMX8MP-C开发板</strong>进行开发的过程中，可能会遇到需要移植驱动的情况。为避免用户因不了解移植驱动的过程而影响开发进度，今天小编会以写一个hello驱动为例，演示移植驱动的过程，有需求的小伙伴可参考此方法自行操作。</p><p> </p>
<p><a data-linktype="1" href="https://www.forlinx.com/product/135.html" target="_blank"></a></p>
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<section><strong>01</strong></section>
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<p>进入源码的drivers目录下，并创建一个名为hello的目录：</p>
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<code>forlinx@ubuntu:~$cd/home/forlinx/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$mkdirhello</code></pre>
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<section><strong>02</strong></section>
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<p>进入hello目录，创建hello.c：<code style="color: rgb(221, 221, 221); white-space: pre-wrap;">forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$ cd hello</code><code style="color: rgb(221, 221, 221); white-space: pre-wrap;">forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$ vi hello.c</code></p>
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<p>在hello.c中写入如下内容：</p>
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<code>#include<linux/init.h></code><code>#include<linux/module.h></code><code>staticint hello_init(void)</code><code>{</code><code>printk(KERN_ALERT"Hello world\n");</code><code>return0;</code><code>}</code><code>staticvoid hello_exit(void)</code><code>{</code><code>printk(KERN_ALERT"Goodbye world\n");</code><code>}</code><code>module_init(hello_init);</code><code>module_exit(hello_exit);</code><code>MODULE_LICENSE("DualBSD/GPL");</code></pre>
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<p><strong>程序含义：</strong>insmod驱动挂载时打印Hello world，rmmod驱动卸载时打印 Goodbye world</p>
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<section><strong>03</strong></section>
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<p>在该文件夹下创建Kconfig，Makefile两个文件。</p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$viKconfig</code></pre>
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<p>在Kconfig文件中写入如下内容：</p>
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<code>configHAVE_HELLO</code><code>tristate "hello driver"</code><code>help</code><code>Thishellodriverisjusttoshowhowtodevelopdriverprocess.</code>
<code>Thisdrivercanalsobebuiltasamodule.Ifso,themodule willbecalled.</code><code>defaulty</code><code>#endmenu</code></pre>
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<p>表示如果使能了CONFIG_HAVE_HELLO，在内核裁剪配置文件中，将显示hellodrivers菜单，默认编译进内核：</p>
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<p><strong>y：编译进内核</strong></p>
<p><strong>m：编译为模块.ko文件</strong></p>
<p><strong>n：表示不编译，未使能。</strong></p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$viKconfig</code></pre>
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<p>在Makefile文件中写入如下内容：</p>
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<code>obj-$(CONFIG_HAVE_HELLO) += hello.o</code></pre>
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<p><strong>注意：</strong></p>
<p>宏定义的名字要和Kconfig中的一样。后面添加需要编译的文件名，因为内核会自动添加前缀CONFIG，所以我们这里也要在名字前面添加CONFIG_，表示CONFIG_HAVE_HELLO使能时，编译规则指定的文件为hello.c。</p>
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<p>给添加的这三个文件权限：</p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$chmod777 hello.c</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$chmod777 Kconfig</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$chmod777 Makefile</code></pre>
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<p>编辑drivers顶层的Kconfig,Makefile文件。</p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$cd..</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$vi Kconfig</code></pre>
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<p>在Kconfig文件中写入如下内容：</p>
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<code>source"drivers/counter/Kconfig"</code><code>source"drivers/mxc/Kconfig"</code><code>source"drivers/hello/Kconfig" //在endmenu前添加hello文件夹的配置文件解析</code><code>endmenu</code></pre>
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<p>如此一来，配置系统就会按照这个配置去解析hello文件夹下的Kconfig。</p>
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<p>编辑Makefile：</p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$vi Makefile</code></pre>
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<p>在Makefile文件中写入如下内容：</p>
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<code>obj-$(CONFIG_COUNTER) += counter/</code><code>obj-y += mxc/</code><code>obj-$(CONFIG_HAVE_HELLO) += hello/ //在Makefile最后加入这一句</code></pre>
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<p>这句话的作用是当CONFIG_HAVE_HELLO使能后，在哪里去找源文件。再结合hello文件下模块Makefile就形成了层次式Makefile。注意不要少了/，这里添加自定义文件夹的名字，表示把这个文件夹编译进内核。</p>
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<p>开始编译：</p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$cd ../..</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk$./opt/fsl-imx-xwayland/5.4-zeus/environment-setup-aarch64-poky-linux</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk$.environment-setup-aarch64-poky-linux</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk$cdOK8MP-linux-kernel</code><code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel$make modules</code><code>scripts/kconfig/conf --syncconfig Kconfig</code><code>drivers/hello/Kconfig:7:warning:ignoring unsupported character '�'</code><code>drivers/hello/Kconfig:7:warning:ignoring unsupported character '�'</code><code>drivers/hello/Kconfig:7:warning:ignoring unsupported character '�'</code><code>drivers/hello/Kconfig:7:warning:ignoring unsupported character '�'</code><code>*</code><code>* Restart config...</code><code>*</code><code>*</code><code>* Device Drivers</code><code>*</code><code>Trust the bootloaderto initialize Linux's CRNG (RANDOM_TRUST_BOOTLOADER) n</code><code>Platform support forChrome hardware (transitional) (MFD_CROS_EC) y</code><code>Trusted ExecutionEnvironment support (TEE) y</code><code>hello driver(HAVE_HELLO) (NEW) m //将hello驱动编译进内核就配置为m</code><code>CALL scripts/checksyscalls.sh</code><code>CALL scripts/atomic/check-atomics.sh</code><code>CHK include/generated/compile.h</code><code>GZIP kernel/config_data.gz</code><code>CC kernel/configs.o</code><code>[…]</code><code>LD vmlinux</code><code>SORTEXvmlinux</code><code>SYSMAPSystem.map</code><code>Building modules,stage 2.</code><code>MODPOST 536 modules</code><code>CC drivers/hello/hello.mod.o</code><code>LD drivers/hello/hello.ko</code></pre>
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<p>编译完成后，即可在OK8MP-linux-kernel/drivers/hello目录下看到编译生成的驱动了：</p>
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<code>forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/$ls drivers/hello</code><code>hello.chello.kohello.modhello.mod.chello.mod.ohello.oKconfigMakefile modules.order</code>
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<section><strong>6</strong></section>
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<p>将hello.ko使用U盘或TF卡拷贝到开发板里进行验证：</p>
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<code>rootK8MP:~# cd /run/media/sda1/ //进入U盘的路径下</code><code>root@OK8MP:/run/media/sda1# insmod hello.ko //挂载hello.ko</code><code>[ 138.679964] Hello world //挂载驱动打印信息</code><code>root@OK8MP:/run/media/sda1# rmmod hello.ko //卸载hello.ko</code><code>[ 142.022115] Goodbye world //卸载驱动打印信息</code><code>root@OK8MP:/run/media/sda1#</code></pre>
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<p>由上述测试可看，hello.ko驱动可正常运行。</p>
<p>以上就是小编为大家演示的自行书写并添加一个驱动的过程，若您想要移植某一个模块，可向模块厂家索要现成的驱动.c文件，之后再按照上述步骤配置Makefile和Kconfig即可。</p>
这个编译，是要跟固件一起编译吗，还是单独的编译。如果全编译，需要时间久吗？ <p>感谢分享，学习了！！</p>
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