ElfBoard技術(shù)貼|在NXP源碼基礎(chǔ)上適配ELF 1開(kāi)發(fā)板的按鍵功能

本次源碼適配工作是在NXP i.MX6ULL EVK評(píng)估板的Linux內(nèi)核源碼（特定版本：Linux-imx_4.1.15）基礎(chǔ)上進(jìn)行的。主要目標(biāo)是調(diào)整功能接口引腳配置，以適應(yīng)ELF 1開(kāi)發(fā)板。接下來(lái)，將以按鍵功能的適配作為具體示例，深入解析整個(gè)適配的流程。

elf@ubuntu:~/work$ tar jvxf linux-imx-imx_4.1.15_2.0.0_ga.tar.bz2
elf@ubuntu:~/work$ cd linux-imx-imx_4.1.15_2.0.0_ga/
elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ ls

2、添加默認(rèn)配置文件

將arch/arm/configs路徑下的imx_v7_mfg_defconfig復(fù)制一份，命名為imx6ull_elf1_defconfig：

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ cp arch/arm/configs/imx_v7_mfg_defconfig arch/arm/configs/imx6ull_elf1_defconfig

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ cp arch/arm/boot/dts/imx6ull-14x14-evk.dts arch/arm/boot/dts/imx6ull-elf1-emmc.dts

打開(kāi)arch/arm/boot/dts/Makefile，找到CONFIG_SOC_IMX6ULL，將imx6ull-elf1-emmc.dts添加到Makefile中：

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ vi arch/arm/boot/dts/Makefile

4、建立交叉編譯腳本

建立一個(gè)編譯腳本build.sh：

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ vim build.sh

#!/bin/bash
export CPUS=`grep -c processor /proc/cpuinfo` 
source /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi
make distclean
make imx6ull_elf1_defconfig
make -j${CPUS}
rm -rf ./.tmp
make modules_install INSTALL_MOD_PATH=./.tmp/rootfs/
cd .tmp/rootfs/
tar -jcvf modules.tar.bz2 *

給予腳本權(quán)限：

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ chmod 777 build.sh

1、硬件原理

34引腳信號(hào)名稱為SNVS_TAMPER2；

22引腳的信號(hào)名稱為SNVS_TAMPER4；

43引腳的信號(hào)名稱為SNVS_TAMPER9。

?

因?yàn)樾枰褂眠@幾個(gè)引腳控制按鍵，所以需要把它們復(fù)用成GPIO功能，在arch/arm/boot/dts/imx6ull-pinfunc-snvs.h中找到它們的宏定義，分別如下：

pinctrl_keys: keysgrp {
              fsl,pins = <
                 MX6ULL_PAD_SNVS_TAMPER4__GPIO5_IO04     0x80000000
                 MX6ULL_PAD_SNVS_TAMPER2__GPIO5_IO02     0x80000000
                 MX6ULL_PAD_SNVS_TAMPER9__GPIO5_IO09     0x80000000
               >;
};

效果如下：

gpio-keys {
                compatible = "gpio-keys";
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_keys>;
                #address-cells = <1>;
                #size-cells = <0>;
                autorepeat;
                key1 {
                label = "KEY1";
                linux,code = <KEY_ENTER>;
                gpios = <&gpio5 4 GPIO_ACTIVE_LOW>;
                };
                key2 {
                label = "KEY2";
                linux,code = <KEY_UP>;
                gpios = <&gpio5 2 GPIO_ACTIVE_LOW>;
                };
                key3 {
                label = "KEY3";
                linux,code = <KEY_DOWN>;
                gpios = <&gpio5 9 GPIO_ACTIVE_LOW>;
                };
        };

4、配置按鍵驅(qū)動(dòng)編譯進(jìn)內(nèi)核

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ . /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi 
elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ make imx6ull_elf1_defconfig
elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ make menuconfig

-> Device Drivers
->Input device support
->Keyboards

5、編譯

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ ./build.sh

將編譯生成的zImage和imx6ull-elf-emmc.dtb拷貝到ELF 1開(kāi)發(fā)板的/run/media/mmcblk1p1 路徑下：

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ scp arch/arm/boot/zImage   root@172.16.0.175:/run/media/mmcblk1p1/
elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ scp arch/arm/boot/dts/imx6ull-elf1-emmc.dtb root@172.16.0.175:/run/media/mmcblk1p1/

保存并重啟開(kāi)發(fā)板：

root@ELF1~# sync
root@ELF1~# reboot

查看key設(shè)備對(duì)應(yīng)的event事件：

root@ELF1:~# cat /proc/bus/input/devices

可以看到其對(duì)應(yīng)的是event2，如果連接了其他設(shè)備，比如觸摸屏，event事件可能會(huì)有變化，請(qǐng)以實(shí)際為準(zhǔn)。

終端輸入evtest命令，選擇event number為2，然后分別按下按鍵K1，K2，K3，會(huì)看到上報(bào)數(shù)據(jù)。

root@ELF1:~# evtest

可以看到KEY1上報(bào)的鍵值是28，KEY2上報(bào)的鍵值是103，KEY3上報(bào)的鍵值是108，與在設(shè)備樹(shù)中配置的鍵值一致。