driver jni for proc image nfc ive com att

本人在開發Android Nfc POS之初，探索調試了一番驅動，目前在Nexus 5X 7.1.1上已經調成，之前的步驟可以參考我發的文章，Android驅動開發經驗分享如下。

1. Linux 內核驅動實例

以下均在Android Linux內核目錄下操作， 在drivers目錄下創建驅動目錄hello
這個目下要創建3個文件，hello.c, Makefile and Kconfig
1.1 hello.c
cd drivers
mkdir hello

vim hello.c
code as follows:

/linux kernel driver: hello.c => /dev/hello

/
please find the code in the below. here skip the code to make the page clean and clear.

1.2 Makefile
Create the Makefile and add:
obj-y += hello.o
1.3 Kconfig
Create Kconfig and add:

config?HELLO?
    tristate?"Eric: First Android Driver"
default?n
help
  This?is?the?first?Android?driver.

this file is used when we make menuconfig.

1.4 Modify drivers/Makefile
Add following in the end
obj-y += hello.o
1.5 Add the driver into system configuration
Before we build the kernal, we need to config the system.
1.5.1 Modify arch/arm64/Kconfig
Add following in the end
source "drivers/hello/Kconfig"
It seems that this config not work, may be skipped.
1.5.2 Modify drivers/Kconfig
Following the menu:
menu "Device Drivers"
Please add
source "drivers/hello/Kconfig"
1.5.3 Modify drivers/Kconfig

make menuconfig
To enble the menu ‘Eric: First Android Driver‘ in the "Device Drivers" item.
And save , then to build the linux kernel code.

2. 測試驅動

以下是需要操作的目錄在AOSP目錄下

2.1 create the application on externel
在external下創建hello目錄
目錄下將有兩個文件:hello.c and Android.mk
cd external
mkdir hello
vim hello.c
/ AOSP app : ./external/hello.c =>/system/bin/hello/
Android.mk as follows:

 LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := hello
LOCAL_SRC_FILES := $(call all-subdir-c-files)
include $(BUILD_EXECUTABLE)

2.2 build the application
To build the hello application
mmm external/hello/
Add it into the system.img
make snod
2.3 Test/Debug the driver hello

Before flash, we can build the AOSP again, of cource, don‘t forget replace the linux kernel file ‘Image.gz-dtb‘.
After flash into the phone, reboot the phone, and then do follows:

C:\Users\ylgi>adb devices
List of devices attached
01059f9781509a67        device

C:\Users\ylgi>adb -s 01059f9781509a67 shell
bullhead:/ $ ls

cd /system/bin
./hello

運行效果如上圖，表示Linux驅動已經成功加載。

Android驅動開發---Linux Kernel/HAL Layer/Jni Layer實例全集