android jni控制gpio （rk3288）

1.添加驱动程序

2.编写jni c程序编译为库给java调用

3.app调用jni静态链接库操作底层驱动

　1.添加驱动程序

　修改/work/rk3288/firefly-rk3288_android5.1_git_20180126/kernel/drivers/Makefile
    添加一行obj-y     += carroll/
    
    将carroll文件夹添加至此目录下/work/rk3288/firefly-rk3288_android5.1_git_20180126/kernel/drivers/
    文件夹包含驱动源码及Makefile
    # carroll
    obj-y        = test_led.o

　test_led.源码

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#ifdef CONFIG_OF
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/of_platform.h>
#endif

#include <linux/fb.h>
#include <linux/device.h>
#include <linux/miscdevice.h>

#define INVALID_GPIO -1
int led1_gpio = INVALID_GPIO;
int led2_gpio = INVALID_GPIO;
int led_gpio_active = ;

static int led_open(struct inode *inode, struct file *file)
{
    printk("carroll led_open ok \n");

    return ;
}

static int led_release(struct inode *inode, struct file *file)
{
    printk("carroll led_close \n");

    return ;
}

/* app : ioctl(fd, cmd, arg) */
static long led_ioctl(struct file *filp, unsigned int cmd,
        unsigned long arg)
{
    /* 根据传入的参数设置GPIO */
    /* cmd : 0-off, 1-on */
    /* arg : 0-1, which led */

    if ((cmd != ) && (cmd != ))
        return -EINVAL;

    if (arg > )
        return -EINVAL;

    if(arg == )
    {
        if(led1_gpio != INVALID_GPIO)
            gpio_set_value(led1_gpio, !cmd);
    }
    else if(arg == )
    {
        if(led2_gpio != INVALID_GPIO)
            gpio_set_value(led2_gpio, !cmd);
    }

    printk("carroll led_ioctl: %d \n", cmd);

    return ;
}

static struct file_operations led_fops = {
        .owner   = THIS_MODULE,
        .open    = led_open,
        .release    = led_release,
        .unlocked_ioctl   = led_ioctl,
};

static struct miscdevice led_dev =
{
    .minor = MISC_DYNAMIC_MINOR,
    .name = "test_led",
    .fops = &led_fops,
};

static int firefly_led_probe(struct platform_device *pdev)
{
    int ret = -;
    enum of_gpio_flags flags;
    struct device_node *hello_node = pdev->dev.of_node;

    printk("%s-%d: carroll \n",__FUNCTION__,__LINE__);

    /* register test_led dev file */
    ret = misc_register(&led_dev);
    if (ret < ){
            printk("carroll led register err!\n");
            return ret;
    }

    /* led1 init */
    led1_gpio = of_get_named_gpio_flags(hello_node,"led1", ,&flags);
    if (!gpio_is_valid(led1_gpio)){
        printk("carroll: invalid gpio : %d\n",led1_gpio);
        return -;
    }
    ret = gpio_request(led1_gpio, "test_led");
    if (ret != ) {
        gpio_free(led1_gpio);
        printk("carroll: led1_gpio free\n");
        return -EIO;
    }
    gpio_direction_output(led1_gpio, !led_gpio_active);

    /* led2 init */
    led2_gpio = of_get_named_gpio_flags(hello_node,"led2", ,&flags);
    if (!gpio_is_valid(led2_gpio)){
        printk("carroll: invalid gpio : %d\n",led2_gpio);
        return -;
    }
    ret = gpio_request(led2_gpio, "test_led");
    if (ret != ) {
        gpio_free(led2_gpio);
        printk("carroll: led2_gpio free\n");
        return -EIO;
    }
    gpio_direction_output(led2_gpio, !led_gpio_active);

    gpio_set_value(led1_gpio, led_gpio_active);
    gpio_set_value(led2_gpio, led_gpio_active);
    mdelay();
    gpio_set_value(led1_gpio, !led_gpio_active);
    gpio_set_value(led2_gpio, !led_gpio_active);

    return ;  //return Ok
}

static int firefly_led_remove(struct platform_device *pdev)
{
    return ;
}

#ifdef CONFIG_OF
static const struct of_device_id of_firefly_led_match[] = {
    { .compatible = "firefly,test_led" },
    { /* Sentinel */ }
};
#endif

static struct platform_driver firefly_led_driver = {
    .probe        = firefly_led_probe,
    .remove        = firefly_led_remove,
    .driver        = {
        .name    = "test_led",
        .owner    = THIS_MODULE,
#ifdef CONFIG_OF
        .of_match_table    = of_firefly_led_match,
#endif
    },

};

static int major;
static struct class *cls;

static int __init led_init(void)
{
    printk(KERN_INFO "carroll register led dev %s\n", __FUNCTION__);

    return platform_driver_register(&firefly_led_driver);
}

static void __exit led_exit(void)
{
    platform_driver_unregister(&firefly_led_driver);
    printk(KERN_INFO "carroll unregister led dev %s\n", __FUNCTION__);
}

subsys_initcall(led_init);
module_exit(led_exit);

MODULE_AUTHOR("carroll <[e-mail]>");
MODULE_DESCRIPTION("carroll led driver");
MODULE_LICENSE("GPL");

　　

修改/work/rk3288/firefly-rk3288_android5.1_git_20180126/kernel/arch/arm/boot/dts/firefly-rk3288.dts
    firefly-led{
        compatible = "firefly,led";
        led-work = <&gpio8 GPIO_A2 GPIO_ACTIVE_LOW>;
        led-power = <&gpio8 GPIO_A1 GPIO_ACTIVE_LOW>;
        //carrol add start
        status = "disabled";
    };

test-led{
        compatible = "firefly,test_led";
        led1= <&gpio8 GPIO_A1 GPIO_ACTIVE_LOW>;
        led2= <&gpio8 GPIO_A2 GPIO_ACTIVE_LOW>;
        status = "okay";
    };
        //carrol add end
    编译内核烧录即可

　内核启动过程中闪烁一次，并产生/dev/test_led文件
    添加可执行权限
    su
    chmod 777 /dev/test_led

2.编写jni c程序编译为库给java调用

　　hardcontrol.c源码

#include <jni.h>  /* /usr/lib/jvm/java-1.7.0-openjdk-amd64/include/ */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>

#include <android/log.h>  /* liblog */

//__android_log_print(ANDROID_LOG_DEBUG, "JNIDemo", "native add ...");

#if 0
typedef struct {
    char *name;          /* Java里调用的函数名 */
    char *signature;    /* JNI字段描述符, 用来表示Java里调用的函数的参数和返回值类型 */
    void *fnPtr;          /* C语言实现的本地函数 */
} JNINativeMethod;
#endif

static jint fd;

jint ledOpen(JNIEnv *env, jobject cls)
{
    fd = open("/dev/test_led", O_RDWR);
    __android_log_print(ANDROID_LOG_DEBUG, "LEDDemo", "native ledOpen /dev/test_led: %d", fd);
    if (fd >= )
        return ;
    else
        return -;
}

void ledClose(JNIEnv *env, jobject cls)
{
    __android_log_print(ANDROID_LOG_DEBUG, "LEDDemo", "native ledClose ...");
    close(fd);
}

jint ledCtrl(JNIEnv *env, jobject cls, jint which, jint status)
{
    int ret = ioctl(fd, status, which);
    __android_log_print(ANDROID_LOG_DEBUG, "LEDDemo", "native ledCtrl : %d, %d, %d", which, status, ret);
    return ret;
}

static const JNINativeMethod methods[] = {
    {"ledOpen", "()I", (void *)ledOpen},
    {"ledClose", "()V", (void *)ledClose},
    {"ledCtrl", "(II)I", (void *)ledCtrl},
};

/* System.loadLibrary */
JNIEXPORT jint JNICALL
JNI_OnLoad(JavaVM *jvm, void *reserved)
{
    JNIEnv *env;
    jclass cls;

    if ((*jvm)->GetEnv(jvm, (void **)&env, JNI_VERSION_1_4)) {
        return JNI_ERR; /* JNI version not supported */
    }
    cls = (*env)->FindClass(env, "com/thisway/hardlibrary/HardControl");
    if (cls == NULL) {
        return JNI_ERR;
    }

    /* 2. map java hello <-->c c_hello */
    if ((*env)->RegisterNatives(env, cls, methods, sizeof(methods)/sizeof(methods[])) < )
        return JNI_ERR;

    return JNI_VERSION_1_4;
}

根据rk3288 android5.1 linux3.1编译库,必须使用arm-linux-gcc库（也可采用android studio cmake或ndk编译）

  arm-linux-gcc -fPIC -shared hardcontrol.c -o libhardcontrol.so -I /usr/lib/jvm/java-1.7.-openjdk-amd64/include/  -nostdlib /work/rk3288/firefly-rk3288_android5.1_git_20180126/prebuilts/ndk//platforms/android-/arch-arm/usr/lib/libc.so  -I /work/rk3288/firefly-rk3288_android5.1_git_20180126/prebuilts/ndk//platforms/android-/arch-arm/usr/include  /work/rk3288/firefly-rk3288_android5.1_git_20180126/prebuilts/ndk//platforms/android-/arch-arm/usr/lib/liblog.so

没有安装arm-linux-gcc的可以按照以下方法

安装交叉编译工具

    sudo tar xvzf arm-linux-gcc-4.5.-v6-vfp-.tgz -C /

    注意： C 后面有个空格，并且 C 是大写的，它是英文单词“ Change”的第一个字母，在此 是改变目录的意思。
    执行该命令，将把 arm-linux-gcc 安装到/opt/FriendlyARM/toolschain/4.5. 目录。

    Step2：把编译器路径加入系统环境变量，运行命令
    sudo gedit ~/.bashrc
    编辑 /root/.bashrc 文件， 注意“bashrc”前面有一个“.”，修改最后一行为
    export PATH=$PATH:/opt/FriendlyARM/toolschain/4.5./bin
    注意路径一定要写对，否则将不会有效。
    如图，保存退出

编译产生libhardcontrol.so库文件，app将会使用到

3.app调用jni静态链接库操作底层驱动

android app包结构必须相同，上边jni程序已经指定class名为 "com/thisway/hardlibrary/HardControl"，

在app/libs/armeabi/目录下添加编译好的库，没有目录自己新建目录

MainActivity.java

package com.thisway.app_0001_leddemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.view.View;
import android.widget.CheckBox;
import android.widget.Toast;
import com.thisway.hardlibrary.*;

public class MainActivity extends AppCompatActivity {

    private boolean ledon = false;
    private Button button = null;
    private CheckBox checkBoxLed1 = null;
    private CheckBox checkBoxLed2 = null;
    private CheckBox checkBoxLed3 = null;
    private CheckBox checkBoxLed4 = null;

    class MyButtonListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            ledon = !ledon;
            if (ledon) {
                button.setText("ALL OFF");
                checkBoxLed1.setChecked(true);
                checkBoxLed2.setChecked(true);
                checkBoxLed3.setChecked(true);
                checkBoxLed4.setChecked(true);

                for (int i = 0; i < 4; i++)
                    HardControl.ledCtrl(i, 1);
            }
            else {
                button.setText("ALL ON");
                checkBoxLed1.setChecked(false);
                checkBoxLed2.setChecked(false);
                checkBoxLed3.setChecked(false);
                checkBoxLed4.setChecked(false);

                for (int i = 0; i < 4; i++)
                    HardControl.ledCtrl(i, 0);
            }
        }
    }

    public void onCheckboxClicked(View view) {
        // Is the view now checked?
        boolean checked = ((CheckBox) view).isChecked();

        // Check which checkbox was clicked
        switch(view.getId()) {
            case R.id.LED1:
                if (checked) {
                    // Put some meat on the sandwich
                    Toast.makeText(getApplicationContext(), "LED1 on", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(0, 1);
                }
                else {
                    // Remove the meat
                    Toast.makeText(getApplicationContext(), "LED1 off", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(0, 0);
                }
                break;
            case R.id.LED2:
                if (checked) {
                    // Put some meat on the sandwich
                    Toast.makeText(getApplicationContext(), "LED2 on", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(1, 1);
                }
                else {
                    // Remove the meat
                    Toast.makeText(getApplicationContext(), "LED2 off", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(1, 0);
                }
                break;

            case R.id.LED3:
                if (checked) {
                    // Put some meat on the sandwich
                    Toast.makeText(getApplicationContext(), "LED3 on", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(2, 1);
                }
                else {
                    // Remove the meat
                    Toast.makeText(getApplicationContext(), "LED3 off", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(2, 0);
                }
                break;

            case R.id.LED4:
                if (checked) {
                    // Put some meat on the sandwich
                    Toast.makeText(getApplicationContext(), "LED4 on", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(3, 1);
                }
                else {
                    // Remove the meat
                    Toast.makeText(getApplicationContext(), "LED4 off", Toast.LENGTH_SHORT).show();
                    HardControl.ledCtrl(3, 0);
                }
                break;
            // TODO: Veggie sandwich
        }
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button = (Button) findViewById(R.id.BUTTON);

        HardControl.ledOpen();

        checkBoxLed1 = (CheckBox) findViewById(R.id.LED1);
        checkBoxLed2 = (CheckBox) findViewById(R.id.LED2);
        checkBoxLed3 = (CheckBox) findViewById(R.id.LED3);
        checkBoxLed4 = (CheckBox) findViewById(R.id.LED4);

        button.setOnClickListener(new MyButtonListener());
/*
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Perform action on click
                ledon = !ledon;
                if (ledon)
                    button.setText("ALL OFF");
                else
                    button.setText("ALL ON");
            }
        });
*/
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

HardControl.java

package com.thisway.hardlibrary;

public class HardControl {
    public static native int ledCtrl(int which, int status);
    public static native int ledOpen();
    public static native void ledClose();

    static {
        try {
            System.loadLibrary("hardcontrol");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

然后就可通过app控制两个gpio