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linux中老是open失败

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悬赏园豆:10 [待解决问题]

各位大神,麻烦帮忙看一下如下程序,我在应用程序调用底层的open函数时,在jni那里老是open失败,字符设备已经注册进系统,相应的文件节点也有,就是fd返回老是-1,还请各位帮忙看一下

jni file:

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "HardControl hardcontrol.cpp"
#include <utils/Log.h>

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include "jni.h"

jint fd;

jint ledOpen(JNIEnv *env, jobject cls)
{
    
    ALOGI("jkk native ledOpen 1:%d",fd);
    fd = open("/dev/leds_test", O_RDWR);
    ALOGI("jkk native ledOpen 2:%d",fd);
    if (fd >= 0)
        return 0;
    else{
        ALOGI("jkk native ledOpen failed,fd=%d",fd);
        return -1;
    }
//    return 0;
}

jint ledClose(JNIEnv *env, jobject cls)
{
    ALOGI("native ledClose ...");
    
    return 0;
}


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

static const char *classPathName = "com/lenovo/hardlibrary/HardControl";

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

/*
 * Register several native methods for one class.
 */
static int registerNativeMethods(JNIEnv* env, const char* className,
    JNINativeMethod* gMethods, int numMethods)
{
    jclass clazz;

    clazz = env->FindClass(className);
    if (clazz == NULL) {
        ALOGE("Native registration unable to find class '%s'", className);
        return JNI_FALSE;
    }
    if (env->RegisterNatives(clazz, gMethods, numMethods) < 0) {
        ALOGE("RegisterNatives failed for '%s'", className);
        return JNI_FALSE;
    }

    return JNI_TRUE;
}

/*
 * Register native methods for all classes we know about.
 *
 * returns JNI_TRUE on success.
 */
static int registerNatives(JNIEnv* env)
{
  if (!registerNativeMethods(env, classPathName,
                 methods, sizeof(methods) / sizeof(methods[0]))) {
    return JNI_FALSE;
  }

  return JNI_TRUE;
}


// ----------------------------------------------------------------------------

/*
 * This is called by the VM when the shared library is first loaded.
 */
 
typedef union {
    JNIEnv* env;
    void* venv;
} UnionJNIEnvToVoid;

jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
    UnionJNIEnvToVoid uenv;
    uenv.venv = NULL;
    jint result = -1;
    JNIEnv* env = NULL;
    
    ALOGI("JNI_OnLoad");

    if (vm->GetEnv(&uenv.venv, JNI_VERSION_1_4) != JNI_OK) {
        ALOGE("ERROR: GetEnv failed");
        goto bail;
    }
    env = uenv.env;

    if (registerNatives(env) != JNI_TRUE) {
        ALOGE("ERROR: registerNatives failed");
        goto bail;
    }
    
    result = JNI_VERSION_1_4;
    
bail:
    return result;
}

driver file:

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/leds.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>


static int major;
static struct class *cls;

//struct cdev *my_cdev;


static int led_open(struct inode * inode, struct file * file)
{
/*
    int err;
    
    err = gpio_request(0, "led1");        
            
    err = gpio_direction_output(0,1);

    err = gpio_request(1, "led2");        
            
    err = gpio_direction_output(1,1);

    err = gpio_request(2, "led3");        
            
    err = gpio_direction_output(2,1);

    err = gpio_request(3, "led4");        
            
    err = gpio_direction_output(3,1);
*/
    printk("jkk led_open.\n");
    return 0;
}

static long led_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
   
    printk("jkk led_ioctl, %d,%lu.\n",cmd,arg);
    return 0;
}


static struct file_operations leds_ops={
    .owner = THIS_MODULE,
    .open = led_open,
    .unlocked_ioctl = led_ioctl,
    
};



int leds_init(void)
{

 //   int err,devno = MKDEV(major,minor);

//    cdev_init(my_cdev,&leds_ops);
//    my_cdev->owner = THIS_MODULE;
//    my_cdev->ops = &leds_ops;
//    err = cdev_add(my_cdev,devno,1);
//    if(err)
//        printk("add failed,err=%d.\n",err);

    
    printk("jkk leds_init.\n");


    major = register_chrdev(0, "leds_test", &leds_ops);

    printk("jkk leds_init  major=%d.\n",major);
    cls = class_create(THIS_MODULE, "leds_test");

    device_create(cls, NULL, MKDEV(major, 0), NULL, "leds_test"); /* /dev/leds_jkk */
    return 0;
}

void leds_exit(void)
{
   device_destroy(cls, MKDEV(major, 0));
   class_destroy(cls);
   unregister_chrdev(major, "leds_test");
}

module_init(leds_init);
module_exit(leds_exit);
MODULE_LICENSE("GPL");

 

 

 

 

damon.jin的主页 damon.jin | 初学一级 | 园豆:192
提问于:2016-11-02 15:58
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所有回答(1)
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open返回-1后,看下errno这个全局变量,根据这个确认是啥类别的错误

jni调用设备,是否是权限的问题?

2012 | 园豆:19149 (专家六级) | 2016-11-03 11:28
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