[android-porting] How to add new HAL layer to system.img

[hm_tsai]

Hello,

   I study android HAL layer and create new virtual HAL in 
hardware/libhardware/modules/hello.
Then modify the Android.mk in hardware/libhardware/modules to add my folder.
I use lunch aosp_arm-eng and make -j4 to build image, but I always can't 
see hello.default.so in the out/target/product/generic/system/lib/hw.
However, I use mmm hardware/libhardware/modules/hello. It is ok. I can't 
understand why make -j4 can't build my folder.
I use android source code's version is 4.4.2_r2.


The attached files are my code. 

Can you give me some suggestions?

Thanks.

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Android.mk
Description: Binary data

#define LOG_TAG "HelloStub"

#include <hardware/hardware.h>
#include <hardware/hello.h>
#include <fcntl.h>
#include <errno.h>
#include <cutils/log.h>
#include <cutils/atomic.h>

#define DEVICE_NAME "/dev/hello"
#define MODULE_NAME "Hello"
#define MODULE_AUTHOR "hmtsai"

/*open and close function*/
static int hello_device_open(const struct hw_module_t* module, const char* name, struct hw_device_t** device);
static int hello_device_close(struct hw_device_t* device);

/*device support function*/
static int hello_set_val(struct hello_device_t* dev, int val);
static int hello_get_val(struct hello_device_t* dev, int* val);

/*module method table*/
static struct hw_module_methods_t hello_module_methods = {
	open: hello_device_open
};

/*module variable */
struct hello_module_t HAL_MODULE_INFO_SYM = {
	common: {
		tag: HARDWARE_MODULE_TAG,
		version_major: 1,
		version_minor: 0,
		id: HELLO_HARDWARE_MODULE_ID,
		name: MODULE_NAME,
		author: MODULE_AUTHOR,
		methods: &hello_module_methods,
	}
};

static int hello_device_open(const struct hw_module_t* module, const char* name, struct hw_device_t** device) {
	struct hello_device_t* dev;dev = (struct hello_device_t*)malloc(sizeof(struct hello_device_t));
	
	if(!dev) {
		ALOGE("Hello Stub: failed to alloc space");
		return -EFAULT;
	}

	memset(dev, 0, sizeof(struct hello_device_t));
	dev->common.tag = HARDWARE_DEVICE_TAG;
	dev->common.version = 0;
	dev->common.module = (hw_module_t*)module;
	dev->common.close = hello_device_close;
	dev->set_val = hello_set_val;dev->get_val = hello_get_val;

	/*if((dev->fd = open(DEVICE_NAME, O_RDWR)) == -1) {
		LOGE("Hello Stub: failed to open /dev/hello -- %s.", strerror(errno));free(dev);
		return -EFAULT;
	}*/

	*device = &(dev->common);
	ALOGI("Hello Stub: open /dev/hello successfully.");

	return 0;
}

static int hello_device_close(struct hw_device_t* device) {
	struct hello_device_t* hello_device = (struct hello_device_t*)device;

	if(hello_device) {
		close(hello_device->fd);
		free(hello_device);
	}
	
	return 0;
}

static int hello_set_val(struct hello_device_t* dev, int val) {
	ALOGI("Hello Stub: set value %d to device.", val);

	//write(dev->fd, &val, sizeof(val));

	return 0;
}

static int hello_get_val(struct hello_device_t* dev, int* val) {
	if(!val) {
		ALOGE("Hello Stub: error val pointer");
		return -EFAULT;
	}
	*val = 4567;
	//read(dev->fd, val, sizeof(*val));

	ALOGI("Hello Stub: get value %d from device", *val);

	return 0;
}
#ifndef ANDROID_HELLO_INTERFACE_H
#define ANDROID_HELLO_INTERFACE_H
#include <hardware/hardware.h>

__BEGIN_DECLS

/*define hardware ID*/
#define HELLO_HARDWARE_MODULE_ID "hello"

/*hardware module struct*/
struct hello_module_t {
	struct hw_module_t common;
};

/*hardware device struct*/
struct hello_device_t {
	struct hw_device_t common;
	int fd;
	int (*set_val)(struct hello_device_t* dev, int val);
	int (*get_val)(struct hello_device_t* dev, int* val);
};

__END_DECLS

#endif