android驱动开发流程2-HAL
1、hello.h
/*定义模块ID*/
#define HELLO_HARDWARE_MODULE_ID "hello"
/*硬件模块结构体*/
struct hello_module_t {
struct hw_module_t common;
};
/*硬件接口结构体*/
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);
};
2.hello.c
/*模块实例变量*/
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,
}
}
/*模块方法表*/
static struct hw_module_methods_t hello_module_methods = {
open: hello_device_open
};
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) {
LOGE("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);
LOGI("Hello Stub: open /dev/hello successfully.");
return 0;
}
在hello 目录下新建Android.mk 文件：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_PRELINK_MODULE := false
LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/hw
LOCAL_SHARED_LIBRARIES := liblog
LOCAL_SRC_FILES := hello.c
LOCAL_MODULE := hello.default
include $(BUILD_SHARED_LIBRARY)
权限修改:
system/core/rootdir 目录，uevent.rc 文件，往里面添加一行：
/dev/hello 0666 root root
