android指纹模块

1. android指纹模块流程图
2. android setting指纹模块入口
3. nexus 6p无法启用finger问题原因

1 android指纹模块流程图

Tee : trusted excution env

2 android setting指纹模块入口

主要涉及到一下几个文件

packages/apps/Settings/src/com/android/settings/SecuritySettings.java
frameworks/base/core/java/android/hardware/fingerprint/FingerprintManager.java
frameworks/base/services/core/java/com/android/server/fingerprint/FingerprintService.java
frameworks/base/core/java/android/hardware/fingerprint/IFingerprintDaemon.aidl
system/core/fingerprintd/IFingerprintDaemon.cpp
system/core/fingerprintd/FingerprintDaemonProxy.cpp
hardware/libhardware/hardware.c
hardware/libhardware/modules/fingerprint/fingerprint.c

具体流程如下:

Settings在做页面展示的时候会调用maybeAddFingerprintPreference函数判断是否添加fingerprint preference.
maybeAddFingerprintPreference内部调用FingerprintManager的isHardwareDetected 函数.
FingerprintManager调用FingerprintService中的isHardwareDetected函数.
FingerprintService中的isHardwareDetected函数首先进行权限检查,然后如果 mDeviceHalId等于0返回false,表示没有检测到指纹相关的硬件.否则返回ture. mDeviceHalId为底层openHal的返回值.

openHal函数的实现非常简单,代码片段如下.

int64_t FingerprintDaemonProxy::openHal() {
  ALOG(LOG_VERBOSE, LOG_TAG, "nativeOpenHal()\n");
  int err;
  const hw_module_t *hw_module = NULL;
  if (0 != (err = hw_get_module(FINGERPRINT_HARDWARE_MODULE_ID, &hw_module))) {
    ALOGE("Can't open fingerprint HW Module, error: %d", err);
    return 0;
  }
  if (NULL == hw_module) {
    ALOGE("No valid fingerprint module");
    return 0;
  }

  mModule = reinterpret_cast<const fingerprint_module_t *>(hw_module);

  if (mModule->common.methods->open == NULL) {
    ALOGE("No valid open method");
    return 0;
  }

  hw_device_t *device = NULL;

  if (0 != (err = mModule->common.methods->open(hw_module, NULL, &device))) {
    ALOGE("Can't open fingerprint methods, error: %d", err);
    return 0;
  }

  if (kVersion != device->version) {
    ALOGE("Wrong fp version. Expected %d, got %d", kVersion, device->version);
    // return 0; // FIXME
  }

  mDevice = reinterpret_cast<fingerprint_device_t *>(device);
  err = mDevice->set_notify(mDevice, hal_notify_callback);
  if (err < 0) {
    ALOGE("Failed in call to set_notify(), err=%d", err);
    return 0;
  }

  // Sanity check - remove
  if (mDevice->notify != hal_notify_callback) {
    ALOGE("NOTIFY not set properly: %p != %p", mDevice->notify,
          hal_notify_callback);
  }

  ALOG(LOG_VERBOSE, LOG_TAG, "fingerprint HAL successfully initialized");
  return reinterpret_cast<int64_t>(mDevice); // This is just a handle
}

openHal函数主要实现以下3个功能

调用hw_get_module加载对应的库文件

调用module结构体的common.methods->open指向的函数 module结构体定义如下

static struct hw_module_methods_t fingerprint_module_methods = {
    .open = fingerprint_open,
};

fingerprint_module_t HAL_MODULE_INFO_SYM = {
    .common =
        {
            .tag = HARDWARE_MODULE_TAG,
            .module_api_version = FINGERPRINT_MODULE_API_VERSION_2_0,
            .hal_api_version = HARDWARE_HAL_API_VERSION,
            .id = FINGERPRINT_HARDWARE_MODULE_ID,
            .name = "Emulator Fingerprint HAL",
            .author = "The Android Open Source Project",
            .methods = &fingerprint_module_methods,
        },
};

fingerprint_open函数定义如下

static int fingerprint_open(const hw_module_t *module, const char __unused *id,
                            hw_device_t **device) {
  if (device == NULL) {
    ALOGE("NULL device on open");
    return -EINVAL;
  }

  fingerprint_device_t *dev = malloc(sizeof(fingerprint_device_t));
  memset(dev, 0, sizeof(fingerprint_device_t));

  dev->common.tag = HARDWARE_DEVICE_TAG;
  dev->common.version = FINGERPRINT_MODULE_API_VERSION_2_0;
  dev->common.module = (struct hw_module_t *)module;
  dev->common.close = fingerprint_close;

  dev->pre_enroll = fingerprint_pre_enroll;
  dev->enroll = fingerprint_enroll;
  dev->get_authenticator_id = fingerprint_get_auth_id;
  dev->cancel = fingerprint_cancel;
  dev->remove = fingerprint_remove;
  dev->set_active_group = fingerprint_set_active_group;
  dev->authenticate = fingerprint_authenticate;
  dev->set_notify = set_notify_callback;
  dev->notify = NULL;

  *device = (hw_device_t *)dev;
  return 0;
}

调用set_notify设置回调函数

hw_get_module函数主要实现底层so库加载具体加载过程可以参考android hw_get_module 分析

hw_get_module内部调用hw_get_module_by_class实现加载过程

/** Base path of the hal modules */
#if defined(__LP64__)
#define HAL_LIBRARY_PATH1 "/system/lib64/hw"
#define HAL_LIBRARY_PATH2 "/vendor/lib64/hw"
#else
#define HAL_LIBRARY_PATH1 "/system/lib/hw"
#define HAL_LIBRARY_PATH2 "/vendor/lib/hw"
#endif

/**
 * There are a set of variant filename for modules. The form of the filename
 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
 *
 * led.trout.so
 * led.msm7k.so
 * led.ARMV6.so
 * led.default.so
 */

static const char *variant_keys[] = {
    "ro.hardware", /* This goes first so that it can pick up a different
                      file on the emulator. */
    "ro.product.board",
    "ro.board.platform",
    "ro.arch"};

hw_get_module_by_class根据优先级搜索对应的so文件,文件名主要由两部分构成. 第一部分为模块名,第二部分为类型.其中模块名固定,第二部分优先级顺序为: 硬件 > 产品 > cpu > arch > default.

如果以上函数都执行成功,那么fingerprint module则加载完成.

3 nexus 6p无法启用finger问题原因

清华镜像的源码选择angler product,编译出来的system.img里没有fingerprintd可执行文件.
没有加载fingerprint module对应的库文件.
hardware so库加载顺序有误.
解决方法以移植goldfish为例
1. 拷贝device/generic/goldfish/fingerprint目录到device/huawei/angler目录下
2. 修改device/huawei/angler/device.mk文件,添加fingerprint模块
```
#Fingerprint
PRODUCT_PACKAGES += \
                 fingerprintd \
                 fingerprint.msm8994
```
3. 修改模块加载顺序由于源码编译出来的image文件,在system/vendor/lib64下含有fingerprint.angler.so. 所以在hw_get_module会加载fingerprint.angler.so而忽略fingerprint.msm8994.so. 所以修改hardware.c文件中的默认搜索顺序,把ro.board.platform放到第一即可.
```
static const char *variant_keys[] = {
    "ro.board.platform",
    "ro.hardware", /* This goes first so that it can pick up a different
                      file on the emulator. */
    "ro.product.board",
    // "ro.board.platform",
    "ro.arch"};
```

Table of Contents

1 android指纹模块流程图

2 android setting指纹模块入口

3 nexus 6p无法启用finger问题原因