android bluetooth 移植相关注意事项

bluedroid的通用架构框图：

由上图可知，bluedroid包含如下的核心组件：

Bluetooth core stack library

HCI library

Vendor Specific HCI library

UART, RFKILL,TUN/TAP and UHID device drivers

移植过程

基于android上bluedroid上的蓝牙移植涉及到文件有：

bluetooth.apk

bludroid协议栈涉及到的库：

bluetooth.default.so

libbt-hci.so

libbt-utils.so

libbt-vendor.so

audio.a2dp.default.so

android.hardware.bluetooth.xml：该文件用于控制是否显示蓝牙的设置界面，位于/etc/permissions/目录下

bluetooth.default.so依赖于libbt-hci.so、libbt-utils.so、libbt-vendor.so等动态库，该库是蓝牙bluedroid协议栈的核心，该库的核心文件bluetooth.c实现了蓝牙的HAL层。

该硬件抽象层对应的接口定义如下(hardware/include/hardware/bluetooth.h)：

/** NOTE: By default, no profiles are initialized at the time of init/enable.
 *  Whenever the application invokes the 'init' API of a profile, then one of
 *  the following shall occur:
 *
 *    1.) If Bluetooth is not enabled, then the Bluetooth core shall mark the
 *        profile as enabled. Subsequently, when the application invokes the
 *        Bluetooth 'enable', as part of the enable sequence the profile that were
 *        marked shall be enabled by calling appropriate stack APIs. The
 *        'adapter_properties_cb' shall return the list of UUIDs of the
 *        enabled profiles.
 *
 *    2.) If Bluetooth is enabled, then the Bluetooth core shall invoke the stack
 *        profile API to initialize the profile and trigger a
 *        'adapter_properties_cb' with the current list of UUIDs including the
 *        newly added profile's UUID.
 *
 *   The reverse shall occur whenever the profile 'cleanup' APIs are invoked
 */


/** Represents the standard Bluetooth DM interface. */
typedef struct {
    /** set to sizeof(bt_interface_t) */
    size_t size;
    /**
     * Opens the interface and provides the callback routines
     * to the implemenation of this interface.
     */
    int (*init)(bt_callbacks_t* callbacks );


    /** Enable Bluetooth. */
    int (*enable)(void);


    /** Disable Bluetooth. */
    int (*disable)(void);


    /** This ensures the chip is Powered ON  to support other radios in the combo chip.
     * If the chip is OFF it set the chip to ON, if it is already ON it just increases the radio ref count
     * to keep track when to Power OFF */
    int (*enableRadio)(void);


    /** This decreases radio ref count  and ensures that chip is Powered OFF
     * when the radio ref count becomes zero. */
    int (*disableRadio)(void);


    /** Closes the interface. */
    void (*cleanup)(void);


    /** Get all Bluetooth Adapter properties at init */
    int (*get_adapter_properties)(void);


    /** Get Bluetooth Adapter property of 'type' */
    int (*get_adapter_property)(bt_property_type_t type);


    /** Set Bluetooth Adapter property of 'type' */
    /* Based on the type, val shall be one of
     * bt_bdaddr_t or bt_bdname_t or bt_scanmode_t etc
     */
    int (*set_adapter_property)(const bt_property_t *property);


    /** Get all Remote Device properties */
    int (*get_remote_device_properties)(bt_bdaddr_t *remote_addr);


    /** Get Remote Device property of 'type' */
    int (*get_remote_device_property)(bt_bdaddr_t *remote_addr,
                                      bt_property_type_t type);


    /** Set Remote Device property of 'type' */
    int (*set_remote_device_property)(bt_bdaddr_t *remote_addr,
                                      const bt_property_t *property);


    /** Get Remote Device's service record  for the given UUID */
    int (*get_remote_service_record)(bt_bdaddr_t *remote_addr,
                                     bt_uuid_t *uuid);


    /** Start SDP to get remote services */
    int (*get_remote_services)(bt_bdaddr_t *remote_addr);


    /** Start Discovery */
    int (*start_discovery)(void);


    /** Cancel Discovery */
    int (*cancel_discovery)(void);


    /** Create Bluetooth Bonding */
    int (*create_bond)(const bt_bdaddr_t *bd_addr);


    /** Remove Bond */
    int (*remove_bond)(const bt_bdaddr_t *bd_addr);


    /** Cancel Bond */
    int (*cancel_bond)(const bt_bdaddr_t *bd_addr);


    /** BT Legacy PinKey Reply */
    /** If accept==FALSE, then pin_len and pin_code shall be 0x0 */
    int (*pin_reply)(const bt_bdaddr_t *bd_addr, uint8_t accept,
                     uint8_t pin_len, bt_pin_code_t *pin_code);


    /** BT SSP Reply - Just Works, Numeric Comparison and Passkey
     * passkey shall be zero for BT_SSP_VARIANT_PASSKEY_COMPARISON &
     * BT_SSP_VARIANT_CONSENT
     * For BT_SSP_VARIANT_PASSKEY_ENTRY, if accept==FALSE, then passkey
     * shall be zero */
    int (*ssp_reply)(const bt_bdaddr_t *bd_addr, bt_ssp_variant_t variant,
                     uint8_t accept, uint32_t passkey);


    /** Get Bluetooth profile interface */
    const void* (*get_profile_interface) (const char *profile_id);


    /** Bluetooth Test Mode APIs - Bluetooth must be enabled for these APIs */
    /* Configure DUT Mode - Use this mode to enter/exit DUT mode */
    int (*dut_mode_configure)(uint8_t enable);


    /* Send any test HCI (vendor-specific) command to the controller. Must be in DUT Mode */
    int (*dut_mode_send)(uint16_t opcode, uint8_t *buf, uint8_t len);


   /* Send  service level Authorization response */
   int (*authorize_response)(const bt_bdaddr_t *bd_addr, bt_service_id_t service_id,
                             uint8_t authorize, uint8_t save_settings);


    /** Get FM module interface */
    const void* (*get_fm_interface) ();


    /** BLE Test Mode APIs */
    /* opcode MUST be one of: LE_Receiver_Test, LE_Transmitter_Test, LE_Test_End */
    int (*le_test_mode)(uint16_t opcode, uint8_t *buf, uint8_t len);
} bt_interface_t;

bluetooth.c和bluetooth.h对应到上面图1中的libhardware层。

而bluetooth services和bluetooth JNI编译出来的结果就是bluetooth.apk, bluetooth services透过bluetooth JNI，bluetooth JNI透过硬件抽象层，直接调用到bluedroid的核心协议栈，而核心协议栈通过uart driver，rfkill driver，UHID，TUN等vfs文件接口直接调用到内核空间的驱动。

audio.a2dp.default.so文件是音频模块针对ad2p的硬件抽象层的实现，供音频模块来控制a2dp的通路切换，声音和音量的控制。注意该模块跟BT_PROFILE_ADVANCED_AUDIO_ID模块的关系。

libbt-vendor.so是需要根据特定的蓝牙芯片去客制化实现的。

具体该移植库（libbt-vendor.so），需要实现如下的通用接口（external/bluetooth/bluedroid/hci/include/bt_vendor_lib.h）：

/*
 * Bluetooth Host/Controller VENDOR Interface
 */
typedef struct {
    /** Set to sizeof(bt_vndor_interface_t) */
    size_t          size;

    /*
     * Functions need to be implemented in Vendor libray (libbt-vendor.so).
     */

    /**
     * Caller will open the interface and pass in the callback routines
     * to the implemenation of this interface.
     */
    int   (*init)(const bt_vendor_callbacks_t* p_cb, unsigned char *local_bdaddr);

    /**  Vendor specific operations */
    int (*op)(bt_vendor_opcode_t opcode, void *param);

    /** Closes the interface */
    void  (*cleanup)(void);
} bt_vendor_interface_t;

在以上结构体中，其中大部份的工作是由int (*op)(bt_vendor_opcode_t opcode, void *param);函数实现，该函数更具OPCODE操作码的不同，一般通过switch语句来实现。

各个OPCODE操作码对应的功能说明如下：（external/bluetooth/bluedroid/hci/include/bt_vendor_lib.h）

/** Vendor specific operations OPCODE */
typedef enum {
/*  [operation]
 *      Power on or off the BT Controller.
 *  [input param]
 *      A pointer to int type with content of bt_vendor_power_state_t.
 *      Typecasting conversion: (int *) param.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      None.
 */
    BT_VND_OP_POWER_CTRL,


/*  [operation]
 *      Perform any vendor specific initialization or configuration
 *      on the BT Controller. This is called before stack initialization.
 *  [input param]
 *      None.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      Must call fwcfg_cb to notify the stack of the completion of vendor
 *      specific initialization once it has been done.
 */
    BT_VND_OP_FW_CFG,


/*  [operation]
 *      Perform any vendor specific SCO/PCM configuration on the BT Controller.
 *      This is called after stack initialization.
 *  [input param]
 *      None.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      Must call scocfg_cb to notify the stack of the completion of vendor
 *      specific SCO configuration once it has been done.
 */
    BT_VND_OP_SCO_CFG,


/*  [operation]
 *      Open UART port on where the BT Controller is attached.
 *      This is called before stack initialization.
 *  [input param]
 *      A pointer to int array type for open file descriptors.
 *      The mapping of HCI channel to fd slot in the int array is given in
 *      bt_vendor_hci_channels_t.
 *      And, it requires the vendor lib to fill up the content before returning
 *      the call.
 *      Typecasting conversion: (int (*)[]) param.
 *  [return]
 *      Numbers of opened file descriptors.
     *      Valid number:
     *          1 - CMD/EVT/ACL-In/ACL-Out via the same fd (e.g. UART)
     *          2 - CMD/EVT on one fd, and ACL-In/ACL-Out on the other fd
     *          4 - CMD, EVT, ACL-In, ACL-Out are on their individual fd
 *  [callback]
 *      None.
 */
    BT_VND_OP_USERIAL_OPEN,


/*  [operation]
 *      Close the previously opened UART port.
 *  [input param]
 *      None.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      None.
 */
    BT_VND_OP_USERIAL_CLOSE,


/*  [operation]
 *      Get the LPM idle timeout in milliseconds.
 *      The stack uses this information to launch a timer delay before it
 *      attempts to de-assert LPM WAKE signal once downstream HCI packet
 *      has been delivered.
 *  [input param]
 *      A pointer to uint32_t type which is passed in by the stack. And, it
 *      requires the vendor lib to fill up the content before returning
 *      the call.
 *      Typecasting conversion: (uint32_t *) param.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      None.
 */
    BT_VND_OP_GET_LPM_IDLE_TIMEOUT,


/*  [operation]
 *      Enable or disable LPM mode on BT Controller.
 *  [input param]
 *      A pointer to uint8_t type with content of bt_vendor_lpm_mode_t.
 *      Typecasting conversion: (uint8_t *) param.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      Must call lpm_cb to notify the stack of the completion of LPM
 *      disable/enable process once it has been done.
 */
    BT_VND_OP_LPM_SET_MODE,


/*  [operation]
 *      Assert or Deassert LPM WAKE on BT Controller.
 *  [input param]
 *      A pointer to uint8_t type with content of bt_vendor_lpm_wake_state_t.
 *      Typecasting conversion: (uint8_t *) param.
 *  [return]
 *      0 - default, don't care.
 *  [callback]
 *      None.
 */
    BT_VND_OP_LPM_WAKE_SET_STATE,
} bt_vendor_opcode_t;

以上注释中说明了各个操作码的功能，也就是我们基于bluedroid进行蓝牙移植的最主要的工作量。easy吧？呵呵！简单就是美。

另外还有就是蓝协议栈的配置选项，分为两种：

一种是编译时的配置选项

一种是运行时的配置选项

涉及蓝牙相关的通用配置选项有（具体配置格式的组织是 vendor specific的）：

1：uart的端口号，如/dev/ttyS1, /dev/ttS2,/dev/ttyO1等等

2： uart的boadrate，如921600，460800，3000000等

3： 蓝牙固件的名字和路径

4： 是否使能LPM mode（低功耗管理模式）

5： PCM的配置

6： 如果是cob（chip on board）的蓝牙芯片，还需要指定蓝牙mac地址，如果是模块的一般直接可有从模块里读出来，则不需要该项

调试过程

在软件包按上面说的已经准备好的情况，在开发版上实际调试时，应该经历如下的步骤:

硬件方面有如下的check点：

1：蓝牙的power_enable是否正常

2：蓝牙的32Khz是否正常，并且是否足够接近32768HZ

3：蓝牙的26MHZ是否正常

4：蓝牙的硬件流控双方是否支持，如果不支持，需要硬件上进行欺骗：譬如brcm的蓝牙芯片是必须需要硬件流控，而我们uart 主控的硬件流控却有问题，因此

5：我们将brcm的蓝牙端的cts pin硬件拉地（low active），这样就是相当于告诉拨通的蓝牙芯片，我们的uart controller始终都是准备好可以接收数据的。从而实现

6：无硬件流控也可以实现互通讯

7：uart是否需要电平转换，像我们的AP 输出的都是3.3v的电平，而拨通的蓝牙则则只能输出1.8v的电平，这样的话，就需要在拨通的rts和tx pin上接电平转换，将拨通的1.8v提升到3.3v，这样可以让我们AP能够正确检测到高电平。

8：蓝牙芯片的工作电压是否正常

软件方面的调试:

1：通过控制台命令：echo 1/0 > /sys/class/rfkill/rfill0/state来检测power enabe pin和32KHZ的输出/关闭是否正常

2：通过配置文件/etc/bluetooth/bt_stack.conf文件，我们可以来用来控制调试信息的显示，和蓝牙封包的保存，他能够将hci层的cmd，data，event包都保存到btsnoop_hci.log文件中，然后可以通过frontline公司的capture file viewer工具来查看封包的格式和含义。

bt_stack.conf的格式如下：

/system/etc/bluetooth #
/system/etc/bluetooth # cat bt_stack.conf
# Set the phone BT device name
#Name=Bluetooth Phone

# Set the phone BT device COD (Class of Device)
#Class={0x5A, 0x02, 0x0C}

# Enable BtSnoop logging function
# valid value : true, false
BtSnoopLogOutput=false

# BtSnoop log output file
BtSnoopFileName=/sdcard/btsnoop_hci.log

# Enable trace level reconfiguration function
# Must be present before any TRC_ trace level settings
TraceConf=true

# Trace level configuration
#   BT_TRACE_LEVEL_NONE    0    ( No trace messages to be generated )
#   BT_TRACE_LEVEL_ERROR   1    ( Error condition trace messages )
#   BT_TRACE_LEVEL_WARNING 2    ( Warning condition trace messages )
#   BT_TRACE_LEVEL_API     3    ( API traces )
#   BT_TRACE_LEVEL_EVENT   4    ( Debug messages for events )
#   BT_TRACE_LEVEL_DEBUG   5    ( Full debug messages )
#   BT_TRACE_LEVEL_VERBOSE 6    ( Verbose messages ) - Currently supported for TRC_BTAPP only.
TRC_BTM=2
TRC_HCI=2
TRC_L2CAP=2
TRC_RFCOMM=2
TRC_OBEX=2
TRC_AVCT=2
TRC_AVDT=2
TRC_AVRC=2
TRC_AVDT_SCB=2
TRC_AVDT_CCB=2
TRC_A2D=2
TRC_SDP=2
TRC_GATT=2
TRC_SMP=2
TRC_BTAPP=2
TRC_PROTOCOL=0

3：上一种方法有一个局限性，那就是只能保存完整的hci包，如果hci包不完整，则不能够通过btsnoop_hci.log文件来查看，这个时候可以在hci_h4.c文件中的hci_h4_send_msg函数和userial.c文件中的userial_read_thread函数中添加array2strings（）来将串口上发送和接收的数据都打印出来，这样就可以发现那些不完整的hci包。array2strings实现如下：

int array2strings(char* header, char * array_buf, int array_len)
{
#if BT_DEBUG
    int n,i;
    uint8_t buf_strings[1600];
    //IS_DEBUG_ENABLE_CMD_EVENT;
    memset(buf_strings,0,sizeof(buf_strings));
    char * tmpbuf = (char * )buf_strings;
    array_len = (array_len>32)?32:array_len;
    for(i=0; i<array_len; i++)
    {
        n = sprintf(tmpbuf,"0x%x ",array_buf[i]);
        tmpbuf += n;
    }
    ALOGD("%s:len=%d %s", header, array_len, buf_strings);
#endif
    return 0;
}

4：在没有硬件流控的情况下，需要注意的问题：

有些ap的uart cotroller并不支持硬件流控，这样的话在蓝牙芯片初始化过程中，会碰到如下一些问题：

A： 在切换波特率时会出现错误：

原因就是有些蓝牙芯片，如brcm的6330/6476等芯片在蓝牙芯片和uart controller的波特率切换到较高的波特率时，蓝牙芯片端会忙一段时间，在这段时间里，uart controller就不能够给蓝牙芯片段发送命令或数据。

否则会导致命令或数据超时无响应。如果支持硬件流控则不会存在该问题，因为蓝牙芯片端在切换到高波特率时，在忙的时间段，他会自动将芯片的rts脚拉高，uart controller端在检测到cts变高，认为接收端在忙，

从而不会将数据发送出去，而只是将数据缓存在tty xmit buffer中，待cts变低后，再继续从tty xmit buffer取数据通过dma方式发送出去。

B： 会出现应用层已经将数据写到了/dev/ttyS1设备里，但uart controller并未将数据在tx pin上发送出来。

uart驱动的调试

uart drivers的调试方法有：

1： 可以考虑将蓝牙芯片uart口的tx pin在接到AP端的uart口的rx pin的同时也接到pc com口上的rx pin，同理将蓝牙芯片uart口上rx pin同时接到pc com上rx pin，这样可以通过pc上uart debug tool可以看到AP发送给蓝牙芯片的数据和蓝牙芯片送回来的数据。以检查串口收发数据的正确性。局限性是：由于目前pc com上的波特率不能设置太高，所以一般只能在低速的115200上进行调试。

2：在串口驱动添加/proc文件属性来动态的观察uart drivers的工作状况。

譬如在蓝牙串口出错时，我们可以命令：cat /proc/bt_debug来查看串口的如下信息：

a: uart controller的寄存器上下文

b: uart DMA rx buffer中是否还有剩余数据未通过tty_insert_flip_string_fixed_flag函数提交到tty io层

会导致bluedroid层收到一个不完整的数据包，但uart controller其实已经收到了一个完整的数据包

c: uart xmit circ_buf中是否还有剩余数据未能及时发送出去

这会导致蓝牙芯片收到一个不完整的hci包，从而导致蓝牙出错

d: 在proc的文件属性中，还可以添加关键的一些变量的值，这样检测出错时，这些是否正确。

譬如打印port.icount.rx，port.icount.tx，port.icount.overrun，port.icount.parity

port.icount.cts

3： 内存数据查看工具：mu命令

该命令可以查看DMA tx buf和DMA rx buf中的数据内容，可以非常的方便检查数据收发是否正确