大家好,我是痞子衡,是正经搞技术的痞子。今天痞子衡给大家介绍的是飞思卡尔Kinetis系列MCU的KBOOT架构

  Bootloader是嵌入式MCU开发里很常见的一种专用的应用程序,在一个没有Bootloader的嵌入式系统里如果要更新Application,只能通过外部硬件调试器/下载器,而如果有了Bootloader,我们可以轻松完成Application的更新升级以及加载启动,除此以外在Bootloader中还可以引入更多高级特性,比如Application完整性检测、可靠升级、加密特性等。

  KBOOT是设计运行于Kinetis芯片上的一种Bootloader,KBOOT由飞思卡尔(现恩智浦)官方推出,其功能非常全面,今天痞子衡就为你揭开KBOOT的神秘面纱:

一、KBOOT由来

  飞思卡尔Kinetis系列MCU是从2010年开始推出的,早期的Kinetis产品比如MK60, MKL25并没有配套标准Bootloader功能,不过可以从飞思卡尔官网上找到很多风格迥异的Bootloader参考设计,比如AN2295(UART型)、AN4655(I2C型)、AN4379(USB-MSD型)等,这些Bootloader参考方案都是不同的飞思卡尔应用工程师设计的,因此所用的通信协议以及上位机工具都不相同,虽然这些AN一定程度上能解决客户使用Bootloader的需求,但是在Bootloader后续维护升级以及拓展性方面有一定缺陷。

  飞思卡尔也逐渐意识到了这一点,为了完善软件生态建设与服务质量,于是在2013年初组建了一支专门开发Kinetis Bootloader的软件团队,即KBOOT Team,这个Team成立的目的就是要开发出一个Unified Kinetis Bootloader(简称KBOOT),这个bootloader必须拥有良好的架构,易于扩展和维护,功能全面且经过完善的验证。

  KBOOT项目发展至今(2017)已近5年,目前被广泛应用于主流Kinetis芯片上,是Kinetis芯片集成Bootloader的首选,其官方主页是 www.nxp.com/kboot

二、KBOOT架构

  从架构角度来分析KBOOT,抛开各种附加特性,其实KBOOT最核心的就是这三大组件:Peripheral Interface、Command & Data Processor、Memory Interface,如下图所示:

痞子衡嵌入式:飞思卡尔Kinetis系列MCU启动那些事(1)- KBOOT架构-LMLPHP

2.1 Peripheral Interface

  KBOOT首要功能是能够与Host进行数据传输,我们知道数据传输接口种类有很多,KBOOT设计上可同时支持多种常见传输接口(UART, SPI, I2C, USB-HID, CAN),为此KBOOT在Peripheral Interface组件中抽象了Peripheral的行为(byte/packet层传输等),使得在Peripheral种类拓展上更容易。

  KBOOT中使用一个名叫g_peripherals[]的结构体数组来集合所有外设,下面示例仅包含UART, USB:

//! @brief Peripheral array.
const peripheral_descriptor_t g_peripherals[] = {
#if BL_CONFIG_LPUART_0
// LPUART0
{.typeMask = kPeripheralType_UART,
.instance = 0,
.pinmuxConfig = uart_pinmux_config,
.controlInterface = &g_lpuartControlInterface,
.byteInterface = &g_lpuartByteInterface,
.packetInterface = &g_framingPacketInterface },
#endif // BL_CONFIG_LPUART_0 #if BL_CONFIG_USB_HID
// USB HID
{.typeMask = kPeripheralType_USB_HID,
.instance = 0,
.pinmuxConfig = NULL,
.controlInterface = &g_usbHidControlInterface,
.byteInterface = NULL,
.packetInterface = &g_usbHidPacketInterface },
#endif // BL_CONFIG_USB_HID { 0 } // Terminator
};

  如下便是用于抽象外设行为的Peripheral descriptor原型,该原型可以描述所有类型的peripheral:

//! @brief Peripheral descriptor.
//!
//! Instances of this struct describe a particular instance of a peripheral that is
//! available for bootloading.
typedef struct PeripheralDescriptor
{
//! @brief Bit mask identifying the peripheral type.
//! See #_peripheral_types for a list of valid bits.
// 外设的类型名,KBOOT用于识别当前外设的类型
uint32_t typeMask; //! @brief The instance number of the peripheral.
// 外设的编号,KBOOT可以支持同一外设的多个实例
uint32_t instance; //! @brief Configure pinmux setting for the peripheral.
// 外设的I/O初始化
void (*pinmuxConfig)(uint32_t instance, pinmux_type_t pinmux); //! @brief Control interface for the peripheral.
// 外设的行为控制
const peripheral_control_interface_t *controlInterface; //! @brief Byte-level interface for the peripheral.
//! May be NULL since not all periperhals support this interface.
// 外设的byte级别传输控制
const peripheral_byte_inteface_t *byteInterface; //! @brief Packet level interface for the peripheral.
// 外设的packet级别传输控制
const peripheral_packet_interface_t *packetInterface;
} peripheral_descriptor_t; //! @brief Peripheral control interface.
typedef struct _peripheral_control_interface
{
// 检测是否外设是否被激活
bool (*pollForActivity)(const peripheral_descriptor_t *self);
// 外设IP底层初始化
status_t (*init)(const peripheral_descriptor_t *self, serial_byte_receive_func_t function);
// 外设IP底层恢复
void (*shutdown)(const peripheral_descriptor_t *self);
// 特殊外设pump控制(比如USB-MSC, DFU等)
void (*pump)(const peripheral_descriptor_t *self);
} peripheral_control_interface_t; //! @brief Peripheral abstract byte interface.
typedef struct _peripheral_byte_inteface
{
// byte传输初始化,一般为NULL
status_t (*init)(const peripheral_descriptor_t *self);
// byte发送
status_t (*write)(const peripheral_descriptor_t *self, const uint8_t *buffer, uint32_t byteCount);
} peripheral_byte_inteface_t; //! @brief Peripheral Packet Interface.
typedef struct _peripheral_packet_interface
{
// packet传输初始化
status_t (*init)(const peripheral_descriptor_t *self);
// 接收一包packet
status_t (*readPacket)(const peripheral_descriptor_t *self, uint8_t **packet, uint32_t *packetLength, packet_type_t packetType);
// 发送一包packet
status_t (*writePacket)(const peripheral_descriptor_t *self, const uint8_t *packet, uint32_t byteCount, packet_type_t packetType);
// 立即终止当前packet
void (*abortDataPhase)(const peripheral_descriptor_t *self);
// 完成当前packet
status_t (*finalize)(const peripheral_descriptor_t *self);
// 获取最大packet包长
uint32_t (*getMaxPacketSize)(const peripheral_descriptor_t *self);
// byte接收callback
void (*byteReceivedCallback)(uint8_t byte);
} peripheral_packet_interface_t;

2.2 Memory Interface

  KBOOT其次功能是能够读写存储空间,Kinetis上涉及的存储空间包括内部SRAM, Flash,Register、I/O以及外部QuadSPI NOR Flash(可以映射在MCU内部存储空间),为此KBOOT在Memory Interface组件中抽象了Memory的行为(read/write/erase等),使得在Memory种类拓展上更容易。

  KBOOT中使用一个名叫g_memoryMap[]的结构体数组来集合所有存储空间,下面示例包含了典型的存储空间(Flash、RAM、Register、I/O、QSPI NOR Flash):

//! @brief Memory map.
//!
//! This map is not const because it is updated at runtime with the actual sizes of
//! flash and RAM for the chip we're running on.
//! @note Do not change the index of Flash, SRAM, or QSPI (see memory.h).
memory_map_entry_t g_memoryMap[] = {
{ 0x00000000, 0x0003ffff, kMemoryIsExecutable, &g_flashMemoryInterface }, // Flash array (256KB)
{ 0x1fff0000, 0x2002ffff, kMemoryIsExecutable, &g_normalMemoryInterface }, // SRAM (256KB)
{ 0x68000000, 0x6fffffff, kMemoryNotExecutable, &g_qspiMemoryInterface }, // QSPI memory
{ 0x04000000, 0x07ffffff, kMemoryNotExecutable, &g_qspiAliasAreaInterface }, // QSPI alias area
{ 0x40000000, 0x4007ffff, kMemoryNotExecutable, &g_deviceMemoryInterface }, // AIPS0 peripherals
{ 0x40080000, 0x400fefff, kMemoryNotExecutable, &g_deviceMemoryInterface }, // AIPS1 peripherals
{ 0x400ff000, 0x400fffff, kMemoryNotExecutable, &g_deviceMemoryInterface }, // GPIO
{ 0xe0000000, 0xe00fffff, kMemoryNotExecutable, &g_deviceMemoryInterface }, // M4 private peripherals
{ 0 } // Terminator
};

  如下便是用于抽象存储器操作的memory_map_entry原型,该原型可以描述所有类型的memory:

//! @brief Structure of a memory map entry.
typedef struct _memory_map_entry
{
// 存储空间起始地址
uint32_t startAddress;
// 存储空间结束地址
uint32_t endAddress;
// 存储空间属性(Flash/RAM,是否能XIP)
uint32_t memoryProperty;
// 存储空间操作接口
const memory_region_interface_t *memoryInterface;
} memory_map_entry_t; typedef struct _memory_region_interface
{
// 存储空间(IP控制器)初始化
status_t (*init)(void);
// 从存储空间指定范围内读取数据
status_t (*read)(uint32_t address, uint32_t length, uint8_t *buffer);
// 将数据写入存储空间指定范围内
status_t (*write)(uint32_t address, uint32_t length, const uint8_t *buffer);
// 将pattern填充入存储空间指定范围内
status_t (*fill)(uint32_t address, uint32_t length, uint32_t pattern);
// 对于支持page/section编程的存储器做一次page/section数据写入
status_t (*flush)(void);
// 将存储空间指定范围内容擦除
status_t (*erase)(uint32_t address, uint32_t length);
} memory_region_interface_t;

2.3 Command & Data Processor

  KBOOT核心功能便是与Host之间的命令交互,KBOOT主要工作于Slave模式,实时监听来自Host的命令并做出响应,KBOOT仅能识别事先规定好的命令格式,因此KBOOT必须配套一个专用上位机工具使用。你可能会疑问,为什么这个组件又叫Data Processor?因为有些命令是含有Data phase的(比如read memory, write memory),对于这些命令时除了基本的命令交互响应之后,还必须有数据传输交互响应。

  KBOOT中使用如下名叫g_commandInterface和g_commandHandlerTable[]的结构变量来实现核心命令交互,KBOOT中一共实现了19条命令:

// See bl_command.h for documentation on this interface.
command_interface_t g_commandInterface =
{
bootloader_command_init,
bootloader_command_pump,
(command_handler_entry_t *)&g_commandHandlerTable,
&g_commandData
}; //! @brief Command handler table.
const command_handler_entry_t g_commandHandlerTable[] = {
// cmd handler // data handler or NULL
{ handle_flash_erase_all, NULL }, // kCommandTag_FlashEraseAll = 0x01
{ handle_flash_erase_region, NULL }, // kCommandTag_FlashEraseRegion = 0x02
{ handle_read_memory, handle_data_producer }, // kCommandTag_ReadMemory = 0x03
{ handle_write_memory, handle_data_consumer }, // kCommandTag_WriteMemory = 0x04
{ handle_fill_memory, NULL }, // kCommandTag_FillMemory = 0x05
{ handle_flash_security_disable, NULL }, // kCommandTag_FlashSecurityDisable = 0x06
{ handle_get_property, NULL }, // kCommandTag_GetProperty = 0x07
{ handle_receive_sb_file, handle_data_consumer }, // kCommandTag_ReceiveSbFile = 0x08
{ handle_execute, NULL }, // kCommandTag_Execute = 0x09
{ handle_call, NULL }, // kCommandTag_Call = 0x0a
{ handle_reset, NULL }, // kCommandTag_Reset = 0x0b
{ handle_set_property, NULL }, // kCommandTag_SetProperty = 0x0c
{ handle_flash_erase_all_unsecure, NULL }, // kCommandTag_FlashEraseAllUnsecure = 0x0d
{ handle_flash_program_once, NULL }, // kCommandTag_ProgramOnce = 0x0e
{ handle_flash_read_once, NULL }, // kCommandTag_ReadOnce = 0x0f
{ handle_flash_read_resource, handle_data_producer }, // kCommandTag_ReadResource = 0x10
{ handle_configure_memory, NULL }, // kCommandTag_ConfigureMemory = 0x11
{ handle_reliable_update, NULL }, // kCommandTag_ReliableUpdate = 0x12
{ handle_generate_key_blob, handle_key_blob_data }, // kCommandTag_GenerateKeyBlob = 0x13
};

  如下便是用于核心命令交互的Command interface原型:

//! @brief Interface to command processor operations.
typedef struct CommandInterface
{
// command处理控制单元初始化
status_t (*init)(void);
// command处理控制单元pump
status_t (*pump)(void);
// command服务函数查找表
const command_handler_entry_t *handlerTable;
// command处理控制单元状态数据
command_processor_data_t *stateData;
} command_interface_t; //! @brief Format of command handler entry.
typedef struct CommandHandlerEntry
{
// command服务函数
void (*handleCommand)(uint8_t *packet, uint32_t packetLength);
// command的data级处理函数(只有少部分command有此函数)
status_t (*handleData)(bool *hasMoreData);
} command_handler_entry_t; //! @brief Command processor data format.
typedef struct CommandProcessorData
{
// command处理控制状态机当前状态(command/data两种状态)
int32_t state;
// 指向当前处理的packet地址
uint8_t *packet;
// 当前处理的packet长度
uint32_t packetLength;
// command的data级处理控制状态数据
struct DataPhase
{
uint8_t *data; //!< Data for data phase
uint32_t count; //!< Remaining count to produce/consume
uint32_t address; //!< Address for data phase
uint32_t memoryId; //!< ID of the target memory
uint32_t dataBytesAvailable; //!< Number of bytes available at data pointer
uint8_t commandTag; //!< Tag of command running data phase
uint8_t option; //!< option for special command
} dataPhase;
// 指向command服务函数查找表地址
const command_handler_entry_t *handlerEntry; //! Pointer to handler table entry for packet in process
} command_processor_data_t;

  至此,飞思卡尔Kinetis系列MCU的KBOOT架构痞子衡便介绍完毕了,掌声在哪里~~~

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痞子衡嵌入式:飞思卡尔Kinetis系列MCU启动那些事(1)- KBOOT架构-LMLPHP

04-28 14:03