移植FreeRTOS到A核

古道上的西风与瘦马

已于 2025-07-14 17:49:26 修改

阅读量871

点赞数 19

CC 4.0 BY-SA版权

文章标签： linux

于 2025-07-14 17:48:35 首次发布

本文链接：https://blog.youkuaiyun.com/weixin_43082062/article/details/149335920

1.1 可以参考此工程移植：

https://github.com/FreeRTOS/FreeRTOS/tree/main/FreeRTOS/Demo/CORTEX_A53_64-bit_UltraScale_MPSoC

1.2 链接脚本

MEMORY

{

ddr_0_MEM_0 : ORIGIN = 0x88000000, LENGTH = 0x40000000

}

/* Specify the default entry point to the program */

ENTRY(_vector_table) //入口

1.3 汇编入口

_vector_table

-》b _boot //此时位于EL2

-》mrs x0, currentEL //获取当前的EL级别

-》cmp x0, #0x8 //如果为8，表明当前是EL2

-》beq switch_to_el1_from_el2 //从EL2切换到EL1

-》el1_entry

-》b _boot //进入EL1

-》bl invalidate_dcaches //无效cache

-》Enable MMU //使能MMU

-》b _startup //jump to start

-》bl __libc_init_array

-》bl main //进入main函数

-》prvSetupHardware()

-》XScuGic_LookupConfig( XPAR_SCUGIC_SINGLE_DEVICE_ID )

-》XScuGic_CfgInitialize( &xInterruptController, pxGICConfig, pxGICConfig->CpuBaseAddress )

-》vTaskStartScheduler(); //开启调度

-》prvCreateIdleTasks()

-》xTimerCreateTimerTask() //创建调度用的timer

-》xPortStartScheduler() //配置调用用的 timer 硬件

-》configSETUP_TICK_INTERRUPT()

-》vConfigureTickInterrupt()

-》enable_generic_timer(TICK_INIT_VALUE); //初始化arm v8 generic timer

-》Register_Irq(29, FreeRTOS_Tick_Handler, NULL, portLOWEST_USABLE_INTERRUPT_PRIORITY, ucLevelSensitive);

XScuGic_SetPriorityTriggerType( &xInterruptController, Int_Id, Priority << portPRIORITY_SHIFT, ucLevelSensitive ) //配置GIC-400的优先级寄存器

XScuGic_Connect( &xInterruptController, Int_Id, (Xil_ExceptionHandler) Handler, ( void * ) CallBackRef ) //配置中断处理函数

XScuGic_Enable( &xInterruptController, Int_Id) //使能该中断呈

-》while(1) {} //死循环

1.4 初始化armv8 generic timer

/*******************************************************************/

#define ARCH_TIMER_PHYS_ACCESS 0

#define ARCH_TIMER_VIRT_ACCESS 1

#define ARCH_TIMER_MEM_PHYS_ACCESS 2

#define ARCH_TIMER_MEM_VIRT_ACCESS 3

#define ARCH_TIMER_CTRL_ENABLE (1 << 0)

#define ARCH_TIMER_CTRL_IT_MASK (1 << 1)

#define ARCH_TIMER_CTRL_IT_STAT (1 << 2)

enum arch_timer_reg {

ARCH_TIMER_REG_CTRL,

ARCH_TIMER_REG_TVAL,

};

#define __stringify_1(x...) #x

#define __stringify(x...) __stringify_1(x)

* Unlike read_cpuid, calls to read_sysreg are never expected to be

* optimized away or replaced with synthetic values.

#define read_sysreg(r) ({ \

u64 __val; \

asm volatile("mrs %0, " __stringify(r) : "=r" (__val)); \

__val; \

})

* The "Z" constraint normally means a zero immediate, but when combined with

* the "%x0" template means XZR.

#define write_sysreg(v, r) do { \

u64 __val = (u64)(v); \

asm volatile("msr " __stringify(r) ", %x0" \

: : "rZ" (__val)); \

} while (0)

static void arch_timer_reg_write_cp15(enum arch_timer_reg reg, u32 val)

{

switch (reg) {

case ARCH_TIMER_REG_CTRL:

write_sysreg(val, cntp_ctl_el0);

break;

case ARCH_TIMER_REG_TVAL:

write_sysreg(val, cntp_tval_el0);

break;

}

static u32 arch_timer_reg_read_cp15(enum arch_timer_reg reg)

{

switch (reg) {

case ARCH_TIMER_REG_CTRL:

return read_sysreg(cntp_ctl_el0);

case ARCH_TIMER_REG_TVAL:

return read_sysreg(cntp_tval_el0);

}

static u32 arch_timer_reg_read(enum arch_timer_reg reg)

{

u32 val;

val = arch_timer_reg_read_cp15(reg);

return val;

}

static void arch_timer_reg_write(enum arch_timer_reg reg, u32 val)

{

arch_timer_reg_write_cp15(reg, val);

}

static __always_inline void enable_generic_timer(unsigned long evt)

{

unsigned long ctrl;

ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);

ctrl |= ARCH_TIMER_CTRL_ENABLE;

ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;

arch_timer_reg_write(ARCH_TIMER_REG_TVAL, evt);

arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);

}

1.5 Freertos中断处理过程

FreeRTOS_IRQ_Handler

-》BL vApplicationIRQHandler

-》pxVectorEntry->Handler( pxVectorEntry->CallBackRef ) // Handler ()由XScuGic_Connect()注册进来

-》portSAVE_CONTEXT //保存当前任务上下文

-》BL vTaskSwitchContext

-》vTaskSwitchContext

-》taskSELECT_HIGHEST_PRIORITY_TASK()

-》listGET_OWNER_OF_NEXT_ENTRY( pxCurrentTCB, &( pxReadyTasksLists[ uxTopPriority ] ) ) //找到当前要执行的TCB

-》portRESTORE_CONTEXT //真正进行任务切换

1.6 注册CLI命令行

void vUARTCommandConsoleStart( uint16_t usStackSize, unsigned portBASE_TYPE uxPriority )

{

vRegisterSampleCLICommands();

/* Create that task that handles the console itself. */

xTaskCreate( prvUARTCommandConsoleTask, /* The task that implements the command console. */

"CLI", /* Text name assigned to the task. This is just to assist debugging. The kernel does not use this name itself. */

usStackSize, /* The size of the stack allocated to the task. */

NULL, /* The parameter is not used, so NULL is passed. */

uxPriority, /* The priority allocated to the task. */

NULL ); /* A handle is not required, so just pass NULL. */

}