想了解更多内容，鸿蒙请访问：
和华为官方合作共建的移植源码鸿蒙技术社区
https://harmonyos.51cto.com/#zz
项目最新更新，可以查看码仓 https://gitee.com/liangzili/harmony-raspberry
1、树莓切换启动模式
树莓派默认启动在HYP模式，派下我们需要在内核启动前改为SVC模式
kernel\liteos_a\arch\arm\arm\src\startup\reset_vector_up.S 在115行左右，修改reset_vector:下面添加
mrs r0,鸿蒙cpsr //读取CPU模式寄存器 bic r0,r0,#0x1F //清除CPU模式位(如果处于催眠模式，它将是移植源码1A)保留所有其他 orr r0,r0,#0x13 //设置CPU_MODE为SVC_MODE (0x13)，而ORR仍然保留所有其他位 msr spsr_cxsf,树莓r0 //将其写入spsr_cxsf寄存器，以便在调用交换机时加载该寄存器。派下 add r0,修改pc,#4 //从pc计算要进入SVC_MODE的地址(后面的两个操作码很长) msr ELR_hyp,r0 //将地址值写入ELR_hyp寄存器 eret //执行了回车指令 2、修改串口驱动
2.1、鸿蒙为了方便调试，移植源码先设置一个字符打印函数
kernel\liteos_a\platform\uart\amba_pl011\amba_pl011.c在46行左右处添加下面的树莓代码，uart_putc_phy使用物理地址打印字符，派下uart_putc_virt使用虚拟地址打印。修改当内核代码启动MMU之后，需用使用uart_putc_virt来打印字符。
/*---------自定义函数----------*/ #define RPI_BASE_UART_REGISTER (0x3f201000) //HI3516:0x120A0000 rpi2:0x3F201000 #define AMBA_UART_DR (*(volatile unsigned char *)(RPI_BASE_UART_REGISTER + 0x00)) #define AMBA_UART_FR (*(volatile unsigned char *)(RPI_BASE_UART_REGISTER + 0x18)) #define RPI_BASE_UART_REGISTER1 IO_DEVICE_ADDR(0x3F201000) //HI3516:0x120A0000 rpi2:0x3F201000 #define AMBA_UART_DR1 (*(volatile unsigned char *)(RPI_BASE_UART_REGISTER1 + 0x00)) #define AMBA_UART_FR1 (*(volatile unsigned char *)(RPI_BASE_UART_REGISTER1 + 0x18)) /*---------------------------*/ void uart_putc_phy(unsigned char c) { //UART_Type *uartRegs = (UART_Type *)UART4_REG_PBASE; //while ((uartRegs->USART_ISR & (1<<5)) == 0); //uartRegs->USART_TDR = c; while (AMBA_UART_FR & (1 << 5)); AMBA_UART_DR = c; } void uart_putc_virt(unsigned char c) { //UART_Type *uartRegs = (UART_Type *)UART_REG_BASE; //while ((uartRegs->USART_ISR & (1<<5)) == 0); //uartRegs->USART_TDR = c; while (AMBA_UART_FR1 & (1 << 5)); AMBA_UART_DR1 = c; } 例如：kernel\liteos_a\arch\arm\arm\src\startup\reset_vector_up.S
ldr sp, =0x00000000 + 0x5000000 //调用C函数前，得先设置栈，树莓派物理内存从0x0开始 mov r0, #m bl uart_putc_phy //在MMU启动之前使用的是物理地址打印 bl mmu_setup /* set up the mmu */ mov r0, #M bl uart_putc_virt //在MMU启动之后使用的是虚拟地址打印 2.2、添加串口中断，亿华云串口输入代码
vendor\broadcom\BCM2836\driver\uart\uart_hardware.c 2.2.1、 串口的中断函数，产生中断时，这个函数调用
static irqreturn_t BCM2836_uart_irq(int irq, void *data) { char buf[FIFO_SIZE]; unsigned int count = 0; struct BCM2836_port *port = NULL; struct uart_driver_data *udd = (struct uart_driver_data *)data; UART_Type *uartRegs; uint32_t status; if (udd == NULL) { uart_error("udd is null!\n"); return IRQ_HANDLED; } port = (struct BCM2836_port *)udd->private; uartRegs = (UART_Type *)port->phys_base; READ_UINT32(status, UART_REG_BASE + UART_FR); if ((UARTREG(UART_REG_BASE,UART_FR)&(1<<4)) == 0) { do { buf[count++] = UARTREG(UART_REG_BASE,UART_DR);//*(volatile UINT32 *)((UINTPTR)(UART_REG_BASE + UART_DR)); //去读取硬件得到数据 if (udd->num != CONSOLE_UART) { continue; } if (CheckMagicKey(buf[count - 1])) { //数据放在buf里 goto end; } if (buf[count-1] == \r) //对windows和liteos回车换行的处理 buf[count-1] = \n; } while (UARTREG(UART_REG_BASE,UART_DR)); udd->recv(udd, buf, count); //调用udd里的recv函数把数据发送给上一级 } UARTREG(UART_REG_BASE, UART_ICR) = 0x3ff; end: /* clear all interrupt */ return 0; } 2.2.2、串口的初始化函数
static int BCM2836_startup(struct uart_driver_data *udd) { int ret = 0; struct BCM2836_port *port = NULL; if (udd == NULL) { uart_error("udd is null!\n"); return -EFAULT; } port = (struct BCM2836_port *)udd->private;//*private是一个指针，指向 struct { enable,phys_base,irq_num,*udd} if (!port) { uart_error("port is null!"); return -EFAULT; } /* enable the clock */ LOS_TaskLock(); LOS_TaskUnlock(); ret = request_irq(port->irq_num, (irq_handler_t)BCM2836_uart_irq,0, "uart_dw", udd); //去注册一个串口的接收中断函数 /* 1.uart interrupt priority should be the highest in interrupt preemption mode */ //ret = LOS_HwiCreate(NUM_HAL_INTERRUPT_UART, 0, 0, (HWI_PROC_FUNC)uart_handler, NULL); /* 2.clear all irqs */ UARTREG(UART_REG_BASE, UART_ICR) = 0x3ff; //*(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F201044)) = 0x3ff; /* disable FIFO mode */ //uartRegs->USART_CR1 &= ~(1<<29); //*(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F20102C)) = 0x60; UARTREG(UART_REG_BASE, UART_LCR_H) = (1 << 6 | 1 << 5| 1 << 4); /* 3.set fifo trigger level */ //*(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F201034)) = 0x0; UARTREG(UART_REG_BASE, UART_IFLS) = 0; /* 4.enable rx interrupt 开启串口接收中断，第4位*/ UARTREG(UART_REG_BASE, UART_IMSC) = (1 << 4 | 1 << 6); //*(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F201038)) = 0x10; /* 5.enable receive */ UARTREG(UART_REG_BASE, UART_CR) |= (1 << 9); //*(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F201030)) = 0x301; //HalIrqUnmask(NUM_HAL_INTERRUPT_UART);//6. *(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F00B214)) = 0x02000000;//Unmask接收25号中断 BCM2836_config_in(udd); return ret; } 2.2.3、串口写函数
static int BCM2836_start_tx(struct uart_driver_data *udd, const char *buf, size_t count) { unsigned int tx_len = count; struct BCM2836_port *port = NULL; char value; unsigned int i; int ret = 0; if (udd == NULL) { uart_error("udd is null!\n"); return -EFAULT; } port = (struct BCM2836_port *)udd->private; if (!port) { uart_error("port is null!"); return -EFAULT; } /* UART_WITH_LOCK: there is a spinlock in the function to write reg in order. */ for (i = 0; i < tx_len; i++ ){ ret = LOS_CopyToKernel((void *)&value, sizeof(char),(void *)(buf++), sizeof(char)); if (ret) { return i; } (void)UartPutsReg(port->phys_base, &value, 1, UART_WITH_LOCK); } return count; } 2、系统时钟初始化
2.1、main函数的各种调用,验证参数
kernel\liteos_a\platform\main.c->main()
kernel\liteos_a\kernel\common\los_config.c->OsMain()
kernel\liteos_a\arch\arm\arm\src\los_hw_tick.c->OsTickInit()
systemClock //vendor里设置的是50000000 tickPerSecond //鸿蒙默认设置的是100 LITE_OS_SEC_TEXT_INIT UINT32 OsTickInit(UINT32 systemClock, UINT32 tickPerSecond) { //只是验证了下传入的这两个参数,并未使用 HalClockInit(); return LOS_OK; } 2.2、先获取当前时钟频率,注册中断
kernel\liteos_a\platform\hw\arm\timer\arm_generic\arm_generic_timer.c
OS_TICK_INT_NUM//中断号,在vendor\***\***\board\include\asm\hal_platform_ints.h下定义,查手册确定 MIN_INTERRUPT_PRIORITY//优先级 OsTickEntry//中断函数 LITE_OS_SEC_TEXT_INIT VOID HalClockInit(VOID) { ... g_sysClock = HalClockFreqRead(); //先获取当前时钟频率 //调用LOS_HwiCreate函数新建中断，系统中断由它注册 ret = LOS_HwiCreate(OS_TICK_INT_NUM, MIN_INTERRUPT_PRIORITY, 0, OsTickEntry, 0);//参数1:中断号、参数4:执行函数 //这个函数就不深入了，大体就是将中断号好和对应的执行函数放到一个数组 //比如这里就是云南idc服务商，当发生OS_TICK_INT_NUM这个中断时，执行OsTickEntry()函数 ... } 2.3、时钟中断的执行函数OsTickEntry()
kernel\liteos_a\platform\hw\arm\timer\arm_generic\arm_generic_timer.c
不过此时这是注册了这个函数，时钟并未启动，得执行了（三.启动时钟）之后才会调用这个函数 LITE_OS_SEC_TEXT VOID OsTickEntry(VOID) { TimerCtlWrite(0); OsTickHandler(); TimerCvalWrite(TimerCvalRead() + OS_CYCLE_PER_TICK); TimerCtlWrite(1); //使用最后一个cval生成下一个tick的时间是绝对和准确的。不要使用tval来驱动一般时间，在这种情况下tick会变慢。 } 2.3、启动时钟
main() => OsStart(VOID) => OsTickStart() => HalClockStart(VOID)
kernel\liteos_a\platform\hw\arm\timer\arm_generic\arm_generic_timer.c => HalClockStart(VOID)
//树莓派2没有GIC所以这个函数要爆改 LITE_OS_SEC_TEXT_INIT VOID HalClockStart(VOID) { HalIrqUnmask(OS_TICK_INT_NUM); //wendor里定义的 OS_TICK_INT_NUM = 29 TimerCtlWrite(0); TimerTvalWrite(OS_CYCLE_PER_TICK); TimerCtlWrite(1); } 2.3.1、HalIrqUnmask; //接收中断(通过设置寄存器，允许CPU响应该中断)
HalIrqUnmask(OS_TICK_INT_NUM); HalIrqUnmask(29); GIC_REG_32(GICD_ISENABLER(29 >> 5)) = 1U << (29 % 32); (GICD_ISENABLER(29 >> 5))拆开 GIC_REG_32(GICD_OFFSET + 0x100 + (29 >> 5) * 4) = 1U << (29 % 32);/* 中断使能 Registers */ GIC_REG_32拆开，(29 % 32)=1D GIC_BASE_ADDR + (GICD_OFFSET + 0x100 + (29 >> 5) * 4) = 1U << (29 % 32) #define GIC_BASE_ADDR IO_DEVICE_ADDR(0x3F00A100) #define GICD_OFFSET 0x1000 /* interrupt distributor offset */ 2.3.2、TimerCtlWrite(0); //关闭Timer
参考：ARM ArchitectureReference Manual ARMv7-A and ARMv7-R edition.pdf
《B3.17 Organization of the CP15 registers in a VMSA implementation》
WRITE_TIMER_REG32(TIMER_REG_CTL, 0); ARM_SYSREG_WRITE(TIMER_REG_CTL, 0) ARM_SYSREG_WRITE(TIMER_REG(_CTL), 0) ARM_SYSREG_WRITE(CP15_REG(c14, 0, c2, 1)), 0) "mcr " (CP15_REG(c14, 0, c2, 1) :: "r" (val) 反汇编 r8 0 mcr p15, #0, r8, c14, c2, #1 CNTP_CTL,PL1物理定时器控制寄存器 2.3.3、TimerTvalWrite(OS_CYCLE_PER_TICK); //设置Tval
反汇编 r0 192000 mcr p15, #0, r0, c14, c2, #0 CNTP_TVAL,PL1物理时间值寄存器 2.3.4、TimerCtlWrite(1); //再开启Timer
反汇编 r5 1 mcr p15, #0, r5, c14, c2, #1 CNTP_CTL,PL1物理定时器控制寄存器 2.4、代码移植
Z:\bright\harmony-100ask\kernel\liteos_a\platform\hw\arm\interrupt\gic\gic_v2.c
VOID HalIrqUnmask(UINT32 vector) { if ((vector > OS_USER_HWI_MAX) || (vector < OS_USER_HWI_MIN)) { return; } //GIC_REG_32(GICD_ISENABLER(vector >> 5)) = 1U << (vector % 32); //替换 *(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F00B218)) = 1; //使能ARM Timer IRQ } Z:\bright\harmony-100ask\kernel\liteos_a\platform\hw\arm\timer\arm_generic\arm_generic_timer.c
STATIC_INLINE VOID TimerCtlWrite(UINT32 cntpCtl) { //WRITE_TIMER_REG32(TIMER_REG_CTL, cntpCtl);//替换 if(cntpCtl == 0){ *(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F00B408)) = 0x003E0000; } else { *(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F00B408)) = 0x003E00A2; } } STATIC_INLINE VOID TimerTvalWrite(UINT32 tval) { //WRITE_TIMER_REG32(TIMER_REG_TVAL, tval);//替换 *(volatile UINT32 *)((UINTPTR)IO_DEVICE_ADDR(0x3F00B400)) = tval; //设置倒计时时间，鸿蒙是10ms } =======完整内容======
#2020征文-开发板# 鸿蒙 移植 树莓派(上)搭建环境下载源码
#2020征文-开发板# 鸿蒙 移植 树莓派(中)添加单板
#2020征文-开发板# 鸿蒙 移植 树莓派(下)修改源码
©著作权归作者和HarmonyOS技术社区共同所有，如需转载，请注明出处，否则将追究法律责任.
想了解更多内容，请访问：
和华为官方合作共建的站群服务器鸿蒙技术社区
https://harmonyos.51cto.com/#zz
