鸿蒙 移植 树莓派（下）修改源码
目录：
1、切换启动模式
树莓派默认启动在HYP模式，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，reset_vector:下面添加
mrs r0,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,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。
add r0,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、为了方便调试，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代码，uart_putc_phy使用物理地址打印字符，uart_putc_virt使用虚拟地址打印。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，串口输入代码
vendor\broadcom\BCM2836\driver\uart\uart_hardware.c2.2.1、 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;
}3、系统时钟初始化
3.1、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;
}3.2、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，当发生OS_TICK_INT_NUM这个中断时，执行OsTickEntry()函数
...
}3.3、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。
}3.3、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);
}3.3.1、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 */3.3.2、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3.3.3、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3.3.4、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3.4、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
}作者： 亮子力
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