ARM 无法进入WFI 模式

我们的是使用OMAP138， ARM使用linux系统, DSP 是BIOS系统

现在想要让ARM 的linux 系统进入WFI 模式（ ARM Wait-For-Interrupt Sleep Mode）

按照omap-138的datasheet 介绍

You can enable the WFI mode via the CP15 register #7 using the following instruction:
• MCR p15, #0, <Rd>, c7, c0, #4
Once the ARM module transitions into the WFI mode, it will remain in this state until an interrupt
(IRQ/FIQ) occurs.
The following sequence exemplifies how to enter the WFI mode:
• Enable any interrupt (for example, an external interrupt) that you plan to use as the wake-up
to exit from the WFI mode.
• Enable the WFI mode using the following CP15 instruction:
– MCR p15, #0, r3, c7, c0, #4
The following sequence describes the procedure to wake-up from the WFI mode:
• To wake-up from the WFI mode, trigger any enabled interrupt (for example, an external inter
• The ARM’s PC jumps to the IRQ/FIQ vector and you must handle the interrupt in an interrup
routine (ISR).

我在linux 内核态执行了语句

asm ( " MCR p15, #0, r3, c7, c0, #4\n\t" );

但是系统并没有发生什么变化，供电的电流也没什么变化，好像并没有进入WFI模式

请问如何让arm的linux 进入WFI模式？

sz su：

回复 Shine:

请问linux 下如何进去  supervisor mode ？是在软中断中吗

sz su：

回复 Shine:

你好，我在内核定时器中执行了asm ( "MCR p15, #0, r3, c7, c0, #4\n\t" );语句，但是系统也是没什么变化的，

理论上内核定时器的执行是在软中断的，那么这条语句应该是supervisor mode 模式下执行的

static void wfi_timer_func(unsigned long arg){  printk("wfi_timer_func\n");  printk("asm start 111 \n");

    asm ( "    teq    r3, #0\n\t");  asm ( "MCR p15, #0, r3, c7, c0, #4\n\t" );  printk("asm end111\n");

//  asm ( "mcr p15, #0, r1, c7, c0, #4\n\t" );//  printk("asm end222\n");

  return 0; }

struct timer_list wfitimer; 

static int funcIn(void)  {   printk("funcIn\n");// struct timer_list wfitimer;    init_timer(&wfitimer);  wfitimer.data = 0x1234;  wfitimer.function = wfi_timer_func;  wfitimer.expires = jiffies + msecs_to_jiffies(1000);   add_timer(&wfitimer);      return 0;  }

static void funcOut(void)  {    printk("funcIn\n");    return;  } 

理论上内核定时器的执行是在软中断的，那么这条语句应该是supervisor mode 模式下执行的

但是系统依旧没什么变化，我的执行过程是否有什么问题

 

 

在TI 的官网上，找到进入WFI 的示例代码，如下

int main(void){

    printf("OMAPL138 is in WFI mode. Insert/Remove the SD card to generate interrupt for wakeup.\n");

    /* The Local PSC number for GPIO is 3. GPIO belongs to PSC1 module.*/    PSCModuleControl(SOC_PSC_1_REGS, HW_PSC_GPIO, PSC_POWERDOMAIN_ALWAYS_ON,             PSC_MDCTL_NEXT_ENABLE);

    /* Pin Multiplexing of pins GP6[12], GP6[13], GP2[12], GP0[9], for LEDs in OMAPL138 LCDK board */    PinMuxSetup_leds();

    /* LEDs SETUP */

        /* Sets the pin 109 (GP6[12]) as output.*/        GPIODirModeSet(SOC_GPIO_0_REGS, 109, GPIO_DIR_OUTPUT);

        /* Sets the pin 110 (GP6[13]) as output.*/        GPIODirModeSet(SOC_GPIO_0_REGS, 110, GPIO_DIR_OUTPUT);

        /* Sets the pin 45 (GP2[12]) as output.*/        GPIODirModeSet(SOC_GPIO_0_REGS, 45, GPIO_DIR_OUTPUT);

        /* Sets the pin 10 (GP0[9]) as output.*/        GPIODirModeSet(SOC_GPIO_0_REGS, 10, GPIO_DIR_OUTPUT);

    /* Initializes the UART instance.*/    UARTStdioInit();

    /* Pin Multiplexing of pin 0 of GPIO Bank 4.*/    GPIOBank4Pin0PinMuxSetup();

    /* Sets the pin 65(GP4[0]) as input.*/    GPIODirModeSet(SOC_GPIO_0_REGS, 65, GPIO_DIR_INPUT);

    /*    ** Configure rising edge and falling edge triggers on pin 65 to generate    ** an interrupt    */    GPIOIntTypeSet(SOC_GPIO_0_REGS, 65, GPIO_INT_TYPE_BOTHEDGE);

    /* Enable interrupts for Bank 4.*/    GPIOBankIntEnable(SOC_GPIO_0_REGS, 4);

    /* Configuring the AINTC to handle interrupts.*/    SetupInt();

    /* Configure GPIO interrupts */    ConfigureIntGPIO();

    //UARTPuts("StarterWare GPIO Demo Application.\r\n", -2);    //UARTPuts("Insert an MMC/SD card.\r\n", -2);

    printf("StarterWare GPIO Demo Application\n");    printf("Insert an MMC/SD card.\n");

    //Titus : ARM WFI code    SysCfgRegistersUnlock();

    asm ( "    teq    r1, #0\n\t");

    asm ( "    mcr p15, #0, r1, c7, c0, #4\n\t" );

    //Here, code get stuck due to WFI and it resume when SD card interrupt raised.

    SysCfgRegistersLock();

    //LED D5 would glow when ARM comes out of WFI mode (i.e, when interrupt generated).    GPIOPinWrite(SOC_GPIO_0_REGS, 109, GPIO_PIN_HIGH);

    printf("Comes out of WFI mode; Resume to normal operation.\n");

    while(1)    {        if(flag == 1)        {            CheckCardStatus();        }    }

}

这边是否有完整的代码？

以及SysCfgRegistersUnlock();和    SysCfgRegistersLock();

这些函数具体都完成了什么功能呢

请帮忙看看，谢谢啦

 

Shine：

回复 sz su:

置顶贴里有基于starterware的示例。http://www.deyisupport.com/question_answer/dsp_arm/omap_l1x/f/54/t/103692.aspx