标准linu休眠和唤醒机制分析(四)【转】

转自：http://blog.csdn.net/lizhiguo0532/article/details/6453552

suspend第三、四、五阶段：platform、processor、core

static int suspend_enter(suspend_state_t state)

{

int error;

if (suspend_ops->prepare) {

// 平台特定的函数，mtkpm.c, 有定义，对pmic和cpu dll的一些设置

error = suspend_ops->prepare();

if (error)

return error;

}

error = dpm_suspend_noirq(PMSG_SUSPEND);

// 对于一些non-sysdev devices，需要调用禁止中断的dpm_suspend函数来suspend那些设备

if (error) {

printk(KERN_ERR "PM: Some devices failed to power down/n");

goto Platfrom_finish;

}

if (suspend_ops->prepare_late) { // 这里没定义

error = suspend_ops->prepare_late();

if (error)

goto Power_up_devices;

}

if (suspend_test(TEST_PLATFORM))       // suspend第3阶段到此为止

goto Platform_wake;

error = disable_nonboot_cpus();  // disable nonboot cpus

if (error || suspend_test(TEST_CPUS))  // suspend第4阶段到此为止

goto Enable_cpus;

arch_suspend_disable_irqs();             // 中断禁止

BUG_ON(!irqs_disabled());

error = sysdev_suspend(PMSG_SUSPEND);    // kernel/driver/base/sys.c

// suspend system devices

if (!error) {

if (!suspend_test(TEST_CORE))               // suspend第5阶段到此为止

error = suspend_ops->enter(state);

// 真正才进入suspend，调用的函数时平台特定的suspend enter函数， //  mtkpm.c, 在下面列出mtk平台的该函数实现，供分析：

//  如果有唤醒源被操作，那么处理将会被wakeup，先做一些平台相                         //  关的动作，最后从函数suspend_ops->enter()中返回，这之后的唤                          // 醒操作实际上是按照suspend流程的相反顺序的来走的。

sysdev_resume();         // resuem system devices

// 跳到本文档最后面，将会有一个总结，这里会展示出正常的suspend和resume的时候函数调用

}

arch_suspend_enable_irqs();

BUG_ON(irqs_disabled());

Enable_cpus:

enable_nonboot_cpus();

Platform_wake:

if (suspend_ops->wake)       // 平台无定义

suspend_ops->wake();

Power_up_devices:

dpm_resume_noirq(PMSG_RESUME);

Platfrom_finish:

if (suspend_ops->finish) // 做和函数suspend_ops->prepare()相反的工作

suspend_ops->finish();

return error;

}

static int mtk_pm_enter(suspend_state_t state)

{

_Chip_pm_enter(state);

return 0;

}

int _Chip_pm_enter(suspend_state_t state)

{

MSG_FUNC_ENTRY();

printk("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@/n");

printk("_Chip_pm_enter @@@@@@@@@@@@@@@@@@@@@@/n");

printk(" @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@/n");

/* ensure the debug is initialised (if enabled) */

switch (state)

{

case PM_SUSPEND_ON:

MSG(SUSP,"mt6516_pm_enter PM_SUSPEND_ON/n/r");

break;

case PM_SUSPEND_STANDBY:

MSG(SUSP,"mt6516_pm_enter PM_SUSPEND_STANDBY/n/r");

break;

case PM_SUSPEND_MEM:  // 只支持mem的系统省电模式

MSG(SUSP,"mt6516_pm_enter PM_SUSPEND_MEM/n/r");

if (g_ChipVer == CHIP_VER_ECO_2)

mt6516_pm_SuspendEnter();

// 让cpu进入省电模式的函数，真正休眠之后，执行的代码会停在这个函数中，直到外部有EINT将其cpu唤醒，停下来的代码才继续执行，也就是正常按下了唤醒键的时候。

break;

case PM_SUSPEND_MAX:

MSG(SUSP,"mt6516_pm_enter PM_SUSPEND_MAX/n/r");

MSG(SUSP,"Not support for MT6516/n/r");

break;

default:

MSG(SUSP,"mt6516_pm_enter Error state/n/r");

break;

}

return 0;

}

void mt6516_pm_SuspendEnter(void)

{

UINT32 u32TCM = 0xF0400000;

UINT32 u4SuspendAddr = 0;

UINT32 u4Status, u4BATVol;

UINT32 counter = 0;

/* Check Chip Version*/

if (g_ChipVer == CHIP_VER_ECO_1)

u4SuspendAddr = u32TCM;

else if(g_ChipVer == CHIP_VER_ECO_2)

u4SuspendAddr = __virt_to_phys((unsigned long)MT6516_CPUSuspend);

/*wifi low power optimization : shutdown MCPLL & VSDIO */

wifi_lowpower_opt(TRUE);

/* Check PM related register*/

mt6516_pm_RegDump();

//mt6326_check_power();

DRV_WriteReg32(APMCUSYS_PDN_SET0,0x04200000);

/* STEP7: Set AP_SM_CNF(DxF003C22C) to wanted wake-up source. 设置唤醒源*/

#if defined(PLATFORM_EVB)

mt6516_pm_SetWakeSrc((1<< WS_KP)|(1<<WS_EINT)|(1<<WS_RTC));

#elif defined(PMIC_BL_SETTING)

mt6516_pm_SetWakeSrc((1<<

WS_KP)|(1<<WS_EINT)|(1<<WS_CCIF)|(1<<WS_SM)|(1<<WS_RTC));

#else

mt6516_pm_SetWakeSrc((1<<WS_EINT)|(1<<WS_CCIF)|(1<<WS_SM)|(1<<WS_RTC));

//mt6516_pm_SetWakeSrc((1<<WS_SM));

#endif

/* Save interrupt masks*/

irqMask_L = *MT6516_IRQ_MASKL;

irqMask_H = *MT6516_IRQ_MASKH;

mt6516_pm_Maskinterrupt(); // 20100316 James

while(1)

{

#ifdef AP_MD_EINT_SHARE_DATA

/* Update Sleep flag*/

mt6516_EINT_SetMDShareInfo();

mt6516_pm_SleepWorkAround();

#endif

/* Enter suspend mode, mt6516_slpctrl.s */

if ( g_Sleep_lock <= 0 )

u4Status = MT6516_CPUSuspend (u4SuspendAddr, u32TCM);

else

MSG(SUSP,"Someone lock sleep/n/r");

#ifdef AP_MD_EINT_SHARE_DATA

mt6516_pm_SleepWorkAroundUp();

#endif

/* Check Sleep status*/

u4Status = mt6516_pm_CheckStatus();

if (u4Status == RET_WAKE_TIMEOUT)

{

#ifndef PLATFORM_EVB

DRV_WriteReg32(APMCUSYS_PDN_CLR0,0x04200000);

u4BATVol = (mt6516_pm_GetOneChannelValue(VBAT_CHANNEL,VBAT_COUNT)/VBAT_COUNT);

DRV_WriteReg32(APMCUSYS_PDN_SET0,0x04200000);

MSG(SUSP,"counter = %d, vbat = %d/n/r",counter++, u4BATVol);

if(u4BATVol <= LOW_BAT_ALARM)

{

MSG(SUSP,"Battery Low!!Power off/n/r");

bBAT_UVLO = TRUE;

goto SLP_EXIT;

}

#endif

}

else

{

MSG(SUSP,"leave sleep, wakeup!!/n/r");

goto SLP_EXIT;

//break;

}

}

SLP_EXIT:

wifi_lowpower_opt(FALSE);

/* Restore interrupt mask ;  */

*MT6516_IRQ_MASKL = irqMask_L;

*MT6516_IRQ_MASKH = irqMask_H;

}

函数MT6516_CPUSuspend (u4SuspendAddr, u32TCM)是一段汇编代码，在文件：

Kernel/arch/arm/amch-mt6516/mt6516_slpctrl.S中。下面是这段汇编代码片段，看一看也蛮有意思，因为处理进入low power模式之后，是停留在该函数之中的。

ENTRY(MT6516_CPUSuspend)

stmfd sp!, {r4-r12, lr}

// r0 = MT6516_CPUSuspend physical address,

// r1 = TCM address

mov r4, r0

mov r9, r1

// Set SVC mode

mrs r0, cpsr

bic r0, r0, #MODE_MASK1

orr r1, r0, #Mode_SVC

// Set I/F bit, disable IRQ and FIQ

orr r1, r1, #I_Bit|F_Bit

// Update CPSR

msr cpsr_cxsf, r1

// calculate the physical address of instruction after disable MMU

ldr r0, =PhysicalPart

ldr r1, =MT6516_CPUSuspend

sub r0, r0, r1

mov r1, r4

// Now r0 is the physical address of PhysicalPart

add r0, r0, r1

...

...

// Power down Cache and MMU, MCU_MEM_PDN

ldr r0, =0xF0001308

ldr r1, [r0]

// ldr r1, =0xFFFFFFFF

orr r1, r1, #0x0F

str r1, [r0]

// STEP1: Set AP SLEEP (IRQ CODE: 0x36) to level sensitive on CIRQ.

// already done when system start.

// STEP2: Unmask AP SLEEP CTRL interrupt.

// already done at mt6516_pm_Maskinterrupt.

// STEP3: EOI AP SLEEP interrupt.

// already done at mt6516_pm_Maskinterrupt.

// STEP4: Read clear AP_SM_STA (OxF003C21C).

// already done at mt6516_pm_Maskinterrupt.

// STEP5: Set AP_SM_PAUSE_M(0x8003C200) and AP_SM_PAUSE_L(0x8003C204) for sleep duration. 16 seconds as default

...

// STEP6: Set AP_SM_CLK_SETTLE(0xF003C208) to 0x64. Must over 5ms

...

// STEP7: Set AP_SM_CNF(DxF003C22C) to wanted wake-up source. (TP, GPT, MSDC, RTC, EINT, KP or SM)

// already done at mt6516_pm_SuspendEnter

// STEP8: Set AP_SM_CON[1]:PAUSE_START to 1 to enable AP sleep controller.

...

// STEP9: Execute the CP15 command(MCR p15, 0, r0, c7, c0, 4),

// then ARM9 MCU enters low power state

// and STANDBYWFI signal becomes HIGH. CLOCK_OFF signal is issued to Clock Management Unit,

// and then AP MCU Sub-system clock is gated and VCXO OFF signal is issued to AP Sleep Controller.

mov r0, #0

mcr p15, 0, r0,c7,c0,4

// wait till interrupt occurs

// polling AP_SM_STA

mov r2, #0

mov r3, #0x10

15:

//mov r10, r1

// Power up I-Cache

...

//delay

...

// Power up I-Cache upper 16KB

...

//delay

...

// Power up D-Cache

...

//delay

...

// Power up D-Cache upper 16KB

...

//delay

...

// Clean and invalid DCache

// Invalidate instruction cache

// TCM_START_UA saved in r9

mov r2, r9

add r1, r1, r2

// make sure no stall on ¨mov pc,r0〃 below

cmp r1, #0

// restore MMU

mov r4, #0

// access domain 0

// TTB

// flush TLBs

// Turn on MMU

//test

mcr p15, 0, r6, c1, c0, 0

//mov pc, r1

nop

nop

VirtualPart:

nop

nop

mov r0, r10

ldmia sp!, {r4-r12, lr}

mov pc, lr

Nop

六、系统正常suspend和resume时函数调用和配对

enter_state(state)

--> sys_sync()

--> suspend_prepare()

--> pm_prepare_console()

--> pm_notifier_call_chain(PM_SUSPEND_PREPARE)

--> usermodehelper_disable()

--> suspend_freeze_processes()

--> suspend_devices_and_enter(state)

--> suspend_ops->begin(state)

--> _Chip_pm_begin()

--> suspend_console()  // 此后串口无信息出来，缓存起来等后面resume打出

--> dpm_suspend_start(PMSG_SUSPEND)

--> dpm_prepare(state)

--> device_prepare(dev, state)

--> dpm_suspend(state)

--> device_suspend(dev, state)

--> suspend_enter(state)

--> suspend_ops->prepare()

--> _Chip_pm_prepare()

--> SetARM9Freq(DIV_4_104)

--> dpm_suspend_noirq(PMSG_SUSPEND)

--> suspend_ops->prepare_late() // 无定义

--> disable_nonboot_cpus()

--> arch_suspend_disable_irqs()

--> sysdev_suspend(PMSG_SUSPEND)

--> suspend_ops->enter(state)

--> _Chip_pm_enter(state)

--> mt6516_pm_SuspendEnter()

--> MT6516_CPUSuspend() // 汇编函数，suspend cpu

<-- MT6516_CPUSuspend() // 汇编函数，resume cpu

<-- mt6516_pm_CheckStatus()

<-- return 0

<-- return 0

<-- sysdev_resume()

<-- arch_suspend_enable_irqs()

<-- enable_nonboot_cpus()

<-- suspend_ops->wake() // 无定义

<-- dpm_resume_noirq(PMSG_RESUME)

<-- suspend_ops->finish()

<-- _Chip_pm_finish()

<-- SetARM9Freq(DIV_1_416)

<-- return 0

<-- return 0

<-- dpm_resume_end(PMSG_RESUME)

<-- dpm_resume(state)

<-- device_resume(dev, state)

<-- dpm_complete(state)

<-- device_complete(dev, state)

<-- resume_console()   // 打印出缓存中的信息

<-- suspend_ops->end()

<-- return 0

<-- suspend_finish()

<-- suspend_thaw_processes()

<-- usermodehelper_enable()

<-- pm_notifier_call_chain(PM_POST_SUSPEND)

<-- pm_restore_console()

<-- return 0