s3c2440 省电模式开发详解

1、源码包
Kernel：linux-2.6.18.2
Uboot：u-boot-1.1.4
Gcc：arm-linux-gcc-3.4.1.tar.bz2

开发流程及详细步骤
1、休眠部分

1.电源管理守护进程
省略

2.内核接口文件（arch/arm/kernel/apm.c）
电源守护进程通过apm.c的ioctl函数来使内核开始进入sleep模式。
case APM_IOC_SUSPEND:
        as->suspend_result = -EINTR;
        if (as->suspend_state == SUSPEND_READ) {
               as->suspend_state = SUSPEND_ACKED;
               suspends_pending--;
        } else {
               queue_event(APM_USER_SUSPEND, as);
        }
        if (suspends_pending == 0)
               apm_suspend(); //由此进入sleep
       调用的顺序如下：

3.进sleep前的准备工作
A.关闭系统进程（kernel/power/ console.c）
int pm_prepare_console(void) //该函数使所有系统进程休眠或关闭。
B.关闭外设驱动电源（drivers/base/power/suspend.c）
int device_power_down(pm_message_t state) //该函数使所有设备驱动sleep

4.进入sleep前的设置（arch/arm/mach-s3c2410/pm.c）
static int s3c2410_pm_enter(suspend_state_t state) //该函数引导进sleep前的设置

static int s3c2410_pm_enter(suspend_state_t state)
{
unsigned long regs_save[16];
unsigned long tmp;

s3c2410_pm_debug_init(); //sleep中uart不能再用，此函数实现uart重新初始化用来调试

DBG("s3c2410_pm_enter(%d)n", state); //打印信息

if (state != PM_SUSPEND_MEM) {
        printk(KERN_ERR PFX "error: only PM_SUSPEND_MEM supportedn");
        return -EINVAL;
} //判断是否是休眠只用ram实现，应为该项目不支持硬盘休眠功能。

if (!any_allowed(s3c_irqwake_intmask, s3c_irqwake_intallow) &&
    !any_allowed(s3c_irqwake_eintmask, s3c_irqwake_eintallow)) {
        printk(KERN_ERR PFX "No sources enabled for wake-up!n");
        printk(KERN_ERR PFX "Aborting sleepn");
        return -EINVAL;
} //判断中断唤醒是否允许，不允许则不能进入休眠。

s3c2410_pm_check_prepare(); //如果需要在sleep前检查ram则此函数会运行，否则此函数为空，即如果CONFIG_S3C2410_PM_CHECK被定义。

s3c2410_sleep_save_phys = virt_to_phys(regs_save);
//将用来保存系统寄存器的数组地址转为物理地址，以供后面调用。
DBG("s3c2410_sleep_save_phys=0x%08lxn", s3c2410_sleep_save_phys); //打印信息
__raw_writel(virt_to_phys(s3c2410_cpu_resume), S3C2410_GSTATUS3);
                             //将系统唤醒时需要调用的函数地址写入GSTATUS3寄存器。
DBG("GSTATUS3 0x%08xn", __raw_readl(S3C2410_GSTATUS3)); //打印信息
DBG("GSTATUS4 0x%08xn", __raw_readl(S3C2410_GSTATUS4)); //打印信息

s3c2410_pm_do_save(gpio_save, ARRAY_SIZE(gpio_save));  //保存io口配置状态
s3c2410_pm_do_save(irq_save, ARRAY_SIZE(irq_save));      //保存中断配置状态
s3c2410_pm_do_save(core_save, ARRAY_SIZE(core_save));  //保存核心配置状态
s3c2410_pm_do_save(uart_save, ARRAY_SIZE(uart_save));    //保存串口配置状态

s3c2410_pm_configure_extint(); //配置外部中断唤醒，使系统休眠中可以按键唤醒

DBG("sleep: irq wakeup masks: %08lx,%08lxn",
    s3c_irqwake_intmask, s3c_irqwake_eintmask); //打印信息

__raw_writel(s3c_irqwake_intmask, S3C2410_INTMSK);        //屏蔽系统定义中断
__raw_writel(s3c_irqwake_eintmask, S3C2410_EINTMASK); //打开外部唤醒中断

__raw_writel(__raw_readl(S3C2410_EINTPEND), S3C2410_EINTPEND);
//通过写已经被申请的位，将中断请求寄存器清空

arm920_flush_kern_cache_all(); //清缓冲区

s3c2410_pm_check_store();//如果需要在sleep前检查ram则此函数会运行，否则此函数为空，即如果CONFIG_S3C2410_PM_CHECK被定义。

__raw_writel(0x00, S3C2410_CLKCON);  //关闭所有外设时钟

s3c2410_cpu_suspend(regs_save); //调用汇编函数s3c2410_cpu_suspend 进入sleep。
/************************************************************************/
上为进入休眠部分，下为唤醒部分。
/************************************************************************/
cpu_init(); //CPU初始化

tmp = __raw_readl(S3C2410_GSTATUS2);
tmp &= S3C2410_GSTATUS2_OFFRESET;
__raw_writel(tmp, S3C2410_GSTATUS2); //清除唤醒复位标记

s3c2410_pm_do_restore_core(core_save, ARRAY_SIZE(core_save)); //恢复核心配置
s3c2410_pm_do_restore(gpio_save, ARRAY_SIZE(gpio_save));       //恢复io口配置
s3c2410_pm_do_restore(irq_save, ARRAY_SIZE(irq_save));            //恢复中断配置
s3c2410_pm_do_restore(uart_save, ARRAY_SIZE(uart_save));         //恢复串口配置

s3c2410_pm_debug_init(); //串口调试函数初始化

DBG("post sleep: IRQs 0x%08x, 0x%08xn",
    __raw_readl(S3C2410_SRCPND),
    __raw_readl(S3C2410_EINTPEND)); //打印信息

s3c2410_pm_show_resume_irqs(IRQ_EINT0, __raw_readl(S3C2410_SRCPND),
                          s3c_irqwake_intmask); //查看中断唤醒源信息
s3c2410_pm_show_resume_irqs(IRQ_EINT4-4, __raw_readl(S3C2410_EINTPEND),
                          s3c_irqwake_eintmask); //查看中断唤醒源信息

DBG("post sleep, preparing to returnn");

s3c2410_pm_check_restore();//如果需要在sleep前检查ram则此函数会运行，否则此函数为空，即如果CONFIG_S3C2410_PM_CHECK被定义。

DBG("S3C2410 PM Resume (post-restore)n");
return 0;
}

5.进休眠前的最后汇编段程序（arch/arm/mach-s3c2410/sleep.s）
ENTRY(s3c2410_cpu_suspend)
stmfd      sp!, { r4 - r12, lr }

@@ store co-processor registers

mrc p15, 0, r4, c15, c1, 0     @ CP access register
mrc p15, 0, r5, c13, c0, 0     @ PID
mrc p15, 0, r6, c3, c0, 0       @ Domain ID
mrc p15, 0, r7, c2, c0, 0       @ translation table base address
mrc p15, 0, r8, c1, c0, 0       @ control register

stmia       r0, { r4 - r13 }

@@ flush the caches to ensure everything is back out to
@@ SDRAM before the core powers down

#ifndef CONFIG_CPU_DCACHE_WRITETHROUGH
bl    arm920_flush_kern_cache_all
#endif

@@ prepare cpu to sleep

ldr   r4, =S3C2410_REFRESH
ldr   r5, =S3C24XX_MISCCR
ldr   r6, =S3C2410_CLKCON
ldr   r7, [ r4 ]         @ get REFRESH (and ensure in TLB)
ldr   r8, [ r5 ]         @ get MISCCR (and ensure in TLB)
ldr   r9, [ r6 ]         @ get CLKCON (and ensure in TLB)

orr   r7, r7, #S3C2410_REFRESH_SELF    @ SDRAM sleep command
orr   r8, r8, #(S3C2410_MISCCR_USBSUSPND0 | S3C2410_MISCCR_USBSUSPND1) @suspend usb
orr   r8, r8, #(S3C2400_MISCCR_SPUCR_LDIS | S3C2400_MISCCR_SPUCR_HDIS) @suspend d(0-31)
orr   r8, r8, #S3C2410_MISCCR_SDSLEEP @ SDRAM power-down signals
orr   r9, r9, #S3C2410_CLKCON_POWER    @ power down command

teq   pc, #0                   @ first as a trial-run to load cache
bl    s3c2410_do_sleep
teq   r0, r0                    @ now do it for real
b     s3c2410_do_sleep   @

@@ align next bit of code to cache line
.align      8
s3c2410_do_sleep:
streq       r7, [ r4 ]                @ SDRAM sleep command
    mov r0, #0x1000

1: subs r0, r0, #1          @wait until the SelfRefresh is released
    bne 1b
streq       r8, [ r5 ]                @ SDRAM power-down config
streq       r9, [ r6 ]                @ CPU sleep
1:     beq 1b
mov pc, r14

2、唤醒部分
1、Uboot部分(u-boot-1.1.4/cpu/arm920t/start.s)
reset:
#if 0
mrs r0, cpsr      /* Set the cpu to SVC32 mode */
bic   r0, r0, #0x1f
orr   r0, r0, #0xd3
msr cpsr, r0
#endif

/* disable watchdog timer */
mov r0, #WTCON_BASE
ldr r1, =0x0
str r1, [r0, #oWTCON]
/*
* mask all IRQs by setting all bits in the INTMR - default
*/
mov r0, #INT_BASE
ldr   r1, =0xffffffff
str    r1, [r0, #oINTMSK]

ldr   r1, =0x7ff
str    r1, [r0, #oINTSUBMSK]

mov r0, #CLK_BASE
ldr r1, =0xffffffff
str r1, [r0, #oLOCKTIME]

/* FCLK:HCLK:PCLK */
ldr r1, =0x0
str r1, [r0, #oCAMDIVN]

ldr r1, =_clkdivn
str r1, [r0, #oCLKDIVN]

mrc p15, 0, r1, c1, c0, 0           /* read ctrl register */
orr r1, r1, #0xc0000000           /* Asynchronous */
mcr p15, 0, r1, c1, c0, 0           /* write ctrl register */

/* UPLL setup */
ldr r1, =_upllcon
str r1, [r0, #oUPLLCON]

nop
nop
nop         /* wait until upll has the effect */
nop
nop

/* PLL setup */
ldr r1, =_mpllcon
str r1, [r0, #oMPLLCON]
/* configure memory */
bl    memset
/* Power Manage  Check if this is a wake-up from sleep */
ldr r1, PMST_ADDR
ldr r0, [r1]
@bic r0,r0,#0xfffffffd
tst r0, #(0x02)
bne WakeupStart
WakeupStart:
    /* Clear sleep reset bit */   
    ldr r0, PMST_ADDR
    mov r1, #0x0       @PMST_SMR
    str r1, [r0]
  
    ldr r0, PMCTL1_ADDR  /* Release the SDRAM signal protections */
    ldr r1, =0x00010330
   str r1, [r0]
   
    ldr r0, =0x48000024
    ldr r1, [r0]
    bic r1, r1, #0x400000
    str r1, [r0]
     
   mov r1, #0x1000
1: subs r1, r1, #1 /* wait until the SelfRefresh is released. */
    bne 1b
   
    /* Go... */  
    ldr r0, =0x560000B8 /* read a return address  go to s3c2410_cpu_resume*/
    ldr r1, [r0]
      
    mov pc, r1
    nop
    nop
1: b   1b      /* infinite loop */