linux内核对S3C2410睡眠模式的支持(1)(2)

六、Linux系统对S3C2410 掉电模式的支持

1）内核接口驱动文件

Linux-2.6.26.5内核的/drivers/char/apm-emulation.c提供了系统进入睡眠的入口函数。早期的版本的接口文件为：arch/arm/kernel/apm.c

2）与进入sleep前的准备相关的内核文件

kernel/power/console.c

该文件提供了使所有系统进程休眠或关闭的函数

drivers/base/power/suspend.c

该文件使所有设备驱动suspend的函数

3）进入sleep前的设置相关的文件

arch/arm/mach-s3c2410/pm.c

4）进休眠前的汇编段程序文件

arch/arm/mach-s3c2410/sleep.s

5）睡眠唤醒部分在Uboot中

cpu/arm920t/start.s

6）内核中唤醒阶段相关的汇编段程序文件

arch/arm/mach-s3c2410/sleep.s

七、实现方法

具体的实现原理可以通过阅读上述相关文件获取。下面如何实现系统的睡眠及唤醒

1）内核修改过程

根据硬件的实际情况，设置睡眠唤醒中断源。我的系统是让中断0-3作为唤醒源。所以让内核允许EINT0--3外部中断将其唤醒。内核版本是2.6.26.5。系统默认容许EINT0..EINT15和IRQ_RTC作为中断唤醒源。

s3c_irqwake_intmask和s3c_irqwake_eintmask是屏蔽码。为了让EINT0--3外部中断可以作为唤醒源，

需要修改：

arch/arm/plat-s3c24xx/irq.c中

unsigned long s3c_irqwake_intmask = 0xffffffffL;

为：

unsigned long s3c_irqwake_intmask = 0xfffffff0L;

2）修改U-boot

系统睡眠在唤醒后会运行复位程序，当然就是U-boot了。为了让唤醒后的系统能够恢复正常工作状态，及进入到睡眠前运行的位置，需要修改U-boot

将下面的代码加入到uboot的cpu/arm920t/start.s中，注意：要放在sdram初始化后，参考本文的第四标题“S3C2410掉电模式唤醒过程”

/* Power Manage Check if this is a wake-up from sleep */

ldr r1, =0x560000B4

ldr r0, [r1]

tst r0, #0x02

beq notPowerOFF

/****led test****

ldr r0, =0x56000050

ldr r1,=0x55555555

str r1,[r0]

ldr r0, =0x56000054

ldr r1,=0x0

str r1,[r0]

*/

WakeupStart:

//Clear sleep reset bit

ldr r0, =0x560000B4

mov r1, #0x2

str r1, [r0]

ldr r0, =0x56000080 //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

/*

ldr r0, =0x56000050

ldr r1,=0x55555555

str r1,[r0]

ldr r0, =0x56000054

ldr r1,=0x5555

str r1,[r0]

*/

ldr r0, =0x560000B8 //read a return address go to s3c2410_cpu_resume

ldr r1, [r0]

mov pc, r1 //go to resume 恢复到睡眠前的位置

nop

nop

1: b 1b

notPowerOFF:

3）编写测试程序

#include

#include

#include

#include

#include

#include

#define APM_IOC_STANDBY _IO('A', 1)

#define APM_IOC_SUSPEND _IO('A', 2)

int main (void)

{

int fd;

fd = open ("/dev/apm_bios",O_RDWR);

if (fd < 0) {

printf ("fd open failed\n");

exit(0);

}

printf ("\n/dev/apm_bios opened, fd=%d\n",fd);

ioctl (fd, APM_IOC_SUSPEND);

close (fd);

printf ("/dev/apm_bios closed :)\n");

return 0;

}

4）测试效果

#./test

.....

sleep: irq wakeup masks: fffffff0,fffffff0

GSTATUS3 0x30367140

GSTATUS4 0x00000000

进入睡眠状态，此时按K10按键，即中断0，唤醒系统

GPIO[0] CON 007fffff => 007fffff, DAT 00000000 => 00000000

GPIO[1] CON 00044555 => 00044555, DAT 00000540 => 00000540

GPIO[2] CON aaaaaaaa => aaaaaaaa, DAT 00000000 => 00000000

GPIO[3] CON aaaaaaaa => aaaaaaaa, DAT 00000000 => 00000000

GPIO[4] CON aaaaa6aa => aaaaa6aa, DAT 0000ffc5 => 0000ffc5

GPIO[5] CON 000055aa => 000055aa, DAT 000000fe => 000000ff

GPIO[6] CON ffa5ff30 => ffa5ffba, DAT 0000aced => 0000aced

GPIO[7] CON 002afaaa => 002afaaa, DAT 000001ff => 000001fb

post sleep: IRQs 0x02000001, 0x00000200

IRQ 16 asserted at resume

post sleep, preparing to return

S3C2410 PM Resume (post-restore)

s3c2410-sdi s3c2410-sdi: powered down.

s3c24xx-pm: check if we have anything to wake-up with

Disabling IRQ 52 (pin 192)

Disabling IRQ 53 (pin 193)

Disabling IRQ 55 (pin 195)

dma3: restoring configuration

timer tcon=00000000, tcnt a2c1, tcfg 00000200,00000000, usec 00001eb8

s3c2410-wdt: watchdog disabled

s3c2410-i2c s3c2410-i2c: slave address 0x10

s3c2410-i2c s3c2410-i2c: bus frequency set to 390 KHz

s3c2410-nand s3c2410-nand: Tacls=3, 30ns Twrph0=7 70ns, Twrph1=3 30ns

s3c2410-sdi s3c2410-sdi: running at 0kHz (requested: 0kHz).

s3c2410-sdi s3c2410-sdi: running at 98kHz (requested: 97kHz).

s3c2410-sdi s3c2410-sdi: running at 98kHz (requested: 97kHz).

s3c2410-sdi s3c2410-sdi: running at 98kHz (requested: 97kHz).

s3c2410-sdi s3c2410-sdi: powered down.

usb usb1: root hub lost power or was reset

Restarting tasks ... done.

/dev/apm_bios closed :)

#

此时系统恢复了正常运行。