在arm2440上实现休眠功能的方法

下面如何实现系统的睡眠及唤醒（转自http://www.52rd.com/Blog/Detail_RD.Blog_farsight2009_20389.html）

（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 <stdio.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/ioctl.h>
#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。

关于恢复是重新启动的问题可参照http://www.linuxforum.net/forum/showflat.php?Cat=&Board=embedded&Number=725407&page=0&view=collapsed&sb=5&o=0