suspend mode trace in kernel

Restarting tasks ... done.
suspend: exit suspend, ret = 0 (1970-01-01 00:01:54.572740128 UTC)
soc-audio soc-audio.2: resume work completed
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.00 seconds) done.
Freezing remaining freezable tasks ... (elapsed 0.00 seconds) done.

:legacy_bus_drivername---:mmcblk

legacy_bus_name:mmc
suspend---platform_driver->name=soc-audio

:pm_bus_drivername---:soc-audio
pm_bus_name:platform
legacy_class_name:rfkill
suspend---platform_driver->name=alarm

:pm_bus_drivername---:alarm
pm_bus_name:platform
legacy_class_name:rtc

:pm_bus_drivername---:MXC Video Output
pm_bus_name:platform
suspend---platform_driver->name=mxc_v4l2

:pm_bus_drivername---:mxc_v4l2
pm_bus_name:platform
suspend---platform_driver->name=fsl-usb2-udc
USB Gadget suspended

:pm_bus_drivername---:fsl-usb2-udc
pm_bus_name:platform
suspend---platform_driver->name=lcd-backlight

:pm_bus_drivername---:lcd-backlight
pm_bus_name:platform
suspend---platform_driver->name=pmic_leds

:pm_bus_drivername---:pmic_leds
pm_bus_name:platform
suspend---platform_driver->name=pmic_leds

:pm_bus_drivername---:pmic_leds
pm_bus_name:platform
suspend---platform_driver->name=pmic_leds

:pm_bus_drivername---:pmic_leds
pm_bus_name:platform
suspend---platform_driver->name=pmic_light

:pm_bus_drivername---:pmic_light
pm_bus_name:platform
pm_bus_name:platform

:pm_bus_drivername---:pmic_rtc
pm_bus_name:platform
suspend---platform_driver->name=pmic_battery

:pm_bus_drivername---:pmic_battery
pm_bus_name:platform
suspend---platform_driver->name=pmic_adc

:pm_bus_drivername---:pmic_adc
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform

:pm_bus_drivername---:mc13892-regulatr
pm_bus_name:platform
pm_bus_name:platform

legacy_bus_name:i2c

legacy_bus_name:i2c

:legacy_bus_drivername---:sgtl5000-i2c

legacy_bus_name:i2c

legacy_bus_name:i2c

:legacy_bus_drivername---:mc13892

legacy_bus_name:i2c

:legacy_bus_drivername---:isa1200

legacy_bus_name:i2c

:legacy_bus_drivername---:tps60250

legacy_bus_name:i2c
i2c-adapter i2c-0: ACK not received
AKI2C_TxData: transfer error

:legacy_bus_drivername---:akm8973

legacy_bus_name:i2c

:legacy_bus_drivername---:mma7456

legacy_bus_name:i2c

:legacy_bus_drivername---:ov3640

legacy_bus_name:i2c

:legacy_bus_drivername---:si4702

legacy_bus_name:i2c
suspend---platform_driver->name=mxcintuart

:pm_bus_drivername---:mxcintuart
pm_bus_name:platform
suspend---platform_driver->name=mxcintuart

:pm_bus_drivername---:mxcintuart
pm_bus_name:platform
suspend---platform_driver->name=mxcintuart

:pm_bus_drivername---:mxcintuart
pm_bus_name:platform

:pm_bus_drivername---:android_usb
pm_bus_name:platform

:pm_bus_drivername---:android_pmem
pm_bus_name:platform

:pm_bus_drivername---:android_pmem
pm_bus_name:platform
suspend---platform_driver->name=gps_ioctrl

:pm_bus_drivername---:gps_ioctrl
pm_bus_name:platform

:pm_bus_drivername---:mxc_bt
pm_bus_name:platform

:pm_bus_drivername---:imx-3stack-sgtl5000
pm_bus_name:platform
pm_bus_name:platform
suspend---platform_driver->name=mxsdhci

:pm_bus_drivername---:mxsdhci
pm_bus_name:platform
suspend---platform_driver->name=mxsdhci

:pm_bus_drivername---:mxsdhci
pm_bus_name:platform
suspend---platform_driver->name=mxc_nandv2_flash

:pm_bus_drivername---:mxc_nandv2_flash
pm_bus_name:platform
suspend---platform_driver->name=gpio-trackball

:pm_bus_drivername---:gpio-trackball
pm_bus_name:platform
suspend---platform_driver->name=gpio-keys

:pm_bus_drivername---:gpio-keys
pm_bus_name:platform

:pm_bus_drivername---:timed-i2c
pm_bus_name:platform
suspend---platform_driver->name=mxc_mc13892_bl

:pm_bus_drivername---:mxc_mc13892_bl
pm_bus_name:platform
suspend---platform_driver->name=mxc_sdc_fb

:pm_bus_drivername---:mxc_sdc_fb
pm_bus_name:platform
suspend---platform_driver->name=mxc_sdc_fb

:pm_bus_drivername---:mxc_sdc_fb
pm_bus_name:platform
suspend---platform_driver->name=mxc_sdc_fb

:pm_bus_drivername---:mxc_sdc_fb
pm_bus_name:platform
pm_bus_name:platform

:pm_bus_drivername---:lcd_spi
pm_bus_name:platform
suspend---platform_driver->name=pwm-backlight

:pm_bus_drivername---:pwm-backlight
pm_bus_name:platform

:pm_bus_drivername---:mxc_pwm
pm_bus_name:platform
pm_bus_name:platform

:pm_bus_drivername---:mxc_iim
pm_bus_name:platform
suspend---platform_driver->name=mxc_dvfs_core

:pm_bus_drivername---:mxc_dvfs_core
pm_bus_name:platform

:pm_bus_drivername---:sdram_autogating
pm_bus_name:platform
suspend---platform_driver->name=busfreq

:pm_bus_drivername---:busfreq
pm_bus_name:platform

:pm_bus_drivername---:mx51_lpmode
pm_bus_name:platform
suspend---platform_driver->name=tve

:pm_bus_drivername---:tve
pm_bus_name:platform
pm_bus_name:platform
suspend---platform_driver->name=mxc_vpu

:pm_bus_drivername---:mxc_vpu
pm_bus_name:platform

:pm_bus_drivername---:mxc_ipu
pm_bus_name:platform
pm_bus_name:platform
pm_bus_name:platform
suspend---platform_driver->name=mxc_i2c_hs

:pm_bus_drivername---:mxc_i2c_hs
pm_bus_name:platform

:pm_bus_drivername---:mxc_i2c
pm_bus_name:platform

:pm_bus_drivername---:mxc_i2c
pm_bus_name:platform

:pm_bus_drivername---:mxc_spi
pm_bus_name:platform
suspend---platform_driver->name=mxc_wdt

:pm_bus_drivername---:mxc_wdt
pm_bus_name:platform

:pm_bus_drivername---:power
pm_bus_name:platform
wakeup wake lock: evdev
resume---platform_driver->name=mxc_wdt
resume---platform_driver->name=mxc_i2c_hs
resume---platform_driver->name=mxc_vpu
resume---platform_driver->name=tve
resume---platform_driver->name=busfreq
resume---platform_driver->name=mxc_dvfs_core
resume---platform_driver->name=pwm-backlight
resume---platform_driver->name=mxc_sdc_fb
mxc_ipu mxc_ipu: Channel already disabled 9
mxc_ipu mxc_ipu: Channel already uninitialized 9
resume---platform_driver->name=mxc_sdc_fb
resume---platform_driver->name=mxc_sdc_fb
resume---platform_driver->name=mxc_mc13892_bl
resume---platform_driver->name=gpio-keys
resume---platform_driver->name=gpio-trackball
resume---platform_driver->name=mxc_nandv2_flash
resume---platform_driver->name=mxsdhci
resume---platform_driver->name=mxsdhci
resume---platform_driver->name=gps_ioctrl
resume---platform_driver->name=mxcintuart
resume---platform_driver->name=mxcintuart
resume---platform_driver->name=mxcintuart
i2c-adapter i2c-0: ACK not received
AKI2C_TxData: transfer error
resume---platform_driver->name=pmic_adc
resume---platform_driver->name=pmic_battery
resume---platform_driver->name=pmic_light
resume---platform_driver->name=pmic_leds
resume---platform_driver->name=pmic_leds
resume---platform_driver->name=pmic_leds
resume---platform_driver->name=lcd-backlight
resume---platform_driver->name=fsl-usb2-udc
udc run
USB Gadget resumed
resume---platform_driver->name=mxc_v4l2
resume---platform_driver->name=alarm
Changed RF State to 0
resume---platform_driver->name=soc-audio

machine ID mismatch

1
_arch_info has machine ID embedded
2
arch/arm/include/asm/mach/arch.h

.arch.info.init
{
.nr = MACH_TYPE_##_type;
}
3
bootloader provide this tag

for uboot include/asm/mach-types.h

kernel debug Low level

CONFIG_DEBUG_LL
CONFIG_DEBUG_KERNEL

arch/arm/plat-mxc/include/mach/debug-macro.S

add definition:
#define MXC_LL_UART_PADDR UART1_BASE_ADDR
#define MXC_LL_UART_VADDR AIPS1_IO_ADDRESS(UART1_BASE_ADDR)

嵌入式Linux内核时钟初始化问题

c
嵌入式Linux内核时钟初始化问题

内核版本:Linux 2.6.18
平台: FOR ARM

首先搞清楚RTC在kernel内的作用:

linux系统有两个时钟：一个是由主板电池驱动的“Real Time Clock”也叫做RTC或者叫CMOS时钟，
硬件时钟。当操作系统关机的时候，用这个来记录时间，但是对于运行的系统是不用这个时间的。
另一个时间是 “System clock”也叫内核时钟或者软件时钟，是由软件根据时间中断来进行计数的，
内核时钟在系统关机的情况下是不存在的，所以，当操作系统启动的时候，内核时钟是要读取RTC时间
来进行时间同步。并且在系统关机的时候将系统时间写回RTC中进行同步。

如前所述，Linux内核与RTC进行互操作的时机只有两个：
1) 内核在启动时从RTC中读取启动时的时间与日期；
2) 内核在需要时将时间与日期回写到RTC中。

系统启动时，内核通过读取RTC来初始化内核时钟,又叫墙上时间，该时间放在xtime变量中。
The current time of day (the wall time) is defined in kernel/timer.c:
struct timespec xtime;

The timespec data structure is defined in as:
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* nanoseconds */
};

问题1：系统启动时在哪读取RTC的值并设置内核时钟进行时间同步的呢?
最有可能读取RTC设置内核时钟的位置应该在arch/arm/kernel/time.c里的time_init函数内.
time.c为系统的时钟驱动部分.time_init函数会在系统初始化时,由init/main.c里的start_kernel函数内调用.X86架构就是在这里读RTC值并初始化系统时钟xtime的.

ARM架构的time_init代码如下:
/* arch/arm/kernel/time.c */
void __init time_init(void)
{
if (system_timer->offset == NULL)
system_timer->offset = dummy_gettimeoffset;
system_timer->init();
#ifdef CONFIG_NO_IDLE_HZ
if (system_timer->dyn_tick)
system_timer->dyn_tick->lock = SPIN_LOCK_UNLOCKED;
#endif
}

上面system_timer->init()实际执行的是时钟驱动体系架构相关(具体平台)部分定义的init函数,若是 s3c2410平台,则执行的为arch/arm/mach-s3c2410/time.c里定义的s3c2410_timer_init函数.不过 s3c2410_timer_init()也没有读RTC的代码.整个时钟驱动初始化的过程大致就执行这些代码.
既然在系统时钟驱动初始化的过程中没有读RTC值并设置内核时钟,那会在哪设置呢?

我搜了一下,发现内核好象只有在arch/cris/kernel/time.c里有RTC相关代码,如下:
/* arch/cris/kernel/time.c */
/* grab the time from the RTC chip */
//读RTC的函数
unsigned long get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
…………
return mktime(year, mon, day, hour, min, sec);
}

这个函数会在update_xtime_from_cmos内被调用：
void update_xtime_from_cmos(void)
{
if(have_rtc) {
xtime.tv_sec = get_cmos_time();
xtime.tv_nsec = 0;
}
}

另外还有设置rtc的函数
int set_rtc_mmss(unsigned long nowtime); /* write time into RTC chip */

不过我加了printk测试了一下，好象arch/cris/kernel/time.c这个文件和这两个函数只是适用与X86？
ARM平台启动时并不走这边.因此执行不到这些函数。
那ARM平台启动时，系统是在哪读RTC的值并对内核时钟（WallTime)进行初始化的呢？

已解决：
嵌入式Linux内核(ARM)是在系统启动时执行/etc/init.d/hwclock.sh脚本,这个脚本会调用hwclock小程序读取RTC的值并设置系统时钟。
(换句话说，这要取决于你制作的文件系统里是否有这样的脚本)

/* /etc/init.d/hwclock.sh */
DAEMON1=/sbin/hwclock
start() {
local RET ERROR=
[ ! -f /etc/adjtime ] && echo "0.0 0 0.0" > /etc/adjtime
log_status_msg "Setting the System Clock using the Hardware Clock as reference..." -n
# Copies Hardware Clock time to System Clock using the correct
# timezone for hardware clocks in local time, and sets kernel
# timezone. DO NOT REMOVE.
[ "$HWCLOCKACCESS" != no ] && $DAEMON1 --hctosys $GMT $BADYEAR
#
# Now that /usr/share/zoneinfo should be available,
# announce the local time.
#
log_status_msg "System Clock set. Local time: `date`"
log_status_msg ""
return 0
}

hwclock最先读取的设备文件是 /dev/rtc ，busybox里面的hwclock是这样实现的：
static int xopen_rtc(int flags)
{
int rtc;
if (!rtcname) {
rtc = open("/dev/rtc", flags);
if (rtc >= 0)
return rtc;
rtc = open("/dev/rtc0", flags);
if (rtc >= 0)
return rtc;
rtcname = "/dev/misc/rtc";
}
return xopen(rtcname, flags);
}

2. 内核如何更新RTC时钟?
通过set_rtc函数指针指向的函数,set_rtc在arch/arm/kernel/time.c内
/* arch/arm/kernel/time.c */
/*
* hook for setting the RTC's idea of the current time.
*/
int (*set_rtc)(void);
但是set_rtc函数指针在哪初始化的呢？set_rtc应该是和RTC驱动相关的函数.
搜索kernel源码后发现，好象内核其他地方并没有对其初始化。待解决！

set_rtc在do_set_rtc内调用
static inline void do_set_rtc(void)
{
……
if (set_rtc())
/*
* rtc update failed. Try again in 60s
*/
next_rtc_update = xtime.tv_sec + 60;
else
next_rtc_update = xtime.tv_sec + 660; /* update every ~11 minutes by default*/
}

do_set_rtc在timer_tick里调用
/*
* Kernel system timer support.
*/
void timer_tick(struct pt_regs *regs)
{
profile_tick(CPU_PROFILING, regs);
do_leds();
do_set_rtc();
do_timer(1);
……
}
timer_tick为Kernel提供的体系架构无关的时钟中断处理函数,通常会在体系架构相关的时钟中断处理函数内调用它。如s3c2410是这样的:
在arch/arm/mach-s3c2410/time.c中
* IRQ handler for the timer
*/
static irqreturn_t
s3c2410_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
write_seqlock(&xtime_lock);
timer_tick(regs);
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}

trace clock source of RTC

1. gettimeofday();
2. system_call sys_gettimeofday
3 kernel level: do_gettimeofday

4 kernel /time /jiffies.c jiffies
5 kernel/time/clocksource.c clocksource0

tty driver

http://blog.chinaunix.net/u1/51562/showart_1092220.html

kernel memory detect

arm linux中一般在cmdline或传递tag参数中设置, 个别板子在machine_desc.fixup函数中设置. 按顺序分别说明:

1, 出现顺序(内核版本2.6.25.20,下同)
start_kernel()
->setup_arch()
->mdesc->fixup()
->parse_tags()
->parse_tag_mem32()
->parse_cmdline()
->early_mem()

2, fixup()函数
这个函数arm平台用的很少. 我只找到eseries.c, mach-smdk2413.c, mach-vstms.c这几个arm板子有, smdk2413_fixup()是在bootloader传递tag地址与machine_desc预设tag地址(mem_PA+0x100)不同时设置memory的start和size. 如果fixup起作用, 会从tag中把mem tag改为ATAG_NONE, 后面的"parse_tag_mem32"就没用了.

3, parse_tag_mem32()
该函数定义在"arch\arm\kernel\setup.c". 把bootloader传入的mem tag(ATAG_MEM)的start和size参数通过"arm_add_memory()"加入到meminfo的最后一个bank中. start是memory物理起始地址.

4, early_mem()
该函数定义在"arch\arm\kernel\setup.c". 处理cmdline中的"mem=size@start".
如果没有定义mem起始地址, 使用PHYS_OFFSET(arm中应由arm开发板设置)作为start. early_mem()会覆盖前面设置的meminfo.

呵呵, 你为什么会想到找这个? 我当初是板级移植u-boot到s3c2410时分析的代码, 当时还不知道sourceinsight, 用grep查找的:(

"arch\arm\mm\init.c"文件和这个好像没关系, 里面的"bootmem_init()"会根据这里设置的meminfo计算出high_memory. 系统物理memory会1:1映射到"PAGE_OFFSET---high_memory-1".