How to keep RTC time

Bernie Chen

Other Parts Discussed in Thread: TPS65910

Good holiday TI

We use tps65910 external RTC , and I have check it in u-boot using i2c-probe: (valid: 0x2D),then I check code in board file in kernel.

static struct i2c_board_info /*__initdata*/ am335x_i2c1_boardinfo[] = {

I2C_BOARD_INFO("tps65910", TPS65910_I2C_ID1),

.platform_data = &am335x_tps65910_info,

}

But the message below in kernel

omap_rtc am33xx-rtc: rtc core: registered am33xx-rtc as rtc0

I think the message below is correct

tps65910-rtc tps65910-rtc: rtc core: registered tps65910-rtc as rtc0

So , I command the CONFIG_RTC_DRV_OMAP in config, and the message is

drivers/rtc/hctosys.c: unable to open rtc device (rtc0)

and we can't make "hwclock -r". Please tell me whether the coin battery with RTC can't be kept has relationship with this ? Thank you.

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi,

I will forward this to the SW team.

0 Matthijs van Duin over 10 years ago

Mastermind 8040 points

Is CONFIG_RTC_DRV_TPS65910 set? (or if built as module, try adding "rtc-tps65910" to /etc/modules )

0 Bernie Chen over 10 years ago in reply to Matthijs van Duin

Expert 2190 points

Hello TI

I don't see anything about CONFIG_RTC_DRV_TPS65910 , only the CONFIG_RTC_DRV_TEST is familiar, we use "linux-3.2.0-psp04.06.00.11"

Thank you.

0 Matthijs van Duin over 10 years ago in reply to Bernie Chen

Mastermind 8040 points

Bernie Chen said:
we use "linux-3.2.0-psp04.06.00.11"

Ah, that's a rather old version of linux. It appears you need 3.7 or later to have the rtc-tps65910 driver.

0 Bernie Chen over 10 years ago in reply to Matthijs van Duin

Expert 2190 points

Oh no, It looks a very large scale engineering of porting new kernel. Dear Matthijs. Is any direction I can check to let the board powered off then use coin battery to keep RTC time when reboot the board ?

Thank you.

0 Bernie Chen over 10 years ago in reply to Bernie Chen

Expert 2190 points

Hi Matthijs

I found this thread, his kernel version is same as mine. But he has the rtc core : registered tps65910_rtc as rtc0

e2e.ti.com/.../1213431

Thank you.

0 Bernie Chen over 10 years ago in reply to Bernie Chen

Expert 2190 points

Hi TI

What I need to try are

1 make tps65910 register rtc"1" --> How to do ?

2 make tps65910 register rtc"0"

Thank you.

0 Matthijs van Duin over 10 years ago in reply to Bernie Chen

Mastermind 8040 points

Based on drivers/rtc/Kconfig it seems like the tps65910 rtc functionality is provided by the rtc-twl driver (CONFIG_RTC_DRV_TWL4030) in this kernel version. Based on the post you linked to it also looks like some kind of setup is needed in your board file, but I'm afraid I'm really not familiar with the way things were done before Device Tree.

0 Bernie Chen over 10 years ago in reply to Matthijs van Duin

Expert 2190 points

Hi TI

What about I use i2c tool to write value to register of 0x2d(tps65910 & RTC)? It is weird that I can dump all of values of registers, but I can't set any value into SECONDS_REG, MINUTES_REG, HOURS_REG, etc. The case in u-boot is the same. What is wrong ? Thank you.

0 Matthijs van Duin over 10 years ago in reply to Bernie Chen

Mastermind 8040 points

Check RTC_PWDN in the DEVCTRL register?

0 Bernie Chen over 10 years ago in reply to Matthijs van Duin

Expert 2190 points

I check the register(RTC_PWDN) is set to 1.

0x3f value is 70 and i set value to 0x50 --> no work.

Thank you.

Bernie

0 Bernie Chen over 10 years ago in reply to Bernie Chen

Expert 2190 points

Hi TI

What is condition that I can use i2c tool write values into seconds register? Because I have checked offset 0x3f has value 70(RTC_PWDN) is set 1, but I steel can't write value into seconds, minutes, hours register. Thank you.

0 Matthijs van Duin over 10 years ago in reply to Bernie Chen

Mastermind 8040 points

You need to clear RTC_PWDN. As the documentation explains, if the RTC_PWDN bit is set then all RTC registers and logic are held in reset. Hence, writes to RTC registers will have no effect.

(and you'll also want to clear CK32K_CTRL of course since the internal RC osc is unlikely to be useul as time base).

0 Bernie Chen over 10 years ago in reply to Matthijs van Duin

Expert 2190 points

Hi Matthijs

Thanks your reply，I have ported rtc-tps65910.c into sdk6，and observed RTC_PWDN just like you say, it is not to be set 1(0x3f = 0x10), then it work fine ! Thank you.

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How to keep RTC time