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Bug 1707139 - DS3231 RTC Module doesn't work properly
Summary: DS3231 RTC Module doesn't work properly
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: rawhide
Hardware: armhfp
OS: Linux
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
Depends On:
Blocks: ARMTracker
TreeView+ depends on / blocked
Reported: 2019-05-06 21:28 UTC by Michael
Modified: 2021-06-12 15:24 UTC (History)
21 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2021-06-12 15:24:11 UTC
Type: Bug

Attachments (Terms of Use)

Description Michael 2019-05-06 21:28:23 UTC
Description of problem:
I have DS3231 RTC Module that works fine under centos arm arch, but under Fedora arm arch I can't get current date and time from this hardware RTC clock

Version-Release number of selected component (if applicable):
last updates

Steps to Reproduce:
1. connect DS3231 RTC to Raspberry Pi 3 
2. add options to file /boot/efi/config.txt
3. create file
echo -e "i2c-dev" >> /etc/modules-load.d/i2c.conf
4. dnf -y install i2c-tools && reboot

Actual results:
dmesg shows
hctosys: unable to open rtc device (rtc0)

sudo hwclock -r
hwclock: Cannot access the Hardware Clock via any known method.
hwclock: Use the --verbose option to see the details of our search for an access method.

Expected results:
hwclock have to get actual time from hardwate RTC

Additional info:

sudo hwclock -r --verbose
hwclock из util-linux 2.33.2
System Time: 1557177406.430509
Trying to open: /dev/rtc0
Trying to open: /dev/rtc
Trying to open: /dev/misc/rtc
hwclock: Cannot access the Hardware Clock via any known method.

Comment 1 Michael 2019-06-08 08:52:09 UTC
I've fixed my problem. I added new systemd unit

cat >> /lib/systemd/system/ebb_hwclock.service

Description=EBB RTC Service

ExecStartPre=/bin/sh -c "/bin/echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device"
ExecStart=/sbin/hwclock -s -f /dev/rtc1


Then enable new unit and reboot system

sudo systemctl enable ebb_hwclock
sudo reboot

Comment 2 Peter Robinson 2020-04-14 07:36:18 UTC
This is nothing to do with i2c-tools.

Comment 3 Peter Robinson 2021-06-12 15:24:11 UTC
There's documentation on how to use HATs with Fedora here:

The hw clock support was improved in F-34.

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