From 5d43882dd6b9099012540f9cdf7d91613a0ccf0f Mon Sep 17 00:00:00 2001
From: KemoNine <kemonine@lollipopcloud.solutions>
Date: Fri, 12 Apr 2019 00:47:16 +0100
Subject: [PATCH] Updates and improvements on adding rtc boards

---
 hardware/rtc.md | 81 +++++++++++++++++++------------------------------
 1 file changed, 31 insertions(+), 50 deletions(-)

diff --git a/hardware/rtc.md b/hardware/rtc.md
index 3b9e902..e6ba2a4 100644
--- a/hardware/rtc.md
+++ b/hardware/rtc.md
@@ -35,15 +35,17 @@ armbian-config # enable i2c busses
 systemctl reboot # reboot to enable bus(es)
 apt install i2c-tools # install tools
 i2cdetect -l # check to ensure busses are present
-i2cdetect -y 0 # 0 for orange pi zero ; 1 for recent pi's
+i2cdetect -y 1 # 0 for orange pi zero ; 1 for recent pi's
 modprobe rtc-pcf8523 # load the proper rtc module (adafruit cheap model)
-echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-0/new_device # setup device so it's seen
+echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-1/new_device # setup device so it's seen
 dmesg | grep rtc # verify the kernel sees the rtc
 ls /dev/rtc* # should have rtc1
+hwclock -r -f /dev/rtc1 # See if anything is on the rtc
 hwclock -f /dev/rtc1 --systohc -D --noadjfile --utc # set / init the rtc
 hwclock -r -f /dev/rtc1 # read the value from the rtc
 hwclock -w -f /dev/rtc1 # write the current time to the rtc
 apt remove --purge fake-hwclock # purge the fake hwclock as we have a real one now
+systemctl disable fake-hwclock # Disable any dangling services
 
 ```
 
@@ -58,50 +60,6 @@ EOF
 
 ```
 
-## Internal RTC Adjustments
-
-A systemd service to ensure the internal RTC is 'close' to the real time w/o battery.
-
-``` bash
-
-# Set the internal RTC on shutdown to match ntpified time
-cat > /etc/systemd/system/rtc0-shutdown-fix.service <<EOF
-[Unit]
-Description=Set sunxi internal RTC on shutdown
-DefaultDependencies=no
-Before=shutdown.target reboot.target halt.target
-
-[Service]
-Type=oneshot
-ExecStart=/sbin/hwclock --systohc -D --noadjfile --utc -f /dev/rtc0
-
-[Install]
-WantedBy=halt.target reboot.target shutdown.target
-EOF
-
-systemctl daemon-reload
-systemctl enable rtc0-shutdown-fix
-
-# Trick for getting the early boot time 'close'
-cat > /etc/systemd/system/rtc0-online.service <<EOF
-[Unit]
-Description=Set system clock to rtc0
-DefaultDependencies=no
-Before=time-sync.target
-
-[Service]
-Type=oneshot
-ExecStart=/sbin/hwclock -s -f /dev/rtc0
-
-[Install]
-WantedBy=time-sync.target
-EOF
-
-systemctl daemon-reload
-systemctl enable rtc0-online
-
-```
-
 ## External RTC On Boot
 
 A systemd unit that brings the external RTC online during boot
@@ -113,17 +71,15 @@ cat > /etc/systemd/system/rtc1-online.service <<EOF
 Description=Setup rtc1 as primary clock
 DefaultDependencies=no
 Before=time-sync.target
-After=rtc0-online.service
 
 [Service]
 Type=oneshot
-ExecStart=/bin/sh -c '/sbin/modprobe rtc_pcf8523 \
-&& echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-0/new_device \
+ExecStart=/bin/sh -c '/sbin/modprobe rtc-pcf8523  \
+&& echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-1/new_device \
 && /sbin/hwclock -s -f /dev/rtc1'
 
 [Install]
 WantedBy=time-sync.target
-After=rtc0-online
 EOF
 
 systemctl daemon-reload
@@ -131,6 +87,31 @@ systemctl enable rtc1-online
 
 ```
 
+## Set RTC on shutdown
+
+A systemd unit that sets the current time to the rtc on shutdown to minimize clock drift during next boot
+
+``` bash
+
+cat > /etc/systemd/system/rtc1-shutdown-fix.service <<EOF
+[Unit]
+Description=Set rtc1 on shutdown
+DefaultDependencies=no
+Before=shutdown.target reboot.target halt.target
+
+[Service]
+Type=oneshot
+ExecStart=/sbin/hwclock --systohc -D --noadjfile --utc -f /dev/rtc1
+
+[Install]
+WantedBy=halt.target reboot.target shutdown.target
+EOF
+
+systemctl daemon-reload
+systemctl enable rtc1-shutdown-fix
+
+```
+
 ## Misc Notes
 
 ``` bash