installer: improve RTC handling (#188)

* Add 'abx80x' to list of possible RTC drivers

* Add 'module_enable' function in installer script for modules to be loaded
  in installed system

* Use 'dtoverlay_enable' function in various places it was not being used

* Ensure module for the RTC has been loaded during installation

* Stop adding 'hwclock' call to /etc/rc.local as it is no longer needed
  - systems using sysvinit already have a udev rule to do this
  - systems using systemd will use service unit described below

* Add systemd service unit to read RTC on startup
  - as seen in Debian bug 855203, systems using systemd don't read the RTC
    during startup if the RTC's driver is loaded as a module; since all
    Raspberry Pi kernels are configured this way, a service unit is required
    to read the RTC during system startup

* Ensure module for the RTC will be loaded in installed system

* Ensure that RTC date/time is set in UTC mode

The 'ensure module loaded' bits are required because at least one RTC module
(abx80x) is not automatically loaded even though the proper Device Tree overlay
has been configured. For those which are autoloaded, having the module name
in /etc/modules (or /etc/modules-load.d/rtc.conf) won't cause any harm.

Signed-off-by: Kevin P. Fleming <[email protected]>

doc/INSTALL_CUSTOM.md

@@ -55,7 +55,7 @@ Note that if the networking configuration is set to use DHCP, no additional pack
 | `sound_usb_first` | `0` | `0`/`1` | Set to "1" to define USB audio as default if onboard audio is also enabled. The options `sound_enable=1` and `sound_usb_enable=1` have to be set to take effect. |
 | `camera_enable` | `0` | `0`/`1` | Set to "1" to enable the camera module. This enables all camera-related parameters in config.txt. |
 | `camera_disable_led` | `0` | `0`/`1` | Disables the camera LED. The option `camera_enable=1` has to be set to take effect. |
-| `rtc` |  | `ds1307`/  `ds1339`/  `ds3231`/  `mcp7940x`/  `mcp7941x`/  `pcf2127`/  `pcf8523`/  `pcf8563` | Select an RTC if it is connected via I²C. |
+| `rtc` |  | `ds1307`/  `ds1339`/  `ds3231`/  `mcp7940x`/  `mcp7941x`/  `pcf2127`/  `pcf8523`/  `pcf8563`/  `abx80x` | Select an RTC if it is connected via I²C. |
 | `dt_overlays` |  |  | Enables additional device tree overlays (comma separated and quoted). (e.g. 'dt_overlays="hifiberry-dac,lirc-rpi"') |
 
 ## SSH

scripts/opt/raspberrypi-ua-netinst/install.sh

@@ -487,6 +487,16 @@ dtoverlay_enable() {
 	fi
 }
 
+module_enable() {
+	local module="${1}"
+	local purpose="${2}"
+	if [ "${init_system}" = "systemd" ]; then
+		echo "${module}" > "/rootfs/etc/modules-load.d/${purpose}.conf"
+	else
+		echo "${module}" >> /rootfs/etc/modules
+	fi
+}
+
 #######################
 ###    INSTALLER    ###
 #######################
@@ -755,7 +765,7 @@ fi
 if [ -n "${rtc}" ] ; then
 	echo -n "  Enabling RTC configuration... "
 	if ! grep -q "^dtoverlay=i2c-rtc,${rtc}\>" /boot/config.txt; then
-		echo -e "\ndtoverlay=i2c-rtc,${rtc}" >> /boot/config.txt
+		dtoverlay_enable "/boot/config.txt" "i2c-rtc,${rtc}"
 		preinstall_reboot=1
 	fi
 	echo "OK"
@@ -913,6 +923,17 @@ if [ -n "${drivers_to_load}" ]; then
 	echo
 fi
 
+if [ -n "${rtc}" ] ; then
+	echo -n "Ensuring RTC module has been loaded... "
+	modprobe "rtc-${rtc}" || fail
+	echo "OK"
+	echo -n "Checking hardware clock access... "
+	mdev -s
+	sleep 3s
+	/opt/busybox/bin/hwclock --show &> /dev/null || fail
+	echo "OK"
+fi
+
 echo -n "Waiting for ${ifname}... "
 for i in $(seq 1 "${installer_networktimeout}"); do
 	if ifconfig "${ifname}" &> /dev/null; then
@@ -1391,13 +1412,6 @@ for i in $(seq 1 5); do
 done
 echo
 
-if [ -n "${rtc}" ] ; then
-	echo -n "Checking hardware clock access... "
-	/opt/busybox/bin/hwclock --show &> /dev/null || fail
-	echo "OK"
-	echo
-fi
-
 # fdisk's boot offset is 2048, so only handle $bootoffset is it's larger then that
 if [ -n "${bootoffset}" ] && [ "${bootoffset}" -gt 2048 ]; then
 	emptyspaceend=$((bootoffset - 1))
@@ -2025,8 +2039,25 @@ if [ "${use_systemd_services}" = "0" ]; then
 		sed -i "s/^\(exit 0\)/\/sbin\/hwclock --hctosys\n\1/" /rootfs/etc/rc.local
 	fi
 else
-	# enable systemd-timesyncd
 	ln -s /lib/systemd/system/systemd-timesyncd.service /rootfs/etc/systemd/system/multi-user.target.wants/systemd-timesyncd.service
+
+	if [ -n "${rtc}" ]; then
+		cat > /rootfs/etc/systemd/system/hwclock-to-sysclock.service << EOF
+[Unit]
+Description=Set system clock from hardware clock
+After=systemd-modules-load.service
+
+[Service]
+Type=oneshot
+ExecStart=/sbin/hwclock --hctosys --utc
+
+[Install]
+WantedBy=basic.target
+
+EOF
+		mkdir /rootfs/etc/systemd/system/basic.target.wants
+		ln -s /etc/systemd/system/hwclock-to-sysclock.service /rootfs/etc/systemd/system/basic.target.wants/hwclock-to-sysclock.service
+	fi
 fi
 
 # copy apt's sources.list to the target system
@@ -2248,7 +2279,7 @@ if [ "${i2c_enable}" = "1" ]; then
 		sed -i "s/^\(dtparam=i2c_arm=.*\)/#\1/" /rootfs/boot/config.txt
 		echo "dtparam=i2c_arm=on" >> /rootfs/boot/config.txt
 	fi
-	echo "i2c-dev" >> /rootfs/etc/modules
+	module_enable "i2c-dev" "i2c"
 	if [ -n "${i2c_baudrate}" ]; then
 		if grep -q "i2c_baudrate=" /rootfs/boot/config.txt; then
 			sed -i "s/\(.*i2c_baudrate=.*\)/#\1/" /rootfs/boot/config.txt
@@ -2379,11 +2410,8 @@ fi
 
 # enable rtc if specified in the configuration file
 if [ -n "${rtc}" ]; then
-	sed -i "s/^#\(dtoverlay=i2c-rtc,${rtc}\)/\1/" /rootfs/boot/config.txt
-	if [ "$(grep -c "^dtoverlay=i2c-rtc,.*" /rootfs/boot/config.txt)" -ne 1 ]; then
-		sed -i "s/^\(dtoverlay=i2c-rtc,\)/#\1/" /rootfs/boot/config.txt
-		echo "dtoverlay=i2c-rtc,${rtc}" >> /rootfs/boot/config.txt
-	fi
+	dtoverlay_enable "/rootfs/boot/config.txt" "i2c-rtc,${rtc}"
+	module_enable "rtc-${rtc}" "rtc"
 fi
 
 # enable custom dtoverlays
@@ -2456,7 +2484,7 @@ if echo "${cdebootstrap_cmdline} ${packages_postinstall}" | grep -q "fake-hwcloc
 	echo "OK"
 elif [ -n "${rtc}" ]; then
 	echo -n "Saving current time to RTC... "
-	/opt/busybox/bin/hwclock --systohc || fail
+	/opt/busybox/bin/hwclock --systohc --utc || fail
 	echo "OK"
 fi