rules: add battery charge limit udev and hwdb files

Set per battery-specific start/stop charge limits in udev as environment
variable with the option to allow a user to override the default 60%
start and 80% stop charge limit.

Signed-off-by: Kate Hsuan <hpa@redhat.com>

rules/60-upower-battery.hwdb

@@ -0,0 +1,30 @@
+# This file is part of upower.
+#
+# The lookup keys are composed in:
+#   60-upower-battery.rules
+#
+# Match string format:
+# battery:<kernel>:<model_name>:dmi:<dmi pattern>
+#
+# The kernel is the name of battery in /sys/class/power_supply for
+# differentiating between multiple batteries.
+#
+# The model_name is battery model name in for example
+# /sys/class/power_supply/BAT0/model_name.
+#
+# The full DMI string of the running machine can be read from
+#   /sys/class/dmi/id/modalias
+# That requires a kernel built with CONFIG_DMIID set, which is common.
+# The full DMI string is not needed here and the meaning of individual parts
+# can be seen in the source of the DMIID kernel module
+#   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/dmi-id.c
+#
+# To add local overrides, create a new file
+# /etc/udev/hwdb.d/61-battery-local.hwdb
+# and add your rules there. To load the new rules execute (as root):
+# systemd-hwdb  update
+# udevadm trigger -v -p /sys/class/power_supply/BAT
+# where BAT is the battery in question.
+
+battery:*:*:dmi:*
+ CHARGE_LIMIT=60,80

rules/60-upower-battery.rules

@@ -0,0 +1,7 @@
+ACTION=="remove", GOTO="battery_end"
+
+SUBSYSTEM=="power_supply",ATTR{charge_control_start_threshold}!="" \
+  IMPORT{builtin}="hwdb 'battery:$kernel:$attr{model_name}:$attr{[dmi/id]modalias}'", \
+  GOTO="battery_end"
+
+LABEL="battery_end"

rules/meson.build

@@ -1,10 +1,12 @@
 rules = [
+    '60-upower-battery.rules',
     '95-upower-wup.rules',
     '95-upower-hid.rules',
 ]
 
 hwdb = [
     '95-upower-hid.hwdb',
+    '60-upower-battery.hwdb',
 ]
 
 if os_backend == 'linux'