feat(acpi): Add custom LID event handling

We disable the default ACPI handler script logic for LID events.
We _only_ disable that in the script - the default handler script will
still fire for LID events, just not do anything in its routine. That is
so that in the future it is easy to rectify with any upstream changes.
If, over time we add more custom event and action chain to our ACPI
settings, we can think about spinning out all event types into our own
rules and completely disabling the deafult handler script.

Our custom LID action only fires for LID open close events, and only
logs that the lid has been opened for open events. For close events, it
adds one extra step before suspending: Checking if any DP screens are
connected - and inhibiting suspend then. That way we still automatically
suspend when closing the screen lid if we are in portable mode (no
external screens connected) but do nothing if they are.

roles/acpi/files/actions/button-lid.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+# Specifically handling LID events
+# Can take the form:
+# button/lid LID close
+# button/lid LID open
+# We are only interested in value $3.
+
+# Do not turn off machine if external screens are connected.
+
+case "$3" in
+
+close)
+    should_sleep=true
+    screens=$(find /sys/devices -type f -wholename '*drm/*card*-DP-*/status')
+    while IFS= read -r screen; do
+        if [ "$(cat "$screen")" = connected ]; then
+            should_sleep=false
+        fi
+    done <<EOF
+$screens
+EOF
+
+    if [ "$should_sleep" = true ]; then
+        suspend-to-ram
+        logger "LID closed, no external screens, suspending..."
+        zzz
+    else
+        logger "LID closed, external screens, not suspending."
+    fi
+    ;;
+
+open) logger "LID opened" ;;
+
+*) logger "ACPI action undefined (LID): $*" ;;
+
+esac

roles/acpi/files/default-handler.sh

@@ -0,0 +1,97 @@
+#!/bin/sh
+# Default acpi script that takes an entry for all actions
+
+# NOTE: This is a 2.6-centric script.  If you use 2.4.x, you'll have to
+#       modify it to not use /sys
+
+# $1 should be + or - to step up or down the brightness.
+step_backlight() {
+    for backlight in /sys/class/backlight/*/; do
+        [ -d "$backlight" ] || continue
+        step=$(( $(cat "$backlight/max_brightness") / 20 ))
+        [ "$step" -gt "1" ] || step=1 #fallback if gradation is too low
+        printf '%s' "$(( $(cat "$backlight/brightness") $1 step ))" >"$backlight/brightness"
+    done
+}
+
+minspeed="/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq"
+maxspeed="/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq"
+setspeed="/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed"
+
+
+case "$1" in
+    button/power)
+        case "$2" in
+            PBTN|PWRF)
+                logger "PowerButton pressed: $2, shutting down..."
+                shutdown -P now
+                ;;
+            *)  logger "ACPI action undefined: $2" ;;
+        esac
+        ;;
+    button/sleep)
+        case "$2" in
+            SBTN|SLPB)
+                # suspend-to-ram
+                logger "Sleep Button pressed: $2, suspending..."
+                zzz
+                ;;
+            *)  logger "ACPI action undefined: $2" ;;
+        esac
+        ;;
+    ac_adapter)
+        case "$2" in
+            AC|ACAD|ADP0)
+                case "$4" in
+                    00000000)
+                        cat "$minspeed" >"$setspeed"
+                        #/etc/laptop-mode/laptop-mode start
+                    ;;
+                    00000001)
+                        cat "$maxspeed" >"$setspeed"
+                        #/etc/laptop-mode/laptop-mode stop
+                    ;;
+                esac
+                ;;
+            *)  logger "ACPI action undefined: $2" ;;
+        esac
+        ;;
+    battery)
+        case "$2" in
+            BAT0)
+                case "$4" in
+                    00000000)   #echo "offline" >/dev/tty5
+                    ;;
+                    00000001)   #echo "online"  >/dev/tty5
+                    ;;
+                esac
+                ;;
+            CPU0)
+                ;;
+            *)  logger "ACPI action undefined: $2" ;;
+        esac
+        ;;
+    # HANDLED IN SEPARATE ACTION FILE
+    button/lid) ;;
+    #     case "$3" in
+    #         close)
+    #             # suspend-to-ram
+    #             # logger "LID closed, suspending..."
+    #             # zzz
+    #             ;;
+    #         open)
+    #             logger "LID opened"
+    #             ;;
+    #         *)  logger "ACPI action undefined (LID): $2";;
+    #     esac
+    #     ;;
+    video/brightnessdown)
+        step_backlight -
+        ;;
+    video/brightnessup)
+        step_backlight +
+        ;;
+    *)
+        logger "ACPI group/action undefined: $1 / $2"
+        ;;
+esac

roles/acpi/files/events/button-lid

@@ -0,0 +1,3 @@
+# Only pass lid events
+event=button/lid
+action=/etc/acpi/actions/button-lid.sh %e

roles/acpi/handlers/main.yaml

@@ -0,0 +1,9 @@
+---
+- name: Reload acpid rules
+  become: true
+  ansible.builtin.command:
+    argv:
+      - pkill
+      - -1
+      - acpid
+  listen: acpi-rule-reload

roles/acpi/tasks/main.yaml

@@ -1,4 +1,38 @@
 ---
+# ACPI comes preinstalled on void systems
+- name: Remove lid handling from default handler
+  ansible.builtin.copy:
+    src: default-handler.sh
+    dest: /etc/acpi/handler.sh
+    mode: 0755
+    force: true
+  notify: acpi-rule-reload
+
+- name: Ensure acpi config directories exist
+  ansible.builtin.file:
+    dest: "/etc/acpi/{{ item }}"
+    state: directory
+    mode: 0755
+  loop:
+    - events
+    - actions
+
+- name: Add separate lid button event rule
+  ansible.builtin.copy:
+    src: events/button-lid
+    dest: /etc/acpi/events/button-lid
+    mode: 0644
+    force: true
+  notify: acpi-rule-reload
+
+- name: Add corresponding lid handler action
+  ansible.builtin.copy:
+    src: actions/button-lid.sh
+    dest: /etc/acpi/actions/button-lid.sh
+    mode: 0755
+    force: true
+  notify: acpi-rule-reload
+
 - name: Activate acpid service
   ansible.builtin.file:
     src: "/etc/sv/acpid"