device-google-sargo: Reload I2C drivers on error

It's common for the I2C touch driver on the Google Pixel 3a to crash
resulting in touch input not working, see [1].

This patch adds a systemd service that can be used to monitor for errors
and reload the drivers on error, the original idea came from [2].

The actual script is not systemd specific, so that the script can be
ported to openrc if required.

1: https://gitlab.com/sdm670-mainline/linux/-/work_items/6
2: https://gitlab.com/sdm670-mainline/linux/-/work_items/6#note_3104050714

Signed-off-by: Alistair Francis <alistair@alistair23.me>
Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8409>

device/community/device-google-sargo/APKBUILD

@@ -3,7 +3,7 @@ maintainer="Richard Acayan <mailingradian@gmail.com>"
 pkgname=device-google-sargo
 pkgdesc="Google Pixel 3a"
 pkgver=18
-pkgrel=0
+pkgrel=1
 url="https://postmarketos.org"
 license="MIT"
 arch="aarch64"
@@ -36,10 +36,13 @@ source="
 	no-hexagonrpcd-on-suspend.sh
 	plasmacamerarc
 	q6voiced.conf
+	reload-rmi-touch.service
+	reload-rmi-touch.sh
 "
 subpackages="
 	$pkgname-openrc
 	$pkgname-plasma-camera:plasma_camera
+	$pkgname-systemd
 "
 
 build() {
@@ -59,6 +62,12 @@ package() {
 	# The q6voiced configuration can only be used if the ADSP is brought up
 	# via non-free firmware.
 	install -Dm644 "$srcdir"/q6voiced.conf "$pkgdir"/etc/conf.d/q6voiced
+
+	install -Dm755 "$srcdir"/reload-rmi-touch.sh \
+		"$pkgdir"/usr/lib/$pkgname/reload-rmi-touch
+
+	install -Dm644 "$srcdir"/reload-rmi-touch.service \
+		-t "$pkgdir"/usr/lib/systemd/system
 }
 
 openrc() {
@@ -84,4 +93,6 @@ b6208c254b6e44ac4f6d748a38cc6b05da0db2c90235ada2011b138b82ccc3372687df2f5ad97e88
 2972005a9cf6ca57061965075593dddfa8ee479bc6c21cd41851b1a14768cb1cddbd31a17975ae17adc36d40d294ccbc6bf83defbd69fc7b363f638d8564fbbc  no-hexagonrpcd-on-suspend.sh
 53bec3338d875ecedf2ae981cf9a0f9066e276f09570b3bd06217414461126a76942b70e01c3bb18831fbefeb188621dd5a341ab2604e8fb0c6de8a3025177e2  plasmacamerarc
 3a4a9322839d4b3ef9d79668a37840a9f444954759ae3c512e694051d2f9a2573db42ad6c4c1a5c75eeb861232a27ba1a8cef9b503decd54ead25a96e3dd6f98  q6voiced.conf
+20b932e853ea65f9e61bee775af8efec4846766f69f04b73cd104b3aa889d5b8570f26dbcf971d3abff75b3c057c9b585687af5846cb2be8d694f9bca35981b2  reload-rmi-touch.service
+d04653b5d22a43c6b694608b507d792c03842b77865003cecf291a83bef3762531765227b88275036b24f1307ba5a798f225d68915e4d0773ec36fc6d1650702  reload-rmi-touch.sh
 "

device/community/device-google-sargo/reload-rmi-touch.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=Reload RMI touch driver on I2C errors
+
+[Service]
+ExecStart=/usr/lib/device-google-sargo/reload-rmi-touch
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=default.target

device/community/device-google-sargo/reload-rmi-touch.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+# Reload RMI touch driver on I2C errors.
+
+trap 'exit 0' INT TERM
+
+last_reload=0
+
+while IFS= read -r line; do
+	case "$line" in
+	*"geni_i2c a84000.i2c:"*"failed"*)
+		echo "I2C touch error detected on geni_i2c a84000.i2c"
+		now=$(date +%s)
+		# Debounce: only reload if it's been at least 30 seconds since the
+		# last reload, in case errors come in bursts.
+		if [ $((now - last_reload)) -ge 30 ]; then
+			echo "Reloading RMI touch driver"
+			modprobe -r rmi_i2c
+			modprobe -r rmi_core
+			modprobe rmi_core
+			modprobe rmi_i2c
+			last_reload=$(date +%s)
+		fi
+		;;
+	esac
+done < /dev/kmsg