diff options
Diffstat (limited to 'meta-google/recipes-google/gpio/gpio-ctrl/lib.sh')
| -rw-r--r-- | meta-google/recipes-google/gpio/gpio-ctrl/lib.sh | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/meta-google/recipes-google/gpio/gpio-ctrl/lib.sh b/meta-google/recipes-google/gpio/gpio-ctrl/lib.sh new file mode 100644 index 000000000..a75c41306 --- /dev/null +++ b/meta-google/recipes-google/gpio/gpio-ctrl/lib.sh @@ -0,0 +1,250 @@ +#!/bin/bash +# Copyright 2021 Google LLC +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +# This is intended to be used as a library for managing gpio line values. +# Executing this directly will do nothing. +[ -n "${gpio_ctrl_init-}" ] && return + +# Map names of GPIOs to GPIO number +# This maps a schematic name to a gpiochip and line at a specific offset +declare -A GPIO_NAMES_TO_SCM=( + # Examples + #['SYS_RESET_N']='label=/pinctrl@f0800000/gpio@f0012000 21' + #['PWRBTN_N']='label=/pinctrl@f0800000/gpio@f0012000 23' + #['PCH_SLP_S5_R_N']='of_node=/ahb/apb/i2c@8e000/cpu_seq@6b 9' + #['PCH_PWRGOOD_R']='of_node=/ahb/apb/i2c@8e000/cpu_seq@6b 6' +) + +# Load configurations from a known location in the filesystem to populate +# named GPIOs +shopt -s nullglob +for conf in /usr/share/gpio-ctrl/conf.d/*.sh; do + source "$conf" +done + +declare -A gpio_sysfs_lookup_cache=() +declare -A gpio_lookup_cache=() + +declare -A gpio_init=() + +################################################## +# Looks up the sysfs GPIO number +# Arguments: +# $1: GPIO name +# Return: +# 0 if success, non-zero if error +# stdout: The GPIO number +################################################## +gpio_name_to_num() { + local name="$1" + + if [ -n "${gpio_lookup_cache["$name"]+1}" ]; then + echo "${gpio_lookup_cache["$name"]}" + return 0 + fi + + local scm="${GPIO_NAMES_TO_SCM["$name"]-}" + if [ -z "$scm" ]; then + echo "Missing gpio definition: $name" >&2 + return 1 + fi + local id="${scm% *}" + local type="${id%=*}" + local val="${id#*=}" + local offset="${scm#* }" + + local sysfs + if [ -n "${gpio_sysfs_lookup_cache["$id"]+1}" ]; then + sysfs="${gpio_sysfs_lookup_cache["$id"]}" + else + case "$type" in + label) + if ! sysfs="$(grep -xl "$val" /sys/class/gpio/gpiochip*/label)"; then + echo "Failed to find gpiochip: $val" >&2 + return 1 + fi + sysfs="${sysfs%/label}" + ;; + of_node) + for sysfs in $(echo /sys/class/gpio/gpiochip*); do + local link + # Ignore errors because not all devices have of_nodes + link="$(readlink -f "$sysfs/device/of_node" 2>/dev/null)" || continue + [ "${link#/sys/firmware/devicetree/base}" = "$val" ] && break + sysfs= + done + if [ -z "$sysfs" ]; then + echo "Failed to find gpiochip: $val" >&2 + return 1 + fi + ;; + *) + echo "Invalid GPIO type $type" >&2 + return 1 + ;; + esac + gpio_sysfs_lookup_cache["$id"]="$sysfs" + fi + + local ngpio=$(cat "$sysfs"/ngpio) + if (( ngpio <= offset )); then + echo "$name with gpiochip $sysfs only has $ngpio but wants $offset" >&2 + return 1 + fi + + gpio_lookup_cache["$name"]=$(( $(cat "$sysfs"/base) + offset )) + echo "${gpio_lookup_cache["$name"]}" +} + + +################################################## +# Populates the GPIO lookup cache +# Most calls to gpio_name_to_num that would +# normally cache the sysfs lookups for gpios run +# inside subshells. This prevents them from +# populating a global cache and greatly speeding +# up future lookups. This call allows scripts to +# populate the cache prior to looking up gpios. +################################################## +gpio_build_cache() { + local timeout="${1-0}" + shift + local gpios=("$@") + + if (( ${#gpios[@]} == 0 )); then + gpios="${!GPIO_NAMES_TO_SCM[@]}" + fi + + local deadline=$(( timeout + SECONDS )) + local name + for name in "${gpios[@]}"; do + while true; do + gpio_name_to_num "$name" >/dev/null && break + if (( deadline <= SECONDS )); then + echo "Timed out building gpio cache" >&2 + return 1 + fi + done + done +} + +################################################## +# Initializes the gpio state +# This operation is idempotent and can be applied +# repeatedly to the same gpio. It will make sure the +# gpio ends up in the initialized state even if it +# was. +# Arguments: +# $1: GPIO name +# Return: +# 0 if success, non-zero if error +################################################## +gpio_init_() { + local name="$1" + local num="$2" + + if [ -n "${gpio_init["$name"]+1}" ]; then + return 0 + fi + + if [ ! -e "/sys/class/gpio/gpio$num" ]; then + if ! echo "$num" >'/sys/class/gpio/export'; then + echo "Failed to export $name gpio$num" >&2 + return 1 + fi + fi + local active_low=0 + if [[ "${name%_N}" != "$name" ]]; then + active_low=1 + fi + if ! echo "$active_low" >"/sys/class/gpio/gpio$num/active_low"; then + echo "Failed to set active_low for $name gpio$num" >&2 + return 1 + fi + gpio_init["$name"]=1 +} +gpio_init() { + local name="$1" + + # Ensure the cache is updated by not running in a subshell + gpio_name_to_num "$name" >/dev/null || return + + gpio_init_ "$name" "$(gpio_name_to_num "$name")" +} + +################################################## +# Sets the output GPIO value. +# Arguments: +# $1: GPIO name +# $2: GPIO value, "1" or "0" +# Return: +# 0 if success, non-zero if error +################################################## +gpio_set_value_() { + local name="$1" + local num="$2" + local val="$3" + + gpio_init_ "$name" "$num" || return + if ! echo out >"/sys/class/gpio/gpio$num/direction"; then + echo "Failed to set output for $name gpio$num" >&2 + return 1 + fi + if ! echo "$val" >"/sys/class/gpio/gpio$num/value"; then + echo "Failed to set $name gpio$num = $val" >&2 + return 1 + fi +} +gpio_set_value() { + local name="$1" + local val="$2" + + # Ensure the cache is updated by not running in a subshell + gpio_name_to_num "$name" >/dev/null || return + + gpio_set_value_ "$name" "$(gpio_name_to_num "$name")" "$val" +} + +################################################## +# Get GPIO value +# Arguments: +# $1: GPIO name +# Return: +# 0 if success, non-zero if error +# stdout: The value of the gpio +################################################## +gpio_get_value_() { + local name="$1" + local num="$2" + + gpio_init_ "$name" "$num" || return + if ! cat "/sys/class/gpio/gpio$num/value"; then + echo "Failed to get $name gpio$num value" >&2 + return 1 + fi +} +gpio_get_value() { + local name="$1" + + # Ensure the cache is updated by not running in a subshell + gpio_name_to_num "$name" >/dev/null || return + + gpio_get_value_ "$name" "$(gpio_name_to_num "$name")" +} + +gpio_ctrl_init=1 +return 0 2>/dev/null +echo "gpio-ctrl is a library, not executed directly" >&2 +exit 1 |