blob: a2db0d633f503f975259a7f605656c3c0a62e3f6 [file] [log] [blame]
#!/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 "${gpio_ctrl_init-}" ] && return
# Map names of GPIOs to GPIO number
# This maps a schematic name to a gpiochip and line at a specific offset
declare -A GPIO_NAMES_TO_SCM=(
# Examples
#['SYS_RESET_N']='label=/pinctrl@f0800000/gpio@f0012000 21'
#['PWRBTN_N']='label=/pinctrl@f0800000/gpio@f0012000 23'
#['PCH_SLP_S5_R_N']='of_node=/ahb/apb/i2c@8e000/cpu_seq@6b 9'
#['PCH_PWRGOOD_R']='of_node=/ahb/apb/i2c@8e000/cpu_seq@6b 6'
)
# Load configurations from a known location in the filesystem to populate
# named GPIOs
shopt -s nullglob
for conf in /usr/share/gpio-ctrl/conf.d/*.sh; do
# shellcheck source=/dev/null
source "$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"]="$sysfs"
fi
local ngpio
ngpio=$(<"$sysfs"/ngpio)
if (( ngpio <= offset )); then
echo "$name with gpiochip $sysfs only has $ngpio but wants $offset" >&2
return 1
fi
gpio_lookup_cache["$name"]=$(( $(<"$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