1#!/bin/bash
2# Copyright 2021 Google LLC
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#      http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15
16# This is intended to be used as a library for managing gpio line values.
17# Executing this directly will do nothing.
18[ -n "${gpio_ctrl_init-}" ] && return
19
20# Map names of GPIOs to GPIO number
21# This maps a schematic name to a gpiochip and line at a specific offset
22declare -A GPIO_NAMES_TO_SCM=(
23  # Examples
24  #['SYS_RESET_N']='label=/pinctrl@f0800000/gpio@f0012000 21'
25  #['PWRBTN_N']='label=/pinctrl@f0800000/gpio@f0012000 23'
26  #['PCH_SLP_S5_R_N']='of_node=/ahb/apb/i2c@8e000/cpu_seq@6b 9'
27  #['PCH_PWRGOOD_R']='of_node=/ahb/apb/i2c@8e000/cpu_seq@6b 6'
28)
29
30# Load configurations from a known location in the filesystem to populate
31# named GPIOs
32shopt -s nullglob
33for conf in /usr/share/gpio-ctrl/conf.d/*.sh; do
34  # shellcheck source=/dev/null
35  source "$conf"
36done
37
38declare -A gpio_sysfs_lookup_cache=()
39declare -A gpio_lookup_cache=()
40
41declare -A gpio_init=()
42
43##################################################
44# Looks up the sysfs GPIO number
45# Arguments:
46#   $1: GPIO name
47# Return:
48#   0 if success, non-zero if error
49#   stdout: The GPIO number
50##################################################
51gpio_name_to_num() {
52  local name="$1"
53
54  if [ -n "${gpio_lookup_cache["$name"]+1}" ]; then
55    echo "${gpio_lookup_cache["$name"]}"
56    return 0
57  fi
58
59  local scm="${GPIO_NAMES_TO_SCM["$name"]-}"
60  if [ -z "$scm" ]; then
61    echo "Missing gpio definition: $name" >&2
62    return 1
63  fi
64  local id="${scm% *}"
65  local type="${id%=*}"
66  local val="${id#*=}"
67  local offset="${scm#* }"
68
69  local sysfs
70  if [ -n "${gpio_sysfs_lookup_cache["$id"]+1}" ]; then
71    sysfs="${gpio_sysfs_lookup_cache["$id"]}"
72  else
73    case "$type" in
74    label)
75      if ! sysfs="$(grep -xl "$val" /sys/class/gpio/gpiochip*/label)"; then
76        echo "Failed to find gpiochip: $val" >&2
77        return 1
78      fi
79      sysfs="${sysfs%/label}"
80      ;;
81    of_node)
82      for sysfs in $(echo /sys/class/gpio/gpiochip*); do
83        local link
84        # Ignore errors because not all devices have of_nodes
85        link="$(readlink -f "$sysfs/device/of_node" 2>/dev/null)" || continue
86        [ "${link#/sys/firmware/devicetree/base}" = "$val" ] && break
87        sysfs=
88      done
89      if [ -z "$sysfs" ]; then
90        echo "Failed to find gpiochip: $val" >&2
91        return 1
92      fi
93      ;;
94    *)
95      echo "Invalid GPIO type $type" >&2
96      return 1
97      ;;
98    esac
99    gpio_sysfs_lookup_cache["$id"]="$sysfs"
100  fi
101
102  local ngpio
103  ngpio=$(<"$sysfs"/ngpio)
104  if (( ngpio <= offset )); then
105    echo "$name with gpiochip $sysfs only has $ngpio but wants $offset" >&2
106    return 1
107  fi
108
109  gpio_lookup_cache["$name"]=$(( $(<"$sysfs"/base) + offset ))
110  echo "${gpio_lookup_cache["$name"]}"
111}
112
113
114##################################################
115# Populates the GPIO lookup cache
116# Most calls to gpio_name_to_num that would
117# normally cache the sysfs lookups for gpios run
118# inside subshells. This prevents them from
119# populating a global cache and greatly speeding
120# up future lookups. This call allows scripts to
121# populate the cache prior to looking up gpios.
122##################################################
123gpio_build_cache() {
124  local timeout="${1-0}"
125  shift
126  local gpios=("$@")
127
128  if (( ${#gpios[@]} == 0 )); then
129    gpios=("${!GPIO_NAMES_TO_SCM[@]}")
130  fi
131
132  local deadline=$(( timeout + SECONDS ))
133  local name
134  for name in "${gpios[@]}"; do
135    while true; do
136      gpio_name_to_num "$name" >/dev/null && break
137      if (( deadline <= SECONDS )); then
138        echo "Timed out building gpio cache" >&2
139        return 1
140      fi
141    done
142  done
143}
144
145##################################################
146# Initializes the gpio state
147# This operation is idempotent and can be applied
148# repeatedly to the same gpio. It will make sure the
149# gpio ends up in the initialized state even if it
150# was.
151# Arguments:
152#   $1: GPIO name
153# Return:
154#   0 if success, non-zero if error
155##################################################
156gpio_init_() {
157  local name="$1"
158  local num="$2"
159
160  if [ -n "${gpio_init["$name"]+1}" ]; then
161    return 0
162  fi
163
164  if [ ! -e "/sys/class/gpio/gpio$num" ]; then
165    if ! echo "$num" >'/sys/class/gpio/export'; then
166      echo "Failed to export $name gpio$num" >&2
167      return 1
168    fi
169  fi
170  local active_low=0
171  if [[ "${name%_N}" != "$name" ]]; then
172    active_low=1
173  fi
174  if ! echo "$active_low" >"/sys/class/gpio/gpio$num/active_low"; then
175    echo "Failed to set active_low for $name gpio$num" >&2
176    return 1
177  fi
178  gpio_init["$name"]=1
179}
180gpio_init() {
181  local name="$1"
182
183  # Ensure the cache is updated by not running in a subshell
184  gpio_name_to_num "$name" >/dev/null || return
185
186  gpio_init_ "$name" "$(gpio_name_to_num "$name")"
187}
188
189##################################################
190# Sets the output GPIO value.
191# Arguments:
192#   $1: GPIO name
193#   $2: GPIO value, "1" or "0"
194# Return:
195#   0 if success, non-zero if error
196##################################################
197gpio_set_value_() {
198  local name="$1"
199  local num="$2"
200  local val="$3"
201
202  gpio_init_ "$name" "$num" || return
203  if ! echo out >"/sys/class/gpio/gpio$num/direction"; then
204    echo "Failed to set output for $name gpio$num" >&2
205    return 1
206  fi
207  if ! echo "$val" >"/sys/class/gpio/gpio$num/value"; then
208    echo "Failed to set $name gpio$num = $val" >&2
209    return 1
210  fi
211}
212gpio_set_value() {
213  local name="$1"
214  local val="$2"
215
216  # Ensure the cache is updated by not running in a subshell
217  gpio_name_to_num "$name" >/dev/null || return
218
219  gpio_set_value_ "$name" "$(gpio_name_to_num "$name")" "$val"
220}
221
222##################################################
223# Get GPIO value
224# Arguments:
225#   $1: GPIO name
226# Return:
227#   0 if success, non-zero if error
228#   stdout: The value of the gpio
229##################################################
230gpio_get_value_() {
231  local name="$1"
232  local num="$2"
233
234  gpio_init_ "$name" "$num" || return
235  if ! cat "/sys/class/gpio/gpio$num/value"; then
236    echo "Failed to get $name gpio$num value" >&2
237    return 1
238  fi
239}
240gpio_get_value() {
241  local name="$1"
242
243  # Ensure the cache is updated by not running in a subshell
244  gpio_name_to_num "$name" >/dev/null || return
245
246  gpio_get_value_ "$name" "$(gpio_name_to_num "$name")"
247}
248
249gpio_ctrl_init=1
250