#!/bin/sh

##############################################################################
#
# GPIO setup script for SvxLink server. Run this script to set up the GPIO
# configuration specified in the GPIO specific configuration file
# @SVX_SYSCONF_INSTALL_DIR@/gpio.conf
#
##############################################################################

# Exit on failed commands and undefined variables
set -eu

# Read configuration file
GPIO_CONF=${GPIO_CONF-"@SVX_SYSCONF_INSTALL_DIR@/gpio.conf"}
[ -r "${GPIO_CONF}" ] && . "${GPIO_CONF}"


# Print error message to stderr and exit
#
#   MSG -- The message to print
#
error()
{
  local MSG="$1"; shift
  echo "*** ERROR: ${MSG}" 1>&2
  exit 1
}


# Set up the given GPIO pin.
#
# Enable the given GPIO pin, set direction (in/out), set active state (active
# low or active high) and reset outputs to OFF value. Also set user, group and
# mode for the pin.
#
# The function take three arguments:
#
#   PIN           -- The name of the GPIO pin (e.g. gpio4)
#   DIRECTION     -- If this is an input or output pin ("in" or "out")
#   ACTIVE_LEVEL  -- What level signifies active state ("low" or "high")
#
gpio_setup()
{
  local PIN="$1"; shift
  local DIRECTION="$1"; shift
  local ACTIVE_LEVEL="$1"; shift

  if [ -z "${PIN}" ]; then
    error "GPIO pin name is empty"
    return 1
  fi

  local direction="${DIRECTION}"
  if [ "${ACTIVE_LEVEL}" = "high" ]; then
    local active_low="0"
    [ "${DIRECTION}" = "out" ] && direction="low"
  else
    local active_low="1"
    [ "${DIRECTION}" = "out" ] && direction="high"
  fi

  local pin_path="${GPIO_PATH}/${PIN}"
  local value_path="${pin_path}/value"
  local active_low_path="${pin_path}/active_low"
  local direction_path="${pin_path}/direction"
  local changed="false"

  if [ ! -e "${pin_path}" ]; then
    # Extract pinnumber from the full pin name (e.g. gpio4_pd0 -> 4)
    local pinnum=$(echo "${PIN}" | sed 's/^[^0-9]*\([0-9][0-9]*\).*$/\1/')
    if ! echo ${pinnum} > "${GPIO_PATH}/export"; then
      error "Failed to export GPIO pin \"${PIN}\" (pin number ${pinnum})"
    fi
    local retries=5
    while [ ! -e "${pin_path}" ]; do
      retries=$((retries - 1))
      if [ ${retries} -eq 0 ]; then
        error "GPIO pin \"${pin_path}\" not created within ${retries} seconds"
      fi
      sleep 1
    done
    if [ -n "${GPIO_USER:-}" ]; then
      if ! chown "${GPIO_USER}" "${value_path}"; then
        error "Failed to change owner of GPIO pin \"${value_path}\""
      fi
    fi
    if [ -n "${GPIO_GROUP:-}" ]; then
      if ! chgrp "${GPIO_GROUP}" "${value_path}"; then
        error "Failed to change group of GPIO pin \"${value_path}\""
      fi
    fi
    if [ -n "${GPIO_MODE:-}" ]; then
      if ! chmod "${GPIO_MODE}" "${value_path}"; then
        error "Failed to change mode of GPIO pin \"${value_path}\""
      fi
    fi
    changed="true"
  fi

  if [ ! -e "${active_low_path}" ]; then
    error "Missing path \"${active_low_path}\" for GPIO pin"
  fi
  if $changed || [ "$(cat "${active_low_path}")" != "${active_low}" ]; then
     if ! echo "${active_low}" > "${active_low_path}"; then
      error "Failed to set active_low state of GPIO pin \"${active_low_path}\""
    fi
    changed="true"
  fi

  if [ ! -e "${direction_path}" ]; then
    error "Missing path \"${direction_path}\" for GPIO pin"
  fi
  if $changed || [ "$(cat "${direction_path}")" != "${DIRECTION}" ]; then
    if ! echo "${direction}" > "${direction_path}"; then
      error "Failed to set direction of GPIO pin \"${direction_path}\""
    fi
  fi
}


## Set up GPIO input pins that should be active high
for pin in ${GPIO_IN_HIGH:-}; do
  gpio_setup "${pin}" "in" "high"
done

## Set up GPIO input pins that should be active low
for pin in ${GPIO_IN_LOW:-}; do
  gpio_setup "${pin}" "in" "low"
done

## Set up GPIO output pins that should be active high
for pin in ${GPIO_OUT_HIGH:-}; do
  gpio_setup "${pin}" "out" "high"
done

## Set up GPIO output pins that should be active low
for pin in ${GPIO_OUT_LOW:-}; do
  gpio_setup "${pin}" "out" "low"
done
