From edfbfa49c810ebb6a3f4ed705eef4f3dba291f35 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Thu, 30 Dec 2021 22:34:57 +0100
Subject: sensors: init is now idempotent

---
 files/common/openwrt/sensors.module_lua | 52 +++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 9 deletions(-)

(limited to 'files/common')

diff --git a/files/common/openwrt/sensors.module_lua b/files/common/openwrt/sensors.module_lua
index 8a209dce..6c279188 100644
--- a/files/common/openwrt/sensors.module_lua
+++ b/files/common/openwrt/sensors.module_lua
@@ -5,6 +5,7 @@ local io = require("io")
 local string = require("string")
 local time = require "posix.time"
 local unistd = require "posix.unistd"
+local sys_stat = require "posix.sys.stat"
 
 local _M = {}
 local _internal_ = {}
@@ -58,6 +59,29 @@ function _M.i2c_delete_device(bus, address)
     return _internal_.write_to_file(_M.i2c_bus_path(bus) .. "/delete_device", string.format("0x%02x", address))
 end
 
+function _M.i2c_add_or_replace_device(bus, address, name)
+    local s, _ = sys_stat.stat(_M.i2c_device_path(bus, address))
+    if s == nil then
+        local ret, err = _M.i2c_add_device(bus, address, name)
+        if not ret then return nil, err end
+        return true, nil
+    end
+
+    local contents, _ = _internal_.read_from_file(_M.i2c_device_path(bus, address) .. "/name")
+    if contents == nil or contents:gsub("%s+", "") ~= name then
+        local ret, err = _M.i2c_delete_device(bus, address)
+        if not ret then return nil, err end
+
+        time.nanosleep({tv_sec = 0, tv_nsec = 100000000})
+
+        ret, err = _M.i2c_add_device(bus, address, name)
+        if not ret then return nil, err end
+        return true, nil
+    end
+
+    return false, nil
+end
+
 function _M.i2c_get_bus_number_from_name(name)
     local bus_paths, glob_result = glob.glob("/sys/bus/i2c/devices/i2c-*", 0)
     if not bus_paths then
@@ -102,7 +126,7 @@ function _M.i2c_get_mux_channels(parent, address)
 end
 
 
-function _M.i2c_add_devices_recursive(bus_num, bus_name, devices)
+function _M.i2c_setup_devices_recursive(bus_num, bus_name, devices)
     if bus_num == nil then
         local err
         bus_num, err = _M.i2c_get_bus_number_from_name(bus_name)
@@ -112,12 +136,12 @@ function _M.i2c_add_devices_recursive(bus_num, bus_name, devices)
     local num_sensors = 0
     local device
     for _, device in base.ipairs(devices) do
-        local ret, err = _M.i2c_add_device(bus_num, device.address, device.type)
-        if not ret then return nil, err end
+        local changed, err = _M.i2c_add_or_replace_device(bus_num, device.address, device.type)
+        if changed == nil then return nil, err end
 
         local setup_function = _internal_.setup[device.type]
         if setup_function ~= nil then
-            time.nanosleep({tv_sec = 0, tv_nsec = 100000000})
+            if changed then time.nanosleep({tv_sec = 0, tv_nsec = 100000000}) end
             local ret, err = setup_function(bus_num, device.address)
             if ret == nil then return nil, err end
             num_sensors = num_sensors + ret
@@ -130,8 +154,8 @@ function _M.i2c_add_devices_recursive(bus_num, bus_name, devices)
             local channel
             for _, channel in base.ipairs(device.channels) do
                 if not mux_channels[channel.number] then return nil, string.format("i2c-mux %s has no channel %d", _M.i2c_device_name(bus_num, device.address), channel.number) end
-                local tmp, err = _M.i2c_add_devices_recursive(mux_channels[channel.number], nil, channel.devices)
-                if ret == nil then return nil, err end
+                local tmp, err = _M.i2c_setup_devices_recursive(mux_channels[channel.number], nil, channel.devices)
+                if tmp == nil then return nil, err end
                 num_sensors = num_sensors + tmp
             end
         end
@@ -246,6 +270,16 @@ function _M.gpio_unexport_pin(number)
     return _internal_.write_to_file("/sys/class/gpio/unexport", string.format("%d", number))
 end
 
+function _M.gpio_setup_pin(number)
+    local s, _ = sys_stat.stat(_M.gpio_pin_path(number))
+    if s == nil then
+        local ret, err = _M.gpio_export_pin(number)
+        if not ret then return nil, err end
+        return true, nil
+    end
+    return false, nil
+end
+
 function _M.gpio_read_pin(number)
     local value, err = _internal_.read_from_file(_M.gpio_pin_path(number) .. "/value")
     if not value then return nil, err end
@@ -257,8 +291,8 @@ function _M.gpio_setup_pins(pins)
     local num_pins = 0
     local pin
     for _, pin in base.ipairs(pins) do
-        local ret, err = _M.gpio_export_pin(pin.number)
-        if ret == nil then return nil, err end
+        local changed, err = _M.gpio_setup_pin(pin.number)
+        if changed == nil then return nil, err end
         num_pins = num_pins + 1
     end
 
@@ -458,7 +492,7 @@ function _M.setup(config)
     if config.i2c then
         local i2c_bus
         for _, i2c_bus in base.ipairs(config.i2c) do
-            local tmp, err = _M.i2c_add_devices_recursive(i2c_bus.number, i2c_bus.name, i2c_bus.devices)
+            local tmp, err = _M.i2c_setup_devices_recursive(i2c_bus.number, i2c_bus.name, i2c_bus.devices)
             if tmp == nil then return nil, err end
             num_sensors = num_sensors + tmp
         end
-- 
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