Initial commitHEADmaster

Create a basic but functional power manager, as well as a systemd unit
file.

3 files changed, 150 insertions, 0 deletions

diff --git a/src/Config.hs b/src/Config.hs
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+++ b/src/Config.hs
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+-- Copyright 2016 Benjamin Barenblat
+--
+-- 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.
+
+-- | Application configuration.
+
+module Config
+    ( Config(..)
+    , load
+    ) where
+
+import Control.Applicative ((<$>))
+import Data.Bifunctor (bimap)
+import qualified Data.ConfigFile as ConfigFile
+
+data Config = Config
+    { stopCapacity :: Int
+        -- ^ percentage charge required to enter the “fully charged” state
+    , stopCurrent :: Int
+        -- ^ maximum charge current (in microamperes, µA) to remain in the
+        -- “fully charged” state
+    , startCapacity :: Int
+        -- ^ percentage at or below which charging will begin
+    } deriving (Eq, Show)
+
+defaultConfig :: Config
+defaultConfig = Config
+    { stopCapacity = 99
+    , stopCurrent = 80000
+    , startCapacity = 95
+    }
+
+configFilePath :: FilePath
+configFilePath = "/etc/pndpowerd.conf"
+
+load :: IO (Either String Config)
+load =
+    bimap show parse <$> ConfigFile.readfile ConfigFile.emptyCP configFilePath
+
+parse :: ConfigFile.ConfigParser -> Config
+parse serialized =
+    let get field name = either (const $ field defaultConfig) id $
+            ConfigFile.get serialized "DEFAULT" name
+    in Config { stopCapacity = get stopCapacity "stopCapacity"
+              , stopCurrent = get stopCurrent "stopCurrent"
+              , startCapacity = get startCapacity "startCapacity"
+              }
diff --git a/src/Main.hs b/src/Main.hs
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+-- Copyright 2016 Benjamin Barenblat
+--
+-- 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.
+
+module Main where
+
+import Control.Applicative ((<$>))
+import Control.Concurrent (threadDelay)
+import Control.Monad (forever, when)
+import Data.Either.Utils (forceEither)
+import qualified Config
+import qualified Pandora
+
+main :: IO ()
+main = do
+    config <- forceEither <$> Config.load
+    forever $ do
+        percent <- Pandora.chargePercent
+        current <- Pandora.chargeCurrent
+        chargingEnabled <- Pandora.chargingEnabled
+        if chargingEnabled
+            && Config.stopCapacity config <= percent
+            && 0 < current
+            && current < Config.stopCurrent config
+            then Pandora.setCharging False
+            else when (not chargingEnabled
+                       && percent <= Config.stopCapacity config) $
+                Pandora.setCharging True
+        threadDelay (secondsToMicroseconds 60)
+
+secondsToMicroseconds :: Int -> Int
+secondsToMicroseconds = (* 1000000)
diff --git a/src/Pandora.hs b/src/Pandora.hs
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+++ b/src/Pandora.hs
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+-- Copyright 2016 Benjamin Barenblat
+--
+-- 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.
+
+module Pandora
+    ( chargePercent
+    , chargeCurrent
+    , chargingEnabled
+    , setCharging
+    ) where
+
+import Control.Applicative ((<$>))
+import System.FilePath ((</>))
+
+fuelGauge :: String
+fuelGauge = "/sys/class/power_supply/bq27500-0"
+
+acCharger :: String
+acCharger = "/sys/class/power_supply/twl4030_ac"
+
+chargePercent :: IO Int
+chargePercent = read <$> readFile (fuelGauge </> "capacity")
+
+-- | Determines the charge current in microamperes (µA).
+chargeCurrent :: IO Int
+chargeCurrent = read <$> readFile (fuelGauge </> "current_now")
+
+chargingEnabled :: IO Bool
+chargingEnabled = do
+    t <- readFile (acCharger </> "enable")
+    return $ case t of
+        "0\n" -> False
+        "1\n" -> True
+        _ -> error "no parse"
+
+setCharging :: Bool -> IO ()
+setCharging = writeFile (acCharger </> "enable") . showAsInt
+
+showAsInt :: Bool -> String
+showAsInt False = "0"
+showAsInt True  = "1"