{-# LANGUAGE CApiFFI #-}

-- FFI bindings to `libgpiod` for direct GPIO hardware access.
--
-- Exposes only the minimal required subset of `libgpiod` functionality used by
-- this project. The bindings are suitable for low-level hardware control.
--
-- Future work could expand this into a comprehensive `gpiod` binding package.
module Hsm.GPIO.FFI
  ( chipOpen
  , chipClose
  , input
  , output
  , LineValue
  , active
  , inactive
  , lineSettingsNew
  , lineSettingsFree
  , lineSettingsSetDirection
  , lineSettingsSetOutputValue
  , lineConfigNew
  , lineConfigFree
  , lineConfigAddLineSettings
  , requestConfigNew
  , requestConfigFree
  , requestConfigSetConsumer
  , LineRequest
  , chipRequestLines
  , lineRequestRelease
  , lineRequestSetValue
  , lineRequestSetValues
  ) where

import Foreign.C.String (CString)
import Foreign.C.Types (CInt(CInt), CSize(CSize), CUInt(CUInt))
import Foreign.Ptr (Ptr)
import Foreign.Storable (Storable)

data Chip

foreign import ccall unsafe "gpiod.h gpiod_chip_open" chipOpen :: CString -> IO (Ptr Chip)

foreign import ccall unsafe "gpiod.h gpiod_chip_close" chipClose :: Ptr Chip -> IO ()

data LineSettings

newtype LineDirection =
  LineDirection CInt
  deriving (Show)

foreign import capi unsafe "gpiod.h value GPIOD_LINE_DIRECTION_INPUT" input :: LineDirection

foreign import capi unsafe "gpiod.h value GPIOD_LINE_DIRECTION_OUTPUT" output :: LineDirection

newtype LineValue =
  LineValue CInt
  deriving (Show, Storable)

foreign import capi unsafe "gpiod.h value GPIOD_LINE_VALUE_ACTIVE" active :: LineValue

foreign import capi unsafe "gpiod.h value GPIOD_LINE_VALUE_INACTIVE" inactive :: LineValue

foreign import ccall unsafe "gpiod.h gpiod_line_settings_new" lineSettingsNew :: IO (Ptr LineSettings)

foreign import ccall unsafe "gpiod.h gpiod_line_settings_free" lineSettingsFree :: Ptr LineSettings -> IO ()

foreign import ccall unsafe "gpiod.h gpiod_line_settings_set_direction" lineSettingsSetDirection :: Ptr LineSettings -> LineDirection -> IO CInt

foreign import ccall unsafe "gpiod.h gpiod_line_settings_set_output_value" lineSettingsSetOutputValue :: Ptr LineSettings -> LineValue -> IO CInt

data LineConfig

foreign import ccall unsafe "gpiod.h gpiod_line_config_new" lineConfigNew :: IO (Ptr LineConfig)

foreign import ccall unsafe "gpiod.h gpiod_line_config_free" lineConfigFree :: Ptr LineConfig -> IO ()

foreign import ccall unsafe "gpiod.h gpiod_line_config_add_line_settings" lineConfigAddLineSettings :: Ptr LineConfig -> Ptr CUInt -> CSize -> Ptr LineSettings -> IO CInt

data RequestConfig

foreign import ccall unsafe "gpiod.h gpiod_request_config_new" requestConfigNew :: IO (Ptr RequestConfig)

foreign import ccall unsafe "gpiod.h gpiod_request_config_free" requestConfigFree :: Ptr RequestConfig -> IO ()

foreign import ccall unsafe "gpiod.h gpiod_request_config_set_consumer" requestConfigSetConsumer :: Ptr RequestConfig -> CString -> IO ()

data LineRequest

foreign import ccall unsafe "gpiod.h gpiod_chip_request_lines" chipRequestLines :: Ptr Chip -> Ptr RequestConfig -> Ptr LineConfig -> IO (Ptr LineRequest)

foreign import ccall unsafe "gpiod.h gpiod_line_request_release" lineRequestRelease :: Ptr LineRequest -> IO ()

foreign import ccall unsafe "gpiod.h gpiod_line_request_set_value" lineRequestSetValue :: Ptr LineRequest -> CUInt -> LineValue -> IO CInt

foreign import ccall unsafe "gpiod.h gpiod_line_request_set_values" lineRequestSetValues :: Ptr LineRequest -> Ptr LineValue -> IO CInt