Basic GPIO driver

include/luares.h

@@ -6,6 +6,7 @@ extern char lua_computer[];
 extern char lua_debug[];
 extern char lua_eeprom[];
 extern char lua_filesystem[];
+extern char lua_gpio[];
 extern char lua_init[];
 extern char lua_internet[];
 extern char lua_sandbox[];

src/c/modules.c

@@ -16,6 +16,7 @@ void setup_modules(lua_State *L) {
   pushstuple(L, "debug", lua_debug);
   pushstuple(L, "eeprom", lua_eeprom);
   pushstuple(L, "filesystem", lua_filesystem);
+  pushstuple(L, "gpio", lua_gpio);
   pushstuple(L, "internet", lua_internet);
   pushstuple(L, "sandbox", lua_sandbox);
   pushstuple(L, "textgpu", lua_textgpu);

src/lua/core/gpio.lua

@@ -0,0 +1,74 @@
+local gpio = {}
+
+local fopen = native.fs_open
+local fread = native.fs_read
+local fwrite = native.fs_write
+local fclose = native.fs_close
+local fexists = native.fs_exists
+
+local function _read(file)
+  local fd = fopen(file, "r")
+  if not fd then
+    return nil, "Can't open " .. file .. " for reading"
+  end
+  local v = fread(fd, 1024)
+  fclose(fd)
+  return v
+end
+
+local function _write(file, value)
+  local fd = fopen(file, "w")
+  if not fd then
+    return false, "Can't open " .. file .. " for writing"
+  end
+  fwrite(fd, value)
+  fclose(fd)
+  return true
+end
+
+gpio.register = function ()
+  if not fexists("/sys/class/gpio") then
+    return
+  end
+  local component = {}
+  function component.pinMode(pin, mode) --TODO: return current mode if no new is specified
+    checkArg(1, pin, "number")
+    checkArg(2, mode, "string")
+    pin = tostring(math.floor(pin))
+    if mode ~= "in" and mode ~= "out" then
+      return false, "Invalid mode string"
+    end
+    if not fexists("/sys/class/gpio/gpio" .. pin) then
+      _write("/sys/class/gpio/export", pin)
+    end
+    if not _write("/sys/class/gpio/gpio" .. pin .. "/direction", mode) then
+      return false, "Couldn't set pin mode"
+    end
+    return mode
+  end
+
+  function component.write(pin, value)
+    checkArg(1, pin, "number")
+    checkArg(2, pin, "boolean", "number", "nil")
+    pin = tostring(math.floor(pin))
+    value = (value == true or value > 0) and "1" or "0"
+    if not fexists("/sys/class/gpio/gpio" .. pin) then
+      return false, "Set pin mode first"
+    end
+    if not _write("/sys/class/gpio/gpio" .. pin .. "/value", value) then
+      return false, "Couldn't set pin value"
+    end
+  end
+
+  function component.read(pin)
+    checkArg(1, pin, "number")
+    pin = tostring(math.floor(pin))
+    if not fexists("/sys/class/gpio/gpio" .. pin) then
+      return false, "Set pin mode first"
+    end
+    return _read("/sys/class/gpio/gpio" .. pin .. "/value")
+  end
+  return modules.component.api.register(uuid, "gpio", component)
+end
+
+return gpio

src/lua/core/init.lua

@@ -61,6 +61,7 @@ function main()
 
   --Components
   loadModule("eeprom")
+  loadModule("gpio")
   loadModule("textgpu")
   loadModule("filesystem")
   loadModule("internet")
@@ -75,6 +76,7 @@ function main()
   _G.pushEvent = modules.computer.api.pushSignal
 
   modules.eeprom.register()
+  modules.gpio.register()
   modules.internet.start()
   modules.filesystem.register("root")
   if native.debug then