refactor: simplify libgpiod implementation

Author: bgilby59

include/sensor_trigger/jetson_gpio.hpp

@@ -25,8 +25,8 @@
 
 #define SYSFS_GPIO_DIR "/sys/class/gpio"
 #define BUFFER_SIZE 64
-#define GPIO_OUTPUT 1
-#define GPIO_INPUT 0
+#define GPIO_OUTPUT gpiod::line_request::DIRECTION_OUTPUT
+#define GPIO_INPUT gpiod::line_request::DIRECTION_INPUT
 #define GPIO_HIGH 1
 #define GPIO_LOW 0
 
@@ -35,29 +35,22 @@ typedef int gpio_state;
 
 namespace jetson_gpio
 {
-// Mapping of GPIO number to pin number for ROSCubeX
-// Note: pin 5->216 is pin 5 on the DB50 connector, run by GPIO chip 216 (starting at GPIO number
-// 216)
-static std::map<int, int> pin_gpio_mapping{{5, 216}, {51, 408}, {52, 350}, {53, 446}, {54, 445}};
-
 class JetsonGpio
 {
 public:
-  JetsonGpio() : state_file_descriptor_(-1) {}
+  JetsonGpio() = default;
   ~JetsonGpio();
   bool init_gpio_pin(unsigned int gpio_chip, unsigned int gpio_line, gpio_direction direction);
   bool set_gpio_pin_state(gpio_state state);
 
 protected:
-  bool export_gpio();
-  bool unexport_gpio();
+  bool close_gpio();
   bool set_gpio_direction(gpio_direction direction);
 
-  int state_file_descriptor_;
   int gpio_;
 
   gpiod::chip gpio_chip_;
-  gpiod::line_bulk gpio_lines_;
+  gpiod::line gpio_line_;
   gpiod::line_request gpio_request_;
 };
 }  // namespace jetson_gpio

src/jetson_gpio.cpp

@@ -22,15 +22,11 @@ namespace jetson_gpio
 {
 JetsonGpio::~JetsonGpio()
 {
-  if (state_file_descriptor_ > -1) {
-    close(state_file_descriptor_);
-  }
-
   // Regardless of the existence of other processes that uses the same GPIO pin
   // (incl. zombie GPIO port opening because of failure exit),
-  // this unexport closes the target GPIO pin anyway.
+  // this function closes the target GPIO pin anyway.
   // This behavior intends to make next try to use this GPIO pin success.
-  unexport_gpio();
+  close_gpio();
 }
 
 bool JetsonGpio::init_gpio_pin(
@@ -39,49 +35,29 @@ bool JetsonGpio::init_gpio_pin(
   std::string gpio_character_device = "/dev/gpiochip" + std::to_string(gpio_chip);
 
   gpio_chip_ = gpiod::chip(gpio_character_device);
-  gpio_lines_ = gpio_chip_.get_lines(
-    std::vector<unsigned int>({gpio_line}));  // XXX: 143 = Anvil misc.I/O GP_Out_1, 108 = PWM_Out_0
+  gpio_line_ = gpio_chip_.get_line(gpio_line);
   gpio_request_ = {
-    "sensor_trigger",  // consumer name. XXX: fixed name may conflict for multiple instances
-    gpiod::line_request::DIRECTION_OUTPUT,  // request_type
-    0                                       // flag
+    "sensor_trigger",   // consumer name
+    direction,          // request_type
+    0                   // flag
   };
 
-  if (!set_gpio_direction(direction)) {
-    return false;
-  }
 
-  gpio_lines_.request(gpio_request_, std::vector<int>({GPIO_LOW}));
+  gpio_line_.request(gpio_request_, GPIO_LOW);
 
   return true;
 }
 
-bool JetsonGpio::export_gpio() { return true; }
-
-bool JetsonGpio::unexport_gpio()
+bool JetsonGpio::close_gpio()
 {
   gpio_chip_.~chip();
 
   return true;
 }
 
-bool JetsonGpio::set_gpio_direction(gpio_direction direction)
-{
-  switch (direction) {
-    case GPIO_INPUT:
-      gpio_request_.request_type = gpiod::line_request::DIRECTION_INPUT;
-      break;
-    case GPIO_OUTPUT:
-      gpio_request_.request_type = gpiod::line_request::DIRECTION_OUTPUT;
-      break;
-  }
-
-  return true;
-}
-
 bool JetsonGpio::set_gpio_pin_state(gpio_state state)
 {
-  gpio_lines_.set_values(std::vector<int>({state}));
+  gpio_line_.set_value(state);
 
   return true;
 }

src/sensor_trigger.cpp

@@ -136,14 +136,13 @@ void SensorTrigger::run()
         target_nsec = start_nsec;
         wait_nsec = 1e9 - now_nsec + start_nsec - 1e7;
       }
-      // Keep waiting for half the remaining time until the last millisecond.
+      // Keep waiting for half the remaining time until the last 10 milliseconds.
       // This is required as sleep_for tends to oversleep significantly
       if (wait_nsec > 1e7) {
         rclcpp::sleep_for(std::chrono::nanoseconds(wait_nsec / 2));
       }
     } while (wait_nsec > 1e7);
-    // std::lock_guard<std::mutex> guard(iomutex_);
-    // Block the last millisecond
+    // Block the last 10 milliseconds
     now_nsec = rclcpp::Clock{RCL_SYSTEM_TIME}.now().nanoseconds() % (uint64_t)1e9;
     if (start_nsec == end_nsec) {
       while (now_nsec > 1e7) {