tlbmc/hal/sysfs/led.h

#ifndef THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HAL_SYSFS_LED_H_
#define THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HAL_SYSFS_LED_H_

#include <cstdint>
#include <string>
#include <vector>

#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"

namespace milotic_tlbmc {

struct LedSysfsConfig {
  std::string led_sysfs_path = "/sys/class/leds/";
};

// An abstraction for interacting with the Linux LED sysfs subsystem.
//
// The Linux LED subsystem exposes LEDs at /sys/class/leds/<led_name>/ with
// the following key attributes:
//   - brightness:     Current brightness level (0 to max_brightness).
//   - max_brightness: Maximum brightness value supported by the LED.
//   - trigger:        The trigger source that controls the LED behavior
//                     (e.g., "none", "timer", "heartbeat", "default-on").
//   - delay_on:       Duration in milliseconds the LED stays on during
//                     blinking (only available when trigger is "timer").
//   - delay_off:      Duration in milliseconds the LED stays off during
//                     blinking (only available when trigger is "timer").
//
// The class is thread-safe. Thread safety is mostly guaranteed by the
// underlying sysfs filesystem.
class LedSysfs {
 public:
  // Default constructor for unit tests.
  LedSysfs() : LedSysfs(LedSysfsConfig()) {}

  explicit LedSysfs(const LedSysfsConfig& config) : config_(config) {}

  virtual ~LedSysfs() = default;

  // Returns the current brightness of the LED.
  virtual absl::StatusOr<uint32_t> GetBrightness(
      absl::string_view led_name) const;

  // Sets the brightness of the LED to the given value.
  // The value must be in the range [0, max_brightness].
  virtual absl::Status SetBrightness(absl::string_view led_name,
                                     uint32_t brightness) const;

  // Returns the maximum brightness value supported by the LED.
  virtual absl::StatusOr<uint32_t> GetMaxBrightness(
      absl::string_view led_name) const;

  // Returns the current trigger of the LED.
  // The active trigger is enclosed in brackets in the sysfs trigger file,
  // e.g., "none [timer] heartbeat default-on".
  virtual absl::StatusOr<std::string> GetTrigger(
      absl::string_view led_name) const;

  // Returns the list of available triggers for the LED.
  virtual absl::StatusOr<std::vector<std::string>> GetAvailableTriggers(
      absl::string_view led_name) const;

  // Sets the trigger of the LED to the given value.
  virtual absl::Status SetTrigger(absl::string_view led_name,
                                  absl::string_view trigger) const;

  // Returns the delay_on value in milliseconds (timer trigger only).
  virtual absl::StatusOr<uint32_t> GetDelayOn(absl::string_view led_name) const;

  // Sets the delay_on value in milliseconds (timer trigger only).
  virtual absl::Status SetDelayOn(absl::string_view led_name,
                                  uint32_t delay_ms) const;

  // Returns the delay_off value in milliseconds (timer trigger only).
  virtual absl::StatusOr<uint32_t> GetDelayOff(
      absl::string_view led_name) const;

  // Sets the delay_off value in milliseconds (timer trigger only).
  virtual absl::Status SetDelayOff(absl::string_view led_name,
                                   uint32_t delay_ms) const;

  // Returns true if the LED exists in sysfs.
  virtual bool IsLedPresent(absl::string_view led_name) const;

  std::string GetLedSysfsPath() const { return config_.led_sysfs_path; }

 private:
  const LedSysfsConfig config_;
};

}  // namespace milotic_tlbmc

#endif  // THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HAL_SYSFS_LED_H_