physical.hpp

#pragma once

#include <fstream>
#include <sdbusplus/bus.hpp>
#include <sdbusplus/server/object.hpp>
#include <string>
#include <xyz/openbmc_project/Led/Physical/server.hpp>
namespace phosphor
{
namespace led
{
/** @brief Acts as input and output file for the current LED power state.
 *   Write "0" to trigger a LED OFF operation.
 *   Write "255" to trigger a LED ON operation.
 *   To know the current power state of the LED, a read on this
 *   would give either 0 or 255 indicating if the LED is currently
 *   Off / On AT THAT moment.
 *   Example: /sys/class/leds/myled/brightness
 */
constexpr auto BRIGHTNESS = "/brightness";

/** @brief Assert LED by writing 255 */
constexpr auto ASSERT = "255";

/** @brief De-assert by writing "0" */
constexpr auto DEASSERT = "0";

/** @brief Write "timer" to this file telling the driver that
 *   the intended operation is BLINK. When the value "timer" is written to
 *   the file, 2 more files get auto generated and are named "delay_on" and
 *   "delay_off"
 *   To move away from blinking, write "none"
 *   Example:  /sys/class/leds/myled/trigger
 */
constexpr auto BLINKCTRL = "/trigger";

/** @brief write number of milliseconds that the LED needs to be ON
 *   while blinking. Default is 500 by the driver.
 *   Example:  /sys/class/leds/myled/delay_on
 */
constexpr auto DELAYON = "/delay_on";

/** @brief Write number of milliseconds that the LED needs to be OFF
 *   while blinking. Default is 500 by the driver.
 *   Example:  /sys/class/leds/myled/delay_off
 */
constexpr auto DELAYOFF = "/delay_off";

/** @class Physical
 *  @brief Responsible for applying actions on a particular physical LED
 */
class Physical : public sdbusplus::server::object::object<
                     sdbusplus::xyz::openbmc_project::Led::server::Physical>
{
  public:
    Physical() = delete;
    ~Physical() = default;
    Physical(const Physical&) = delete;
    Physical& operator=(const Physical&) = delete;
    Physical(Physical&&) = delete;
    Physical& operator=(Physical&&) = delete;

    /** @brief Constructs LED object. Argument 'true' says that we hold off
     *   from sending the signals since we need to do some house keeping and
     *   only when we finish that, we are considered active and can then
     *   broadcast the signal.
     *
     * @param[in] bus       - system dbus handler
     * @param[in] objPath   - The Dbus path that hosts physical LED
     * @param[in] ledPath   - sysfs path where this LED is exported
     */
    Physical(sdbusplus::bus::bus& bus, const std::string& objPath,
             const std::string& ledPath) :

        sdbusplus::server::object::object<
            sdbusplus::xyz::openbmc_project::Led::server::Physical>(
            bus, objPath.c_str(), true),
        path(ledPath)
    {
        // Suppose this is getting launched as part of BMC reboot, then we
        // need to save what the micro-controller currently has.
        setInitialState();

        // We are now ready.
        emit_object_added();
    }

    /** @brief Overloaded State Property Setter function
     *
     *  @param[in] value   -  One of OFF / ON / BLINK
     *  @return            -  Success or exception thrown
     */
    Action state(Action value) override;

  private:
    /** @brief File system location where this LED is exposed
     *   Typically /sys/class/leds/<Led-Name>
     */
    std::string path;

    /** @brief Frequency range that the LED can operate on.
     *  Will be removed when frequency is put into interface
     */
    uint32_t frequency;

    /** @brief Brightness described above */
    std::string brightCtrl;

    /** @brief BlinkCtrl described above */
    std::string blinkCtrl;

    /** @brief delay_on described above */
    std::string delayOnCtrl;

    /** @brief delay_ff described above */
    std::string delayOffCtrl;

    /** @brief reads sysfs and then setsup the parameteres accordingly
     *
     *  @return None
     */
    void setInitialState();

    /** @brief Applies the user triggered action on the LED
     *   by writing to sysfs
     *
     *  @param [in] current - Current state of LED
     *  @param [in] request - Requested state
     *
     *  @return None
     */
    void driveLED(Action current, Action request);

    /** @brief Sets the LED to either ON or OFF state
     *
     *  @param [in] action - Requested action. Could be OFF or ON
     *  @return None
     */
    void stableStateOperation(Action action);

    /** @brief Sets the LED to BLINKING
     *
     *  @return None
     */
    void blinkOperation();

    /** @brief Generic file writer.
     *   There are files like "brightness", "trigger" , "delay_on" and
     *   "delay_off" that will tell what the LED driver needs to do.
     *
     *  @param[in] filename - Name of file to be written
     *  @param[in] data     - Data to be written to
     *  @return             - None
     */
    template <typename T>
    auto write(const std::string& fileName, T&& data)
    {
        if (std::ifstream(fileName))
        {
            std::ofstream file(fileName, std::ios::out);
            file << data;
            file.close();
        }
        return;
    }

    /** @brief Generic file reader.
     *   There are files like "brightness", "trigger" , "delay_on" and
     *   "delay_off" that will tell what the LED driver needs to do.
     *
     *  @param[in] filename - Name of file to be read
     *  @return             - File content
     */
    template <typename T>
    T read(const std::string& fileName)
    {
        T data = T();
        if (std::ifstream(fileName))
        {
            std::ifstream file(fileName, std::ios::in);
            file >> data;
            file.close();
        }
        return data;
    }
};

} // namespace led
} // namespace phosphor