Temperature.h

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/*!****************************************************************************
 *  @file       Temperature.h
 *
 *  @brief      Temperature driver
 *
 *  @anchor ti_drivers_Temperature_Overview
 *  # Overview #
 *  The Temperature driver provides services related to measuring and reacting
 *  to the current temperature of the chip and changes to it.
 *
 *  The two main services provided are:
 *      - Getting the current temperature
 *      - Providing notification callbacks when the temperature changes
 *
 *  @anchor ti_drivers_Temperature_Usage
 *  # Usage #
 *
 *  ## Initialisation #
 *  Unlike most drivers, there is only a single instance of the temperature
 *  driver that is always available once #Temperature_init() is called.
 *  #Temperature_init() should be called once before using other Temperature
 *  driver APIs. It is not called automatically via SysConfig generated code.
 *  Subsequent #Temperature_init() calls will have no effect.
 *
 *  ## Getting the Current Temperature #
 *  The most basic function of the driver is to provide the current temperature
 *  and return it. It is encoded as a signed integer in degrees C.
 *
 *  ## Notifications #
 *  The other major function of the Temperature driver is to notify the
 *  application when the temperature changes and crosses an application-defined
 *  threshold.
 *
 *  There are three default usecases for this:
 *      - High threshold.
 *        The application will receive a notification callback when
 *        currentTemperature >= thresholdHigh.
 *      - Low threshold.
 *        The application will receive a notification callback when
 *        currentTemperature <= thresholdLow.
 *      - Range threshold.
 *        The application will receive a notification callback when
 *        currentTemperature >= thresholdHigh || currentTemperature <=
 *        thresholdLow. This setup addresses usecases
 *        where a notification is required when the temperature changes by a
 *        certain amount regardless of whether it is up or down. Adjusting
 *        clock offsets based on temperature is a good example of this.
 *
 *  ### Registering Notifications
 *  There are three functions that register a notification for the application:
 *      - #Temperature_registerNotifyHigh()
 *      - #Temperature_registerNotifyLow()
 *      - #Temperature_registerNotifyRange()
 *
 *  Multiple notifications may be registered. The different parts of the
 *  application and drivers that need to respond to a temperature change do not
 *  need to know of one another.
 *  Each notification must have its own #Temperature_NotifyObj and must be
 *  registered individually.
 *
 *  ### Notification Callbacks
 *  Once the chip temperature crosses the smallest high threshold or largest
 *  low threshold amongst the registered notifications, the driver will
 *  iterate over the entire list of registered notification and check which
 *  ones have triggered. Notifications that have triggered are removed from
 *  the list of registered notifications and thus are no longer registered.
 *  Their callback function is then invoked.
 *
 *  If an application wishes to re-register a notification that just triggered
 *  and was unregistered, it may register it again from within the notification
 *  callback or another context.
 *
 *  It is possible to determine whether the high or low threshold triggered
 *  the notification callback as follows:
 *      - currentTemperature <= thresholdTemperature: Low threshold triggered
 *      - currentTemperature >= thresholdTemperature: High threshold triggered
 *  This information is only reasonably useful when registering a notification
 *  with both a high and low threshold using #Temperature_registerNotifyRange().
 *  Even then, the expected basic usecase only cares about the current
 *  temperature and adding an offset to it when registering the notification
 *  again.
 *
 *  ### Unregistering Notifications
 *  Registered notifications are unregistered in two ways:
 *      - Automatically when a notification triggers
 *      - By calling #Temperature_unregisterNotify()
 *
 *  Unregistered notifications may be registered again at any time.
 *
 *  # Measured vs True Temperature
 *  While the driver aims to supply and act on an accurate absolute temperature,
 *  there will be differences between the measured vs the true temperature due
 *  to inherent variances in the manufacturing process. The nature of these
 *  differences varies by device family.
 *
 *  Examples of such differences:
 *      - A constant per-chip offset between the measured and the true
 *        temperature
 *      - An temperature dependent per-chip offset between the measured and the
 *        true temperature
 *      - A variance in the measured temperature when measuring multiple times
 *        at the same chip temperature
 *
 *  It is strongly recommended to read the device-specific Temperature driver
 *  documentation for details of the temperature sensor characteristics and
 *  how they might affect choices of threshold values.
 *
 *  @anchor ti_drivers_Temperature_Synopsis
 *  # Synopsis #
 *  @anchor ti_drivers_Temperature_Synopsis_Code
 *  @code
 *  #include <ti/drivers/Temperature.h>
 *
 *  #define WINDOW_DELTA 10
 *
 *  Temperature_init();
 *
 *  currentTemperature = Temperature_getTemperature();
 *
 *  result = Temperature_registerNotifyRange(&notifyObject,
 *                                           currentTemperature + WINDOW_DELTA,
 *                                           currentTemperature - WINDOW_DELTA,
 *                                           myNotifyFxn,
 *                                           clientArg);
 *  @endcode
 *
 *  @anchor ti_drivers_Temperature_Examples
 *  # Examples #
 *
 *  ## Register a High Threshold Notification #
 *
 *  @code
 *
 *  // The notification will trigger when the temperature reaches 40 C
 *  #define THRESHOLD_CUTOFF 40
 *
 *  #include <ti/drivers/Temperature.h>
 *
 *  void thresholdNotifyFxn(int16_t currentTemperature,
 *                          int16_t thresholdTemperature,
 *                          uintptr_t clientArg,
 *                          Temperature_NotifyObj *notifyObject) {
 *     // Post a semaphore, set a flag, or otherwise act upon the temperature
 *     // change.
 *  }
 *
 *  ...
 *
 *  // Initialize the Temperature driver and register a notification.
 *
 *  Temperature_init();
 *
 *  int_fast16_t status = Temperature_registerNotifyHigh(notifyObject,
 *                                                       THRESHOLD_CUTOFF,
 *                                                       thresholdNotifyFxn,
 *                                                       NULL);
 *
 *  if (status != Temperature_STATUS_SUCCESS) {
 *      // Handle error
 *  }
 *
 *  @endcode
 *
 *  ## Register a Range Threshold Notification and Re-register in Callback #
 *
 *  @code
 *
 *  #define THRESHOLD_DELTA 5
 *
 *  #include <ti/drivers/Temperature.h>
 *
 *
 *  void deltaNotificationFxn(int16_t currentTemperature,
 *                        int16_t thresholdTemperature,
 *                        uintptr_t clientArg,
 *                        Temperature_NotifyObj *notifyObject) {
 *      int_fast16_t status;
 *
 *      status = Temperature_registerNotifyRange(notifyObject,
 *                                               currentTemperature + THRESHOLD_DELTA,
 *                                               currentTemperature - THRESHOLD_DELTA,
 *                                               deltaNotificationFxn,
 *                                               NULL);
 *
 *      if (status != Temperature_STATUS_SUCCESS) {
 *          while(1);
 *      }
 *  }
 *
 *   ...
 *
 *  // Initialize the Temperature driver and register a notification.
 *
 *  Temperature_init();
 *
 *  int16_t currentTemperature = Temperature_getTemperature();
 *
 *  int_fast16_t status = Temperature_registerNotifyRange(notifyObject,
 *                                                        currentTemperature + THRESHOLD_DELTA,
 *                                                        currentTemperature - THRESHOLD_DELTA,
 *                                                        deltaNotificationFxn,
 *                                                        NULL);
 *  @endcode
 */

#ifndef ti_drivers_Temperature__include
#define ti_drivers_Temperature__include

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#include <ti/drivers/utils/List.h>

#ifdef __cplusplus
extern "C" {
#endif

#define Temperature_STATUS_RESERVED (-32)

#define Temperature_STATUS_SUCCESS (0)

#define Temperature_STATUS_ERROR (-1)

/* @cond
 *
 * Type declaration for the notification object made separately from the
 * struct definition because of the circular dependency between
 * #Temperature_NotifyFxn() and #Temperature_NotifyObj.
 */
typedef struct Temperature_NotifyObj Temperature_NotifyObj;
/* @endcond */

typedef void (*Temperature_NotifyFxn)(int16_t currentTemperature,
                                      int16_t thresholdTemperature,
                                      uintptr_t clientArg,
                                      Temperature_NotifyObj *notifyObject);

struct Temperature_NotifyObj
{
    List_Elem link;                  
    Temperature_NotifyFxn notifyFxn; 
    int16_t thresholdHigh;           
    int16_t thresholdLow;            
    uintptr_t clientArg;             
    bool isRegistered;               
};

void Temperature_init(void);

int16_t Temperature_getTemperature(void);

int_fast16_t Temperature_registerNotifyHigh(Temperature_NotifyObj *notifyObject,
                                            int16_t thresholdHigh,
                                            Temperature_NotifyFxn notifyFxn,
                                            uintptr_t clientArg);

int_fast16_t Temperature_registerNotifyLow(Temperature_NotifyObj *notifyObject,
                                           int16_t thresholdLow,
                                           Temperature_NotifyFxn notifyFxn,
                                           uintptr_t clientArg);

int_fast16_t Temperature_registerNotifyRange(Temperature_NotifyObj *notifyObject,
                                             int16_t thresholdHigh,
                                             int16_t thresholdLow,
                                             Temperature_NotifyFxn notifyFxn,
                                             uintptr_t clientArg);

int_fast16_t Temperature_unregisterNotify(Temperature_NotifyObj *notifyObject);

int16_t Temperature_getThresholdHigh(Temperature_NotifyObj *notifyObject);

int16_t Temperature_getThresholdLow(Temperature_NotifyObj *notifyObject);

void Temperature_getThresholdRange(Temperature_NotifyObj *notifyObject, int16_t *thresholdHigh, int16_t *thresholdLow);

uintptr_t Temperature_getClientArg(Temperature_NotifyObj *notifyObject);

Temperature_NotifyFxn Temperature_getNotifyFxn(Temperature_NotifyObj *notifyObject);

#ifdef __cplusplus
}
#endif

#endif /* ti_drivers_Temperature__include */