TRNGCC26XX.h

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/*!****************************************************************************
 *  @file       TRNGCC26XX.h
 *
 *  @brief      TRNG driver implementation for the CC26XX family
 *
 *  This file should only be included in the board file to fill the TRNG_config
 *  struct.
 *
 *  # Hardware
 *
 *  The CC26XX family has a dedicated hardware TRNG based on sampling multiple
 *  free running oscillators. With all FROs enabled, the TRNG hardware generates
 *  64 bits of entropy approximately every 5ms. The driver implementation
 *  chains multiple 64-bit entropy generation operations together to generate
 *  an arbitrary amount of entropy.
 *
 *  # Behaviour
 *
 *  The driver keeps a global pool of entropy available to service any requests
 *  immediately. If the pool is not sufficiently large or is too depleted to
 *  service a request, entropy will be generated until the request is serviced.
 *  If there is an ongoing TRNG request that the hardware is generating entropy
 *  for, the driver will queue any other requests and work them off in FIFO
 *  order.
 *
 *  Requests issued by driver instances with polling return behaviour will
 *  preempt any executing requests and be serviced immediately.
 *
 *  After the request queue is emptied, the driver will start an asynchronous
 *  operation in the background to refill the depleted entropy pool.
 *
 *  # Samples Per Cycle
 *
 *  The EIP-75t HW takes 240,000 clock cycles in the default setting to generate
 *  one round of output (i.e. 64 bits). This comes to 5ms on a 48MHz clock. The
 *  clock cycles per round can be configured to be as low as 2^8 (256) to as high
 *  as 2^24 (16,777,216).
 *  Entropy re-generation time can be tailored in a trade-off between speed of
 *  random number generation and amount of entropy in each of those random numbers.
 */

#ifndef ti_drivers_TRNG_TRNGCC26XX__include
#define ti_drivers_TRNG_TRNGCC26XX__include

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

#include <ti/drivers/Power.h>
#include <ti/drivers/TRNG.h>
#include <ti/drivers/cryptoutils/cryptokey/CryptoKey.h>

#include <ti/drivers/dpl/HwiP.h>
#include <ti/drivers/dpl/SemaphoreP.h>

#ifdef __cplusplus
extern "C" {
#endif

#define TRNGCC26XX_SAMPLES_PER_CYCLE_MIN     256

#define TRNGCC26XX_SAMPLES_PER_CYCLE_DEFAULT 240000

#define TRNGCC26XX_SAMPLES_PER_CYCLE_MAX     16777216

#define TRNGCC26XX_MIN_BYTES_PER_ITERATION (2 * sizeof(uint32_t))

#ifndef TRNGCC26XX_ENTROPY_POOL_SIZE
    #define TRNGCC26XX_ENTROPY_POOL_SIZE (32 / sizeof(uint64_t))
#endif

typedef struct
{
    uint8_t intPriority;
    uint32_t swiPriority;
    uint32_t samplesPerCycle;
} TRNGCC26XX_HWAttrs;

typedef struct
{
    List_Elem listElement; /* Must start with a List_Elem
                            * to allow casting of List_Elem
                            * pointer returned by List APIs
                            * to TRNGCC26XX_Object pointers.
                            */
    TRNG_Handle handle;
    TRNG_CryptoKeyCallbackFxn cryptoKeyCallbackFxn;
    TRNG_RandomBytesCallbackFxn randomBytesCallbackFxn;
    uint32_t samplesPerCycle;
    CryptoKey *entropyKey;
    uint8_t *entropyBuffer;
    uint32_t semaphoreTimeout;
    size_t entropyGenerated;
    size_t entropyRequested;
    int_fast16_t returnStatus;
    TRNG_ReturnBehavior returnBehavior;
    bool isOpen;
    bool isEnqueued;
    SemaphoreP_Struct operationSemaphore;
} TRNGCC26XX_Object;

extern int_fast16_t TRNGCC26XX_setSamplesPerCycle(TRNG_Handle handle, uint32_t samplesPerCycle);

#ifdef __cplusplus
}
#endif

#endif /* ti_drivers_TRNG_TRNGCC26XX__include */