NVSLPF3.h

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/*!*****************************************************************************
 *  @file       NVSLPF3.h
 *  @brief      Non-Volatile Storage driver for Low Power F3 devices.
 *
 *  ## Interrupt Latency During Flash Operations #
 *
 *  When writing or erasing flash, interrupts must be disabled to avoid
 *  executing code in flash while the flash is being reprogrammed. This
 *  constraint is handled by the driver. Application code does not need to
 *  safeguard against this.
 *
 *  Additionally, to avoid extremely large interrupt latencies that would be
 *  incurred if entire blocks were written with interrupts disabled, block
 *  writes to flash are broken into multiple smaller sizes. Even with this
 *  scheme in place, latencies of roughly 64 microseconds will be incurred while
 *  flash is being written to.
 *
 *  A similar caveat applies to flash erase operations. Erasing an entire flash
 *  sector (the minimal amount that can be erased at a time) can take roughly 8
 *  milliseconds. This entire operation must be performed with interrupts
 *  disabled. Here again, this requirement is met internally by the driver and
 *  flash region erases are performed one sector at a time to minimize this
 *  significant latency impact.
 *
 *  Care must be taken by the user to not perform flash write or erase
 *  operations during latency critical phases of an application. See the
 *  NVS_lock() and NVS_unlock() API descriptions for more information.
 *
 *  ## Maximum flash writes before erase #
 *
 *  On Low Power F3 devices, memory rows can be 128 or 256 bytes in length;
 *  refer to the device datasheet for the exact size.  A maximum of 83 write
 *  operations can be performed on a memory row.  Once the limit is reached, the
 *  row must be erased before it is written to again. It is the developer's
 *  responsibility to ensure that this limit is not exceeded in their
 *  applications. The developer may also opt to use the third party SPIFFS
 *  library implementation supported by TIRTOS which does track writes.
 *
 *  \note The 83 write limit persists through device reset & power cycles. If 60
 *  write operations were performed on a memory row & the device is reset; the
 *  page can still only be written to 23 more times before it must be erased.
 *
 *  A write "Scoreboard" can be enabled in this driver; the scoreboard keeps
 *  track of how many times a page has been written to.  It is provided as a
 *  debug tool to ensure the 83 write limit is not exceeded.  If a page is
 *  written to more than 83 times, the NVSLPF3 driver will spin forever. Each
 *  byte in the scoreboard corresponds to a memory page in the NVS region. The
 *  byte is incremented when the memory is written to & set to 0 when erased.
 *
 *  To enable the "scoreboard" the "NVSLPF3_INSTRUMENTED" symbol must be
 *  defined when the driver is compiled.  Three new fields are added to the
 *  #NVSLPF3_HWAttrs structure:
 *    * scoreboard - a buffer provided by the application where each byte
 *      represents how many times a page has been written to.
 *    * scoreboardSize - number of bytes in the scoreboard.
 *    * flashPageSize - number of bytes in a flash page (i.e. 128 or 256)
 *
 *  When configured correctly, the scoreboard can be viewed in a memory browser.
 *
 *  \note The scoreboard will only keep track of writes to flash within a NVS
 *         region using a NVS driver.  Writes performed outside the NVS region
 *         or without the NVS driver are untracked.
 *
 *  \note  The scoreboard is in RAM & will be lost on reset or power cycle.
 *
 *
 *  ============================================================================
 */

#ifndef ti_drivers_nvs_NVSLPF3__include
#define ti_drivers_nvs_NVSLPF3__include

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

#if defined(__cplusplus)
extern "C" {
#endif

#define NVSLPF3_STATUS_LOW_VOLTAGE (NVS_STATUS_RESERVED - 1)

extern const NVS_FxnTable NVSLPF3_fxnTable;

typedef struct
{
    void *regionBase; 
    size_t regionSize; 
#if defined(NVSLPF3_INSTRUMENTED)
    uint8_t *scoreboard;    
    size_t scoreboardSize;  
    uint32_t flashPageSize; 
#endif
} NVSLPF3_HWAttrs;

/*
 *  @brief      NVSLPF3 Object
 *
 *  The application must not access any member variables of this structure!
 */
typedef struct
{
    bool opened; /* Has this region been opened */
} NVSLPF3_Object;

extern void NVSLPF3_close(NVS_Handle handle);

extern int_fast16_t NVSLPF3_control(NVS_Handle handle, uint_fast16_t cmd, uintptr_t arg);

extern int_fast16_t NVSLPF3_erase(NVS_Handle handle, size_t offset, size_t size);

extern void NVSLPF3_getAttrs(NVS_Handle handle, NVS_Attrs *attrs);

extern void NVSLPF3_init(void);

extern int_fast16_t NVSLPF3_lock(NVS_Handle handle, uint32_t timeout);

extern NVS_Handle NVSLPF3_open(uint_least8_t index, NVS_Params *params);

extern int_fast16_t NVSLPF3_read(NVS_Handle handle, size_t offset, void *buffer, size_t bufferSize);

extern void NVSLPF3_unlock(NVS_Handle handle);

extern int_fast16_t NVSLPF3_write(NVS_Handle handle,
                                  size_t offset,
                                  void *buffer,
                                  size_t bufferSize,
                                  uint_fast16_t flags);
#if defined(__cplusplus)
}
#endif /* defined (__cplusplus) */

#endif /* ti_drivers_nvs_NVSLPF3__include */