libflash API#

The libflash library provides functions for reading and writing data to SPI flash devices that use the xCORE format shown in the diagram below.

../../../../_images/flash-format2.png — Fig. 9 Flash format diagram#

All functions are prototyped in the header file <flash.h>. Except where otherwise stated, functions return 0 on success and non-zero on failure.

General operations#

The program must explicitly open a connection to the SPI device before attempting to use it, and must disconnect once finished accessing the device.

The functions fl_connect and fl_connectToDevice require an argument of type fl_SPIPorts, which defines the four ports and clock block used to connect to the device.

typedef struct {
  in buffered port:8 spiMISO;
  out port spiSS;
  out port spiCLK;
  out buffered port:8 spiMOSI;
  clock spiClkblk;
} fl_SPIPorts;

int fl_connect(fl_SPIPorts *SPI)#: fl_connect opens a connection to the specified SPI device.

int fl_connectToDevice(fl_SPIPorts *SPI, fl_DeviceSpec spec[], unsigned n)#: fl_connectToDevice opens a connection to an SPI device. It iterates through an array of n SPI device specifications, attempting to connect using each specification until one succeeds.

unsigned fl_getJedecId(void)#

fl_getJedecId returns the response to the ‘Read Identification’ command used during connection, typically the JEDEC ID. This uses the command and size defined by the SPI specification in use.

For the majority of flash devices, this will be the response to command 0x9f.

int fl_getFlashType(void)#

fl_getFlashType returns an enum value for the flash device. The enumeration of devices known to libflash is given below.

typedef enum {
  UNKNOWN = 0,
  ALTERA_EPCS1,
  ATMEL_AT25DF041A,
  ATMEL_AT25FS010,
  ST_M25PE10,
  ST_M25PE20,
  WINBOND_W25X40
} fl_FlashId;

If the function call fl_connectToDevice(p, spec, n) is used to connect to a flash device, fl_getFlashType returns the parameter value spec[i].flashId where i is the index of the connected device.

unsigned fl_getFlashSize(void)#: fl_getFlashSize returns the capacity of the SPI device in bytes.

void fl_copySpec(fl_DeviceSpec *dest)#: fl_copySpec exports the completed SPI specification in use for the current connection.

unsigned fl_getLibraryStatus(void)#

fl_getLibraryStatus returns a bitmask of errors and warnings from connection. The bits are defined as follows:

typedef enum {
  LIBRARY_ERROR_PAGESIZE_MISSING      = 1 << 8,
  LIBRARY_ERROR_NUMPAGES_MISSING      = 1 << 9,
  LIBRARY_ERROR_SECTORSIZE_MISSING    = 1 << 10,
} fl_LibraryStatus;

These generally indicate the reason for connection failure, typically due to incomplete or incorrect SPI specification.

int fl_command(unsigned int cmd, unsigned char input[], unsigned int num_in, unsigned char output[], unsigned int num_out)#: fl_command issues a command to the SPI device at the lowest level. The cmd is sent first, followed by num_in bytes from input. num_out bytes are then read to output.

int fl_disconnect(void)#: fl_disconnect closes the connection to the SPI device.

Boot partition functions#

By default, the size of the boot partition is set to the size of the flash device. Access to boot images is provided through an iterator interface.

int fl_getImageInfo(fl_BootImageInfo *bootImageInfo, const unsigned char page[])#: fl_getImageInfo provides information about a boot image header stored in memory. A single page of the image data must be provided.

int fl_getFactoryImage(fl_BootImageInfo *bootImageInfo)#: fl_getFactoryImage provides information about the factory boot image.

int fl_getNextBootImage(fl_BootImageInfo *bootImageInfo)#: fl_getNextBootImage provides information about the next upgrade image. Once located, an image can be upgraded. Functions are also provided for reading the contents of an upgrade image.

unsigned fl_getImageTag(fl_BootImageInfo *bootImageInfo)#: fl_getImageTag returns the magic number of the specified image.

unsigned fl_getImageVersion(fl_BootImageInfo *bootImageInfo)#: fl_getImageVersion returns the version number of the specified image.

unsigned fl_getImageAddress(fl_BootImageInfo *bootImageInfo)#: fl_getImageAddress returns the start address in flash of the specified image.

unsigned fl_getImageSize(fl_BootImageInfo *bootImageInfo)#: fl_getImageSize returns the size of the specified image.

int fl_getToolsMajor(fl_BootImageInfo *bootImageInfo)#: fl_getToolsMajor returns the tools major version used to build the specified image, or -1 on failure.

int fl_getToolsMinor(fl_BootImageInfo *bootImageInfo)#: fl_getToolsMinor returns the tools minor version used to build the specified image, or -1 on failure.

int fl_getToolsPatch(fl_BootImageInfo *bootImageInfo)#: fl_getToolsPatch returns the tools patch version used to build the specified image, or -1 on failure.

int fl_getImageFormat(fl_BootImageInfo *bootImageInfo)#: fl_getImageFormat returns the compatibility version of the specified image, or -1 on failure.

int fl_startImageReplace(fl_BootImageInfo*, unsigned maxsize)#

fl_startImageReplace prepares the SPI device for replacing an image. The old image can no longer be assumed to exist after this call.

Attempting to write into the data partition or the space of another upgrade image is invalid. A non-zero return value signifies that the preparation is not yet complete and that the function should be called again. Repeated calling of this function is required to iterate over all the sectors needed by the image and erase them.

int fl_startImageAdd(fl_BootImageInfo*, unsigned maxsize, unsigned padding)#

fl_startImageAdd prepares the SPI device for adding an image after the specified image. The start of the new image is at least padding bytes after the previous image.

Attempting to write into the data partition or the space of another upgrade image is invalid. A non-zero return value signifies that the preparation is not yet complete and that the function must be called again. Repeated calling of this function is required to iterate over all the sectors needed by the image and erase them.

int fl_startImageAddAt(unsigned offset, unsigned maxsize)#

fl_startImageAddAt prepares the SPI device for adding an image at the specified address offset from the base of the first sector after the factory image.

Attempting to write into the data partition or the space of another upgrade image is invalid. A non-zero return value signifies that the preparation is not yet complete and that the function must be called again. Repeated calling of this function is required to iterate over all the sectors needed by the image and erase them.

int fl_writeImagePage(const unsigned char page[])#: fl_writeImagePage waits until the SPI device is able to accept a request and then outputs the next page of data to the device. Attempting to write past the maximum size passed to fl_startImageReplace, fl_startImageAdd or fl_startImageAddAt is invalid.

int fl_writeImageEnd(void)#: fl_writeImageEnd waits until the SPI device has written the last page of data to its memory.

int fl_startImageRead(fl_BootImageInfo *b)#: fl_startImageRead prepares the SPI device for reading the contents of the specified upgrade image.

int fl_readImagePage(unsigned char page[])#: fl_readImagePage inputs the next page of data from the SPI device and writes it to the array page.

int fl_deleteImage(fl_BootImageInfo *b)#: fl_deleteImage erases the upgrade image with the specified image.

Data partition functions#

All flash devices are assumed to have uniform page sizes but are not assumed to have uniform sector sizes. Read and write operations occur at the page level, and erase operations occur at the sector level. This means that to write part of a sector, a buffer size of at least one sector is required to preserve other data.

In the following functions, writes to the data partition and erasures from the data partition are not fail-safe. If the operation is interrupted, for example due to a power failure, the data in the page or sector is undefined.

unsigned fl_getDataPartitionSize(void)#: fl_getDataPartitionSize returns the size of the data partition in bytes.

int fl_readData(unsigned offset, unsigned size, unsigned char dst[])#: fl_readData reads a number of bytes from an offset into the data partition and writes them to the array dst.

unsigned fl_getWriteScratchSize(unsigned offset, unsigned size)#: fl_getWriteScratchSize returns the buffer size needed by fl_writeData for the given parameters.

int fl_writeData(unsigned offset, unsigned size, const unsigned char src[], unsigned char buffer[])#: fl_writeData writes the array src to the specified offset in the data partition. It uses the array buffer to preserve page data that must be re-written.

Page-level functions#

unsigned fl_getPageSize(void)#: fl_getPageSize returns the page size in bytes.

unsigned fl_getNumDataPages(void)#: fl_getNumDataPages returns the number of pages in the data partition.

unsigned fl_writeDataPage(unsigned n, const unsigned char data[])#: fl_writeDataPage writes the array data to the n-th page in the data partition. The data array must be at least as big as the page size; if larger, the highest elements are ignored.

unsigned fl_readDataPage(unsigned n, unsigned char data[])#: fl_readDataPage reads the n-th page in the data partition and writes it to the array data. The size of data must be at least as large as the page size.

Sector-level functions#

unsigned fl_getNumDataSectors(void)#: fl_getNumDataSectors returns the number of sectors in the data partition.

unsigned fl_getDataSectorSize(unsigned n)#: fl_getDataSectorSize returns the size of the n-th sector in the data partition in bytes.

unsigned fl_eraseDataSector(unsigned n)#: fl_eraseDataSector erases the n-th sector in the data partition.

unsigned fl_eraseAllDataSectors(void)#: fl_eraseAllDataSectors erases all sectors in the data partition.