Block Device Drivers for Littlefs
Block Device Drivers for littlefs

Overview

Provides a set of block device drivers for the littlefs file system. The drivers' interface is very similar to lfs_rambd.h provided with littlefs. See the API reference manual for driver-specific information.

Features

  • Supports SPI flash and SD card (Card mode) block devices
  • Each driver provides the function to fetch the default configuration of the block device
  • Implements the thread safety for multi-threaded RTOS environments using the abstraction-rtos library
  • Built on top of existing drivers such as serial-flash and HAL
  • Supports Serial Flash Discoverable Parameter (SFDP) mode for SPI flash memories

Quick start

The mtb-example-psoc6-filesystem-littlefs-freertos code example describes the implementation of the littlefs file system on SD card and QSPI NOR flash.

  1. Create an empty application using the Project Creator tool in the ModusToolbox™ software.
  2. Add the mtb-littlefs and retarget-io libraries using the Library Manager.
  3. Add the below code to main.c.
  4. Open a serial terminal. Set the serial port parameters to 8N1 and 115200 baud.
  5. Build the application and program the kit.
#include "cybsp.h"
#include "cy_retarget_io.h"
#include "lfs.h"
#include "lfs_spi_flash_bd.h"
void check_status(char *message, uint32_t status)
{
if (0u != status)
{
printf("\n================================================================================\n");
printf("\nFAIL: %s\n", message);
printf("Error Code: 0x%08"PRIx32"\n", status);
printf("\n================================================================================\n");
while(true);
}
}
int main(void)
{
cy_rslt_t result;
uint32_t boot_count = 0;
/* variables used by the filesystem */
lfs_t lfs;
struct lfs_config lfs_cfg;
lfs_file_t file;
lfs_spi_flash_bd_config_t bd_cfg;
/* Initialize the device and board peripherals */
result = cybsp_init() ;
CY_ASSERT (result == CY_RSLT_SUCCESS);
/* Enable global interrupts */
__enable_irq();
/* Initialize retarget-io to use the debug UART port */
cy_retarget_io_init(CYBSP_DEBUG_UART_TX, CYBSP_DEBUG_UART_RX, CY_RETARGET_IO_BAUDRATE);
printf("\nIncrementing the boot count on SPI flash\n\n");
/* Get the default configuration for the SPI flash block device. */
lfs_spi_flash_bd_get_default_config(&bd_cfg);
/* Initialize the pointers in lfs_cfg to NULL. */
memset(&lfs_cfg, 0, sizeof(lfs_cfg));
/* Create the SPI flash block device. */
result = lfs_spi_flash_bd_create(&lfs_cfg, &bd_cfg);
check_status("Creating SPI flash block device failed.", result);
printf("Number of blocks: %"PRIu32"\n", lfs_cfg.block_count);
printf("Erase block size: %"PRIu32" bytes\n", lfs_cfg.block_size);
printf("Prog size: %"PRIu32" bytes\n", lfs_cfg.prog_size);
/* Mount the filesystem */
int err = lfs_mount(&lfs, &lfs_cfg);
/* Reformat if we cannot mount the filesystem.
* This should only happen on the first boot.
*/
if (err) {
lfs_format(&lfs, &lfs_cfg);
lfs_mount(&lfs, &lfs_cfg);
}
/* Read the current boot count. */
lfs_file_open(&lfs, &file, "boot_count", LFS_O_RDWR | LFS_O_CREAT);
lfs_file_read(&lfs, &file, &boot_count, sizeof(boot_count));
/* Update the boot count. */
boot_count += 1;
lfs_file_rewind(&lfs, &file);
lfs_file_write(&lfs, &file, &boot_count, sizeof(boot_count));
/* The storage is not updated until the file is closed successfully. */
lfs_file_close(&lfs, &file);
/* Release any resources we were using. */
lfs_unmount(&lfs);
/* Print the boot count. */
printf("\nboot_count: %"PRIu32"\n", boot_count);
/* Free the resources associated with the block device. */
lfs_spi_flash_bd_destroy(&lfs_cfg);
for (;;) {}
}

Usage instructions

For the usage in an RTOS environment:

  1. Add FreeRTOS using the Library Manager if FreeRTOS is your choice of RTOS.
  2. Add abstraction-rtos using the Library Manager tool if you are using an RTOS other than FreeRTOS. abstraction-rtos is added automatically when you add FreeRTOS using the Library Manager.
  3. Add FREERTOS to the components list when using FreeRTOS.
  4. Add DEFINES=LFS_THREADSAFE to enable the thread-safety for the littlefs APIs.
  5. Add COMPONENTS=RTOS_AWARE in the Makefile to enable RTOS-friendly features, such as waiting on a semaphore until read completion is indicated through an interrupt or a callback.

Note: The source files under *<littlefs_path>/bd* are ignored from auto-discovery. Therefore, they will be excluded from compilation because some of the files (e.g., lfs_filebd.c) use POSIX file APIs such as open() and close(). POSIX APIs are not supported by the ModusToolbox™. If you implement POSIX APIs, you can include those files for compilation by adding them to the SOURCES and INCLUDES variables in the Makefile.

Dependencies

The dependencies except abstraction-rtos are automatically pulled in when you run the make getlibs command in the ModusToolbox™.

  • littlefs
  • serial-flash

  • abstraction-rtos library if RTOS support is required.

    Note: abstraction-rtos is automatically pulled in only when you add FreeRTOS using the Library Manager; otherwise, add it manually.

Supported Devices

  • PSoC™ 6 MCUs

More Information