How to get started with zephyr fs on external NOR flash

[madblue]

Hi,

I have gone through the lfs file system from zephyr samples but I could not find any solid documentation for fs and spi flash drivers available. 

I have written the  flash driver codes based on SPI and now i want to use the littlefs file system on this. How do I enable lfs by using SPI drivers?

Since most of the initialization is static and adds before main(), I couldn't figure out how to integrate the SPI read/write functions to the file system.

[Simon]

You should be able to use the littlefs sample with external flash over SPI. You need to do the following:

• Swap these configs with these:

CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

Comment out these lines, and add the following:

&qspi {
	status = "disabled";
};

&spi3 {
	status = "okay";
    mosi-pin = <20>;
    miso-pin = <21>;
    sck-pin = <19>;
	cs-gpios = <&gpio0 17 GPIO_ACTIVE_LOW >;
    mx25r64: mx25r6435f@0  {
        compatible = "jedec,spi-nor";
        label = "MX25R64";
        reg = <0>;
        spi-max-frequency = <8000000>;
        jedec-id = [c2 28 17];
        size = <67108864>;
        has-be32k;
        has-dpd;
        t-enter-dpd = <10000>;
        t-exit-dpd = <35000>;
    };
};

This demonstrates how to use the nRF52840 DK onboard mx25r64 flash. If you're using a different flash device, you would need to modify the overlay file accordingly. I have not tested this, so I may have missed out on something

This case may be helpful, even thought it's about qspi, I explain in some detail how stuff works in Zephyr and how everything is coupled together.

https://devzone.nordicsemi.com/f/nordic-q-a/72045/flash-filing-system-for-nrf-connect-sdk

Best regards,

Simon