How to get started with NOR flash on Zephyr ?

[rotem]

Hi,

I'm pretty new to Zephyr and I have to figure out how to connect to a NOR flash over SPI. Final application is the implementation of a file system, e.g. littlefs.

There is very little documentation on the web on that subject and one of the only I could find was this thread here: https://devzone.nordicsemi.com/f/nordic-q-a/75393/how-to-get-started-with-zephyr-fs-on-external-nor-flash?focus=true and those linked with it.

I'm working on a custom platform with a standard 4-wire SPI and the NOR Flash is Microchip SST25VF016. Maybe someone could help me with a general hint because due to little documentation and experience, I'm stucked. Thanks in advance!

First goal is to make the Zephyr NOR-flash example to run.

First problem is that my device handle from the devicetree is always empty. I guess that something is missing/ wrong with the NOR Flash driver but I don't get it. Do I need a binding (.yaml) file for the particular flash type? If so, where can I find a template (like the everywhere used MX25r64)?

In my config I added this:

# support nor flash on spi
CONFIG_FLASH=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

In the devicetree I added "jedec, spi-nor" and "fixed-partitions" object: (the SPI-interface for itself has been tested before and is working).

&spi1 {    
    status = "okay";
    pinctrl-0 = <&spi1_sck_pg2 &spi1_miso_pg3 &spi1_mosi_pg4>;
    pinctrl-names = "default";
      sst25: sst25vf016@0  {
        compatible = "jedec,spi-nor";
        label = "SST25";
        reg = <0>;
        spi-max-frequency = <1000000>;
        jedec-id = [c2 28 17];
        size = <16777216>;
    };
};

&sst25 {
    partitions {
        compatible = "fixed-partitions";
        #address-cells = <1>;
        #size-cells = <1>;

        partition@0 {
          label = "storage";
          reg = <0x01000000 0x00800000>;
        };
    };
};

My initialization looks like this:

#include "stdIncl.h"
#include <drivers/spi.h>
#include <drivers/flash.h>

#if (CONFIG_SPI_NOR - 0) ||                \
    DT_NODE_HAS_STATUS(DT_INST(0, jedec_spi_nor), okay)
#define FLASH_DEVICE DT_LABEL(DT_INST(0, jedec_spi_nor))
#define FLASH_NAME "JEDEC SPI-NOR"
#else
#error "Missing SPI-NOR flash in device tree"
#endif

Everything builds and runs fine. FLASH_DEVICE resolves to "SST25" but after the initialization, the device handle is always null:

static const struct device* s_device_p;

s_device_p = device_get_binding( FLASH_DEVICE ); //becomes 0x0

Any help is appreciated!

[rotem]

Hi again,

I was able to make the NOR-flash run over SPI! Mainly the configuration for the SST25 had to be adapted and some particularity with our board.

I was also able to make the NVS Filesystem sample run.

Now I try with the littleFS sample and here I got stuck again: When building, I get an error saying

/zephyr/include/zephyr/fs/littlefs.h:14:10: fatal error: lfs.h: No such file or directory
   14 | #include <lfs.h>

As this file does not exist nowhere in the filesystem I suppose it should be generated by zephyr but it isn't

Within littlefs.h I find

#include <lfs.h>

When I comment it out, some symbols like

struct lfs_config cfg;

are marked as unknown.

My dts looks like this:

&sst25 {
    partitions {
        compatible = "fixed-partitions";
        #address-cells = <1>;
        #size-cells = <1>;
        /* 16 KBy partition to use for LFS filesystem */
        partition@0001000 {
            label = "storage";
            reg = <0x0001000 0x0004000>;
        };
    };
};

and the node initialization like this:

FS_LITTLEFS_DECLARE_DEFAULT_CONFIG(_LfsConfig);
static struct fs_mount_t lfs_storage_mnt = {
    .type = FS_LITTLEFS,
    .fs_data = &_LfsConfig,
    .storage_dev = (void *)DT_FLASH_AREA_STORAGE_ID,
    .mnt_point = "/lfs",
};

and the conf like this:

CONFIG_FLASH=y
CONFIG_FLASH_MAP=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096
CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_LITTLEFS=y

Any idea what could cause this problem?

Thanx

Marco

[Amanda Hsieh]

Hi, 

Which version of NCS are you using?

If you are using v2.1.1, lfs.h is under modules\fs\littlefs.

-Amanda H.

[rotem]

sorry, or I must be blind but there is no modules\fs\littlefs folder in 2.11:

https://github.com/nrfconnect/sdk-nrf/tree/v2.1.1/modules

Am I missing something?

[Amanda Hsieh]

Hi, 

The spicific module under v2.1.1 is not public on the github. If you install NCS v2.1.1 via Toolchain, you could see it. Please be aware that our support is limited to NCS instead of vanilla Zephyr, so I would suggest you use NCS.  

Regards,
Amanda H.