- Table of contents
- Example SOM QSPI NOR
Example SOM QSPI NOR¶
Goal¶
The goal of this example is to demonstrate how to use the SOM QSPI NOR storage.
This storage can be used for:
- General purpose storage.
- As a boot device
General Purpose Storage¶
Prerequisites¶
- The Device needs to be divided into one or more partitions.
- To use as a Linux file system, a file system must be created in the partition.
Steps¶
- Creating partitions.
The partitions are specified in the Device Tree. See this section of am57xx-mitysom.dtsi
&qspi {
status = "okay";
spi-max-frequency = <76800000>;
m25p80@0 {
compatible = "s25fl256s1", "jedec,spi-nor";
spi-max-frequency = <76800000>;
reg = <0>;
spi-tx-bus-width = <1>;
spi-rx-bus-width = <4>;
#address-cells = <1>;
#size-cells = <1>;
/* MTD partition table.
* The ROM checks the first four physical blocks
* for a valid file to boot and the flash here is
* 64KiB block size.
*/
partition@0 {
label = "QSPI.SPL";
reg = <0x00000000 0x000040000>;
};
partition@1 {
label = "QSPI.u-boot";
reg = <0x00040000 0x00100000>;
};
partition@2 {
label = "QSPI.u-boot-spl-os";
reg = <0x00140000 0x00080000>;
};
partition@3 {
label = "QSPI.u-boot-env";
reg = <0x001c0000 0x00010000>;
};
partition@4 {
label = "QSPI.u-boot-env.backup1";
reg = <0x001d0000 0x0010000>;
};
partition@5 {
label = "QSPI.kernel";
reg = <0x001e0000 0x0800000>;
};
partition@6 {
label = "QSPI.file-system";
reg = <0x009e0000 0x01620000>;
};
};
};
These can be verified by looking at /proc/mtd
root@mitysom-am57x:~# cat /proc/mtd dev: size erasesize name mtd0: 00040000 00010000 "QSPI.SPL" mtd1: 00100000 00010000 "QSPI.u-boot" mtd2: 00080000 00010000 "QSPI.u-boot-spl-os" mtd3: 00010000 00010000 "QSPI.u-boot-env" mtd4: 00010000 00010000 "QSPI.u-boot-env.backup1" mtd5: 00800000 00010000 "QSPI.kernel" mtd6: 01620000 00010000 "QSPI.file-system" root@mitysom-am57x:~#
If you have not created any partitions, then the output of lsblk will be similar to what is shown below:
root@mitysom-am57x:~# lsblk --fs NAME FSTYPE LABEL UUID MOUNTPOINT mtdblock0 mtdblock1 mtdblock2 mtdblock3 mtdblock4 mtdblock5 mtdblock6 mmcblk0 |-mmcblk0p1 vfat boot 7BD4-7472 /run/media/mmcblk0p1 `-mmcblk0p2 ext4 root 0df6ebe8-581f-42c9-8440-b18e6f18b5fa / root@mitysom-am57x:~#
Creating a filesystem¶
To make a partition so it can be mounted and used as a regular filesystem, you can use the mkfs.ext4 command.
Example:
root@mitysom-am57x:~# mkfs.ext4 /dev/mtdblock6
mke2fs 1.44.3 (10-July-2018)
64-bit filesystem support is not enabled. The larger fields afforded by this feature enable full-strength checksumming. Pass -O 64bit to rectify.
Creating filesystem with 22656 1k blocks and 5664 inodes
Filesystem UUID: 92031108-5873-41bb-8c8c-c8b526f20e9e
Superblock backups stored on blocks:
8193
Allocating group tables: done
Writing inode tables: done
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done
root@mitysom-am57x:~#
Note that the above is a very simple example. You may want to consult the manual of the mkfs.ext3 or mkfs.ext4 and use a different filesystem type and one or more of the configuration options.
The output of lsblk is now:
root@mitysom-am57x:~# lsblk --fs NAME FSTYPE LABEL UUID MOUNTPOINT mtdblock0 mtdblock1 mtdblock2 mtdblock3 mtdblock4 mtdblock5 mtdblock6 ext4 92031108-5873-41bb-8c8c-c8b526f20e9e mmcblk0 |-mmcblk0p1 vfat boot 7BD4-7472 /run/media/mmcblk0p1 `-mmcblk0p2 ext4 root 0df6ebe8-581f-42c9-8440-b18e6f18b5fa / root@mitysom-am57x:~#
The output of the parted command for the /dev/mtdblock* devices is:
root@mitysom-am57x:~# for ii in /dev/mtdblock* > do > echo "=====================================> "$ii > parted $ii print > done =====================================> /dev/mtdblock0 Error: /dev/mtdblock0: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock0: 262kB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: =====================================> /dev/mtdblock1 Error: /dev/mtdblock1: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock1: 1049kB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: =====================================> /dev/mtdblock2 Error: /dev/mtdblock2: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock2: 524kB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: =====================================> /dev/mtdblock3 Error: /dev/mtdblock3: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock3: 65.5kB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: =====================================> /dev/mtdblock4 Error: /dev/mtdblock4: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock4: 65.5kB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: =====================================> /dev/mtdblock5 Error: /dev/mtdblock5: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock5: 8389kB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: =====================================> /dev/mtdblock6 Model: Unknown (unknown) Disk /dev/mtdblock6: 23.2MB Sector size (logical/physical): 512B/512B Partition Table: loop Disk Flags: Number Start End Size File system Flags 1 0.00B 23.2MB 23.2MB ext4 root@mitysom-am57x:~#
Mounting the filesystem¶
To mount the filesystem, create a mount point (a directory) and use the mount command.
root@mitysom-am57x:~# cd root@mitysom-am57x:~# mkdir mnt root@mitysom-am57x:~# mount /dev/mtdblock6 mnt [ 4637.165665] EXT4-fs (mtdblock6): mounted filesystem with ordered data mode. Opts: (null) root@mitysom-am57x:~# mount /dev/mmcblk0p2 on / type ext4 (rw,relatime) devtmpfs on /dev type devtmpfs (rw,relatime,size=775152k,nr_inodes=97529,mode=755) . . . /dev/mtdblock6 on /home/root/mnt type ext4 (rw,relatime) root@mitysom-am57x:~#
Using the mounted filesystem¶
The partition can now be used as a regular directory.
# see what files exist root@mitysom-am57x:~# ls mnt lost+found # # Create a file # root@mitysom-am57x:~# touch mnt/my_file # # See what files exist # root@mitysom-am57x:~# ls -l mnt drwx------ 2 root root 12288 Aug 2 16:15 lost+found -rw-r--r-- 1 root root 0 Aug 2 16:22 my_file # # Create a second file # root@mitysom-am57x:~# echo Hello >mnt/hello root@mitysom-am57x:~# ls -l mnt -rw-r--r-- 1 root root 6 Aug 2 16:23 hello drwx------ 2 root root 12288 Aug 2 16:15 lost+found -rw-r--r-- 1 root root 0 Aug 2 16:22 my_file # # Verify the contents of the second file # root@mitysom-am57x:~# cat mnt/hello Hello root@mitysom-am57x:~#
Persistent mount¶
To have a persistent mount on reboot, you may want to make an entry in /etc/fstab.
Unmount the file system¶
root@mitysom-am57x:~# umount /dev/mtdblock6 root@mitysom-am57x:~#
Wipe out the filesystem¶
To remove the filesystem from the device, do the following:
root@mitysom-am57x:~# dd if=/dev/zero of=/dev/mtdblock6 bs=1M count=1 1+0 records in 1+0 records out root@mitysom-am57x:~# parted /dev/mtdblock6 print Error: /dev/mtdblock6: unrecognised disk label Model: Unknown (unknown) Disk /dev/mtdblock6: 23.2MB Sector size (logical/physical): 512B/512B Partition Table: unknown Disk Flags: root@mitysom-am57x:~#
Boot Device¶
To use QSPI NOR as a boot device, the following would need to be done:
- Make a file system image to fit in 32MB.
- Write the uboot image and kernel images to the QSPI NOR
- Change jumper JP8 to boot from QSPI.
- Open is SD, EMMC, USB
- Short is QSPI, SD, USB
- Change the uboot environment variables to read the images from QSPI instead of mmc
# use commands like (exact offsets and sizes may vary) sf probe 0:0 6000000 sf read 42000000 100000 400000 bootm 0x42000000
Conclusion¶
This example has demonstrated how to use the QSPI NOR as a regular filesystem and how it could be used as a boot device.
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