OSPI Flash

An Octal Serial Peripheral Interface (OSPI) Flash is populated on the phyCORE-AM62x as a programmable nonvolatile storage. The OSPI interface supports single, dual, quad, or octal read/write access to the flash device. This guide will walk through how to read and write from the OSPI. The OSPI Flash can be used for a fast boot source, see the guide Flashing the SPI NOR Flash for more on booting from OSPI. For more information on the OSPI interface, see the OSPI chapter in the Hardware Manual

View Available NOR Partitions

Verify that the NOR interface was initialized properly.

phyboard-lyra-am62xx-3:~# mtdinfo
Count of MTD devices:           1
Present MTD devices:            mtd0
Sysfs interface supported:      yes

View basic partition information.

phyboard-lyra-am62xx-3:~# cat /proc/mtd

More detailed information can be viewed using the “mtdinfo” command on a specific partition.

phyboard-lyra-am62xx-3:~# mtdinfo /dev/mtd0
mtd0
Name:                           fc40000.spi.0
Type:                           nor
Eraseblock size:                131072 bytes, 128.0 KiB
Amount of eraseblocks:          512 (67108864 bytes, 64.0 MiB)
Minimum input/output unit size: 1 byte
Sub-page size:                  1 byte
Character device major/minor:   90:0
Bad blocks are allowed:         false
Device is writable:             true

Configuring NOR Partitions

The NOR flash partitions are defined in the U-Boot device tree file (files ending with -u-boot.dtsi). These partition definitions are automatically carried over to the OS device tree.

Each partition is defined with:

A unique base address
A descriptive label
A size specification in the reg property (offset and length)

Here’s an example configuration showing the standard partition layout:

&ospi0 {
        bootph-all;

        flash@0 {
                bootph-all;
                partitions {
                        compatible = "fixed-partitions";
                        #address-cells = <1>;
                        #size-cells = <1>;

                        partition@0 {
                                label = "ospi.tiboot3";
                                reg = <0x00000 0x80000>;
                        };
                        partition@80000 {
                                label = "ospi.tispl";
                                reg = <0x080000 0x200000>;
                        };
                        partition@280000 {
                                label = "ospi.u-boot";
                                reg = <0x280000 0x400000>;
                        };
                        partition@680000 {
                                label = "ospi.env";
                                reg = <0x680000 0x40000>;
                        };
                        partition@6c0000 {
                                label = "ospi.env.backup";
                                reg = <0x6c0000 0x40000>;
                        };
                };
        };
};

Make sure partitions don’t overlap and align them to the flash erase block size (typically 64 KB or 128 KB).

Write to OSPI

Create a random file equal to the size of the /dev/mtd0 partition (512 kBytes).

phyboard-lyra-am62xx-3:~# dd if=/dev/urandom of=test.dat bs=1k count=512
512+0 records in
512+0 records out
524288 bytes (524 kB, 512 KiB) copied, 0.0152006 s, 34.5 MB/s

Copy the generated file to the mtd0 partition.

phyboard-lyra-am62xx-3:~# flashcp -v test.dat /dev/mtd0
Erasing blocks: 4/4 (100%)
Writing data: 512k/512k (100%)
Verifying data: 512k/512k (100%)

Read from OSPI

Dump the contents of /dev/mtd0 partition to a new file:

phyboard-lyra-am62xx-3:~# dd if=/dev/mtd0 of=read.dat bs=1k count=512
512+0 records in
512+0 records out
524288 bytes (524 kB, 512 KiB) copied, 0.167633 s, 3.1 MB/s

Verify that the output files were not corrupted during the transfer using md5sum.

phyboard-lyra-am62xx-3:~# md5sum test.dat read.dat
3497f295076c7ef96443b109ab9be333  test.dat
3497f295076c7ef96443b109ab9be333  read.dat