3.1.1.7. OSPI/QSPI

OSPI/QSPI is a serial peripheral interface like SPI the major difference being the support for Octal/Quad read, uses 8/4 data lines for read compared to 2 lines used by the traditional SPI. This section documents how to write files to the QSPI device and use it to load and then boot the Linux Kernel using a root filesystem also found on QSPI. At this time, no special builds of U-Boot are required to perform these operations on the supported hardware. For simplicity we assume the files are being loaded from an SD card. Using the network interface (if applicable) is documented in U-boot SPI section.

Note

Not all OSPI flashes can be supported. Users are recommended to check whether or not the OSPI flash part chosen for custom board designs meets all the criteria listed at https://e2e.ti.com/support/processors/f/791/t/946418

Note

The sf command is used to access SPI NOR flash, supporting read/write/erase and a few other functions. For more information on sf command in U-boot please refer to the u-boot documentation: here. And for accessing SPI NAND flash, the mtd command is used, supporting read/write/erase and bad block management.

SPI boot is supported on the following platforms:

Board	Config target
AM335x ICE	am335x_evm_spiboot_defconfig

U-Boot # mmc rescan
U-Boot # sf probe 0
U-Boot # sf erase 0x0 0x100000
U-Boot # fatload mmc 0 ${loadaddr} MLO.byteswap
U-Boot # sf write ${loadaddr} 0x0 ${filesize}
U-Boot # fatload mmc 0 ${loadaddr} u-boot.img
U-Boot # sf write ${loadaddr} 0x20000 ${filesize}

Note:

• AM335X ICE boots from SPI by default. To boot from SD card, erase the MLO partition:

U-Boot # sf erase 0x0 0x20000