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 above.
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
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