U-Boot
U-Boot is a bootloader.
Where to load the Device Tree Binary?
fdt_high
fdt addr + fdt resize
bi_boot_params
Communicate with the SST26VF032B[1]
The SST26VF032B contains Block-Protection feature. By default, at reset, all blocks are write-protected and some blocks are read-protected. To be able to write and read into that memory, you have to disable the Block-Protection feature using the WBPR instruction (which requires WREN to be executed before).
| Instruction | Description | Command cycle | Bitlen | Source | Example |
|---|---|---|---|---|---|
| JEDEC-ID | JEDEC-ID Read | 9FH | 32 | U-Boot > sspi 0x7100 32 9f000000
00BF2642 | |
| RDSR | Read the Status Register | 05H | 16 | p. 10 | U-Boot > sspi 0x7100 16 0500
0002 |
| RDCR |
Read the Configuration Register |
35H | 16 | U-Boot > sspi 0x7100 16 3500
0008 | |
| WREN | Write-Enable: required for ULBPR, PP, ... | 06H | 8 | p. 33 | U-Boot > sspi 0x7100 8 06
00 |
| WBPR | Write Block-Protection Register | 42H | 152 | p. 36 | U-Boot > sspi 0x7100 8 06
00 U-Boot > sspi 0x7100 152 42000000000000000000000000000000000000 00000000000000000000000000000000000000 |
| RBPR | Read Block-Protection Register | 72H | 152 | p. 35 | U-Boot > sspi 0x7100 152 72000000000000000000000000000000000000
00FFFFFFFFFFFFFFFFFFFF0000000000000000 |
| ULBPR | Global Block-Protection Unlock | 98H | 8 | p. 39 | U-Boot > sspi 0x7100 8 06
00 U-Boot > sspi 0x7100 8 98 00 |
| Read (40MHz) | 03H | N/A | p. 15 | Read at offset 0 32 bits
U-Boot > sspi 0x7100 64 0300000000000000 00000000FFFFFFFF | |
| SE | Sector-Erase (change to 1) a 4KiB sector | 20H | 32 | p. 25 | |
| PP | Page Program | 02H | N/A | p. 28 |