| # SPDX-License-Identifier: Apache-2.0 |
| |
| .section .text |
| |
| start: |
| |
| # zero-initialize register file |
| addi x1, zero, 0 |
| # x2 (sp) is initialized by reset |
| addi x3, zero, 0 |
| addi x4, zero, 0 |
| addi x5, zero, 0 |
| addi x6, zero, 0 |
| addi x7, zero, 0 |
| addi x8, zero, 0 |
| addi x9, zero, 0 |
| addi x10, zero, 0 |
| addi x11, zero, 0 |
| addi x12, zero, 0 |
| addi x13, zero, 0 |
| addi x14, zero, 0 |
| addi x15, zero, 0 |
| addi x16, zero, 0 |
| addi x17, zero, 0 |
| addi x18, zero, 0 |
| addi x19, zero, 0 |
| addi x20, zero, 0 |
| addi x21, zero, 0 |
| addi x22, zero, 0 |
| addi x23, zero, 0 |
| addi x24, zero, 0 |
| addi x25, zero, 0 |
| addi x26, zero, 0 |
| addi x27, zero, 0 |
| addi x28, zero, 0 |
| addi x29, zero, 0 |
| addi x30, zero, 0 |
| addi x31, zero, 0 |
| |
| # zero initialize scratchpad memory |
| # setmemloop: |
| # sw zero, 0(x1) |
| # addi x1, x1, 4 |
| # blt x1, sp, setmemloop |
| |
| # copy data section |
| la a0, _sidata |
| la a1, _sdata |
| la a2, _edata |
| bge a1, a2, end_init_data |
| loop_init_data: |
| lw a3, 0(a0) |
| sw a3, 0(a1) |
| addi a0, a0, 4 |
| addi a1, a1, 4 |
| blt a1, a2, loop_init_data |
| end_init_data: |
| |
| # zero-init bss section |
| la a0, _sbss |
| la a1, _ebss |
| bge a0, a1, end_init_bss |
| loop_init_bss: |
| sw zero, 0(a0) |
| addi a0, a0, 4 |
| blt a0, a1, loop_init_bss |
| end_init_bss: |
| |
| # call main |
| call main |
| loop: |
| j loop |
| |
| .global flashio_worker_begin |
| .global flashio_worker_end |
| |
| .balign 4 |
| |
| flashio_worker_begin: |
| # a0 ... data pointer |
| # a1 ... data length |
| # a2 ... optional WREN cmd (0 = disable) |
| |
| # address of SPI ctrl reg |
| li t0, 0x28000000 |
| |
| # Set CS high, IO0 is output |
| li t1, 0x120 |
| sh t1, 0(t0) |
| |
| # Enable Manual SPI Ctrl |
| sb zero, 3(t0) |
| |
| # Send optional WREN cmd |
| beqz a2, flashio_worker_L1 |
| li t5, 8 |
| andi t2, a2, 0xff |
| flashio_worker_L4: |
| srli t4, t2, 7 |
| sb t4, 0(t0) |
| ori t4, t4, 0x10 |
| sb t4, 0(t0) |
| slli t2, t2, 1 |
| andi t2, t2, 0xff |
| addi t5, t5, -1 |
| bnez t5, flashio_worker_L4 |
| sb t1, 0(t0) |
| |
| # SPI transfer |
| flashio_worker_L1: |
| |
| # If byte count is zero, we're done |
| beqz a1, flashio_worker_L3 |
| |
| # Set t5 to count down 32 bits |
| li t5, 32 |
| # Load t2 from address a0 (4 bytes) |
| lw t2, 0(a0) |
| |
| flashio_worker_LY: |
| # Set t6 to count down 8 bits |
| li t6, 8 |
| |
| flashio_worker_L2: |
| # Clock out the bit (msb first) on IO0 and read bit in from IO1 |
| srli t4, t2, 31 |
| sb t4, 0(t0) |
| ori t4, t4, 0x10 |
| sb t4, 0(t0) |
| lbu t4, 0(t0) |
| andi t4, t4, 2 |
| srli t4, t4, 1 |
| slli t2, t2, 1 |
| or t2, t2, t4 |
| |
| # Decrement 32 bit count |
| addi t5, t5, -1 |
| bnez t5, flashio_worker_LX |
| |
| sw t2, 0(a0) |
| addi a0, a0, 4 |
| lw t2, 0(a0) |
| |
| flashio_worker_LX: |
| addi t6, t6, -1 |
| bnez t6, flashio_worker_L2 |
| addi a1, a1, -1 |
| bnez a1, flashio_worker_LY |
| |
| beqz t5, flashio_worker_L3 |
| sw t2, 0(a0) |
| |
| flashio_worker_L3: |
| # Back to MEMIO mode |
| li t1, 0x80 |
| sb t1, 3(t0) |
| |
| ret |
| .balign 4 |
| flashio_worker_end: |
| |