微處理器 - Bouffalo Lab BL808 (Sipeed M1s Dock) - Assembly - Button

參考資訊：
https://github.com/bouffalolab/bl808_linux
https://wiki.sipeed.com/hardware/en/maix/m1s/m1s_dock.html

Button是連接到IO22


每個GPIO都支援多種功能切換


gpio_cfg22


main.s

    .global _start

    .equiv gpio_cfg8,  0x200008e4
    .equiv gpio_cfg22, 0x2000091c
 
    .text
    .org 0x0000
_vector:
    j _start
 
    .org 0x0200
_start:
    fence
    fence.i
    icache.iall
    csrr a5, mhcr
    ori a5, a5, 1
    csrw mhcr, a5

    fence
    fence.i
    fence
    fence.i
    dcache.iall
    csrr a5, mhcr
    lui a4, 1
    addi a4, a4, 62
    or a5, a5, a4
    csrw mhcr, a5
    fence
    fence.i

    li t0, (1 << 6) | (11 << 8) | (1 << 24)
    li a0, gpio_cfg8
    sw t0, 0(a0)
    
    li t0, (1 << 0) | (1 << 4) | (11 << 8)
    li a1, gpio_cfg22
    sw t0, 0(a1)

    li t2, (1 << 24)
0:
    lw t1, 0(a1)
    srl t1, t1, 4
    and t1, t1, t2
    li t0, (1 << 6) | (11 << 8)
    or t0, t0, t1
    sw t0, 0(a0)
    j 0b
    .end

完成