2025-02-12 16:40:25 +01:00

95 lines
1.9 KiB
ArmAsm

// SPDX-FileCopyrightText: 2024 Tillitis AB <tillitis.se>
// SPDX-License-Identifier: BSD-2-Clause
#include "../tk1/picorv32/custom_ops.S"
.section ".text"
.globl syscall_enable
.globl syscall
syscall_enable:
// Enable IRQs
li t0, 0x7fffffff // IRQ31 mask
picorv32_maskirq_insn(zero, t0) // Enable IRQs
ret
syscall:
// Save registers to stack
addi sp, sp, -32*4
sw x0, 0*4(sp)
sw x1, 1*4(sp)
// x2 (sp) is assumed to be preserved by the interrupt handler.
sw x3, 3*4(sp)
sw x4, 4*4(sp)
sw x5, 5*4(sp)
sw x6, 6*4(sp)
sw x7, 7*4(sp)
sw x8, 8*4(sp)
sw x9, 9*4(sp)
// x10 (a0) will contain syscall return value. And should not be saved.
sw x11, 11*4(sp)
sw x12, 12*4(sp)
sw x13, 13*4(sp)
sw x14, 14*4(sp)
sw x15, 15*4(sp)
sw x16, 16*4(sp)
sw x17, 17*4(sp)
sw x18, 18*4(sp)
sw x19, 19*4(sp)
sw x20, 20*4(sp)
sw x21, 21*4(sp)
sw x22, 22*4(sp)
sw x23, 23*4(sp)
sw x24, 24*4(sp)
sw x25, 25*4(sp)
sw x26, 26*4(sp)
sw x27, 27*4(sp)
sw x28, 28*4(sp)
sw x29, 29*4(sp)
sw x30, 30*4(sp)
sw x31, 31*4(sp)
// Trigger syscall interrupt
li t0, (1 << 31)
and t0, a0, t0
li t1, 0xe1000000 // Syscall interrupt trigger address
sw zero, 0(t1) // Trigger interrupt
// Restore registers from stack
lw x0, 0*4(sp)
lw x1, 1*4(sp)
// x2 (sp) is assumed to be preserved by the interrupt handler.
lw x3, 3*4(sp)
lw x4, 4*4(sp)
lw x5, 5*4(sp)
lw x6, 6*4(sp)
lw x7, 7*4(sp)
lw x8, 8*4(sp)
lw x9, 9*4(sp)
// x10 (a0) contains syscall return value. And should not be destroyed.
lw x11, 11*4(sp)
lw x12, 12*4(sp)
lw x13, 13*4(sp)
lw x14, 14*4(sp)
lw x15, 15*4(sp)
lw x16, 16*4(sp)
lw x17, 17*4(sp)
lw x18, 18*4(sp)
lw x19, 19*4(sp)
lw x20, 20*4(sp)
lw x21, 21*4(sp)
lw x22, 22*4(sp)
lw x23, 23*4(sp)
lw x24, 24*4(sp)
lw x25, 25*4(sp)
lw x26, 26*4(sp)
lw x27, 27*4(sp)
lw x28, 28*4(sp)
lw x29, 29*4(sp)
lw x30, 30*4(sp)
lw x31, 31*4(sp)
addi sp, sp, 32*4
ret