adds initial low_level_init

This commit is contained in:
2026-03-10 21:01:01 +01:00
parent 2e955b9342
commit f83e96fbcd

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/***************************************************************************
* Copyright (c) 2024 Microsoft Corporation
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
#include "csr.h"
#include "tx_port.h"
.section .text
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _tx_initialize_low_level RISC-V64/GNU */
/* 6.2.1 */
/* AUTHOR */
/* */
/* Scott Larson, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function is responsible for any low-level processor */
/* initialization, including setting up interrupt vectors, setting */
/* up a periodic timer interrupt source, saving the system stack */
/* pointer for use in ISR processing later, and finding the first */
/* available RAM memory address for tx_application_define. */
/* */
/* INPUT */
/* */
/* None */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* _tx_initialize_kernel_enter ThreadX entry function */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 03-08-2023 Scott Larson Initial Version 6.2.1 */
/* */
/**************************************************************************/
/* VOID _tx_initialize_low_level(VOID)
*/
.global _tx_initialize_low_level
.weak _tx_initialize_low_level
.extern __heap_start
.extern board_init
_tx_initialize_low_level:
STORE sp, _tx_thread_system_stack_ptr, t0 // Save system stack pointer
la t0, __heap_start // Pickup first free address
STORE t0, _tx_initialize_unused_memory, t1 // Save unused memory address
li t0, MSTATUS_MIE
csrrc zero, mstatus, t0 // clear MSTATUS_MIE bit
li t0, (MSTATUS_MPP_M | MSTATUS_MPIE )
csrrs zero, mstatus, t0 // set MSTATUS_MPP, MPIE bit
li t0, (MIE_MTIE | MIE_MSIE | MIE_MEIE)
csrrs zero, mie, t0 // set mie
#ifdef __riscv_flen
li t0, MSTATUS_FS
csrrs zero, mstatus, t0 // set MSTATUS_FS bit to open f/d isa in riscv
fscsr x0
#endif
addi sp, sp, -8
STORE ra, 0(sp)
call board_init
LOAD ra, 0(sp)
addi sp, sp, 8
la t0, trap_entry
csrw mtvec, t0
ret