source: rtems/bsps/riscv/riscv/start/start.S @ 5f5c450

/*
 * Copyright (c) 2015 University of York.
 * Hesham Almatary <hesham@alumni.york.ac.uk>
 *
 * Copyright (c) 2013, The Regents of the University of California (Regents).
 * All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <rtems/asm.h>
#include <rtems/score/cpu.h>
#include <rtems/score/riscv-utility.h>
#include <bsp/linker-symbols.h>
#include <bspopts.h>

EXTERN(bsp_section_bss_begin)
EXTERN(bsp_section_bss_end)
EXTERN(ISR_Handler)
EXTERN(bsp_section_stack_begin)

PUBLIC(bsp_start_vector_table_begin)
PUBLIC(bsp_start_vector_table_end)
PUBLIC(_start)

        .section        .bsp_start_text, "wax", @progbits
        .align  2

TYPE_FUNC(_start)
SYM(_start):
        /* Load global pointer */
        .option push
        .option norelax
        la      gp, __global_pointer$
        .option pop

#ifdef RTEMS_SMP
        csrr    s0, mhartid
        bnez    s0, .Lwait_for_go
#endif

        /* load stack and frame pointers */
        la      sp, _Configuration_Interrupt_stack_area_end

#ifdef BSP_START_COPY_FDT_FROM_U_BOOT
        mv      a0, a1
        call    bsp_fdt_copy
#endif

        la      t0, ISR_Handler
        csrw    mtvec, t0

        /* Clear .bss */
        la      a0, bsp_section_bss_begin
        li      a1, 0
        la      a2, bsp_section_bss_size
        call    memset

#ifdef RTEMS_SMP
        /* Give go to secondary processors */
        la      t0, .Lsecondary_processor_go
        fence   iorw,ow
        amoswap.w       zero, zero, 0(t0)
#endif

        /* Init FPU unit if it's there */
        li      t0, MSTATUS_FS
        csrs    mstatus, t0

        j       boot_card

#ifdef RTEMS_SMP
        /* Wait for go issued by the boot processor (mhartid == 0) */
.Lwait_for_go:
        la      t0, .Lsecondary_processor_go
.Lwait_for_go_again:
        lw      t1, 0(t0)
        fence   iorw, iorw
        sext.w  t1, t1
        bnez    t1, .Lwait_for_go_again
.Lloop_forever:
        j       .Lloop_forever

.Lsecondary_processor_go:
        .word   0xdeadbeef
#endif

        .align  4
bsp_start_vector_table_begin:
        .word   _RISCV_Exception_default /* User int */
        .word   _RISCV_Exception_default /* Supervisor int */
        .word   _RISCV_Exception_default /* Reserved */
        .word   _RISCV_Exception_default /* Machine int */
        .word   _RISCV_Exception_default /* User timer int */
        .word   _RISCV_Exception_default /* Supervisor Timer int */
        .word   _RISCV_Exception_default /* Reserved */
        .word   _RISCV_Exception_default /* Machine Timer int */
        .word   _RISCV_Exception_default /* User external int */
        .word   _RISCV_Exception_default /* Supervisor external int */
        .word   _RISCV_Exception_default /* Reserved */
        .word   _RISCV_Exception_default /* Machine external int */
        .word   _RISCV_Exception_default
        .word   _RISCV_Exception_default
        .word   _RISCV_Exception_default
        .word   _RISCV_Exception_default
bsp_start_vector_table_end: