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u-boot/arch/riscv/cpu/nx25/start.S
Rick Chen d58717e425 riscv: ae250: Support DT provided by the board at runtime 
Enable CONFIG_OF_BOAD to support delivery dtb to u-boot
at run time instead of embedded.

There are two methods to delivery dtb.
 1 Pass from loader:
   When u-boot boot from RAM, gdb or loader can pass dtb
   via a2 to u-boot dynamically. Of course gdb or loader
   shall be in charge of dtb delivery.

 2 Configure CONFIG_SYS_FDT_BASE:
   It can be configured as RAM or ROM base statically,
   no mater u-boot boot from RAM or ROM.
   If it was configured as ROM base, dtb can be burned
   into ROM(spi flash) by spi driver.

Meanwhile remove CONFIG_SKIP_LOWLEVEL_INIT which is
useless in nx25-ae250 configuration.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Cc: Greentime Hu <green.hu@gmail.com>
2018-03-30 13:13:56 +08:00

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/*
* Startup Code for RISC-V Core
*
* Copyright (c) 2017 Microsemi Corporation.
* Copyright (c) 2017 Padmarao Begari <Padmarao.Begari@microsemi.com>
*
* Copyright (C) 2017 Andes Technology Corporation
* Rick Chen, Andes Technology Corporation <rick@andestech.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <common.h>
#include <elf.h>
#include <asm/encoding.h>
#ifdef CONFIG_32BIT
#define LREG lw
#define SREG sw
#define REGBYTES 4
#define RELOC_TYPE R_RISCV_32
#define SYM_INDEX 0x8
#define SYM_SIZE 0x10
#else
#define LREG ld
#define SREG sd
#define REGBYTES 8
#define RELOC_TYPE R_RISCV_64
#define SYM_INDEX 0x20
#define SYM_SIZE 0x18
#endif
.section .text
.globl _start
_start:
j handle_reset
nmi_vector:
j nmi_vector
trap_vector:
j trap_entry
.global trap_entry
handle_reset:
li t0, CONFIG_SYS_SDRAM_BASE
SREG a2, 0(t0)
la t0, trap_entry
csrw mtvec, t0
csrwi mstatus, 0
csrwi mie, 0
/*
* Do CPU critical regs init only at reboot,
* not when booting from ram
*/
#ifdef CONFIG_INIT_CRITICAL
jal cpu_init_crit /* Do CPU critical regs init */
#endif
/*
* Set stackpointer in internal/ex RAM to call board_init_f
*/
call_board_init_f:
li t0, -16
li t1, CONFIG_SYS_INIT_SP_ADDR
and sp, t1, t0 /* force 16 byte alignment */
#ifdef CONFIG_DEBUG_UART
jal debug_uart_init
#endif
call_board_init_f_0:
mv a0, sp
jal board_init_f_alloc_reserve
mv sp, a0
jal board_init_f_init_reserve
mv a0, zero /* a0 <-- boot_flags = 0 */
la t5, board_init_f
jr t5 /* jump to board_init_f() */
/*
* void relocate_code (addr_sp, gd, addr_moni)
*
* This "function" does not return, instead it continues in RAM
* after relocating the monitor code.
*
*/
.globl relocate_code
relocate_code:
mv s2, a0 /* save addr_sp */
mv s3, a1 /* save addr of gd */
mv s4, a2 /* save addr of destination */
/*
*Set up the stack
*/
stack_setup:
mv sp, s2
la t0, _start
sub t6, s4, t0 /* t6 <- relocation offset */
beq t0, s4, clear_bss /* skip relocation */
mv t1, s4 /* t1 <- scratch for copy_loop */
la t3, __bss_start
sub t3, t3, t0 /* t3 <- __bss_start_ofs */
add t2, t0, t3 /* t2 <- source end address */
copy_loop:
LREG t5, 0(t0)
addi t0, t0, REGBYTES
SREG t5, 0(t1)
addi t1, t1, REGBYTES
blt t0, t2, copy_loop
/*
* Update dynamic relocations after board_init_f
*/
fix_rela_dyn:
la t1, __rel_dyn_start
la t2, __rel_dyn_end
beq t1, t2, clear_bss
add t1, t1, t6 /* t1 <- rela_dyn_start in RAM */
add t2, t2, t6 /* t2 <- rela_dyn_end in RAM */
/*
* skip first reserved entry: address, type, addend
*/
bne t1, t2, 7f
6:
LREG t5, -(REGBYTES*2)(t1) /* t5 <-- relocation info:type */
li t3, R_RISCV_RELATIVE /* reloc type R_RISCV_RELATIVE */
bne t5, t3, 8f /* skip non-RISCV_RELOC entries */
LREG t3, -(REGBYTES*3)(t1)
LREG t5, -(REGBYTES)(t1) /* t5 <-- addend */
add t5, t5, t6 /* t5 <-- location to fix up in RAM */
add t3, t3, t6 /* t3 <-- location to fix up in RAM */
SREG t5, 0(t3)
7:
addi t1, t1, (REGBYTES*3)
ble t1, t2, 6b
8:
la t4, __dyn_sym_start
add t4, t4, t6
9:
LREG t5, -(REGBYTES*2)(t1) /* t5 <-- relocation info:type */
srli t0, t5, SYM_INDEX /* t0 <--- sym table index */
andi t5, t5, 0xFF /* t5 <--- relocation type */
li t3, RELOC_TYPE
bne t5, t3, 10f /* skip non-addned entries */
LREG t3, -(REGBYTES*3)(t1)
li t5, SYM_SIZE
mul t0, t0, t5
add s1, t4, t0
LREG t5, REGBYTES(s1)
add t5, t5, t6 /* t5 <-- location to fix up in RAM */
add t3, t3, t6 /* t3 <-- location to fix up in RAM */
SREG t5, 0(t3)
10:
addi t1, t1, (REGBYTES*3)
ble t1, t2, 9b
/*
* trap update
*/
la t0, trap_entry
add t0, t0, t6
csrw mtvec, t0
clear_bss:
la t0, __bss_start /* t0 <- rel __bss_start in FLASH */
add t0, t0, t6 /* t0 <- rel __bss_start in RAM */
la t1, __bss_end /* t1 <- rel __bss_end in FLASH */
add t1, t1, t6 /* t1 <- rel __bss_end in RAM */
li t2, 0x00000000 /* clear */
beq t0, t1, call_board_init_r
clbss_l:
SREG t2, 0(t0) /* clear loop... */
addi t0, t0, REGBYTES
bne t0, t1, clbss_l
/*
* We are done. Do not return, instead branch to second part of board
* initialization, now running from RAM.
*/
call_board_init_r:
la t0, board_init_r
mv t4, t0 /* offset of board_init_r() */
add t4, t4, t6 /* real address of board_init_r() */
/*
* setup parameters for board_init_r
*/
mv a0, s3 /* gd_t */
mv a1, s4 /* dest_addr */
/*
* jump to it ...
*/
jr t4 /* jump to board_init_r() */
/*
* trap entry
*/
trap_entry:
addi sp, sp, -32*REGBYTES
SREG x1, 1*REGBYTES(sp)
SREG x2, 2*REGBYTES(sp)
SREG x3, 3*REGBYTES(sp)
SREG x4, 4*REGBYTES(sp)
SREG x5, 5*REGBYTES(sp)
SREG x6, 6*REGBYTES(sp)
SREG x7, 7*REGBYTES(sp)
SREG x8, 8*REGBYTES(sp)
SREG x9, 9*REGBYTES(sp)
SREG x10, 10*REGBYTES(sp)
SREG x11, 11*REGBYTES(sp)
SREG x12, 12*REGBYTES(sp)
SREG x13, 13*REGBYTES(sp)
SREG x14, 14*REGBYTES(sp)
SREG x15, 15*REGBYTES(sp)
SREG x16, 16*REGBYTES(sp)
SREG x17, 17*REGBYTES(sp)
SREG x18, 18*REGBYTES(sp)
SREG x19, 19*REGBYTES(sp)
SREG x20, 20*REGBYTES(sp)
SREG x21, 21*REGBYTES(sp)
SREG x22, 22*REGBYTES(sp)
SREG x23, 23*REGBYTES(sp)
SREG x24, 24*REGBYTES(sp)
SREG x25, 25*REGBYTES(sp)
SREG x26, 26*REGBYTES(sp)
SREG x27, 27*REGBYTES(sp)
SREG x28, 28*REGBYTES(sp)
SREG x29, 29*REGBYTES(sp)
SREG x30, 30*REGBYTES(sp)
SREG x31, 31*REGBYTES(sp)
csrr a0, mcause
csrr a1, mepc
mv a2, sp
jal handle_trap
csrw mepc, a0
/*
* Remain in M-mode after mret
*/
li t0, MSTATUS_MPP
csrs mstatus, t0
LREG x1, 1*REGBYTES(sp)
LREG x2, 2*REGBYTES(sp)
LREG x3, 3*REGBYTES(sp)
LREG x4, 4*REGBYTES(sp)
LREG x5, 5*REGBYTES(sp)
LREG x6, 6*REGBYTES(sp)
LREG x7, 7*REGBYTES(sp)
LREG x8, 8*REGBYTES(sp)
LREG x9, 9*REGBYTES(sp)
LREG x10, 10*REGBYTES(sp)
LREG x11, 11*REGBYTES(sp)
LREG x12, 12*REGBYTES(sp)
LREG x13, 13*REGBYTES(sp)
LREG x14, 14*REGBYTES(sp)
LREG x15, 15*REGBYTES(sp)
LREG x16, 16*REGBYTES(sp)
LREG x17, 17*REGBYTES(sp)
LREG x18, 18*REGBYTES(sp)
LREG x19, 19*REGBYTES(sp)
LREG x20, 20*REGBYTES(sp)
LREG x21, 21*REGBYTES(sp)
LREG x22, 22*REGBYTES(sp)
LREG x23, 23*REGBYTES(sp)
LREG x24, 24*REGBYTES(sp)
LREG x25, 25*REGBYTES(sp)
LREG x26, 26*REGBYTES(sp)
LREG x27, 27*REGBYTES(sp)
LREG x28, 28*REGBYTES(sp)
LREG x29, 29*REGBYTES(sp)
LREG x30, 30*REGBYTES(sp)
LREG x31, 31*REGBYTES(sp)
addi sp, sp, 32*REGBYTES
mret
#ifdef CONFIG_INIT_CRITICAL
cpu_init_crit:
ret
#endif
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