nmon is a tiny (<1024 bytes) monitor program
for the RV32I processors.
It can operate with NO working RAM at all!
It uses only the processor registers and NS16550-compatible
UART port for operation, so it can be used for a memory
controller setup code debugging.
Signed-off-by: Antony Pavlov <antonynpavlov@xxxxxxxxx>
---
arch/riscv/Kconfig | 24 +++
arch/riscv/boot/start.S | 13 ++
arch/riscv/include/asm/riscv_nmon.h | 234 ++++++++++++++++++++++++++++
3 files changed, 271 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index fe79cb49b5..9e7faf11d0 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -64,6 +64,30 @@ source arch/riscv/mach-erizo/Kconfig
endmenu
+menu "RISC-V specific settings"
+
+config HAS_NMON
+ bool
+
+config NMON
+ bool "nmon"
+ depends on HAS_NMON
+ depends on DEBUG_LL
+ help
+ Say yes here to add the nmon to pbl.
+ nmon -- nano-monitor program for the RISC-V processors.
+ It can operate with NO working RAM, using only
+ the processor registers.
+
+config NMON_HELP
+ bool "nmon help message"
+ depends on NMON
+ help
+ Say yes here to get the nmon commands message on
+ every nmon start.
+
+endmenu
+
source common/Kconfig
source commands/Kconfig
source net/Kconfig
diff --git a/arch/riscv/boot/start.S b/arch/riscv/boot/start.S
index be3aed1507..4ae2f77f9d 100644
--- a/arch/riscv/boot/start.S
+++ b/arch/riscv/boot/start.S
@@ -21,12 +21,20 @@
#include <asm-generic/memory_layout.h>
+#include "mach/debug_ll.h"
+
+#include "asm/riscv_nmon.h"
+
.text
.section ".text_entry"
.align 2
.globl _start
_start:
+ debug_ll_ns16550_init
+
+ riscv_nmon
+
li sp, STACK_BASE + STACK_SIZE
/* copy barebox to link location */
@@ -55,9 +63,14 @@ copy_loop:
addi a1, a1, LONGSIZE * 4
bgeu a2, a0, copy_loop
+ nmon_outs copy_loop_done_message
+
/* Alas! At the moment I can't load main_entry __link__ address
into a0 with la. Use CONFIG_TEXT_BASE instead. This solution
leads to extra cycles for repeat sp initialization. */
li a0, CONFIG_TEXT_BASE
jalr a0
+
+copy_loop_done_message:
+ .asciz "\r\ncopy loop done\r\nrestarting...\r\n"
diff --git a/arch/riscv/include/asm/riscv_nmon.h b/arch/riscv/include/asm/riscv_nmon.h
new file mode 100644
index 0000000000..717f613349
--- /dev/null
+++ b/arch/riscv/include/asm/riscv_nmon.h
@@ -0,0 +1,234 @@
+/*
+ * nano-monitor for RISC-V CPU
+ *
+ * Copyright (C) 2016, 2017 Antony Pavlov <antonynpavlov@xxxxxxxxx>
+ *
+ * This file is part of barebox.
+ * See file CREDITS for list of people who contributed to this project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __ASM_RISCV_NMON_H
+#define __ASM_RISCV_NMON_H
+
+#define CODE_ESC 0x1b
+
+.macro nmon_outs msg
+
+ la a1, \msg
+
+ jal _nmon_outs
+
+.endm
+
+/*
+ * output a 32-bit value in hex
+ */
+.macro debug_ll_outhexw
+#ifdef CONFIG_DEBUG_LL
+ move t6, a0
+ li t5, 32
+
+202:
+ addi t5, t5, -4
+ srl a0, t6, t5
+
+ /* output one hex digit */
+ andi a0, a0, 15
+ li t4, 10
+ blt a0, t4, 203f
+
+ addi a0, a0, ('a' - '9' - 1)
+
+203:
+ addi a0, a0, '0'
+
+ debug_ll_outc_a0
+
+ li t4, 1
+ bge t5, t4, 202b
+
+#endif /* CONFIG_DEBUG_LL */
+.endm
+
+.macro riscv_nmon
+
+nmon_main_help:
+#ifdef CONFIG_NMON_HELP
+ nmon_outs msg_nmon_help
+#endif /* CONFIG_NMON_HELP */
+
+nmon_main:
+ nmon_outs msg_prompt
+
+ debug_ll_getc
+
+ li a0, 'q'
+ bne s0, a0, 3f
+
+ jal _nmon_outc_a0
+
+ j nmon_exit
+
+3:
+ li a0, 'd'
+ beq s0, a0, nmon_cmd_d
+
+ li a0, 'w'
+ beq s0, a0, nmon_cmd_w
+
+ li a0, 'g'
+ beq s0, a0, nmon_cmd_g
+
+ j nmon_main_help
+
+nmon_cmd_d:
+ jal _nmon_outc_a0
+
+ li a0, ' '
+ jal _nmon_outc_a0
+
+ jal _nmon_gethexw
+
+ nmon_outs msg_nl
+
+ lw a0, (s0)
+ debug_ll_outhexw
+
+ j nmon_main
+
+nmon_cmd_w:
+ jal _nmon_outc_a0
+
+ li a0, ' '
+ jal _nmon_outc_a0
+
+ jal _nmon_gethexw
+ move s2, s0
+
+ li a0, ' '
+ jal _nmon_outc_a0
+ jal _nmon_gethexw
+
+ sw s0, 0(s2)
+ j nmon_main
+
+nmon_cmd_g:
+ jal _nmon_outc_a0
+
+ li a0, ' '
+ jal _nmon_outc_a0
+
+ jal _nmon_gethexw
+ move s2, s0
+
+ nmon_outs msg_nl
+
+ jalr s2
+ j nmon_main
+
+_nmon_outc_a0:
+ debug_ll_outc_a0
+ jr ra
+
+_nmon_outs:
+
+ lb a0, 0(a1)
+ addi a1, a1, 1
+ beqz a0, _nmon_jr_ra_exit
+
+ debug_ll_outc_a0
+
+ j _nmon_outs
+
+_nmon_gethexw:
+
+ li t3, 8
+ li t2, 0
+
+_get_hex_digit:
+ debug_ll_getc
+
+ li s1, CODE_ESC
+ beq s0, s1, nmon_main
+
+ li s1, '0'
+ bge s0, s1, 0f
+ j _get_hex_digit
+
+0:
+ li s1, '9'
+ ble s0, s1, 9f
+
+ li s1, 'f'
+ ble s0, s1, 1f
+ j _get_hex_digit
+
+1:
+ li s1, 'a'
+ bge s0, s1, 8f
+
+ j _get_hex_digit
+
+8: /* s0 \in {'a', 'b' ... 'f'} */
+ sub a3, s0, s1
+ addi a3, a3, 0xa
+ j 0f
+
+9: /* s0 \in {'0', '1' ... '9'} */
+ li a3, '0'
+ sub a3, s0, a3
+
+0: move a0, s0
+ debug_ll_outc_a0
+
+ sll t2, t2, 4
+ or t2, t2, a3
+ li t0, 1
+ sub t3, t3, t0
+
+ beqz t3, 0f
+
+ j _get_hex_digit
+
+0:
+ move s0, t2
+
+_nmon_jr_ra_exit:
+ jr ra
+
+msg_prompt:
+ .asciz "\r\nnmon> "
+
+msg_nl:
+ .asciz "\r\n"
+
+msg_bsp:
+ .asciz "\b \b"
+
+#ifdef CONFIG_NMON_HELP
+msg_nmon_help:
+ .ascii "\r\n\r\nnmon commands:\r\n"
+ .ascii " q - quit\r\n"
+ .ascii " d <addr> - read 32-bit word from <addr>\r\n"
+ .ascii " w <addr> <val> - write 32-bit word to <addr>\r\n"
+ .ascii " g <addr> - jump to <addr>\r\n"
+ .asciz " use <ESC> key to interrupt current command\r\n"
+#endif /* CONFIG_NMON_HELP */
+
+ .align 2
+nmon_exit:
+ nmon_outs msg_nl
+
+.endm
+
+#endif /* __ASM_RISCV_NMON_H */
--
2.17.0
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