Re: [PATCH 1/9] RISC-V: make it possible to run nmon from PBL C code

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello,

On 05.05.21 12:08, Antony Pavlov wrote:
> After migrating to PBL we can't use nmon assembler macro
> in C code anymore. Some changes are introduced to invoke
> nmon from PBL C code:
> 
>   * use 'lla' macro instruction instead of 'la';
>   * don't touch the 'ra' register, use 'a2' instead;
>   * add wrapper C function for nmon.
> 
> Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
> ---
>  arch/riscv/boot/Makefile            |  1 +
>  arch/riscv/boot/nmon_entry.S        | 13 ++++++++++++
>  arch/riscv/include/asm/riscv_nmon.h | 33 ++++++++++++++---------------
>  3 files changed, 30 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile
> index 968a826d16..80f63a4a0a 100644
> --- a/arch/riscv/boot/Makefile
> +++ b/arch/riscv/boot/Makefile
> @@ -1,4 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-y += start.o
>  pbl-y += entry.o uncompress.o
> +pbl-y += nmon_entry.o
>  pbl-$(CONFIG_BOARD_GENERIC_DT) += board-dt-2nd.o
> diff --git a/arch/riscv/boot/nmon_entry.S b/arch/riscv/boot/nmon_entry.S
> new file mode 100644
> index 0000000000..9b30b50627
> --- /dev/null
> +++ b/arch/riscv/boot/nmon_entry.S
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <linux/linkage.h>
> +#include <asm/sections.h>
> +
> +#include "mach/debug_ll.h"
> +#include "asm/riscv_nmon.h"
> +
> +.section .text_bare_init
> +
> +ENTRY(__barebox_nmon_entry)

Perhaps drop the __? __ makes me think I should
not call this or that there is a non __-prefixed
versions, but both don't seem to be true as boards
do directly call this.

> +	riscv_nmon
> +	ret
> +ENDPROC(__barebox_nmon_entry)
> diff --git a/arch/riscv/include/asm/riscv_nmon.h b/arch/riscv/include/asm/riscv_nmon.h
> index caf213cdd8..11b19ab35b 100644
> --- a/arch/riscv/include/asm/riscv_nmon.h
> +++ b/arch/riscv/include/asm/riscv_nmon.h
> @@ -20,9 +20,8 @@


Please add
#ifndef __ASSEMBLY__
void __barebox_nmon_entry(void);
#endif

here.

With that addressed:
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

>  
>  .macro nmon_outs msg
>  
> -	la	a1, \msg
> -
> -	jal	_nmon_outs
> +	lla	a1, \msg
> +	jal	a2, _nmon_outs
>  
>  .endm
>  
> @@ -73,7 +72,7 @@ nmon_main:
>  	li	a0, 'q'
>  	bne	s0, a0, 3f
>  
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
>  	j	nmon_exit
>  
> @@ -90,12 +89,12 @@ nmon_main:
>  	j	nmon_main_help
>  
>  nmon_cmd_d:
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
>  	li	a0, ' '
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
> -	jal	_nmon_gethexw
> +	jal	a2, _nmon_gethexw
>  
>  	nmon_outs	msg_nl
>  
> @@ -105,28 +104,28 @@ nmon_cmd_d:
>  	j	nmon_main
>  
>  nmon_cmd_w:
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
>  	li	a0, ' '
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
> -	jal	_nmon_gethexw
> +	jal	a2, _nmon_gethexw
>  	move	s2, s0
>  
>  	li	a0, ' '
> -	jal	_nmon_outc_a0
> -	jal	_nmon_gethexw
> +	jal	a2, _nmon_outc_a0
> +	jal	a2, _nmon_gethexw
>  
>  	sw	s0, 0(s2)
>  	j	nmon_main
>  
>  nmon_cmd_g:
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
>  	li	a0, ' '
> -	jal	_nmon_outc_a0
> +	jal	a2, _nmon_outc_a0
>  
> -	jal	_nmon_gethexw
> +	jal	a2, _nmon_gethexw
>  	move	s2, s0
>  
>  	nmon_outs	msg_nl
> @@ -136,7 +135,7 @@ nmon_cmd_g:
>  
>  _nmon_outc_a0:
>  	debug_ll_outc_a0
> -	jr	ra
> +	jr	a2
>  
>  _nmon_outs:
>  
> @@ -202,7 +201,7 @@ _get_hex_digit:
>  	move	s0, t2
>  
>  _nmon_jr_ra_exit:
> -	jr	ra
> +	jr	a2
>  
>  msg_prompt:
>  	.asciz "\r\nnmon> "
> 

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