[PATCH 7/9] RISC-V: don't use x8/s0/fp in assembly

[Ahmad Fatoum]

Hello Antony,

On 08.01.22 18:15, Ahmad Fatoum wrote:
> Free up the register to allow building a configuration with x8/s0 used
> as the frame pointer.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
>  arch/riscv/include/asm/debug_ll_litex.h   | 12 +++---
>  arch/riscv/include/asm/debug_ll_ns16550.h |  8 ++--
>  arch/riscv/include/asm/riscv_nmon.h       | 50 +++++++++++------------

I just bumped the s register: s2 -> s3, s1 -> s2, s0 -> s1 to
clear s0. Is that ok?

>  3 files changed, 35 insertions(+), 35 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/debug_ll_litex.h b/arch/riscv/include/asm/debug_ll_litex.h
> index 2fcdd9b0ec3e..295477fc1010 100644
> --- a/arch/riscv/include/asm/debug_ll_litex.h
> +++ b/arch/riscv/include/asm/debug_ll_litex.h
> @@ -90,11 +90,11 @@ static inline void PUTC_LL(char ch)
>  	li	t0, DEBUG_LL_UART_ADDR
>  
>  	/* get line status and check for data present */
> -	lbu	s0, UART_RXEMPTY(t0)
> -	bnez    s0, 243f
> -	li	s0, 1
> +	lbu	s1, UART_RXEMPTY(t0)
> +	bnez    s1, 243f
> +	li	s1, 1
>  	j	244f
> -243:	li	s0, 0
> +243:	li	s1, 0
>  244:	nop
>  #endif /* CONFIG_DEBUG_LL */
>  .endm
> @@ -109,10 +109,10 @@ static inline void PUTC_LL(char ch)
>  	debug_ll_tstc
>  
>  	/* try again */
> -	beqz	s0, 204b
> +	beqz	s1, 204b
>  
>  	/* read a character */
> -	lb	s0, UART_RXTX(t0)
> +	lb	s1, UART_RXTX(t0)
>  	li      t1, UART_EV_RX
>  	sb	t1, UART_EV_PENDING(t0)
>  
> diff --git a/arch/riscv/include/asm/debug_ll_ns16550.h b/arch/riscv/include/asm/debug_ll_ns16550.h
> index e208ef4fb1e1..47f0be328ce8 100644
> --- a/arch/riscv/include/asm/debug_ll_ns16550.h
> +++ b/arch/riscv/include/asm/debug_ll_ns16550.h
> @@ -143,8 +143,8 @@ static inline void debug_ll_ns16550_init(void)
>  	li      t0, DEBUG_LL_UART_ADDR
>  
>  	/* get line status and check for data present */
> -	UART_REG_L	s0, UART_LSR(DEBUG_LL_UART_SHIFT)(t0)
> -	andi	s0, s0, UART_LSR_DR
> +	UART_REG_L	s1, UART_LSR(DEBUG_LL_UART_SHIFT)(t0)
> +	andi	s1, s1, UART_LSR_DR
>  
>  #endif /* CONFIG_DEBUG_LL */
>  .endm
> @@ -159,10 +159,10 @@ static inline void debug_ll_ns16550_init(void)
>  	debug_ll_tstc
>  
>  	/* try again */
> -	beqz	s0, 204b
> +	beqz	s1, 204b
>  
>  	/* read a character */
> -	UART_REG_L	s0, UART_RBR(DEBUG_LL_UART_SHIFT)(t0)
> +	UART_REG_L	s1, UART_RBR(DEBUG_LL_UART_SHIFT)(t0)
>  
>  #endif /* CONFIG_DEBUG_LL */
>  .endm
> diff --git a/arch/riscv/include/asm/riscv_nmon.h b/arch/riscv/include/asm/riscv_nmon.h
> index 8a44e216d72d..3e349025febc 100644
> --- a/arch/riscv/include/asm/riscv_nmon.h
> +++ b/arch/riscv/include/asm/riscv_nmon.h
> @@ -84,7 +84,7 @@ nmon_main:
>  	debug_ll_getc
>  
>  	li	a0, 'q'
> -	bne	s0, a0, 3f
> +	bne	s1, a0, 3f
>  
>  	jal	a2, _nmon_outc_a0
>  
> @@ -92,13 +92,13 @@ nmon_main:
>  
>  3:
>  	li	a0, 'd'
> -	beq	s0, a0, nmon_cmd_d
> +	beq	s1, a0, nmon_cmd_d
>  
>  	li	a0, 'w'
> -	beq	s0, a0, nmon_cmd_w
> +	beq	s1, a0, nmon_cmd_w
>  
>  	li	a0, 'g'
> -	beq	s0, a0, nmon_cmd_g
> +	beq	s1, a0, nmon_cmd_g
>  
>  	j	nmon_main_help
>  
> @@ -112,7 +112,7 @@ nmon_cmd_d:
>  
>  	nmon_outs	msg_nl
>  
> -	lw	a0, (s0)
> +	lw	a0, (s1)
>  	debug_ll_outhexw
>  
>  	j	nmon_main
> @@ -124,13 +124,13 @@ nmon_cmd_w:
>  	jal	a2, _nmon_outc_a0
>  
>  	jal	a2, _nmon_gethexw
> -	move	s2, s0
> +	move	s3, s1
>  
>  	li	a0, ' '
>  	jal	a2, _nmon_outc_a0
>  	jal	a2, _nmon_gethexw
>  
> -	sw	s0, 0(s2)
> +	sw	s1, 0(s3)
>  	j	nmon_main
>  
>  nmon_cmd_g:
> @@ -140,11 +140,11 @@ nmon_cmd_g:
>  	jal	a2, _nmon_outc_a0
>  
>  	jal	a2, _nmon_gethexw
> -	move	s2, s0
> +	move	s3, s1
>  
>  	nmon_outs	msg_nl
>  
> -	jalr	s2
> +	jalr	s3
>  	j	nmon_main
>  
>  _nmon_outc_a0:
> @@ -169,37 +169,37 @@ _nmon_gethexw:
>  _get_hex_digit:
>  	debug_ll_getc
>  
> -	li	s1, CODE_ESC
> -	beq	s0, s1, nmon_main
> +	li	s2, CODE_ESC
> +	beq	s1, s2, nmon_main
>  
> -	li	s1, '0'
> -	bge	s0, s1, 0f
> +	li	s2, '0'
> +	bge	s1, s2, 0f
>  	j	_get_hex_digit
>  
>  0:
> -	li	s1, '9'
> -	ble	s0, s1, 9f
> +	li	s2, '9'
> +	ble	s1, s2, 9f
>  
> -	li	s1, 'f'
> -	ble	s0, s1, 1f
> +	li	s2, 'f'
> +	ble	s1, s2, 1f
>  	j	_get_hex_digit
>  
>  1:
> -	li	s1, 'a'
> -	bge	s0, s1, 8f
> +	li	s2, 'a'
> +	bge	s1, s2, 8f
>  
>  	j	_get_hex_digit
>  
> -8: /* s0 \in {'a', 'b' ... 'f'} */
> -	sub	a3, s0, s1
> +8: /* s1 \in {'a', 'b' ... 'f'} */
> +	sub	a3, s1, s2
>  	addi	a3, a3, 0xa
>  	j	0f
>  
> -9: /* s0 \in {'0', '1' ... '9'} */
> +9: /* s1 \in {'0', '1' ... '9'} */
>  	li	a3, '0'
> -	sub	a3, s0, a3
> +	sub	a3, s1, a3
>  
> -0:	move	a0, s0
> +0:	move	a0, s1
>  	debug_ll_outc_a0
>  
>  	sll	t2, t2, 4
> @@ -212,7 +212,7 @@ _get_hex_digit:
>  	j	_get_hex_digit
>  
>  0:
> -	move	s0, t2
> +	move	s1, t2
>  
>  _nmon_jr_ra_exit:
>  	jr	a2
> 


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