linux-kernel - Re: [PATCH 4/6] tty: serial: amba-pl011: replace TIOCMBIT macros by static functions

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Message-Id: <20231026102424.81c0f7487df505d2ed92cf13@hugovil.com>
Date:   Thu, 26 Oct 2023 10:24:24 -0400
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     Théo Lebrun <theo.lebrun@...tlin.com>
Cc:     Russell King <linux@...linux.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Gregory CLEMENT <gregory.clement@...tlin.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
        Tawfik Bayouk <tawfik.bayouk@...ileye.com>
Subject: Re: [PATCH 4/6] tty: serial: amba-pl011: replace TIOCMBIT macros by
 static functions

On Thu, 26 Oct 2023 12:41:21 +0200
Théo Lebrun <theo.lebrun@...tlin.com> wrote:

Hi,

> The driver uses two TIOCMBIT macros inside pl011_{get,set}_mctrl to
> simplify the logic. Those look scary to checkpatch because they contain
> ifs without do-while loops.
> 
> Avoid the macros by creating small equivalent static functions; that
> lets the compiler do its type checking & avoids checkpatch errors.
> 
> For the second instance __assign_bit is not usable because it deals with
> unsigned long pointers whereas we have an unsigned int in
> pl011_set_mctrl.
> 
> Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
> ---
>  drivers/tty/serial/amba-pl011.c | 46 +++++++++++++++++++++--------------------
>  1 file changed, 24 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 0d53973374de..bb3082c4d35c 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -1087,7 +1087,6 @@ static void pl011_dma_rx_poll(struct timer_list *t)
>  	 */
>  	if (jiffies_to_msecs(jiffies - dmarx->last_jiffies)
>  			> uap->dmarx.poll_timeout) {
> -

This should go into a separate patch, or simply be merged with one
of your other coding style/whitespace cleanup patches.

Hugo.


>  		spin_lock_irqsave(&uap->port.lock, flags);
>  		pl011_dma_rx_stop(uap);
>  		uap->im |= UART011_RXIM;
> @@ -1595,6 +1594,12 @@ static unsigned int pl011_tx_empty(struct uart_port *port)
>  							0 : TIOCSER_TEMT;
>  }
>  
> +static void pl011_maybe_set_bit(bool cond, unsigned int *ptr, unsigned int mask)
> +{
> +	if (cond)
> +		*ptr |= mask;
> +}
> +
>  static unsigned int pl011_get_mctrl(struct uart_port *port)
>  {
>  	struct uart_amba_port *uap =
> @@ -1602,18 +1607,22 @@ static unsigned int pl011_get_mctrl(struct uart_port *port)
>  	unsigned int result = 0;
>  	unsigned int status = pl011_read(uap, REG_FR);
>  
> -#define TIOCMBIT(uartbit, tiocmbit)	\
> -	if (status & uartbit)		\
> -		result |= tiocmbit
> +	pl011_maybe_set_bit(status & UART01x_FR_DCD, &result, TIOCM_CAR);
> +	pl011_maybe_set_bit(status & uap->vendor->fr_dsr, &result, TIOCM_DSR);
> +	pl011_maybe_set_bit(status & uap->vendor->fr_cts, &result, TIOCM_CTS);
> +	pl011_maybe_set_bit(status & uap->vendor->fr_ri, &result, TIOCM_RNG);
>  
> -	TIOCMBIT(UART01x_FR_DCD, TIOCM_CAR);
> -	TIOCMBIT(uap->vendor->fr_dsr, TIOCM_DSR);
> -	TIOCMBIT(uap->vendor->fr_cts, TIOCM_CTS);
> -	TIOCMBIT(uap->vendor->fr_ri, TIOCM_RNG);
> -#undef TIOCMBIT
>  	return result;
>  }
>  
> +static void pl011_assign_bit(bool cond, unsigned int *ptr, unsigned int mask)
> +{
> +	if (cond)
> +		*ptr |= mask;
> +	else
> +		*ptr &= ~mask;
> +}
> +
>  static void pl011_set_mctrl(struct uart_port *port, unsigned int mctrl)
>  {
>  	struct uart_amba_port *uap =
> @@ -1622,23 +1631,16 @@ static void pl011_set_mctrl(struct uart_port *port, unsigned int mctrl)
>  
>  	cr = pl011_read(uap, REG_CR);
>  
> -#define	TIOCMBIT(tiocmbit, uartbit)		\
> -	if (mctrl & tiocmbit)		\
> -		cr |= uartbit;		\
> -	else				\
> -		cr &= ~uartbit
> -
> -	TIOCMBIT(TIOCM_RTS, UART011_CR_RTS);
> -	TIOCMBIT(TIOCM_DTR, UART011_CR_DTR);
> -	TIOCMBIT(TIOCM_OUT1, UART011_CR_OUT1);
> -	TIOCMBIT(TIOCM_OUT2, UART011_CR_OUT2);
> -	TIOCMBIT(TIOCM_LOOP, UART011_CR_LBE);
> +	pl011_assign_bit(mctrl & TIOCM_RTS, &cr, UART011_CR_RTS);
> +	pl011_assign_bit(mctrl & TIOCM_DTR, &cr, UART011_CR_DTR);
> +	pl011_assign_bit(mctrl & TIOCM_OUT1, &cr, UART011_CR_OUT1);
> +	pl011_assign_bit(mctrl & TIOCM_OUT2, &cr, UART011_CR_OUT2);
> +	pl011_assign_bit(mctrl & TIOCM_LOOP, &cr, UART011_CR_LBE);
>  
>  	if (port->status & UPSTAT_AUTORTS) {
>  		/* We need to disable auto-RTS if we want to turn RTS off */
> -		TIOCMBIT(TIOCM_RTS, UART011_CR_RTSEN);
> +		pl011_assign_bit(mctrl & TIOCM_RTS, &cr, UART011_CR_RTSEN);
>  	}
> -#undef TIOCMBIT
>  
>  	pl011_write(cr, uap, REG_CR);
>  }
> 
> -- 
> 2.41.0
>