linux-kernel - Re: [PATCH v2 18/25] tty: serial: samsung_tty: add s3c24xx_port

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Message-ID: <20210215182651.rjte67udhk3vhbsk@kozik-lap>
Date:   Mon, 15 Feb 2021 19:26:51 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Hector Martin <marcan@...can.st>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Marc Zyngier <maz@...nel.org>, Rob Herring <robh@...nel.org>,
        Arnd Bergmann <arnd@...nel.org>,
        Olof Johansson <olof@...om.net>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Tony Lindgren <tony@...mide.com>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Stan Skowronek <stan@...ellium.com>,
        Alexander Graf <graf@...zon.com>,
        Will Deacon <will@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 18/25] tty: serial: samsung_tty: add s3c24xx_port_type

On Mon, Feb 15, 2021 at 09:17:06PM +0900, Hector Martin wrote:
> This decouples the TTY layer PORT_ types, which are exposed to
> userspace, from the driver-internal flag of what kind of port this is.
> 
> This removes s3c24xx_serial_has_interrupt_mask, which was just checking
> for a specific type anyway, and adds the ucon_mask port info member to
> avoid having S3C2440 as a distinct type.

Please split setting the ucon_mask to separate patch. It's a nice
code simplification on its own.

> 
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>  drivers/tty/serial/samsung_tty.c | 131 ++++++++++++++++++-------------
>  1 file changed, 77 insertions(+), 54 deletions(-)
> 
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index 6b661f3ec1ae..21955be680a4 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -56,9 +56,15 @@
>  /* flag to ignore all characters coming in */
>  #define RXSTAT_DUMMY_READ (0x10000000)
>  
> +enum s3c24xx_port_type {
> +	TYPE_S3C24XX,
> +	TYPE_S3C6400,
> +};
> +
>  struct s3c24xx_uart_info {
>  	char			*name;
> -	unsigned int		type;
> +	enum s3c24xx_port_type	type;
> +	unsigned int		port_type;
>  	unsigned int		fifosize;
>  	unsigned long		rx_fifomask;
>  	unsigned long		rx_fifoshift;
> @@ -70,6 +76,7 @@ struct s3c24xx_uart_info {
>  	unsigned long		num_clks;
>  	unsigned long		clksel_mask;
>  	unsigned long		clksel_shift;
> +	unsigned long		ucon_mask;
>  
>  	/* uart port features */
>  
> @@ -228,16 +235,6 @@ static int s3c24xx_serial_txempty_nofifo(struct uart_port *port)
>  	return rd_regl(port, S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXE;
>  }
>  
> -/*
> - * s3c64xx and later SoC's include the interrupt mask and status registers in
> - * the controller itself, unlike the s3c24xx SoC's which have these registers
> - * in the interrupt controller. Check if the port type is s3c64xx or higher.
> - */
> -static int s3c24xx_serial_has_interrupt_mask(struct uart_port *port)
> -{
> -	return to_ourport(port)->info->type == PORT_S3C6400;
> -}
> -
>  static void s3c24xx_serial_rx_enable(struct uart_port *port)
>  {
>  	struct s3c24xx_uart_port *ourport = to_ourport(port);
> @@ -289,10 +286,14 @@ static void s3c24xx_serial_stop_tx(struct uart_port *port)
>  	if (!ourport->tx_enabled)
>  		return;
>  
> -	if (s3c24xx_serial_has_interrupt_mask(port))
> +	switch (ourport->info->type) {
> +	case TYPE_S3C6400:
>  		s3c24xx_set_bit(port, S3C64XX_UINTM_TXD, S3C64XX_UINTM);
> -	else
> +		break;
> +	default:
>  		disable_irq_nosync(ourport->tx_irq);
> +		break;
> +	}
>  
>  	if (dma && dma->tx_chan && ourport->tx_in_progress == S3C24XX_TX_DMA) {
>  		dmaengine_pause(dma->tx_chan);
> @@ -353,10 +354,14 @@ static void enable_tx_dma(struct s3c24xx_uart_port *ourport)
>  	u32 ucon;
>  
>  	/* Mask Tx interrupt */
> -	if (s3c24xx_serial_has_interrupt_mask(port))
> +	switch (ourport->info->type) {
> +	case TYPE_S3C6400:
>  		s3c24xx_set_bit(port, S3C64XX_UINTM_TXD, S3C64XX_UINTM);
> -	else
> +		break;
> +	default:
>  		disable_irq_nosync(ourport->tx_irq);
> +		break;
> +	}
>  
>  	/* Enable tx dma mode */
>  	ucon = rd_regl(port, S3C2410_UCON);
> @@ -386,11 +391,14 @@ static void enable_tx_pio(struct s3c24xx_uart_port *ourport)
>  	wr_regl(port,  S3C2410_UCON, ucon);
>  
>  	/* Unmask Tx interrupt */
> -	if (s3c24xx_serial_has_interrupt_mask(port))
> -		s3c24xx_clear_bit(port, S3C64XX_UINTM_TXD,
> -				  S3C64XX_UINTM);
> -	else
> +	switch (ourport->info->type) {
> +	case TYPE_S3C6400:
> +		s3c24xx_clear_bit(port, S3C64XX_UINTM_TXD, S3C64XX_UINTM);

Please do not re-wrap. It makes reviewing more difficult. You can
perform proper re-wrapping as a separate cleanup patch.

> +		break;
> +	default:
>  		enable_irq(ourport->tx_irq);
> +		break;
> +	}
>  
>  	ourport->tx_mode = S3C24XX_TX_PIO;
>  }
> @@ -513,11 +521,14 @@ static void s3c24xx_serial_stop_rx(struct uart_port *port)
>  
>  	if (ourport->rx_enabled) {
>  		dev_dbg(port->dev, "stopping rx\n");
> -		if (s3c24xx_serial_has_interrupt_mask(port))
> -			s3c24xx_set_bit(port, S3C64XX_UINTM_RXD,
> -					S3C64XX_UINTM);

The same.

Best regards,
Krzysztof