linux-kernel - Re: [PATCH v3] tty: samsung_tty: 32-bit access for TX/RX hold registers

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Message-ID: <20200403104744.GA29385@kozik-lap>
Date:   Fri, 3 Apr 2020 12:47:44 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Hyunki Koo <hyunki00.koo@...sung.com>
Cc:     gregkh@...uxfoundation.org, Kukjin Kim <kgene@...nel.org>,
        Jiri Slaby <jslaby@...e.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] tty: samsung_tty: 32-bit access for TX/RX hold
 registers

On Fri, Apr 03, 2020 at 07:20:41PM +0900, Hyunki Koo wrote:
> Support 32-bit access for the TX/RX hold registers UTXH and URXH.
> 
> This is required for some newer SoCs.
> 
> Signed-off-by: Hyunki Koo <hyunki00.koo@...sung.com>
> ---
> v3: change rd_regl to rd_reg in line 954 for backward compatibility.

I cannot find this change against v2.

> ---
> 
>  drivers/tty/serial/samsung_tty.c | 76 +++++++++++++++++++++++++++++++++-------
>  1 file changed, 64 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index 73f951d65b93..a674a80163ed 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -154,12 +154,47 @@ struct s3c24xx_uart_port {
>  #define portaddrl(port, reg) \
>  	((unsigned long *)(unsigned long)((port)->membase + (reg)))
>  
> -#define rd_regb(port, reg) (readb_relaxed(portaddr(port, reg)))
> +static unsigned int rd_reg(struct uart_port *port, int reg)

You should return here u32 to be consistent with readl_relaxed.

> +{
> +	switch (port->iotype) {
> +	case UPIO_MEM:
> +		return readb_relaxed(portaddr(port, reg));
> +	case UPIO_MEM32:
> +		return readl_relaxed(portaddr(port, reg));
> +	default:
> +		return 0;
> +	}
> +	return 0;
> +}
> +
>  #define rd_regl(port, reg) (readl_relaxed(portaddr(port, reg)))
>  
> -#define wr_regb(port, reg, val) writeb_relaxed(val, portaddr(port, reg))
> +static void wr_reg(struct uart_port *port, int reg, int val)

val should be u32.

> +{
> +	switch (port->iotype) {
> +	case UPIO_MEM:
> +		writeb_relaxed(val, portaddr(port, reg));
> +		break;
> +	case UPIO_MEM32:
> +		writel_relaxed(val, portaddr(port, reg));
> +		break;
> +	}
> +}
> +
>  #define wr_regl(port, reg, val) writel_relaxed(val, portaddr(port, reg))
>  
> +static void write_buf(struct uart_port *port, int reg, int val)

buf is misleading, you do not write here any buffer. Maybe
"wr_reg_barrier()" or "wr_reg_order()"?

Best regards,
Krzysztof