linux-kernel - Re: [PATCH v2] tty: samsung_tty: 32-bit access for TX/RX hold registers

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Date:   Thu, 2 Apr 2020 15:59:03 +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 v2] tty: samsung_tty: 32-bit access for TX/RX hold
 registers

On Thu, Apr 02, 2020 at 08:04:29PM +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>
> ---
>  drivers/tty/serial/samsung_tty.c | 78 +++++++++++++++++++++++++++++++++-------
>  1 file changed, 66 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index 73f951d65b93..826d8c5846a6 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)
> +{
> +	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)
> +{
> +	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)
> +{
> +	switch (port->iotype) {
> +	case UPIO_MEM:
> +		writeb(val, portaddr(port, reg));
> +		break;
> +	case UPIO_MEM32:
> +		writel(val, portaddr(port, reg));
> +		break;
> +	}
> +}
> +
>  /* Byte-order aware bit setting/clearing functions. */
>  
>  static inline void s3c24xx_set_bit(struct uart_port *port, int idx,
> @@ -714,7 +749,7 @@ static void s3c24xx_serial_rx_drain_fifo(struct s3c24xx_uart_port *ourport)
>  		fifocnt--;
>  
>  		uerstat = rd_regl(port, S3C2410_UERSTAT);
> -		ch = rd_regb(port, S3C2410_URXH);
> +		ch = rd_reg(port, S3C2410_URXH);
>  
>  		if (port->flags & UPF_CONS_FLOW) {
>  			int txe = s3c24xx_serial_txempty_nofifo(port);
> @@ -826,7 +861,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
>  	}
>  
>  	if (port->x_char) {
> -		wr_regb(port, S3C2410_UTXH, port->x_char);
> +		wr_reg(port, S3C2410_UTXH, port->x_char);
>  		port->icount.tx++;
>  		port->x_char = 0;
>  		goto out;
> @@ -852,7 +887,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
>  		if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
>  			break;
>  
> -		wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
> +		wr_reg(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
>  		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
>  		port->icount.tx++;
>  		count--;
> @@ -916,7 +951,7 @@ static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port)
>  /* no modem control lines */
>  static unsigned int s3c24xx_serial_get_mctrl(struct uart_port *port)
>  {
> -	unsigned int umstat = rd_regb(port, S3C2410_UMSTAT);
> +	unsigned int umstat = rd_reg(port, S3C2410_UMSTAT);
>  
>  	if (umstat & S3C2410_UMSTAT_CTS)
>  		return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
> @@ -1974,7 +2009,7 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
>  	struct device_node *np = pdev->dev.of_node;
>  	struct s3c24xx_uart_port *ourport;
>  	int index = probe_index;
> -	int ret;
> +	int ret, prop = 0;
>  
>  	if (np) {
>  		ret = of_alias_get_id(np, "serial");
> @@ -2000,10 +2035,29 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
>  			dev_get_platdata(&pdev->dev) :
>  			ourport->drv_data->def_cfg;
>  
> -	if (np)
> +	if (np) {
>  		of_property_read_u32(np,
>  			"samsung,uart-fifosize", &ourport->port.fifosize);
>  
> +		if (of_property_read_u32(np, "reg-io-width", &prop) == 0) {
> +			switch (prop) {
> +			case 1:
> +				ourport->port.iotype = UPIO_MEM;
> +				break;
> +			case 4:
> +				ourport->port.iotype = UPIO_MEM32;
> +				break;
> +			default:
> +				dev_warn(&pdev->dev, "unsupported reg-io-width (%d)\n",
> +						prop);
> +				ret = -EINVAL;
> +				break;
> +			}
> +		} else {
> +			ourport->port.iotype = UPIO_MEM;
> +		}
> +	}

I think this still breaks all non-DT platforms (e.g. s3c).

Best regards,
Krzysztof