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

From: 'Krzysztof Kozlowski' <[email-masked]>
Date: Fri, 3 Apr 2020 09:51:22 +0200

On Fri, Apr 03, 2020 at 04:30:38PM +0900, Hyunki Koo wrote:
> On Thu, Apr 02, 2020 at 10:59:29PM +0900, Krzysztof Kozlowski
> > 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 <[email-masked]>
> > > ---
> > >  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
> 
> Thank you for your comment.
> I  hope ourport->port.iotype  is initialized by below table for non-DT platforms

Indeed, you're right. In this case, this else() you added is not needed.
The default value for non-DT and existing DT platforms will be the same
(UPIO_MEM).

Best regards,
Krzysztof

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