[PATCH v1 1/3] tty: serial: lpuart: Remove unnecessary code from set_mctrl

[PATCH v1 1/3] tty: serial: lpuart: Remove unnecessary code from set_mctrl

[Philippe Schenker]

Currently flow control is not working due to lpuart32_set_mctrl that is
clearing TXCTSE bit in all cases. This bit gets earlier setup by
lpuart32_set_termios.

As I read in Documentation set_mctrl is also not meant for hardware
flow control rather than gpio setting and clearing a RTS signal.
Therefore I guess it is safe to remove the whole code in
lpuart32_set_mctrl.

This was tested with console on a i.MX8QXP SoC.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
---

 drivers/tty/serial/fsl_lpuart.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 537896c4d887..f3271857621c 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1333,18 +1333,7 @@ static void lpuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 
 static void lpuart32_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
-	unsigned long temp;
-
-	temp = lpuart32_read(port, UARTMODIR) &
-			~(UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
-
-	if (mctrl & TIOCM_RTS)
-		temp |= UARTMODIR_RXRTSE;
-
-	if (mctrl & TIOCM_CTS)
-		temp |= UARTMODIR_TXCTSE;
 
-	lpuart32_write(port, temp, UARTMODIR);
 }
 
 static void lpuart_break_ctl(struct uart_port *port, int break_state)
-- 
2.23.0

[PATCH v1 2/3] tty: serial: lpuart: Use defines that correspond to correct register

[Philippe Schenker]

Use UARTMODIR defines instead of UARTMODEM as it is a 32-bit function

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
---

 drivers/tty/serial/fsl_lpuart.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f3271857621c..346b4a070ce9 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1879,10 +1879,10 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	}
 
 	if (termios->c_cflag & CRTSCTS) {
-		modem |= UARTMODEM_RXRTSE | UARTMODEM_TXCTSE;
+		modem |= (UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
 	} else {
 		termios->c_cflag &= ~CRTSCTS;
-		modem &= ~(UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
+		modem &= ~(UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
 	}
 
 	if (termios->c_cflag & CSTOPB)
-- 
2.23.0

[PATCH v1 3/3] tty: serial: lpuart: Add RS485 support for 32-bit uart flavour

[Philippe Schenker]

This commits adds RS485 support for LPUART hardware that uses 32-bit
registers. These are typically found in i.MX8 processors.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

---

 drivers/tty/serial/fsl_lpuart.c | 65 ++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 346b4a070ce9..22df5f8f48b6 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1280,6 +1280,57 @@ static int lpuart_config_rs485(struct uart_port *port,
 	return 0;
 }
 
+static int lpuart32_config_rs485(struct uart_port *port,
+			struct serial_rs485 *rs485)
+{
+	struct lpuart_port *sport = container_of(port,
+			struct lpuart_port, port);
+
+	unsigned long modem = lpuart32_read(&sport->port, UARTMODIR)
+				& ~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
+	lpuart32_write(&sport->port, modem, UARTMODIR);
+
+	/* clear unsupported configurations */
+	rs485->delay_rts_before_send = 0;
+	rs485->delay_rts_after_send = 0;
+	rs485->flags &= ~SER_RS485_RX_DURING_TX;
+
+	if (rs485->flags & SER_RS485_ENABLED) {
+		/* Enable auto RS-485 RTS mode */
+		modem |= UARTMODEM_TXRTSE;
+
+		/*
+		 * RTS needs to be logic HIGH either during transer _or_ after
+		 * transfer, other variants are not supported by the hardware.
+		 */
+
+		if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
+				SER_RS485_RTS_AFTER_SEND)))
+			rs485->flags |= SER_RS485_RTS_ON_SEND;
+
+		if (rs485->flags & SER_RS485_RTS_ON_SEND &&
+				rs485->flags & SER_RS485_RTS_AFTER_SEND)
+			rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
+
+		/*
+		 * The hardware defaults to RTS logic HIGH while transfer.
+		 * Switch polarity in case RTS shall be logic HIGH
+		 * after transfer.
+		 * Note: UART is assumed to be active high.
+		 */
+		if (rs485->flags & SER_RS485_RTS_ON_SEND)
+			modem &= ~UARTMODEM_TXRTSPOL;
+		else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
+			modem |= UARTMODEM_TXRTSPOL;
+	}
+
+	/* Store the new configuration */
+	sport->port.rs485 = *rs485;
+
+	lpuart32_write(&sport->port, modem, UARTMODIR);
+	return 0;
+}
+
 static unsigned int lpuart_get_mctrl(struct uart_port *port)
 {
 	unsigned int temp = 0;
@@ -1878,6 +1929,13 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 		ctrl |= UARTCTRL_M;
 	}
 
+	/*
+	 * When auto RS-485 RTS mode is enabled,
+	 * hardware flow control need to be disabled.
+	 */
+	if (sport->port.rs485.flags & SER_RS485_ENABLED)
+		termios->c_cflag &= ~CRTSCTS;
+
 	if (termios->c_cflag & CRTSCTS) {
 		modem |= (UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
 	} else {
@@ -2405,7 +2463,10 @@ static int lpuart_probe(struct platform_device *pdev)
 		sport->port.ops = &lpuart_pops;
 	sport->port.flags = UPF_BOOT_AUTOCONF;
 
-	sport->port.rs485_config = lpuart_config_rs485;
+	if (lpuart_is_32(sport))
+		sport->port.rs485_config = lpuart32_config_rs485;
+	else
+		sport->port.rs485_config = lpuart_config_rs485;
 
 	sport->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(sport->ipg_clk)) {
@@ -2459,7 +2520,7 @@ static int lpuart_probe(struct platform_device *pdev)
 	    sport->port.rs485.delay_rts_after_send)
 		dev_err(&pdev->dev, "driver doesn't support RTS delays\n");
 
-	lpuart_config_rs485(&sport->port, &sport->port.rs485);
+	sport->port.rs485_config(&sport->port, &sport->port.rs485);
 
 	sport->dma_tx_chan = dma_request_slave_channel(sport->port.dev, "tx");
 	if (!sport->dma_tx_chan)
-- 
2.23.0

Re: [PATCH v1 2/3] tty: serial: lpuart: Use defines that correspond to correct register

[Stefan Agner]

On 2019-10-16 17:18, Philippe Schenker wrote:
> Use UARTMODIR defines instead of UARTMODEM as it is a 32-bit function

This reads a bit strange at first. Also it is helpful for later to state
that this does not make a difference in practise, so how about:

Use define from the 32-bit register description UARTMODIR_* instead of
UARTMODEM_*. The value is the same, so there is no functional change.

Otherwise looks good to me:

Reviewed-by: Stefan Agner <stefan.agner@toradex.com>

--
Stefan

> 
> Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
> ---
> 
>  drivers/tty/serial/fsl_lpuart.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index f3271857621c..346b4a070ce9 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1879,10 +1879,10 @@ lpuart32_set_termios(struct uart_port *port,
> struct ktermios *termios,
>  	}
>  
>  	if (termios->c_cflag & CRTSCTS) {
> -		modem |= UARTMODEM_RXRTSE | UARTMODEM_TXCTSE;
> +		modem |= (UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
>  	} else {
>  		termios->c_cflag &= ~CRTSCTS;
> -		modem &= ~(UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
> +		modem &= ~(UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
>  	}
>  
>  	if (termios->c_cflag & CSTOPB)

RE: [EXT] [PATCH v1 1/3] tty: serial: lpuart: Remove unnecessary code from set_mctrl

[Andy Duan]

From: Philippe Schenker <philippe.schenker@toradex.com> Sent: Wednesday, October 16, 2019 11:19 PM
> Currently flow control is not working due to lpuart32_set_mctrl that is
> clearing TXCTSE bit in all cases. This bit gets earlier setup by
> lpuart32_set_termios.
> 
> As I read in Documentation set_mctrl is also not meant for hardware flow
> control rather than gpio setting and clearing a RTS signal.
> Therefore I guess it is safe to remove the whole code in lpuart32_set_mctrl.
> 
> This was tested with console on a i.MX8QXP SoC.
> 
> Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

Reviewed-by: Fugang Duan <fugang.duan@nxp.com>
> ---
> 
>  drivers/tty/serial/fsl_lpuart.c | 11 -----------
>  1 file changed, 11 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> 537896c4d887..f3271857621c 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1333,18 +1333,7 @@ static void lpuart_set_mctrl(struct uart_port
> *port, unsigned int mctrl)
> 
>  static void lpuart32_set_mctrl(struct uart_port *port, unsigned int mctrl)  {
> -       unsigned long temp;
> -
> -       temp = lpuart32_read(port, UARTMODIR) &
> -                       ~(UARTMODIR_RXRTSE |
> UARTMODIR_TXCTSE);
> -
> -       if (mctrl & TIOCM_RTS)
> -               temp |= UARTMODIR_RXRTSE;
> -
> -       if (mctrl & TIOCM_CTS)
> -               temp |= UARTMODIR_TXCTSE;
> 
> -       lpuart32_write(port, temp, UARTMODIR);
>  }
> 
>  static void lpuart_break_ctl(struct uart_port *port, int break_state)
> --
> 2.23.0

RE: [EXT] [PATCH v1 2/3] tty: serial: lpuart: Use defines that correspond to correct register

[Andy Duan]

From: Philippe Schenker <philippe.schenker@toradex.com> Sent: Wednesday, October 16, 2019 11:19 PM
> Use UARTMODIR defines instead of UARTMODEM as it is a 32-bit function
> 
> Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

Reviewed-by: Fugang Duan <fugang.duan@nxp.com>

> ---
> 
>  drivers/tty/serial/fsl_lpuart.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> f3271857621c..346b4a070ce9 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1879,10 +1879,10 @@ lpuart32_set_termios(struct uart_port *port,
> struct ktermios *termios,
>         }
> 
>         if (termios->c_cflag & CRTSCTS) {
> -               modem |= UARTMODEM_RXRTSE |
> UARTMODEM_TXCTSE;
> +               modem |= (UARTMODIR_RXRTSE |
> UARTMODIR_TXCTSE);
>         } else {
>                 termios->c_cflag &= ~CRTSCTS;
> -               modem &= ~(UARTMODEM_RXRTSE |
> UARTMODEM_TXCTSE);
> +               modem &= ~(UARTMODIR_RXRTSE |
> UARTMODIR_TXCTSE);
>         }
> 
>         if (termios->c_cflag & CSTOPB)
> --
> 2.23.0

RE: [EXT] [PATCH v1 3/3] tty: serial: lpuart: Add RS485 support for 32-bit uart flavour

[Andy Duan]

From: Philippe Schenker <philippe.schenker@toradex.com> Sent: Wednesday, October 16, 2019 11:19 PM
> This commits adds RS485 support for LPUART hardware that uses 32-bit
> registers. These are typically found in i.MX8 processors.
> 
> Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

Reviewed-by: Fugang Duan <fugang.duan@nxp.com>
> 
> ---
> 
>  drivers/tty/serial/fsl_lpuart.c | 65 ++++++++++++++++++++++++++++++++-
>  1 file changed, 63 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> 346b4a070ce9..22df5f8f48b6 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1280,6 +1280,57 @@ static int lpuart_config_rs485(struct uart_port
> *port,
>         return 0;
>  }
> 
> +static int lpuart32_config_rs485(struct uart_port *port,
> +                       struct serial_rs485 *rs485) {
> +       struct lpuart_port *sport = container_of(port,
> +                       struct lpuart_port, port);
> +
> +       unsigned long modem = lpuart32_read(&sport->port, UARTMODIR)
> +                               & ~(UARTMODEM_TXRTSPOL |
> UARTMODEM_TXRTSE);
> +       lpuart32_write(&sport->port, modem, UARTMODIR);
> +
> +       /* clear unsupported configurations */
> +       rs485->delay_rts_before_send = 0;
> +       rs485->delay_rts_after_send = 0;
> +       rs485->flags &= ~SER_RS485_RX_DURING_TX;
> +
> +       if (rs485->flags & SER_RS485_ENABLED) {
> +               /* Enable auto RS-485 RTS mode */
> +               modem |= UARTMODEM_TXRTSE;
> +
> +               /*
> +                * RTS needs to be logic HIGH either during transer _or_
> after
> +                * transfer, other variants are not supported by the
> hardware.
> +                */
> +
> +               if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
> +                               SER_RS485_RTS_AFTER_SEND)))
> +                       rs485->flags |= SER_RS485_RTS_ON_SEND;
> +
> +               if (rs485->flags & SER_RS485_RTS_ON_SEND &&
> +                               rs485->flags &
> SER_RS485_RTS_AFTER_SEND)
> +                       rs485->flags &=
> ~SER_RS485_RTS_AFTER_SEND;
> +
> +               /*
> +                * The hardware defaults to RTS logic HIGH while
> transfer.
> +                * Switch polarity in case RTS shall be logic HIGH
> +                * after transfer.
> +                * Note: UART is assumed to be active high.
> +                */
> +               if (rs485->flags & SER_RS485_RTS_ON_SEND)
> +                       modem &= ~UARTMODEM_TXRTSPOL;
> +               else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
> +                       modem |= UARTMODEM_TXRTSPOL;
> +       }
> +
> +       /* Store the new configuration */
> +       sport->port.rs485 = *rs485;
> +
> +       lpuart32_write(&sport->port, modem, UARTMODIR);
> +       return 0;
> +}
> +
>  static unsigned int lpuart_get_mctrl(struct uart_port *port)  {
>         unsigned int temp = 0;
> @@ -1878,6 +1929,13 @@ lpuart32_set_termios(struct uart_port *port,
> struct ktermios *termios,
>                 ctrl |= UARTCTRL_M;
>         }
> 
> +       /*
> +        * When auto RS-485 RTS mode is enabled,
> +        * hardware flow control need to be disabled.
> +        */
> +       if (sport->port.rs485.flags & SER_RS485_ENABLED)
> +               termios->c_cflag &= ~CRTSCTS;
> +
>         if (termios->c_cflag & CRTSCTS) {
>                 modem |= (UARTMODIR_RXRTSE |
> UARTMODIR_TXCTSE);
>         } else {
> @@ -2405,7 +2463,10 @@ static int lpuart_probe(struct platform_device
> *pdev)
>                 sport->port.ops = &lpuart_pops;
>         sport->port.flags = UPF_BOOT_AUTOCONF;
> 
> -       sport->port.rs485_config = lpuart_config_rs485;
> +       if (lpuart_is_32(sport))
> +               sport->port.rs485_config = lpuart32_config_rs485;
> +       else
> +               sport->port.rs485_config = lpuart_config_rs485;
> 
>         sport->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
>         if (IS_ERR(sport->ipg_clk)) {
> @@ -2459,7 +2520,7 @@ static int lpuart_probe(struct platform_device
> *pdev)
>             sport->port.rs485.delay_rts_after_send)
>                 dev_err(&pdev->dev, "driver doesn't support RTS
> delays\n");
> 
> -       lpuart_config_rs485(&sport->port, &sport->port.rs485);
> +       sport->port.rs485_config(&sport->port, &sport->port.rs485);
> 
>         sport->dma_tx_chan =
> dma_request_slave_channel(sport->port.dev, "tx");
>         if (!sport->dma_tx_chan)
> --
> 2.23.0

Re: [PATCH v1 2/3] tty: serial: lpuart: Use defines that correspond to correct register

[Philippe Schenker]

On Wed, 2019-10-16 at 22:22 +0200, Stefan Agner wrote:
> On 2019-10-16 17:18, Philippe Schenker wrote:
> > Use UARTMODIR defines instead of UARTMODEM as it is a 32-bit
> > function
> 
> This reads a bit strange at first. Also it is helpful for later to
> state
> that this does not make a difference in practise, so how about:
> 
> Use define from the 32-bit register description UARTMODIR_* instead of
> UARTMODEM_*. The value is the same, so there is no functional change.
> 
> Otherwise looks good to me:
> 
> Reviewed-by: Stefan Agner <stefan.agner@toradex.com>

Thanks for your review and comment. And also thanks to Andy Duan for his
reviews!

You're right, I could have included that so it is clear that nothing is
changed. I will send a v2 today with your suggested commit message

Philippe

> 
> --
> Stefan
> 
> > Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
> > ---
> > 
> >  drivers/tty/serial/fsl_lpuart.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/fsl_lpuart.c
> > b/drivers/tty/serial/fsl_lpuart.c
> > index f3271857621c..346b4a070ce9 100644
> > --- a/drivers/tty/serial/fsl_lpuart.c
> > +++ b/drivers/tty/serial/fsl_lpuart.c
> > @@ -1879,10 +1879,10 @@ lpuart32_set_termios(struct uart_port *port,
> > struct ktermios *termios,
> >  	}
> >  
> >  	if (termios->c_cflag & CRTSCTS) {
> > -		modem |= UARTMODEM_RXRTSE | UARTMODEM_TXCTSE;
> > +		modem |= (UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
> >  	} else {
> >  		termios->c_cflag &= ~CRTSCTS;
> > -		modem &= ~(UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
> > +		modem &= ~(UARTMODIR_RXRTSE | UARTMODIR_TXCTSE);
> >  	}
> >  
> >  	if (termios->c_cflag & CSTOPB)