Re: [PATCH v2] USB: serial: xr: Add TIOCGRS485 and TIOCSRS485 ioctls

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Mar 13, 2023 at 10:27:34AM +0200, Jarkko Sonninen wrote:
> Add support for RS-485 in Exar USB adapters.
> RS-485 mode is controlled by TIOCGRS485 and TIOCSRS485 ioctls.
> Gpio mode register is set to enable RS-485.
> 
> Signed-off-by: Jarkko Sonninen <kasper@iki.fi>
> ---
>  drivers/usb/serial/xr_serial.c | 65 +++++++++++++++++++++++++++++++++-
>  1 file changed, 64 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c
> index fdb0aae546c3..480cda0daafc 100644
> --- a/drivers/usb/serial/xr_serial.c
> +++ b/drivers/usb/serial/xr_serial.c
> @@ -93,6 +93,7 @@ struct xr_txrx_clk_mask {
>  #define XR_GPIO_MODE_SEL_DTR_DSR	0x2
>  #define XR_GPIO_MODE_SEL_RS485		0x3
>  #define XR_GPIO_MODE_SEL_RS485_ADDR	0x4
> +#define XR_GPIO_MODE_RS485_TX_H		0x8
>  #define XR_GPIO_MODE_TX_TOGGLE		0x100
>  #define XR_GPIO_MODE_RX_TOGGLE		0x200
>  
> @@ -237,6 +238,8 @@ static const struct xr_type xr_types[] = {
>  struct xr_data {
>  	const struct xr_type *type;
>  	u8 channel;			/* zero-based index or interface number */
> +	struct serial_rs485 rs485;
> +	spinlock_t lock;
>  };
>  
>  static int xr_set_reg(struct usb_serial_port *port, u8 channel, u16 reg, u16 val)
> @@ -629,6 +632,7 @@ static void xr_set_flow_mode(struct tty_struct *tty,
>  	struct xr_data *data = usb_get_serial_port_data(port);
>  	const struct xr_type *type = data->type;
>  	u16 flow, gpio_mode;
> +	unsigned long flags, rs485_flags;
>  	int ret;
>  
>  	ret = xr_get_reg_uart(port, type->gpio_mode, &gpio_mode);
> @@ -645,9 +649,16 @@ static void xr_set_flow_mode(struct tty_struct *tty,
>  	/* Set GPIO mode for controlling the pins manually by default. */
>  	gpio_mode &= ~XR_GPIO_MODE_SEL_MASK;
>  
> +	spin_lock_irqsave(&data->lock, flags);
> +	rs485_flags = data->rs485.flags;
> +	spin_unlock_irqrestore(&data->lock, flags);
> +	if (rs485_flags & SER_RS485_ENABLED)
> +		gpio_mode |= XR_GPIO_MODE_SEL_RS485 | XR_GPIO_MODE_RS485_TX_H;
> +	else if (C_CRTSCTS(tty) && C_BAUD(tty) != B0)
> +		gpio_mode |= XR_GPIO_MODE_SEL_RTS_CTS;
> +
>  	if (C_CRTSCTS(tty) && C_BAUD(tty) != B0) {
>  		dev_dbg(&port->dev, "Enabling hardware flow ctrl\n");
> -		gpio_mode |= XR_GPIO_MODE_SEL_RTS_CTS;
>  		flow = XR_UART_FLOW_MODE_HW;
>  	} else if (I_IXON(tty)) {
>  		u8 start_char = START_CHAR(tty);
> @@ -827,6 +838,57 @@ static void xr_set_termios(struct tty_struct *tty,
>  	xr_set_flow_mode(tty, port, old_termios);
>  }
>  
> +static int xr_get_rs485_config(struct tty_struct *tty,
> +			 unsigned int __user *argp)
> +{
> +	struct usb_serial_port *port = tty->driver_data;
> +	struct xr_data *data = usb_get_serial_port_data(port);
> +
> +	dev_dbg(tty->dev, "Flags %02x\n", data->rs485.flags);
> +	if (copy_to_user(argp, &data->rs485, sizeof(data->rs485)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +static int xr_set_rs485_config(struct tty_struct *tty,
> +			 unsigned long __user *argp)
> +{
> +	struct usb_serial_port *port = tty->driver_data;
> +	struct xr_data *data = usb_get_serial_port_data(port);
> +	struct serial_rs485 rs485;
> +	unsigned long flags;
> +
> +	if (copy_from_user(&rs485, argp, sizeof(rs485)))
> +		return -EFAULT;
> +
> +	dev_dbg(tty->dev, "Flags %02x\n", rs485.flags);
> +	rs485.flags &= SER_RS485_ENABLED;
> +	spin_lock_irqsave(&data->lock, flags);
> +	memcpy(&data->rs485, &rs485, sizeof(rs485));
> +	spin_unlock_irqrestore(&data->lock, flags);
> +	xr_set_flow_mode(tty, port, 0);
> +
> +	if (copy_to_user(argp, &data->rs485, sizeof(data->rs485)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +
> +static int xr_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
> +{
> +	void __user *argp = (void __user *)arg;
> +
> +	switch (cmd) {
> +	case TIOCGRS485:
> +		return xr_get_rs485_config(tty, argp);
> +	case TIOCSRS485:
> +		return xr_set_rs485_config(tty, argp);
> +	}
> +	return -ENOTTY;
> +}
> +
>  static int xr_open(struct tty_struct *tty, struct usb_serial_port *port)
>  {
>  	int ret;
> @@ -1010,6 +1072,7 @@ static struct usb_serial_driver xr_device = {
>  	.set_termios		= xr_set_termios,
>  	.tiocmget		= xr_tiocmget,
>  	.tiocmset		= xr_tiocmset,
> +	.ioctl			= xr_ioctl,
>  	.dtr_rts		= xr_dtr_rts
>  };
>  
> -- 
> 2.34.1
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

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