Re: [PATCH V6 05/10] USB: f81232: implement MCR/MSR function

[Johan Hovold <johan@kernel.org>]

On Mon, Feb 16, 2015 at 03:57:57PM +0800, Peter Hung wrote:
> This patch implement relative MCR/MSR function, such like
> tiocmget()/tiocmset()/dtr_rts().
> 
> The f81232_set_mctrl() replace set_control_lines() to do MCR control
> so we clean-up the set_control_lines() function.
> 
> Signed-off-by: Peter Hung <hpeter+linux_kernel@gmail.com>
> ---
>  drivers/usb/serial/f81232.c | 98 +++++++++++++++++++++++++++++++++++----------
>  1 file changed, 77 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
> index 06d1eb0..e1cdf42 100644
> --- a/drivers/usb/serial/f81232.c
> +++ b/drivers/usb/serial/f81232.c
> @@ -44,6 +44,7 @@ MODULE_DEVICE_TABLE(usb, id_table);
>  #define INTERRUPT_ENABLE_REGISTER  (0x01 + SERIAL_BASE_ADDRESS)
>  #define FIFO_CONTROL_REGISTER      (0x02 + SERIAL_BASE_ADDRESS)
>  #define LINE_CONTROL_REGISTER      (0x03 + SERIAL_BASE_ADDRESS)
> +#define MODEM_CONTROL_REGISTER     (0x04 + SERIAL_BASE_ADDRESS)
>  #define MODEM_STATUS_REGISTER      (0x06 + SERIAL_BASE_ADDRESS)
>  
>  #define CONTROL_DTR			0x01
> @@ -156,6 +157,50 @@ static void f81232_read_msr(struct usb_serial_port *port)
>  	wake_up_interruptible(&port->port.delta_msr_wait);
>  }
>  
> +static int f81232_set_mctrl(struct usb_serial_port *port,
> +					   unsigned int set, unsigned int clear)
> +{
> +	u8 urb_value;
> +	int status;
> +	unsigned long flags;
> +	struct f81232_private *priv = usb_get_serial_port_data(port);
> +
> +	if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0)
> +		return 0;	/* no change */
> +
> +	/* 'set' takes precedence over 'clear' */
> +	clear &= ~set;
> +
> +	/* force enable interrupt with OUT2 */
> +	urb_value = UART_MCR_OUT2 | priv->line_control;

You should rename this one priv->modem_control.

And what about locking above?

> +
> +	if (clear & TIOCM_DTR)
> +		urb_value &= ~UART_MCR_DTR;
> +
> +	if (clear & TIOCM_RTS)
> +		urb_value &= ~UART_MCR_RTS;
> +
> +	if (set & TIOCM_DTR)
> +		urb_value |= UART_MCR_DTR;
> +
> +	if (set & TIOCM_RTS)
> +		urb_value |= UART_MCR_RTS;
> +
> +	dev_dbg(&port->dev, "%s new:%02x old:%02x\n", __func__,
> +			urb_value, priv->line_control);
> +
> +	status = f81232_set_register(port, MODEM_CONTROL_REGISTER, urb_value);
> +	if (status < 0) {
> +		dev_err(&port->dev, "%s set MCR status < 0\n", __func__);

Return here on errors and skip the else branch.

> +	} else {
> +		spin_lock_irqsave(&priv->lock, flags);
> +		priv->line_control = urb_value;
> +		spin_unlock_irqrestore(&priv->lock, flags);

It looks like you could replace the private spin lock with a mutex and
protect all accesses to MCR and MSR using it.

> +	}
> +
> +	return status;

Return 0;

> +}
> +
>  static void f81232_update_modem_status(struct usb_serial_port *port,
>  				      unsigned char *data,
>  				      unsigned int actual_length)
> @@ -267,12 +312,6 @@ static void f81232_process_read_urb(struct urb *urb)
>  	tty_flip_buffer_push(&port->port);
>  }
>  
> -static int set_control_lines(struct usb_device *dev, u8 value)
> -{
> -	/* FIXME - Stubbed out for now */
> -	return 0;
> -}
> -
>  static void f81232_break_ctl(struct tty_struct *tty, int break_state)
>  {
>  	/* FIXME - Stubbed out for now */
> @@ -388,15 +427,41 @@ static void f81232_set_termios(struct tty_struct *tty,
>  
>  static int f81232_tiocmget(struct tty_struct *tty)
>  {
> -	/* FIXME - Stubbed out for now */
> -	return 0;
> +	int r;
> +	struct usb_serial_port *port = tty->driver_data;
> +	struct f81232_private *port_priv = usb_get_serial_port_data(port);
> +	unsigned long flags;
> +	u8 mcr, msr;
> +
> +	/* force get current MSR changed state */
> +	f81232_read_msr(port);
> +
> +	spin_lock_irqsave(&port_priv->lock, flags);
> +	mcr = port_priv->line_control;
> +	msr = port_priv->modem_status;
> +	spin_unlock_irqrestore(&port_priv->lock, flags);
> +
> +	r = (mcr & UART_MCR_DTR ? TIOCM_DTR : 0) |
> +		(mcr & UART_MCR_RTS ? TIOCM_RTS : 0) |
> +		(msr & UART_MSR_CTS ? TIOCM_CTS : 0) |
> +		(msr & UART_MSR_DCD ? TIOCM_CAR : 0) |
> +		(msr & UART_MSR_RI ? TIOCM_RI : 0) |
> +		(msr & UART_MSR_DSR ? TIOCM_DSR : 0);
> +
> +	return r;
>  }
>  
>  static int f81232_tiocmset(struct tty_struct *tty,
>  			unsigned int set, unsigned int clear)
>  {
> -	/* FIXME - Stubbed out for now */
> -	return 0;
> +	int status;
> +	struct usb_serial_port *port = tty->driver_data;
> +
> +	status = f81232_set_mctrl(port, set, clear);
> +	if (status < 0)
> +		return usb_translate_errors(status);
> +	else
> +		return 0;

Remove the else branch and just return 0 at the end.

Johan