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Date: Mon, 29 Jun 2015 00:51:00 +0300
From: Sergei Zviagintsev <sergei@...v.net>
To: Marek Belisko <marek@...delico.com>
Cc: jslaby@...e.cz, gregkh@...uxfoundation.org, arnd@...db.de,
peter@...leysoftware.com, mark.rutland@....com,
gnomes@...rguk.ukuu.org.uk, sre@...nel.org, neil@...wn.name,
grant.likely@...aro.org, linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org, robh+dt@...nel.org,
pawel.moll@....com, hns@...delico.com
Subject: Re: [PATCH RFC v2 2/3] tty: serial_core: Add hooks for uart slave
drivers
Hi,
Some minor comments below.
On Sun, Jun 28, 2015 at 09:46:25PM +0200, Marek Belisko wrote:
> From: "H. Nikolaus Schaller" <hns@...delico.com>
>
> 1. allow drivers to get notified in mctrl changes
> 2. allow drivers to get notified on rx data (indicating to the driver that
> the connected chip is active)
>
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> Signed-off-by: Marek Belisko <marek@...delico.com>
> ---
> drivers/tty/serial/serial_core.c | 102 +++++++++++++++++++++++++++++++++++++--
> include/linux/serial_core.h | 11 ++++-
> 2 files changed, 107 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index ad61441..c8910c4 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -163,6 +163,84 @@ err0:
> }
> EXPORT_SYMBOL_GPL(devm_serial_get_uart_by_phandle);
>
> +void uart_register_slave(struct uart_port *uport, void *slave)
> +{
> + if (!slave) {
> + uart_register_mctrl_notification(uport, NULL);
> + uart_register_rx_notification(uport, NULL, NULL);
> + }
> + uport->slave = slave;
> +}
> +
> +void uart_register_mctrl_notification(struct uart_port *uport, int (*function)(void *slave, int state))
> +{
> + uport->mctrl_notification = function;
> +}
> +
> +static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
> + int init_hw);
> +
> +static void uart_port_shutdown(struct tty_port *port);
> +
> +void uart_register_rx_notification(struct uart_port *uport, int (*function)(void *slave, unsigned int *c), struct ktermios *termios)
> +{
> + struct uart_state *state = uport->state;
> + struct tty_port *tty_port = &state->port;
> +
> + if (!uport->slave)
> + return; /* slave must be registered first */
> +
> + uport->rx_notification = function;
> +
> + if (tty_port->count == 0) {
if (tty_port->count)
return;
> + if (function) {
> + int retval = 0;
Useless initialization.
> +
> + uart_change_pm(state, UART_PM_STATE_ON);
> + retval = uport->ops->startup(uport);
> + if (retval == 0 && termios) {
Indentation is evil in this rather simple function :)
> + int hw_stopped;
> + /*
> + * Initialise the hardware port settings.
> + */
> + uport->ops->set_termios(uport, termios, NULL);
> +
> + /*
> + * Set modem status enables based on termios cflag
> + */
> + spin_lock_irq(&uport->lock);
> + if (termios->c_cflag & CRTSCTS)
> + uport->status |= UPSTAT_CTS_ENABLE;
> + else
> + uport->status &= ~UPSTAT_CTS_ENABLE;
> +
> + if (termios->c_cflag & CLOCAL)
> + uport->status &= ~UPSTAT_DCD_ENABLE;
> + else
> + uport->status |= UPSTAT_DCD_ENABLE;
> +
> + /* reset sw-assisted CTS flow control based on (possibly) new mode */
checkpatch.pl will complain about long line :)
> + hw_stopped = uport->hw_stopped;
> + uport->hw_stopped = uart_softcts_mode(uport) &&
> + !(uport->ops->get_mctrl(uport) & TIOCM_CTS);
> + if (uport->hw_stopped) {
> + if (!hw_stopped)
> + uport->ops->stop_tx(uport);
> + } else {
> + if (hw_stopped)
> + uport->ops->start_tx(uport);
> + }
> + spin_unlock_irq(&uport->lock);
> + }
> + } else
Usage of braces is against CodingStyle.
> + uart_port_shutdown(tty_port);
> + }
> +}
> +
> +EXPORT_SYMBOL_GPL(uart_register_slave);
> +EXPORT_SYMBOL_GPL(uart_register_mctrl_notification);
> +EXPORT_SYMBOL_GPL(uart_register_rx_notification);
> +
> /*
> * This routine is used by the interrupt handler to schedule processing in
> * the software interrupt portion of the driver.
> @@ -220,6 +298,10 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
> port->mctrl = (old & ~clear) | set;
> if (old != port->mctrl)
> port->ops->set_mctrl(port, port->mctrl);
> +
> + if (port->mctrl_notification)
> + (*port->mctrl_notification)(port->slave, port->mctrl);
> +
> spin_unlock_irqrestore(&port->lock, flags);
> }
>
> @@ -259,7 +341,8 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
> uart_circ_clear(&state->xmit);
> }
>
> - retval = uport->ops->startup(uport);
> + if (!state->uart_port->rx_notification)
> + retval = uport->ops->startup(uport);
> if (retval == 0) {
> if (uart_console(uport) && uport->cons->cflag) {
> tty->termios.c_cflag = uport->cons->cflag;
> @@ -295,7 +378,7 @@ static int uart_startup(struct tty_struct *tty, struct uart_state *state,
> int init_hw)
> {
> struct tty_port *port = &state->port;
> - int retval;
> + int retval = 0;
What is the point to initialize `retval'?
>
> if (port->flags & ASYNC_INITIALIZED)
> return 0;
> @@ -341,8 +424,12 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
>
> if (!tty || (tty->termios.c_cflag & HUPCL))
> uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
> -
> - uart_port_shutdown(port);
> + /*
> + * if we have a slave that has registered for rx_notifications
> + * we do not shut down the uart port to be able to monitor the device
> + */
> + if (!uport->rx_notification)
> + uart_port_shutdown(port);
> }
>
> /*
> @@ -1489,8 +1576,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
> /*
> * At this point, we stop accepting input. To do this, we
> * disable the receive line status interrupts.
> + * Unless a slave driver wants to keep input running
> */
> - if (port->flags & ASYNC_INITIALIZED) {
> + if (!uport->rx_notification && (port->flags & ASYNC_INITIALIZED)) {
> unsigned long flags;
> spin_lock_irqsave(&uport->lock, flags);
> uport->ops->stop_rx(uport);
> @@ -3018,6 +3106,10 @@ void uart_insert_char(struct uart_port *port, unsigned int status,
> {
> struct tty_port *tport = &port->state->port;
>
> + if (port->rx_notification)
> + if ((*port->rx_notification)(port->slave, &ch))
> + return; /* slave told us to ignore character */
> +
> if ((status & port->ignore_status_mask & ~overrun) == 0)
> if (tty_insert_flip_char(tport, ch, flag) == 0)
> ++port->icount.buf_overrun;
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index ba23718..77029781 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -35,7 +35,7 @@
> #define uart_console(port) \
> ((port)->cons && (port)->cons->index == (port)->line)
> #else
> -#define uart_console(port) ({ (void)port; 0; })
> +#define uart_console(port) (0)
> #endif
>
> struct uart_port;
> @@ -247,7 +247,11 @@ struct uart_port {
> const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
> struct serial_rs485 rs485;
> void *private_data; /* generic platform data pointer */
> + /* UART slave support */
> struct list_head head; /* list of uarts e.g. to look up by phandle */
> + void *slave; /* optional slave (there can be only one) */
> + int (*mctrl_notification)(void *slave, int state);
> + int (*rx_notification)(void *slave, unsigned int *c);
> };
>
> static inline int serial_port_in(struct uart_port *up, int offset)
> @@ -485,4 +489,9 @@ static inline int uart_handle_break(struct uart_port *port)
> */
> extern struct uart_port *devm_serial_get_uart_by_phandle(struct device *dev,
> const char *phandle, u8 index);
> +/* register to receive notifications */
> +extern void uart_register_slave(struct uart_port *uart, void *slave);
> +extern void uart_register_mctrl_notification(struct uart_port *uart, int (*function)(void *slave, int state));
> +extern void uart_register_rx_notification(struct uart_port *uart, int (*function)(void *slave, unsigned int *c), struct ktermios *termios);
> +
> #endif /* LINUX_SERIAL_CORE_H */
> --
> 1.9.1
>
> --
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