Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752508AbbF1VvN (ORCPT ); Sun, 28 Jun 2015 17:51:13 -0400 Received: from out3-smtp.messagingengine.com ([66.111.4.27]:36678 "EHLO out3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752460AbbF1VvD (ORCPT ); Sun, 28 Jun 2015 17:51:03 -0400 X-Sasl-enc: E+mMgO1Er5uPWqxG5fCgvGOBzvVIBv199I57YkSbnPoa 1435528261 Date: Mon, 29 Jun 2015 00:51:00 +0300 From: Sergei Zviagintsev To: Marek Belisko Cc: jslaby@suse.cz, gregkh@linuxfoundation.org, arnd@arndb.de, peter@hurleysoftware.com, mark.rutland@arm.com, gnomes@lxorguk.ukuu.org.uk, sre@kernel.org, neil@brown.name, grant.likely@linaro.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, robh+dt@kernel.org, pawel.moll@arm.com, hns@goldelico.com Subject: Re: [PATCH RFC v2 2/3] tty: serial_core: Add hooks for uart slave drivers Message-ID: <20150628215100.GC21426@localhost.localdomain> References: <1435520786-31867-1-git-send-email-marek@goldelico.com> <1435520786-31867-3-git-send-email-marek@goldelico.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1435520786-31867-3-git-send-email-marek@goldelico.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8261 Lines: 241 Hi, Some minor comments below. On Sun, Jun 28, 2015 at 09:46:25PM +0200, Marek Belisko wrote: > From: "H. Nikolaus Schaller" > > 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 > Signed-off-by: Marek Belisko > --- > 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/