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Date: Mon, 29 Jun 2015 18:47:22 +0200
From: "Dr. H. Nikolaus Schaller" <hns@...delico.com>
To: Sergei Zviagintsev <sergei@...v.net>
Cc: Marek Belisko <marek@...delico.com>, 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
Subject: Re: [PATCH RFC v2 2/3] tty: serial_core: Add hooks for uart slave drivers
Hi,
thanks again.
Am 28.06.2015 um 23:51 schrieb Sergei Zviagintsev <sergei@...v.net>:
> 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.
Indeed.
>
>> +
>> + 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 :)
Ok.
>
>> + 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.
Ok.
>
>> + 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’?
Probably remains from an intermediate version where we had needed it.
Will be removed.
>
>>
>> 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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