From c7d44a02ac606c2bebf90751deebec2321379d6d Mon Sep 17 00:00:00 2001 From: Doug Anderson Date: Mon, 21 Apr 2014 10:06:43 -0700 Subject: serial_core: Commonalize crlf when working w/ a non open console port In (efe2f29 kgdboc,kdb: Allow kdb to work on a non open console port) support was added to directly use the "write_char" functions when doing kdb over a non-open console port. This is great, but it ends up bypassing the normal code in uart_console_write() that adds a carriage return before any newlines. There appears to have been a trend to add this support directly in some console driver's poll_put_char() functions. This had a few side effects, including: - In this case we were doing LFCR, not CRLF. This was fixed in uart_console_write() back in (d358788 [SERIAL] kernel console should send CRLF not LFCR) - Not all serial drivers had the LFCR code in their poll_put_char() functions. In my case I was running serial/samsung.c which lacked it. I've moved the handling to uart_poll_put_char() to fix the above problems. Now when I use kdb (and don't point console= to the same UART) I no longer get: [0]kdb> [0]kdb> [0]kdb> Signed-off-by: Doug Anderson Reviewed-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_core.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'drivers/tty/serial/8250/8250_core.c') diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 81f909c2101f..ffee9825fbac 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -1926,13 +1926,8 @@ static void serial8250_put_poll_char(struct uart_port *port, wait_for_xmitr(up, BOTH_EMPTY); /* * Send the character out. - * If a LF, also do CR... */ serial_port_out(port, UART_TX, c); - if (c == 10) { - wait_for_xmitr(up, BOTH_EMPTY); - serial_port_out(port, UART_TX, 13); - } /* * Finally, wait for transmitter to become empty -- cgit v1.2.3-59-g8ed1b From 06aa82e498c144c7784a6f3d3b55458b272d6146 Mon Sep 17 00:00:00 2001 From: Murali Karicheri Date: Thu, 1 May 2014 15:04:53 -0400 Subject: serial: uart: add hw flow control support configuration 8250 uart driver currently supports only software assisted hw flow control. The software assisted hw flow control maintains a hw_stopped flag in the tty structure to stop and start transmission and use modem status interrupt for the event to drive the handshake signals. This is not needed if hw has flow control capabilities. This patch adds a DT attribute for enabling hw flow control for a uart port. Also skip stop and start if this flag is present in flag field of the port structure. Signed-off-by: Murali Karicheri CC: Rob Herring CC: Pawel Moll CC: Mark Rutland CC: Ian Campbell CC: Kumar Gala CC: Randy Dunlap CC: Jiri Slaby CC: Santosh Shilimkar Signed-off-by: Greg Kroah-Hartman --- Documentation/devicetree/bindings/serial/of-serial.txt | 1 + drivers/tty/serial/8250/8250_core.c | 6 ++++-- drivers/tty/serial/of_serial.c | 4 ++++ drivers/tty/serial/serial_core.c | 12 +++++++++--- 4 files changed, 18 insertions(+), 5 deletions(-) (limited to 'drivers/tty/serial/8250/8250_core.c') diff --git a/Documentation/devicetree/bindings/serial/of-serial.txt b/Documentation/devicetree/bindings/serial/of-serial.txt index 1928a3e83cd0..77054772a8f4 100644 --- a/Documentation/devicetree/bindings/serial/of-serial.txt +++ b/Documentation/devicetree/bindings/serial/of-serial.txt @@ -37,6 +37,7 @@ Optional properties: - auto-flow-control: one way to enable automatic flow control support. The driver is allowed to detect support for the capability even without this property. +- has-hw-flow-control: the hardware has flow control capability. Example: diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 111ee8acb07e..65556fc57d56 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -2333,9 +2333,11 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, * the trigger, or the MCR RTS bit is cleared. In the case where * the remote UART is not using CTS auto flow control, we must * have sufficient FIFO entries for the latency of the remote - * UART to respond. IOW, at least 32 bytes of FIFO. + * UART to respond. IOW, at least 32 bytes of FIFO. Also enable + * AFE if hw flow control is supported */ - if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) { + if ((up->capabilities & UART_CAP_AFE && (port->fifosize >= 32)) || + (port->flags & UPF_HARD_FLOW)) { up->mcr &= ~UART_MCR_AFE; if (termios->c_cflag & CRTSCTS) up->mcr |= UART_MCR_AFE; diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c index 99246606a256..77ec6a147522 100644 --- a/drivers/tty/serial/of_serial.c +++ b/drivers/tty/serial/of_serial.c @@ -182,6 +182,10 @@ static int of_platform_serial_probe(struct platform_device *ofdev) "auto-flow-control")) port8250.capabilities |= UART_CAP_AFE; + if (of_property_read_bool(ofdev->dev.of_node, + "has-hw-flow-control")) + port8250.port.flags |= UPF_HARD_FLOW; + ret = serial8250_register_8250_port(&port8250); break; } diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 9a01ee4dda6d..fbf6c5ad222f 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -174,8 +174,12 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, if (tty->termios.c_cflag & CBAUD) uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR); } - - if (tty_port_cts_enabled(port)) { + /* + * if hw support flow control without software intervention, + * then skip the below check + */ + if (tty_port_cts_enabled(port) && + !(uport->flags & UPF_HARD_FLOW)) { spin_lock_irq(&uport->lock); if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS)) tty->hw_stopped = 1; @@ -2775,7 +2779,9 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) uport->icount.cts++; - if (tty_port_cts_enabled(port)) { + /* skip below code if the hw flow control is supported */ + if (tty_port_cts_enabled(port) && + !(uport->flags & UPF_HARD_FLOW)) { if (tty->hw_stopped) { if (status) { tty->hw_stopped = 0; -- cgit v1.2.3-59-g8ed1b