From patchwork Sat Oct 6 12:42:44 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell King X-Patchwork-Id: 1557461 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id BEC20DF238 for ; Sat, 6 Oct 2012 12:44:41 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TKTiZ-0002kP-Ab; Sat, 06 Oct 2012 12:42:55 +0000 Received: from [2002:4e20:1eda::1] (helo=caramon.arm.linux.org.uk) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TKTiV-0002in-AY for linux-arm-kernel@lists.infradead.org; Sat, 06 Oct 2012 12:42:52 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=arm.linux.org.uk; s=caramon; h=Date:Sender:Message-Id:Subject:Cc:To:From:References:In-Reply-To; bh=s+XXlGQxXpukywmvQ/tLx/Ga4BfUT19T8yfNNslcToA=; b=RGMdozovqEArrugbqxUSX4V8Dmr9Vty5LpsXhZGthf7/i5iS9NZFXtXkzlF7b6qrClvjei/Ju0kU4qQt8Lf1MlGE3OdSKSOFWg2lWerV0otclvZRWLTyXb9ts4qOoLoIpahOXNvJh3CF4NC++ETgP+15RFDluDQ9SMz8QJu69NY=; Received: from e0022681537dd.dyn.arm.linux.org.uk ([2002:4e20:1eda:1:222:68ff:fe15:37dd]:39602 helo=rmk-PC.arm.linux.org.uk) by caramon.arm.linux.org.uk with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.76) (envelope-from ) id 1TKTiP-000883-8X; Sat, 06 Oct 2012 13:42:45 +0100 Received: from rmk by rmk-PC.arm.linux.org.uk with local (Exim 4.76) (envelope-from ) id 1TKTiO-0002n7-En; Sat, 06 Oct 2012 13:42:44 +0100 In-Reply-To: <20121006123803.GD15246@n2100.arm.linux.org.uk> References: <20121006123803.GD15246@n2100.arm.linux.org.uk> From: Russell King To: Tony Lindgren , Alan Cox , Greg Kroah-Hartman Subject: [RFC 11/24] SERIAL: core: add throttle/unthrottle callbacks for hardware assisted flow control Message-Id: Date: Sat, 06 Oct 2012 13:42:44 +0100 X-Spam-Note: CRM114 invocation failed X-Spam-Score: -1.2 (-) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-1.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.8 RDNS_NONE Delivered to internal network by a host with no rDNS Cc: linux-omap@vger.kernel.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Add two callbacks for hardware assisted flow control; we need to know when the tty layers want us to stop and restart due to their buffer levels. Call a driver specific throttle/unthrottle function if and only if the driver indicates that it is using an enabled hardware assisted flow control method, otherwise fall back to the non-hardware assisted methods. Signed-off-by: Russell King --- drivers/tty/serial/serial_core.c | 31 +++++++++++++++++++++++++++---- include/linux/serial_core.h | 2 ++ 2 files changed, 29 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 02b10bc..4dd609e 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -610,27 +610,50 @@ static void uart_send_xchar(struct tty_struct *tty, char ch) static void uart_throttle(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; + struct uart_port *port = state->uart_port; + uint32_t mask = 0; if (I_IXOFF(tty)) + mask |= UPF_SOFT_FLOW; + if (tty->termios->c_cflag & CRTSCTS) + mask |= UPF_HARD_FLOW; + + if (port->flags & mask) { + port->ops->throttle(port); + mask &= ~port->flags; + } + + if (mask & UPF_SOFT_FLOW) uart_send_xchar(tty, STOP_CHAR(tty)); - if (tty->termios->c_cflag & CRTSCTS) - uart_clear_mctrl(state->uart_port, TIOCM_RTS); + if (mask & UPF_HARD_FLOW) + uart_clear_mctrl(port, TIOCM_RTS); } static void uart_unthrottle(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; struct uart_port *port = state->uart_port; + uint32_t mask = 0; - if (I_IXOFF(tty)) { + if (I_IXOFF(tty)) + mask |= UPF_SOFT_FLOW; + if (tty->termios->c_cflag & CRTSCTS) + mask |= UPF_HARD_FLOW; + + if (port->flags & mask) { + port->ops->unthrottle(port); + mask &= ~port->flags; + } + + if (mask & UPF_SOFT_FLOW) { if (port->x_char) port->x_char = 0; else uart_send_xchar(tty, START_CHAR(tty)); } - if (tty->termios->c_cflag & CRTSCTS) + if (mask & UPF_HARD_FLOW) uart_set_mctrl(port, TIOCM_RTS); } diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 8e8500e..b17d4c9 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -240,6 +240,8 @@ struct uart_ops { unsigned int (*get_mctrl)(struct uart_port *); void (*stop_tx)(struct uart_port *); void (*start_tx)(struct uart_port *); + void (*throttle)(struct uart_port *); + void (*unthrottle)(struct uart_port *); void (*send_xchar)(struct uart_port *, char ch); void (*stop_rx)(struct uart_port *); void (*enable_ms)(struct uart_port *);