From patchwork Tue Sep 21 10:33:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Lindgren X-Patchwork-Id: 12507561 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 182B5C4332F for ; Tue, 21 Sep 2021 10:34:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 017E661038 for ; Tue, 21 Sep 2021 10:34:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231986AbhIUKf2 (ORCPT ); Tue, 21 Sep 2021 06:35:28 -0400 Received: from muru.com ([72.249.23.125]:35532 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231927AbhIUKf2 (ORCPT ); Tue, 21 Sep 2021 06:35:28 -0400 Received: from hillo.muru.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTP id 0B4F380A8; Tue, 21 Sep 2021 10:34:25 +0000 (UTC) From: Tony Lindgren To: Greg Kroah-Hartman Cc: Andy Shevchenko , Jiri Slaby , Johan Hovold , Vignesh Raghavendra , linux-serial@vger.kernel.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/6] serial: core: Add new prep_tx for power management Date: Tue, 21 Sep 2021 13:33:43 +0300 Message-Id: <20210921103346.64824-4-tony@atomide.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210921103346.64824-1-tony@atomide.com> References: <20210921103346.64824-1-tony@atomide.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org If the serial driver implements PM runtime with autosuspend, the port may be powered off for TX. To wake up the port, let's add new prep_tx() call for serial drivers to implement as needed. We call it from serial write_room() and write() functions. If the serial port is not enabled, we just return 0. Signed-off-by: Tony Lindgren --- Documentation/driver-api/serial/driver.rst | 9 +++++++++ drivers/tty/serial/serial_core.c | 23 ++++++++++++++++++++++ include/linux/serial_core.h | 1 + 3 files changed, 33 insertions(+) diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst --- a/Documentation/driver-api/serial/driver.rst +++ b/Documentation/driver-api/serial/driver.rst @@ -136,6 +136,15 @@ hardware. This call must not sleep + prep_tx(port) + Prepare port for transmitting characters. + + Locking: port->lock taken. + + Interrupts: locally disabled. + + This call must not sleep + start_tx(port) Start transmitting characters. diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -118,6 +118,17 @@ static void uart_stop(struct tty_struct *tty) uart_port_unlock(port, flags); } +static int __uart_prep_tx(struct tty_struct *tty) +{ + struct uart_state *state = tty->driver_data; + struct uart_port *port = state->uart_port; + + if (port && !uart_tx_stopped(port) && port->ops->prep_tx) + return port->ops->prep_tx(port); + + return 0; +} + static void __uart_start(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; @@ -574,6 +585,12 @@ static int uart_write(struct tty_struct *tty, return 0; } + ret = __uart_prep_tx(tty); + if (ret < 0) { + uart_port_unlock(port, flags); + return 0; + } + while (port) { c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE); if (count < c) @@ -600,6 +617,12 @@ static unsigned int uart_write_room(struct tty_struct *tty) unsigned int ret; port = uart_port_lock(state, flags); + ret = __uart_prep_tx(tty); + if (ret < 0) { + uart_port_unlock(port, flags); + return 0; + } + ret = uart_circ_chars_free(&state->xmit); uart_port_unlock(port, flags); return ret; diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -40,6 +40,7 @@ struct uart_ops { void (*set_mctrl)(struct uart_port *, unsigned int mctrl); unsigned int (*get_mctrl)(struct uart_port *); void (*stop_tx)(struct uart_port *); + int (*prep_tx)(struct uart_port *); void (*start_tx)(struct uart_port *); void (*throttle)(struct uart_port *); void (*unthrottle)(struct uart_port *);