From patchwork Wed Dec 2 11:39:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 336471 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=-17.0 required=3.0 tests=BAYES_00, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 7B998C83018 for ; Wed, 2 Dec 2020 11:40:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A19722203 for ; Wed, 2 Dec 2020 11:40:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729686AbgLBLkk (ORCPT ); Wed, 2 Dec 2020 06:40:40 -0500 Received: from mail-lf1-f44.google.com ([209.85.167.44]:36387 "EHLO mail-lf1-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726179AbgLBLkj (ORCPT ); Wed, 2 Dec 2020 06:40:39 -0500 Received: by mail-lf1-f44.google.com with SMTP id v14so4165031lfo.3; Wed, 02 Dec 2020 03:40:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Wpl3GUF0Lna+9aQ+M4y15hfBavFW+GP9gpBC+7GpH5Y=; b=D0t+JDpDGdYf2jOcYQV738Dd1nEa7yQK/hjNkEj1X5/NsBNPh53C9FAOwB1/JSwVAJ srCHFBnriqPxnpdZjsmnhUvTC1U+ealhXUQNxStn1Pp7FFy+OenFpoqgq8mt6NwdxuKX nMrvqsW8A49alLdn/XYVWGCwn4OFL4PwC+QJKVMc8OhqTNbpYo/mk5+V2P9ui/zUdDeh QDX1JMz5hOVOXtNnwXjGYZm3ZfBwwuhcpzFuuzcM4aKkzDri6AVb5MCG0x5/5P6pDmrH 5HcS3IhmYvclU4HCeaewN/ICk6NC85Vsvy6oW421mCtfzLlvMih3+7V29S7zRFNVyzLm zRIA== X-Gm-Message-State: AOAM530hMWDvbTW/4xB3jZAGKhNizzr0UtDebi1V8aWidI3oUkluUYmO jgSqMy6P/pZpwtdY6OWHkm0= X-Google-Smtp-Source: ABdhPJwyUJNCE0J39vsIAzAyLSqtGSgb7f96Lf3Wll5DzpTzhWzBGG7xh1QqFM8hjsN1W7HbJXOZmg== X-Received: by 2002:a05:6512:2151:: with SMTP id s17mr1074253lfr.287.1606909190549; Wed, 02 Dec 2020 03:39:50 -0800 (PST) Received: from xi.terra (c-beaee455.07-184-6d6c6d4.bbcust.telenor.se. [85.228.174.190]) by smtp.gmail.com with ESMTPSA id 136sm384688lfn.193.2020.12.02.03.39.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Dec 2020 03:39:48 -0800 (PST) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1kkQUc-000733-VU; Wed, 02 Dec 2020 12:40:19 +0100 From: Johan Hovold To: Greg Kroah-Hartman Cc: Jiri Slaby , "Mychaela N . Falconia" , linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold Subject: [PATCH v2 4/7] serial: core: add sysfs attribute to suppress ready signalling on open Date: Wed, 2 Dec 2020 12:39:39 +0100 Message-Id: <20201202113942.27024-5-johan@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201202113942.27024-1-johan@kernel.org> References: <20201202113942.27024-1-johan@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Add a nordy sysfs attribute to suppress raising the modem-control lines on open to signal DTE readiness. This can be used to prevent undesirable side-effects on open for applications where the DTR and RTS lines are used for non-standard purposes such as generating power-on and reset pulses. Signed-off-by: Johan Hovold --- Documentation/ABI/testing/sysfs-tty | 7 +++++++ drivers/tty/serial/serial_core.c | 26 ++++++++++++++++++++++++++ 2 files changed, 33 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty index e157130a6792..2634b4bf9c7f 100644 --- a/Documentation/ABI/testing/sysfs-tty +++ b/Documentation/ABI/testing/sysfs-tty @@ -161,3 +161,10 @@ Contact: Andy Shevchenko Description: Allows user to detach or attach back the given device as kernel console. It shows and accepts a boolean variable. + +What: /sys/class/tty/ttyS0/nordy +Date: November 2020 +Contact: Johan Hovold +Description: + Show and store the port NORDY flag which suppresses raising + the modem-control lines on open to signal DTE readiness. diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index f41cba10b86b..7db1814b9d99 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2805,6 +2805,30 @@ static ssize_t console_store(struct device *dev, return ret < 0 ? ret : count; } +static ssize_t nordy_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct tty_port *port = dev_get_drvdata(dev); + + return sprintf(buf, "%d\n", tty_port_nordy(port)); +} + +static ssize_t nordy_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct tty_port *port = dev_get_drvdata(dev); + bool val; + int ret; + + ret = kstrtobool(buf, &val); + if (ret) + return ret; + + tty_port_set_nordy(port, val); + + return count; +} + static DEVICE_ATTR_RO(uartclk); static DEVICE_ATTR_RO(type); static DEVICE_ATTR_RO(line); @@ -2819,6 +2843,7 @@ static DEVICE_ATTR_RO(io_type); static DEVICE_ATTR_RO(iomem_base); static DEVICE_ATTR_RO(iomem_reg_shift); static DEVICE_ATTR_RW(console); +static DEVICE_ATTR_RW(nordy); static struct attribute *tty_dev_attrs[] = { &dev_attr_uartclk.attr, @@ -2835,6 +2860,7 @@ static struct attribute *tty_dev_attrs[] = { &dev_attr_iomem_base.attr, &dev_attr_iomem_reg_shift.attr, &dev_attr_console.attr, + &dev_attr_nordy.attr, NULL };