From patchwork Wed Jul 19 05:16:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Lindgren X-Patchwork-Id: 704844 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D54CAC0015E for ; Wed, 19 Jul 2023 05:16:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229921AbjGSFQX (ORCPT ); Wed, 19 Jul 2023 01:16:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229454AbjGSFQW (ORCPT ); Wed, 19 Jul 2023 01:16:22 -0400 Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7F0D01BF2; Tue, 18 Jul 2023 22:16:21 -0700 (PDT) Received: from hillo.muru.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTP id 3501B80AA; Wed, 19 Jul 2023 05:16:19 +0000 (UTC) From: Tony Lindgren To: Greg Kroah-Hartman , Jiri Slaby Cc: Andy Shevchenko , Dhruva Gole , =?utf-8?q?Ilpo_J=C3=A4rvinen?= , John Ogness , Johan Hovold , Sebastian Andrzej Siewior , Vignesh Raghavendra , linux-omap@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] serial: core: Add sysfs links for serial core port instances for ttys Date: Wed, 19 Jul 2023 08:16:11 +0300 Message-ID: <20230719051613.46569-1-tony@atomide.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org Let's allow the userspace to find out the tty name for a serial core controller id if a tty exists. This can be done with: $ grep DEVNAME /sys/bus/serial-base/devices/port*/tty/uevent /sys/bus/serial-base/devices/port.00:04.0/tty/uevent:DEVNAME=ttyS0 /sys/bus/serial-base/devices/port.serial8250.1/tty/uevent:DEVNAME=ttyS1 /sys/bus/serial-base/devices/port.serial8250.2/tty/uevent:DEVNAME=ttyS2 /sys/bus/serial-base/devices/port.serial8250.3/tty/uevent:DEVNAME=ttyS3 And with this, we can add /dev/serial/by-id symlinks to the serial port device instances so we can start using serial core port addressing in addition to the legacy ttyS naming. The naming we can use is dev_name:0.0 where 0.0 are the serial core controller id and port id, so for the ttyS0 example above the naming would be 00:04.0:0.0. Signed-off-by: Tony Lindgren --- Note that this depends on fix for serial core port ids patch "[PATCH] serial: core: Fix serial core port id to not use port->line" --- drivers/tty/serial/serial_core.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) 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 @@ -3371,6 +3371,8 @@ static int serial_core_add_preferred_console(struct uart_driver *drv, int serial_core_register_port(struct uart_driver *drv, struct uart_port *port) { struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL; + struct uart_match match = {port, drv}; + struct device *tty_dev; int ret; mutex_lock(&port_mutex); @@ -3411,10 +3413,21 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port) port->flags &= ~UPF_DEAD; + tty_dev = device_find_child(port->dev, &match, serial_match_port); + if (tty_dev) { + ret = sysfs_create_link(&port->port_dev->dev.kobj, &tty_dev->kobj, + "tty"); + if (ret) + goto err_remove_port; + } + mutex_unlock(&port_mutex); return 0; +err_remove_port: + serial_core_remove_one_port(drv, port); + err_unregister_port_dev: serial_base_port_device_remove(port->port_dev); @@ -3436,12 +3449,18 @@ void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port struct device *phys_dev = port->dev; struct serial_port_device *port_dev = port->port_dev; struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev); + struct uart_match match = {port, drv}; int ctrl_id = port->ctrl_id; + struct device *tty_dev; mutex_lock(&port_mutex); port->flags |= UPF_DEAD; + tty_dev = device_find_child(port->dev, &match, serial_match_port); + if (tty_dev) + sysfs_remove_link(&port->port_dev->dev.kobj, "tty"); + serial_core_remove_one_port(drv, port); /* Note that struct uart_port *port is no longer valid at this point */