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From:   Max Filippov <jcmvbkbc@gmail.com>
To:     linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH] serial: add PORT_ANY definition
Date:   Fri,  6 Oct 2023 04:57:13 -0700
Message-Id: <20231006115713.801322-1-jcmvbkbc@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Current pattern in the linux kernel is that every new serial driver adds
one or more new PORT_ definitions because uart_ops::config_port()
callback documentation prescribes setting port->type according to the
type of port found, or to PORT_UNKNOWN if no port was detected.

When the specific type of the port is not important to the userspace
there's no need for a unique PORT_ value, but so far there's no suitable
identifier for that case.

Provide generic port type identifier other than PORT_UNKNOWN for ports
which type is not important to userspace.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 include/uapi/linux/serial.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 53bc1af67a41..070e50cf9e1e 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -47,6 +47,8 @@ struct serial_struct {
 /*
  * These are the supported serial types.
  */
+/* Generic type identifier for ports which type is not important to userspace. */
+#define PORT_ANY	(-1)
 #define PORT_UNKNOWN	0
 #define PORT_8250	1
 #define PORT_16450	2
-- 
2.30.2