Received-SPF: pass (google.com: domain of linux-kernel+bounces-40232-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
From: Farouk Bouabid <farouk.bouabid@theobroma-systems.com>
Date: Fri, 26 Jan 2024 15:55:13 +0100
Subject: [PATCH v4 4/6] serial: 8250: set rx-enable gpio state when rs485
 is disabled
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <20240126-dev-rx-enable-v4-4-45aaf4d96328@theobroma-systems.com>
References: <20240126-dev-rx-enable-v4-0-45aaf4d96328@theobroma-systems.com>
In-Reply-To: <20240126-dev-rx-enable-v4-0-45aaf4d96328@theobroma-systems.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
 Jiri Slaby <jirislaby@kernel.org>, Rob Herring <robh+dt@kernel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, 
 Conor Dooley <conor+dt@kernel.org>, Heiko Stuebner <heiko@sntech.de>
Cc: Rob Herring <robh@kernel.org>, linux-kernel@vger.kernel.org, 
 linux-serial@vger.kernel.org, devicetree@vger.kernel.org, 
 linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, 
 quentin.schulz@theobroma-systems.com, 
 Farouk Bouabid <farouk.bouabid@theobroma-systems.com>
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?utf-8?B?L09kWVhaa0VwVDJDZXNpb0RDMG1YZSt3OGdEQlNBb01WVWhrVS9lUnlVOHBR?=
 =?utf-8?B?Um1jMG14ZDJhU1BuVHdXNGVYd3diblBEbEg3enhmVU1ZZHpjRnp4ZmtMVlZP?=
 =?utf-8?B?TG5NSEJZanNXMFFibXREbjIzNlU1cE9YdXdZdzNBM0pIU3hhYlhXTVc0TDhM?=
 =?utf-8?B?akhKSm9ZTHVQWkVWUVdmd084SkxsSCs4TGs4TU9wNzlqL05BbzN6UGVtdzVC?=
 =?utf-8?B?YXFGUHJLMXc1T0pjbFpUVS9mQ3lwOS9nRTIyK3RYZHJLNDJvLzZlekVDWExr?=
 =?utf-8?B?T3pvdWN0aUtjMjVqWnd2VDVrclpMNnJTT0laazQ4dXBiS1o3MEwwaTErSllF?=
 =?utf-8?B?OUw4Nk9jNXlBOGlIZk1TNEZGbnh5emsxT2lZdDRJZjl3MmxsT3ZXNG9ZREty?=
 =?utf-8?B?SGhrWkF4NnRNYUJpRjNaSENwdStDS3NzNStKdmFWVldHTG9iKzdGYzcyNkZ6?=
 =?utf-8?B?TTBwQk1iaWZJZHdjTWdZd0IzdWNVNk1UR05CdzFEVDhCM1pXNldadEZGTlJJ?=
 =?utf-8?B?R1NZekdaVTBnUk9JV2U0V2VFR3lYS0g3aDRGSDlyU3lIdFNQMkFHcW5VODh6?=
 =?utf-8?B?RTBxKzBtRzV5dUpjYU9aQnJ6YkFYVVdNald5aXFPL0ZPTjhCcVJXMGhKWFM4?=
 =?utf-8?B?U3FzZzdQejJDMVdrek5ua0dsb0ZPa3I4bkhVOUFqeXFydm4veWY1dmVuZXkw?=
 =?utf-8?B?cnBBR0RreUd3MlYyWk5WVHBpbnE2cHM4eVNROTNIMjV2dEUxcjZ2dnh2cmVK?=
 =?utf-8?B?L09ubzEvNjgzYmlsV0tYc1NvaFptVDhMTW93aVpwdWFjamZ3UlBUTjZBaHky?=
 =?utf-8?B?YjBPS2I5UDg3eWJBQnJvMDMvdjUrcU5QVitpM1V2bkdJMzErSUhCTldRK1ZZ?=
 =?utf-8?B?NDRKVzRlazNmTGYvb3ROcC9WZHVmLzYrekN6M1QyeHlpWVd1cWhPRldFRDBK?=
 =?utf-8?B?Yy9BV3NneUdwclRCaGxVZFRiWW01MEVQTW5nd0kvVjJoTDBacnhhMGxvQldl?=
 =?utf-8?B?QU5aZkZjTm1wYUtmaEx1NkkrVUJaU1lTWmtZalR2SjF4dnN1RXNkOEtUT0Vi?=
 =?utf-8?B?VTgwa2RSbDFpRnhPWHNYckhiR2kydTdJU09oWHYyVitlYi9LWDBkK1JEejV3?=
 =?utf-8?B?VUZJdE92MlRTSk1sT3hOSWx4TXI2U3c3bHFiSmQxK29Oa0RwY0llTVFSVHRs?=
 =?utf-8?B?TlZvYnVwZnhxV281VWRxdmtOYVBJVUVyazB4T2RtcDczNTdWM1B0eUJzVmo0?=
 =?utf-8?B?aTNscUpCdW5LOTd4TEVKNVZRREdKeHZuKzIzbE9TOTdLOUFSOVI2T0ZHa1NS?=
 =?utf-8?B?RFViWXVIQjJsUlVWbGo1NWt0YlA2Vi9vT0Z5RTAzR2ZqV1B0ZlRjNGpsdWpq?=
 =?utf-8?B?NGNZU2pXOTEvOFJDajRaUEEvZkdrQzYrWnlMRXdGNngyaUVqOVhEa2VRbkM1?=
 =?utf-8?B?Qko4Yk9DWlR0QnM3Q25EampsbEdCYXZvYTl1RDlwdmdDQm11V0hQNWo1dmlY?=
 =?utf-8?B?KzBLelhxZmtqbGl6bXlSYlgrVWRQem5hSVFxTGZIVXhpVWpYRzAxYjI1TDBV?=
 =?utf-8?B?alBKckVUbnFFazNmcHJ0SnNPbVJOMTlwT3RaSjl2SDMyWEJFbnBUWUNKajUr?=
 =?utf-8?B?VmN4d1djVDk5Yzl4aEtORG94MkU1bWVhYm1aWXpRVXVqVWY3QmFKOFI5WTN2?=
 =?utf-8?B?ZHh0QlVPQUphYXhFUGgyaTBET0MwdFIzWGpaTjZOVHdkR09LWUJ3RzFId0p5?=
 =?utf-8?B?S1R5RHpKeG5vRjFXbDd4Z3ZMUFlOOGppeVMxQko1RnJwRmwxVTlyQVZLQlk4?=
 =?utf-8?B?N2FabHNoV2dIanYvV3gvV3J1Y1hFU0pjclJTQllYcWJ2RTc0TDVyOFp5ZkNj?=
 =?utf-8?B?a3RBd3JYZmhSUFJMVFYrd0hGbzNSRDZrRDJNbUdld1ZvRytpOWliMVpiSXZG?=
 =?utf-8?B?NDdNeS80bXVVeXAxRHRTeXJMSTNIQUgycGJ4dzF6K1haeGFCS3MyZjlyNUd5?=
 =?utf-8?B?WGFnbmlLeDlmUHZxRnVxU3lkOXdKMy9LbS8zcXJWYWYrZkpnYjFuUEhQN0ky?=
 =?utf-8?B?cEliZVFHWTJpbkdYNVVGVUVkOGFXVGdHaGRoWHNUSmpQUWRXK3JqM3cwK25t?=
 =?utf-8?B?OVFRYTZCWlhRL29pR3F5REk5c1FPR0tBUG1YQ0ppdjhZMjZ6M3FZeStObzlH?=
 =?utf-8?Q?ZntQtaAH5SObQODDmWjjLB4=3D?=
X-OriginatorOrg: theobroma-systems.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 6c0ebeb1-be25-4032-f3ba-08dc1e7f3fc1
X-MS-Exchange-CrossTenant-AuthSource: AM0PR04MB6371.eurprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Jan 2024 14:58:26.0485
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 5e0e1b52-21b5-4e7b-83bb-514ec460677e
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: clzWHEw8xOlS8yBTA2WH9Q4a/FbnYMFn5A0nbIv37DXvRUcuhoPkhhbCpHhh1IhQ2Ubp2UrofvkN9fi36W7PMrLYVncfjvAm8hp9X1m/TFmzDPmJxibZFX+CWEXo0Xw7
X-MS-Exchange-Transport-CrossTenantHeadersStamped: GVXPR04MB9735

Add the possibility to de-activate rx-enable gpio when rs485 is disabled.
This defines the state of RE or DE/RE signal when em485 is disabled.

Signed-off-by: Farouk Bouabid <farouk.bouabid@theobroma-systems.com>
---
 drivers/tty/serial/8250/8250_port.c | 4 ++++
 drivers/tty/serial/serial_core.c    | 6 ++++++
 include/linux/serial_core.h         | 1 +
 3 files changed, 11 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 54d8f809b81e..fbd0212d2397 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -582,12 +582,16 @@ static int serial8250_em485_init(struct uart_8250_port *p)
  */
 void serial8250_em485_destroy(struct uart_8250_port *p)
 {
+	struct uart_port *port = &p->port;
+
 	if (!p->em485)
 		return;
 
 	hrtimer_cancel(&p->em485->start_tx_timer);
 	hrtimer_cancel(&p->em485->stop_tx_timer);
 
+	gpiod_set_value(port->rs485_re_gpio, !port->rs485_re_gpio_inactive_when_rs485_disabled);
+
 	kfree(p->em485);
 	p->em485 = NULL;
 }
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 47aeece985f3..6460646cf83c 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3663,6 +3663,12 @@ int uart_get_rs485_mode(struct uart_port *port)
 	if (port->rs485_rx_during_tx_gpio)
 		port->rs485_supported.flags |= SER_RS485_RX_DURING_TX;
 
+	port->rs485_re_gpio_inactive_when_rs485_disabled = device_property_read_bool(dev,
+		"rs485-rx-enable-inactive-when-rs485-disabled");
+
+	port->rs485_re_gpio = devm_gpiod_get_optional(dev, "rs485-rx-enable",
+		port->rs485_re_gpio_inactive_when_rs485_disabled ? GPIOD_OUT_LOW : GPIOD_OUT_HIGH);
+
 	if (IS_ERR(port->rs485_re_gpio)) {
 		ret = PTR_ERR(port->rs485_re_gpio);
 		port->rs485_re_gpio = NULL;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 364583203a24..fa5a92b56360 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -585,6 +585,7 @@ struct uart_port {
 	struct gpio_desc	*rs485_term_gpio;	/* enable RS485 bus termination */
 	struct gpio_desc	*rs485_rx_during_tx_gpio; /* Output GPIO that sets the state of RS485 RX during TX */
 	struct gpio_desc	*rs485_re_gpio;		/* gpio RS485 receive enable */
+	bool	rs485_re_gpio_inactive_when_rs485_disabled;
 	struct serial_iso7816   iso7816;
 	void			*private_data;		/* generic platform data pointer */
 };

-- 
2.34.1