From: Heiko Stuebner <heiko@sntech.de>
To: gregkh@linuxfoundation.org
Cc: jslaby@suse.com, andriy.shevchenko@linux.intel.com,
matwey.kornilov@gmail.com, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org, heiko@sntech.de, lukas@wunner.de,
christoph.muellner@theobroma-systems.com,
giulio.benetti@micronovasrl.com
Subject: [PATCH DON'T APPLY v2 3/7] serial: 8250: Support rs485 bus termination GPIO
Date: Thu, 26 Mar 2020 00:14:18 +0100 [thread overview]
Message-ID: <20200325231422.1502366-4-heiko@sntech.de> (raw)
In-Reply-To: <20200325231422.1502366-1-heiko@sntech.de>
From: Lukas Wunner <lukas@wunner.de>
Amend the serial core to retrieve the rs485 bus termination GPIO from
the device tree (or ACPI table) and amend the default ->rs485_config()
callback for 8250 drivers to change the GPIO on request from user space.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
drivers/tty/serial/8250/8250_port.c | 5 +++++
drivers/tty/serial/serial_core.c | 25 +++++++++++++++++++++++++
include/linux/serial_core.h | 1 +
3 files changed, 31 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 4440867b7d20..47c059987538 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -30,6 +30,7 @@
#include <linux/uaccess.h>
#include <linux/pm_runtime.h>
#include <linux/ktime.h>
+#include <linux/gpio/consumer.h>
#include <asm/io.h>
#include <asm/irq.h>
@@ -681,6 +682,10 @@ int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485)
memset(rs485->padding, 0, sizeof(rs485->padding));
port->rs485 = *rs485;
+ if (port->rs485_term_gpio)
+ gpiod_set_value(port->rs485_term_gpio,
+ rs485->flags & SER_RS485_TERMINATE_BUS);
+
/*
* Both serial8250_em485_init() and serial8250_em485_destroy()
* are idempotent.
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 43b6682877d5..77702b6371e3 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -27,6 +27,7 @@
#include <linux/irq.h>
#include <linux/uaccess.h>
+#include <linux/gpio/consumer.h>
/*
* This is used to lock changes in serial line configuration.
@@ -3317,6 +3318,7 @@ int uart_get_rs485_mode(struct uart_port *port)
* to get to a defined state with the following properties:
*/
rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
+ SER_RS485_TERMINATE_BUS |
SER_RS485_RTS_AFTER_SEND);
rs485conf->flags |= SER_RS485_RTS_ON_SEND;
@@ -3331,6 +3333,29 @@ int uart_get_rs485_mode(struct uart_port *port)
rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
}
+ if (port->rs485_term_gpio)
+ devm_gpiod_put(dev, port->rs485_term_gpio);
+
+ port->rs485_term_gpio = devm_gpiod_get(dev, "rs485-term",
+ GPIOD_FLAGS_BIT_DIR_OUT);
+ if (IS_ERR(port->rs485_term_gpio)) {
+ ret = PTR_ERR(port->rs485_term_gpio);
+ port->rs485_term_gpio = NULL;
+ if (ret != -ENOENT) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "Cannot get rs485-term-gpios\n");
+ return ret;
+ }
+ } else {
+ ret = gpiod_get_value(port->rs485_term_gpio);
+ if (ret < 0) {
+ dev_err(dev, "Cannot get rs485-term-gpios value\n");
+ return ret;
+ }
+ if (ret)
+ rs485conf->flags |= SER_RS485_TERMINATE_BUS;
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index b649a2b894e7..9521e23b2144 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -251,6 +251,7 @@ struct uart_port {
struct attribute_group *attr_group; /* port specific attributes */
const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
struct serial_rs485 rs485;
+ struct gpio_desc *rs485_term_gpio; /* enable RS485 bus termination */
struct serial_iso7816 iso7816;
void *private_data; /* generic platform data pointer */
};
--
2.24.1
next prev parent reply other threads:[~2020-03-25 23:14 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 23:14 [PATCH RFC v2 0/7] serial: 8250: Add rs485 emulation to 8250_dw Heiko Stuebner
2020-03-25 23:14 ` [PATCH DON'T APPLY v2 1/7] serial: Allow uart_get_rs485_mode() to return errno Heiko Stuebner
2020-03-25 23:14 ` [PATCH DON'T APPLY v2 2/7] dt-bindings: serial: Add binding for rs485 bus termination GPIO Heiko Stuebner
2020-03-25 23:14 ` Heiko Stuebner [this message]
2020-03-30 14:51 ` [PATCH DON'T APPLY v2 3/7] serial: 8250: Support " Andy Shevchenko
2020-03-25 23:14 ` [PATCH v2 4/7] serial: 8250: Handle implementations not having TEMT interrupt using em485 Heiko Stuebner
2020-03-25 23:47 ` Giulio Benetti
2020-03-26 0:05 ` Heiko Stübner
2020-03-26 2:02 ` Giulio Benetti
2020-05-17 15:04 ` Heiko Stübner
2020-05-17 17:28 ` Giulio Benetti
2020-03-30 14:52 ` Andy Shevchenko
2020-05-02 13:49 ` Lukas Wunner
2020-05-05 16:38 ` Maarten Brock
2020-05-17 22:01 ` Heiko Stübner
2020-03-25 23:14 ` [PATCH v2 5/7] dt-bindings: serial: Add binding for rs485 receiver enable GPIO Heiko Stuebner
2020-03-30 14:54 ` Andy Shevchenko
2020-05-02 13:51 ` Lukas Wunner
2020-03-25 23:14 ` [PATCH v2 6/7] serial: 8250: Support separate rs485 rx-enable GPIO Heiko Stuebner
2020-03-30 14:56 ` Andy Shevchenko
2020-05-16 20:14 ` Lukas Wunner
2020-03-25 23:14 ` [PATCH v2 7/7] serial: 8250_dw: add em485 support Heiko Stuebner
2020-05-06 15:25 ` Andy Shevchenko
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