[PATCH v2 2/9] serial: core, 8250: set RS485 termination gpio in serial core
From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Date: 2022-07-03 17:02:11
Also in:
linux-devicetree, linux-serial, lkml
Subsystem:
8250/16?50 (and clone uarts) serial driver, the rest, tty layer and serial drivers · Maintainers:
Greg Kroah-Hartman, Linus Torvalds, Jiri Slaby
From: Lino Sanfilippo <redacted> In serial8250_em485_config() the termination GPIO is set with the uart_port spinlock held. This is an issue if setting the GPIO line can sleep (e.g. since the concerning GPIO expander is connected via SPI or I2C). Fix this by setting the termination line outside of the uart_port spinlock in the serial core and using gpiod_set_value_cansleep() which instead of gpiod_set_value() allows to sleep. Beside fixing the termination GPIO line setting for the 8250 driver this change also makes setting the termination GPIO generic for all UART drivers. Signed-off-by: Lino Sanfilippo <redacted> --- drivers/tty/serial/8250/8250_port.c | 3 --- drivers/tty/serial/serial_core.c | 12 ++++++++++++ 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index ed2a606f2da7..72252d956f17 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c@@ -676,9 +676,6 @@ int serial8250_em485_config(struct uart_port *port, struct ktermios *termios, rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; } - 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 3768663dfa4d..9c29d031b404 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c@@ -1358,12 +1358,23 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 memset(rs485->padding1, 0, sizeof(rs485->padding1)); } +static void uart_set_rs485_termination(struct uart_port *port, + const struct serial_rs485 *rs485) +{ + if (!port->rs485_term_gpio || !(rs485->flags & SER_RS485_ENABLED)) + return; + + gpiod_set_value_cansleep(port->rs485_term_gpio, + !!(rs485->flags & SER_RS485_TERMINATE_BUS)); +} + int uart_rs485_config(struct uart_port *port) { struct serial_rs485 *rs485 = &port->rs485; int ret; uart_sanitize_serial_rs485(port, rs485); + uart_set_rs485_termination(port, rs485); ret = port->rs485_config(port, NULL, rs485); if (ret)
@@ -1406,6 +1417,7 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port, if (ret) return ret; uart_sanitize_serial_rs485(port, &rs485); + uart_set_rs485_termination(port, &rs485); spin_lock_irqsave(&port->lock, flags); ret = port->rs485_config(port, &tty->termios, &rs485);
--
2.25.1
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