serial: Do not hold the port lock when setting rx-during-tx GPIO
authorLino Sanfilippo <l.sanfilippo@kunbus.com>
Wed, 3 Jan 2024 06:18:12 +0000 (07:18 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 4 Jan 2024 15:26:09 +0000 (16:26 +0100)
Both the imx and stm32 driver set the rx-during-tx GPIO in rs485_config().
Since this function is called with the port lock held, this can be a
problem in case that setting the GPIO line can sleep (e.g. if a GPIO
expander is used which is connected via SPI or I2C).

Avoid this issue by moving the GPIO setting outside of the port lock into
the serial core and thus making it a generic feature.

Also with commit c54d48543689 ("serial: stm32: Add support for rs485
RX_DURING_TX output GPIO") the SER_RS485_RX_DURING_TX flag is only set if a
rx-during-tx GPIO is _not_ available, which is wrong. Fix this, too.

Furthermore reset old GPIO settings in case that changing the RS485
configuration failed.

Fixes: c54d48543689 ("serial: stm32: Add support for rs485 RX_DURING_TX output GPIO")
Fixes: ca530cfa968c ("serial: imx: Add support for RS485 RX_DURING_TX output GPIO")
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240103061818.564-2-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/imx.c
drivers/tty/serial/serial_core.c
drivers/tty/serial/stm32-usart.c

index a0fcf18cbeaca3b30b8b283e48e9380f305019b5..8b7d9c5a745513e44b6f2a2e244d01e2406e6b6e 100644 (file)
@@ -1948,10 +1948,6 @@ static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termio
            rs485conf->flags & SER_RS485_RX_DURING_TX)
                imx_uart_start_rx(port);
 
-       if (port->rs485_rx_during_tx_gpio)
-               gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
-                                        !!(rs485conf->flags & SER_RS485_RX_DURING_TX));
-
        return 0;
 }
 
index cc866da50b814b9d9e5e5671495dc5944f60139b..8d381c283cecafcc79e9561bcf5b1f15d98561ea 100644 (file)
@@ -1407,6 +1407,16 @@ static void uart_set_rs485_termination(struct uart_port *port,
                                 !!(rs485->flags & SER_RS485_TERMINATE_BUS));
 }
 
+static void uart_set_rs485_rx_during_tx(struct uart_port *port,
+                                       const struct serial_rs485 *rs485)
+{
+       if (!(rs485->flags & SER_RS485_ENABLED))
+               return;
+
+       gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
+                                !!(rs485->flags & SER_RS485_RX_DURING_TX));
+}
+
 static int uart_rs485_config(struct uart_port *port)
 {
        struct serial_rs485 *rs485 = &port->rs485;
@@ -1418,12 +1428,17 @@ static int uart_rs485_config(struct uart_port *port)
 
        uart_sanitize_serial_rs485(port, rs485);
        uart_set_rs485_termination(port, rs485);
+       uart_set_rs485_rx_during_tx(port, rs485);
 
        uart_port_lock_irqsave(port, &flags);
        ret = port->rs485_config(port, NULL, rs485);
        uart_port_unlock_irqrestore(port, flags);
-       if (ret)
+       if (ret) {
                memset(rs485, 0, sizeof(*rs485));
+               /* unset GPIOs */
+               gpiod_set_value_cansleep(port->rs485_term_gpio, 0);
+               gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio, 0);
+       }
 
        return ret;
 }
@@ -1462,6 +1477,7 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
                return ret;
        uart_sanitize_serial_rs485(port, &rs485);
        uart_set_rs485_termination(port, &rs485);
+       uart_set_rs485_rx_during_tx(port, &rs485);
 
        uart_port_lock_irqsave(port, &flags);
        ret = port->rs485_config(port, &tty->termios, &rs485);
@@ -1473,8 +1489,14 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
                        port->ops->set_mctrl(port, port->mctrl);
        }
        uart_port_unlock_irqrestore(port, flags);
-       if (ret)
+       if (ret) {
+               /* restore old GPIO settings */
+               gpiod_set_value_cansleep(port->rs485_term_gpio,
+                       !!(port->rs485.flags & SER_RS485_TERMINATE_BUS));
+               gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
+                       !!(port->rs485.flags & SER_RS485_RX_DURING_TX));
                return ret;
+       }
 
        if (copy_to_user(rs485_user, &port->rs485, sizeof(port->rs485)))
                return -EFAULT;
index 9781c143def29f2701be9a7c7bddd8454fb9bfec..794b7751274034848c65a7e3374b694bcf61c42d 100644 (file)
@@ -226,12 +226,6 @@ static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *ter
 
        stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
 
-       if (port->rs485_rx_during_tx_gpio)
-               gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
-                                        !!(rs485conf->flags & SER_RS485_RX_DURING_TX));
-       else
-               rs485conf->flags |= SER_RS485_RX_DURING_TX;
-
        if (rs485conf->flags & SER_RS485_ENABLED) {
                cr1 = readl_relaxed(port->membase + ofs->cr1);
                cr3 = readl_relaxed(port->membase + ofs->cr3);
@@ -256,6 +250,8 @@ static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *ter
 
                writel_relaxed(cr3, port->membase + ofs->cr3);
                writel_relaxed(cr1, port->membase + ofs->cr1);
+
+               rs485conf->flags |= SER_RS485_RX_DURING_TX;
        } else {
                stm32_usart_clr_bits(port, ofs->cr3,
                                     USART_CR3_DEM | USART_CR3_DEP);