@@ -129,13 +129,9 @@ static int stm32_config_rs485(struct uart_port *port,
if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
cr3 &= ~USART_CR3_DEP;
rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl & ~TIOCM_RTS);
} else {
cr3 |= USART_CR3_DEP;
rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl | TIOCM_RTS);
}
writel_relaxed(cr3, port->membase + ofs->cr3);
@@ -541,17 +537,42 @@ static void stm32_disable_ms(struct uart_port *port)
/* Transmit stop */
static void stm32_stop_tx(struct uart_port *port)
{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct serial_rs485 *rs485conf = &port->rs485;
+
stm32_tx_interrupt_disable(port);
+
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl & ~TIOCM_RTS);
+ } else {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl | TIOCM_RTS);
+ }
+ }
}
/* There are probably characters waiting to be transmitted. */
static void stm32_start_tx(struct uart_port *port)
{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct serial_rs485 *rs485conf = &port->rs485;
struct circ_buf *xmit = &port->state->xmit;
if (uart_circ_empty(xmit))
return;
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl | TIOCM_RTS);
+ } else {
+ mctrl_gpio_set(stm32_port->gpios,
+ stm32_port->port.mctrl & ~TIOCM_RTS);
+ }
+ }
+
stm32_transmit_chars(port);
}
@@ -851,13 +872,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
cr3 &= ~USART_CR3_DEP;
rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl & ~TIOCM_RTS);
} else {
cr3 |= USART_CR3_DEP;
rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
- mctrl_gpio_set(stm32_port->gpios,
- stm32_port->port.mctrl | TIOCM_RTS);
}
} else {
While the STM32 does support RS485 drive-enable control within the UART IP itself, some systems have the drive-enable line connected to a pin which cannot be pinmuxed as RTS. Add support for toggling the RTS GPIO line using the modem control GPIOs to provide at least some sort of emulation. Fixes: 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control") Signed-off-by: Marek Vasut <marex@denx.de> Cc: Alexandre Torgue <alexandre.torgue@st.com> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Manivannan Sadhasivam <mani@kernel.org> Cc: Fabrice Gasnier <fabrice.gasnier@st.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linux-stm32@st-md-mailman.stormreply.com --- V2: Use mctrl_gpio_set() instead of stm32_set_mctrl() V3: - Actually toggle the RTS line before and after TX - Undo 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control") which was previous version of this patch ; I messed up. --- drivers/tty/serial/stm32-usart.c | 33 ++++++++++++++++++++++++-------- 1 file changed, 25 insertions(+), 8 deletions(-)