Hi Marek,
On 4/30/22 18:28, Marek Vasut wrote:
In case the RS485 mode is emulated using GPIO RTS, use the TC interrupt
to deassert the GPIO RTS, otherwise the GPIO RTS stays asserted after a
transmission ended and the RS485 cannot work.
Could you please add a cover letter to explain the rational of the first
patch ? I understood the goal of the first by reading the commit message
of this second patch.
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
Cc: Erwan Le Ray <erwan.leray@xxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jean Philippe Romain <jean-philippe.romain@xxxxxxxxxxx>
Cc: Valentin Caron <valentin.caron@xxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
To: linux-serial@xxxxxxxxxxxxxxx
---
drivers/tty/serial/stm32-usart.c | 42 ++++++++++++++++++++++++++++++--
drivers/tty/serial/stm32-usart.h | 1 +
2 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 224f359c6051e..764415b8e8f03 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -417,6 +417,14 @@ static void stm32_usart_tx_interrupt_enable(struct uart_port *port)
stm32_usart_set_bits(port, ofs->cr1, USART_CR1_TXEIE);
}
+static void stm32_usart_tc_interrupt_enable(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ stm32_usart_set_bits(port, ofs->cr1, USART_CR1_TCIE);
+}
+
I don't see the added value of this helper (only 1 instruction used 1
time), and other Interrupt Enabled bits are already set/unset in others
functions of this driver.
To keep an homogeneous code in the driver, could you please remove this
helper and set TCIE directly when you need it ?
static void stm32_usart_rx_dma_complete(void *arg)
{
struct uart_port *port = arg;
@@ -442,6 +450,14 @@ static void stm32_usart_tx_interrupt_disable(struct uart_port *port)
stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
}
+static void stm32_usart_tc_interrupt_disable(struct uart_port *port)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+ stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TCIE);
+}
+
Same comment here.
static void stm32_usart_rs485_rts_enable(struct uart_port *port)
{
struct stm32_port *stm32_port = to_stm32_port(port);
@@ -585,6 +601,13 @@ static void stm32_usart_transmit_chars(struct uart_port *port)
u32 isr;
int ret;
+ if (!stm32_port->hw_flow_control &&
+ port->rs485.flags & SER_RS485_ENABLED) {
+ stm32_port->txdone = false;
+ stm32_usart_tc_interrupt_disable(port);
+ stm32_usart_rs485_rts_enable(port);
+ }
+
if (port->x_char) {
if (stm32_usart_tx_dma_started(stm32_port) &&
stm32_usart_tx_dma_enabled(stm32_port))
@@ -625,8 +648,14 @@ static void stm32_usart_transmit_chars(struct uart_port *port)
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
- if (uart_circ_empty(xmit))
+ if (uart_circ_empty(xmit)) {
stm32_usart_tx_interrupt_disable(port);
+ if (!stm32_port->hw_flow_control &&
+ port->rs485.flags & SER_RS485_ENABLED) {
+ stm32_port->txdone = true;
+ stm32_usart_tc_interrupt_enable(port);
+ }
+ }
}
static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
@@ -640,6 +669,13 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
sr = readl_relaxed(port->membase + ofs->isr);
+ if (!stm32_port->hw_flow_control &&
+ port->rs485.flags & SER_RS485_ENABLED &&
+ (sr & USART_SR_TC)) {
+ stm32_usart_tc_interrupt_disable(port);
+ stm32_usart_rs485_rts_disable(port);
+ }
+
if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG)
writel_relaxed(USART_ICR_RTOCF,
port->membase + ofs->icr);
@@ -763,8 +799,10 @@ static void stm32_usart_start_tx(struct uart_port *port)
{
struct circ_buf *xmit = &port->state->xmit;
- if (uart_circ_empty(xmit) && !port->x_char)
+ if (uart_circ_empty(xmit) && !port->x_char) {
+ stm32_usart_rs485_rts_disable(port);
return;
+ }
stm32_usart_rs485_rts_enable(port);
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index d734c4a5fd24c..ee69c203b926d 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -271,6 +271,7 @@ struct stm32_port {
bool hw_flow_control;
bool swap; /* swap RX & TX pins */
bool fifoen;
+ bool txdone;
int rxftcfg; /* RX FIFO threshold CFG */
int txftcfg; /* TX FIFO threshold CFG */
bool wakeup_src;
Regards, Erwan.
