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-rw-r--r--drivers/tty/serial/8250/8250.h2
-rw-r--r--drivers/tty/serial/8250/8250_core.c2
-rw-r--r--drivers/tty/serial/8250/8250_of.c7
-rw-r--r--drivers/tty/serial/8250/8250_omap.c2
-rw-r--r--drivers/tty/serial/8250/8250_port.c82
-rw-r--r--include/linux/serial_8250.h3
6 files changed, 67 insertions, 31 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 83a85210501f..52bb21205bb6 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -157,6 +157,8 @@ void serial8250_rpm_get_tx(struct uart_8250_port *p);
void serial8250_rpm_put_tx(struct uart_8250_port *p);
int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485);
+void serial8250_em485_start_tx(struct uart_8250_port *p);
+void serial8250_em485_stop_tx(struct uart_8250_port *p);
void serial8250_em485_destroy(struct uart_8250_port *p);
/* MCR <-> TIOCM conversion */
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 9a1d09fbb836..f6eb00406ddf 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1007,6 +1007,8 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
uart->port.unthrottle = up->port.unthrottle;
uart->port.rs485_config = up->port.rs485_config;
uart->port.rs485 = up->port.rs485;
+ uart->rs485_start_tx = up->rs485_start_tx;
+ uart->rs485_stop_tx = up->rs485_stop_tx;
uart->dma = up->dma;
/* Take tx_loadsz from fifosize if it wasn't set separately */
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 4a68a8785caa..65e9045dafe6 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -29,11 +29,12 @@ struct of_serial_info {
* Fill a struct uart_port for a given device node
*/
static int of_platform_serial_setup(struct platform_device *ofdev,
- int type, struct uart_port *port,
+ int type, struct uart_8250_port *up,
struct of_serial_info *info)
{
struct resource resource;
struct device_node *np = ofdev->dev.of_node;
+ struct uart_port *port = &up->port;
u32 clk, spd, prop;
int ret, irq;
@@ -155,6 +156,8 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
port->dev = &ofdev->dev;
port->rs485_config = serial8250_em485_config;
+ up->rs485_start_tx = serial8250_em485_start_tx;
+ up->rs485_stop_tx = serial8250_em485_stop_tx;
switch (type) {
case PORT_RT2880:
@@ -201,7 +204,7 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
return -ENOMEM;
memset(&port8250, 0, sizeof(port8250));
- ret = of_platform_serial_setup(ofdev, port_type, &port8250.port, info);
+ ret = of_platform_serial_setup(ofdev, port_type, &port8250, info);
if (ret)
goto err_free;
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index fff70cb25046..dd69226ce918 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1158,6 +1158,8 @@ static int omap8250_probe(struct platform_device *pdev)
up.port.throttle = omap_8250_throttle;
up.port.unthrottle = omap_8250_unthrottle;
up.port.rs485_config = serial8250_em485_config;
+ up.rs485_start_tx = serial8250_em485_start_tx;
+ up.rs485_stop_tx = serial8250_em485_stop_tx;
up.port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
ret = of_alias_get_id(np, "serial");
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 1a71625a0d43..8e8cca690bf9 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -557,17 +557,6 @@ static void serial8250_clear_fifos(struct uart_8250_port *p)
}
}
-static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
-{
- unsigned char mcr = serial8250_in_MCR(p);
-
- if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
- mcr |= UART_MCR_RTS;
- else
- mcr &= ~UART_MCR_RTS;
- serial8250_out_MCR(p, mcr);
-}
-
static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t);
static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t);
@@ -632,7 +621,9 @@ static int serial8250_em485_init(struct uart_8250_port *p)
p->em485->start_tx_timer.function = &serial8250_em485_handle_start_tx;
p->em485->port = p;
p->em485->active_timer = NULL;
- serial8250_em485_rts_after_send(p);
+ p->em485->tx_stopped = true;
+
+ p->rs485_stop_tx(p);
return 0;
}
@@ -1439,9 +1430,21 @@ static void serial8250_stop_rx(struct uart_port *port)
serial8250_rpm_put(up);
}
-static void __do_stop_tx_rs485(struct uart_8250_port *p)
+/**
+ * serial8250_em485_stop_tx() - generic ->rs485_stop_tx() callback
+ * @up: uart 8250 port
+ *
+ * Generic callback usable by 8250 uart drivers to stop rs485 transmission.
+ */
+void serial8250_em485_stop_tx(struct uart_8250_port *p)
{
- serial8250_em485_rts_after_send(p);
+ unsigned char mcr = serial8250_in_MCR(p);
+
+ if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
+ mcr |= UART_MCR_RTS;
+ else
+ mcr &= ~UART_MCR_RTS;
+ serial8250_out_MCR(p, mcr);
/*
* Empty the RX FIFO, we are not interested in anything
@@ -1455,6 +1458,8 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
serial_port_out(&p->port, UART_IER, p->ier);
}
}
+EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx);
+
static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
{
struct uart_8250_em485 *em485;
@@ -1467,8 +1472,9 @@ static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
serial8250_rpm_get(p);
spin_lock_irqsave(&p->port.lock, flags);
if (em485->active_timer == &em485->stop_tx_timer) {
- __do_stop_tx_rs485(p);
+ p->rs485_stop_tx(p);
em485->active_timer = NULL;
+ em485->tx_stopped = true;
}
spin_unlock_irqrestore(&p->port.lock, flags);
serial8250_rpm_put(p);
@@ -1489,7 +1495,7 @@ static void __stop_tx_rs485(struct uart_8250_port *p)
struct uart_8250_em485 *em485 = p->em485;
/*
- * __do_stop_tx_rs485 is going to set RTS according to config
+ * rs485_stop_tx() is going to set RTS according to config
* AND flush RX FIFO if required.
*/
if (p->port.rs485.delay_rts_after_send > 0) {
@@ -1497,8 +1503,9 @@ static void __stop_tx_rs485(struct uart_8250_port *p)
start_hrtimer_ms(&em485->stop_tx_timer,
p->port.rs485.delay_rts_after_send);
} else {
- __do_stop_tx_rs485(p);
+ p->rs485_stop_tx(p);
em485->active_timer = NULL;
+ em485->tx_stopped = true;
}
}
@@ -1572,25 +1579,42 @@ static inline void __start_tx(struct uart_port *port)
}
}
-static inline void start_tx_rs485(struct uart_port *port)
+/**
+ * serial8250_em485_start_tx() - generic ->rs485_start_tx() callback
+ * @up: uart 8250 port
+ *
+ * Generic callback usable by 8250 uart drivers to start rs485 transmission.
+ * Assumes that setting the RTS bit in the MCR register means RTS is high.
+ * (Some chips use inverse semantics.) Further assumes that reception is
+ * stoppable by disabling the UART_IER_RDI interrupt. (Some chips set the
+ * UART_LSR_DR bit even when UART_IER_RDI is disabled, foiling this approach.)
+ */
+void serial8250_em485_start_tx(struct uart_8250_port *up)
{
- struct uart_8250_port *up = up_to_u8250p(port);
- struct uart_8250_em485 *em485 = up->em485;
- unsigned char mcr;
+ unsigned char mcr = serial8250_in_MCR(up);
if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
serial8250_stop_rx(&up->port);
+ if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND)
+ mcr |= UART_MCR_RTS;
+ else
+ mcr &= ~UART_MCR_RTS;
+ serial8250_out_MCR(up, mcr);
+}
+EXPORT_SYMBOL_GPL(serial8250_em485_start_tx);
+
+static inline void start_tx_rs485(struct uart_port *port)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+ struct uart_8250_em485 *em485 = up->em485;
+
em485->active_timer = NULL;
- mcr = serial8250_in_MCR(up);
- if (!!(up->port.rs485.flags & SER_RS485_RTS_ON_SEND) !=
- !!(mcr & UART_MCR_RTS)) {
- if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND)
- mcr |= UART_MCR_RTS;
- else
- mcr &= ~UART_MCR_RTS;
- serial8250_out_MCR(up, mcr);
+ if (em485->tx_stopped) {
+ em485->tx_stopped = false;
+
+ up->rs485_start_tx(up);
if (up->port.rs485.delay_rts_before_send > 0) {
em485->active_timer = &em485->start_tx_timer;
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 6a8e8c48c882..0901c2aa366c 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -81,6 +81,7 @@ struct uart_8250_em485 {
struct hrtimer stop_tx_timer; /* "rs485 stop tx" timer */
struct hrtimer *active_timer; /* pointer to active timer */
struct uart_8250_port *port; /* for hrtimer callbacks */
+ unsigned int tx_stopped:1; /* tx is currently stopped */
};
/*
@@ -132,6 +133,8 @@ struct uart_8250_port {
void (*dl_write)(struct uart_8250_port *, int);
struct uart_8250_em485 *em485;
+ void (*rs485_start_tx)(struct uart_8250_port *);
+ void (*rs485_stop_tx)(struct uart_8250_port *);
/* Serial port overrun backoff */
struct delayed_work overrun_backoff;
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.