[PATCH next v2 2/4] serial: 8250: Split out IER from rs485_stop_tx()

John Ogness
2024-09-13T14:05:43Z

Move IER handling out of rs485_stop_tx() callback and into a new
wrapper serial8250_rs485_stop_tx(). Replace all callback call sites
with wrapper, except for the console write() callback, where it is
inappropriate to modify IER.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
drivers/tty/serial/8250/8250.h | 1 +
drivers/tty/serial/8250/8250_omap.c | 2 +-
drivers/tty/serial/8250/8250_port.c | 30 ++++++++++++++++++++---------
3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 6e90223ba1d6..b1e4b5fef8cc 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -237,6 +237,7 @@ void serial8250_em485_destroy(struct uart_8250_port *p);
extern struct serial_rs485 serial8250_em485_supported;

void serial8250_rs485_start_tx(struct uart_8250_port *up);
+void serial8250_rs485_stop_tx(struct uart_8250_port *p);

/* MCR <-> TIOCM conversion */
static inline int serial8250_TIOCM_to_MCR(int tiocm)
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index afef1dd4ddf4..2b62d49a935d 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -366,7 +366,7 @@ static void omap8250_restore_regs(struct uart_8250_port *up)

if (up->port.rs485.flags & SER_RS485_ENABLED &&
up->port.rs485_config == serial8250_em485_config)
- serial8250_em485_stop_tx(up);
+ serial8250_rs485_stop_tx(up);
}

/*
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index ba8d9cefc451..7ee74ec944d2 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -558,7 +558,7 @@ static int serial8250_em485_init(struct uart_8250_port *p)

deassert_rts:
if (p->em485->tx_stopped)
- p->rs485_stop_tx(p);
+ serial8250_rs485_stop_tx(p);

return 0;
}
@@ -1380,14 +1380,13 @@ static void serial8250_stop_rx(struct uart_port *port)
* @p: uart 8250 port
*
* Generic callback usable by 8250 uart drivers to stop rs485 transmission.
+ * It does not restore RX interrupts. Use the wrapper function
+ * serial8250_rs485_stop_tx() if that is also needed.
*/
void serial8250_em485_stop_tx(struct uart_8250_port *p)
{
unsigned char mcr = serial8250_in_MCR(p);

- /* Port locked to synchronize UART_IER access against the console. */
- lockdep_assert_held_once(&p->port.lock);
-
if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
mcr |= UART_MCR_RTS;
else
@@ -1397,16 +1396,29 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p)
/*
* Empty the RX FIFO, we are not interested in anything
* received during the half-duplex transmission.
- * Enable previously disabled RX interrupts.
*/
- if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
+ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
serial8250_clear_and_reinit_fifos(p);
+}
+EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx);
+
+/**
+ * serial8250_rs485_stop_tx() - stop rs485 transmission, restore RX interrupts
+ * @p: uart 8250 port
+ */
+void serial8250_rs485_stop_tx(struct uart_8250_port *p)
+{
+ /* Port locked to synchronize UART_IER access against the console. */
+ lockdep_assert_held_once(&p->port.lock);
+
+ p->rs485_stop_tx(p);

+ /* Enable previously disabled RX interrupts. */
+ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
p->ier |= UART_IER_RLSI | UART_IER_RDI;
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)
{
@@ -1418,7 +1430,7 @@ static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
serial8250_rpm_get(p);
uart_port_lock_irqsave(&p->port, &flags);
if (em485->active_timer == &em485->stop_tx_timer) {
- p->rs485_stop_tx(p);
+ serial8250_rs485_stop_tx(p);
em485->active_timer = NULL;
em485->tx_stopped = true;
}
@@ -1450,7 +1462,7 @@ static void __stop_tx_rs485(struct uart_8250_port *p, u64 stop_delay)
em485->active_timer = &em485->stop_tx_timer;
hrtimer_start(&em485->stop_tx_timer, ns_to_ktime(stop_delay), HRTIMER_MODE_REL);
} else {
- p->rs485_stop_tx(p);
+ serial8250_rs485_stop_tx(p);
em485->active_timer = NULL;
em485->tx_stopped = true;
}
--
2.39.2