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Message-Id: <20241025105728.602310-5-john.ogness@linutronix.de>
Date: Fri, 25 Oct 2024 13:03:26 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jirislaby@...nel.org>,
Petr Mladek <pmladek@...e.com>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
Esben Haabendal <esben@...nix.com>,
linux-serial@...r.kernel.org,
linux-kernel@...r.kernel.org,
Florian Fainelli <florian.fainelli@...adcom.com>,
Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
Ray Jui <rjui@...adcom.com>,
Scott Branden <sbranden@...adcom.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
Arnd Bergmann <arnd@...db.de>,
Stefan Wahren <wahrenst@....net>,
Uwe Kleine-König <u.kleine-koenig@...libre.com>,
Kevin Hilman <khilman@...libre.com>,
Markus Schneider-Pargmann <msp@...libre.com>,
Ronald Wahl <ronald.wahl@...itan.com>,
Udit Kumar <u-kumar1@...com>,
Griffin Kroah-Hartman <griffin@...ah.com>,
Rengarajan S <rengarajan.s@...rochip.com>,
Lino Sanfilippo <l.sanfilippo@...bus.com>,
Serge Semin <fancer.lancer@...il.com>,
linux-rpi-kernel@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org
Subject: [PATCH tty-next v3 4/6] serial: 8250: Specify console context for rs485_start/stop_tx
For RS485 mode, if SER_RS485_RX_DURING_TX is not available, the
console write callback needs to enable/disable TX. It does this
by calling the rs485_start/stop_tx() callbacks. However, these
callbacks will disable/enable interrupts, which is a problem
for console write, as it must be responsible for
disabling/enabling interrupts.
Add an argument @in_con to the rs485_start/stop_tx() callbacks
to specify if they are being called from console write. If so,
the callbacks will not handle interrupt disabling/enabling.
For all call sites other than console write, there is no
functional change.
Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
drivers/tty/serial/8250/8250.h | 4 +--
drivers/tty/serial/8250/8250_bcm2835aux.c | 4 +--
drivers/tty/serial/8250/8250_omap.c | 2 +-
drivers/tty/serial/8250/8250_port.c | 34 +++++++++++++++--------
include/linux/serial_8250.h | 4 +--
5 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index e5310c65cf52..0d8717be0df7 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -231,8 +231,8 @@ void serial8250_rpm_put_tx(struct uart_8250_port *p);
int serial8250_em485_config(struct uart_port *port, struct ktermios *termios,
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_start_tx(struct uart_8250_port *p, bool in_con);
+void serial8250_em485_stop_tx(struct uart_8250_port *p, bool in_con);
void serial8250_em485_destroy(struct uart_8250_port *p);
extern struct serial_rs485 serial8250_em485_supported;
diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c
index fdb53b54e99e..c9a106a86b56 100644
--- a/drivers/tty/serial/8250/8250_bcm2835aux.c
+++ b/drivers/tty/serial/8250/8250_bcm2835aux.c
@@ -46,7 +46,7 @@ struct bcm2835aux_data {
u32 cntl;
};
-static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up)
+static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up, bool in_con)
{
if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
struct bcm2835aux_data *data = dev_get_drvdata(up->port.dev);
@@ -65,7 +65,7 @@ static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up)
serial8250_out_MCR(up, UART_MCR_RTS);
}
-static void bcm2835aux_rs485_stop_tx(struct uart_8250_port *up)
+static void bcm2835aux_rs485_stop_tx(struct uart_8250_port *up, bool in_con)
{
if (up->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
serial8250_out_MCR(up, 0);
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index b3be0fb184a3..fcbed7e98231 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -365,7 +365,7 @@ 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_em485_stop_tx(up, false);
}
/*
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 09ac521d232a..7c50387194ad 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);
+ p->rs485_stop_tx(p, false);
return 0;
}
@@ -1398,10 +1398,11 @@ static void serial8250_stop_rx(struct uart_port *port)
/**
* serial8250_em485_stop_tx() - generic ->rs485_stop_tx() callback
* @p: uart 8250 port
+ * @in_con: true if called from console write, otherwise false
*
* Generic callback usable by 8250 uart drivers to stop rs485 transmission.
*/
-void serial8250_em485_stop_tx(struct uart_8250_port *p)
+void serial8250_em485_stop_tx(struct uart_8250_port *p, bool in_con)
{
unsigned char mcr = serial8250_in_MCR(p);
@@ -1419,7 +1420,9 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p)
if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
serial8250_clear_and_reinit_fifos(p);
- __serial8250_start_rx_int(p);
+ /* In console context, caller handles interrupt enabling. */
+ if (!in_con)
+ __serial8250_start_rx_int(p);
}
}
EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx);
@@ -1434,7 +1437,7 @@ 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);
+ p->rs485_stop_tx(p, false);
em485->active_timer = NULL;
em485->tx_stopped = true;
}
@@ -1466,7 +1469,7 @@ 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);
+ p->rs485_stop_tx(p, false);
em485->active_timer = NULL;
em485->tx_stopped = true;
}
@@ -1555,6 +1558,7 @@ static inline void __start_tx(struct uart_port *port)
/**
* serial8250_em485_start_tx() - generic ->rs485_start_tx() callback
* @up: uart 8250 port
+ * @in_con: true if called from console write, otherwise false
*
* 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.
@@ -1562,12 +1566,20 @@ static inline void __start_tx(struct uart_port *port)
* 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)
+void serial8250_em485_start_tx(struct uart_8250_port *up, bool in_con)
{
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_RX_DURING_TX)) {
+ /*
+ * In console context, caller handles interrupt disabling. So
+ * only LSR_DR masking is needed.
+ */
+ if (in_con)
+ __serial8250_stop_rx_mask_dr(&up->port);
+ else
+ serial8250_stop_rx(&up->port);
+ }
if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND)
mcr |= UART_MCR_RTS;
@@ -1600,7 +1612,7 @@ static bool start_tx_rs485(struct uart_port *port)
if (em485->tx_stopped) {
em485->tx_stopped = false;
- up->rs485_start_tx(up);
+ up->rs485_start_tx(up, false);
if (up->port.rs485.delay_rts_before_send > 0) {
em485->active_timer = &em485->start_tx_timer;
@@ -3402,7 +3414,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
if (em485) {
if (em485->tx_stopped)
- up->rs485_start_tx(up);
+ up->rs485_start_tx(up, true);
mdelay(port->rs485.delay_rts_before_send);
}
@@ -3440,7 +3452,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
if (em485) {
mdelay(port->rs485.delay_rts_after_send);
if (em485->tx_stopped)
- up->rs485_stop_tx(up);
+ up->rs485_stop_tx(up, true);
}
serial_port_out(port, UART_IER, ier);
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index e0717c8393d7..c25c026d173d 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -161,8 +161,8 @@ struct uart_8250_port {
void (*dl_write)(struct uart_8250_port *up, u32 value);
struct uart_8250_em485 *em485;
- void (*rs485_start_tx)(struct uart_8250_port *);
- void (*rs485_stop_tx)(struct uart_8250_port *);
+ void (*rs485_start_tx)(struct uart_8250_port *up, bool in_con);
+ void (*rs485_stop_tx)(struct uart_8250_port *up, bool in_con);
/* Serial port overrun backoff */
struct delayed_work overrun_backoff;
--
2.39.5
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