[PATCH AUTOSEL 5.16 069/217] serial: 8250_dw: Add StarFive JH7100 quirk

[PATCH AUTOSEL 5.16 069/217] serial: 8250_dw: Add StarFive JH7100 quirk

[Sasha Levin]

From: Emil Renner Berthing <kernel@esmil.dk>

[ Upstream commit 57dcb6ec85d59e04285b7dcf10924bb819c8e46f ]

On the StarFive JH7100 RISC-V SoC the UART core clocks can't be set to
exactly 16 * 115200Hz and many other common bitrates. Trying this will
only result in a higher input clock, but low enough that the UART's
internal divisor can't come close enough to the baud rate target.
So rather than try to set the input clock it's better to skip the
clk_set_rate call and rely solely on the UART's internal divisor.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20211116150119.2171-15-kernel@esmil.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/8250/8250_dw.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 53f57c3b9f42c..1769808031c52 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -414,6 +414,8 @@ static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data)
 
 		if (of_device_is_compatible(np, "marvell,armada-38x-uart"))
 			p->serial_out = dw8250_serial_out38x;
+		if (of_device_is_compatible(np, "starfive,jh7100-uart"))
+			p->set_termios = dw8250_do_set_termios;
 
 	} else if (acpi_dev_present("APMC0D08", NULL, -1)) {
 		p->iotype = UPIO_MEM32;
@@ -696,6 +698,7 @@ static const struct of_device_id dw8250_of_match[] = {
 	{ .compatible = "cavium,octeon-3860-uart" },
 	{ .compatible = "marvell,armada-38x-uart" },
 	{ .compatible = "renesas,rzn1-uart" },
+	{ .compatible = "starfive,jh7100-uart" },
 	{ /* Sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, dw8250_of_match);
-- 
2.34.1

[PATCH AUTOSEL 5.16 070/217] tty: serial: imx: disable UCR4_OREN in .stop_rx() instead of .shutdown()

[Sasha Levin]

From: Fugang Duan <fugang.duan@nxp.com>

[ Upstream commit 028e083832b06fdeeb290e1e57dc1f6702c4c215 ]

The UCR4_OREN should be disabled before disabling the uart receiver in
.stop_rx() instead of in the .shutdown().

Otherwise, if we have the overrun error during the receiver disable
process, the overrun interrupt will keep trigging until we disable the
OREN interrupt in the .shutdown(), because the ORE status can only be
cleared when read the rx FIFO or reset the controller.  Although the
called time between the receiver disable and OREN disable in .shutdown()
is very short, there is still the risk of endless interrupt during this
short period of time. So here change to disable OREN before the receiver
been disabled in .stop_rx().

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20211125020349.4980-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/imx.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 90f82e6c54e46..6f7f382d0b1fa 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -486,18 +486,21 @@ static void imx_uart_stop_tx(struct uart_port *port)
 static void imx_uart_stop_rx(struct uart_port *port)
 {
 	struct imx_port *sport = (struct imx_port *)port;
-	u32 ucr1, ucr2;
+	u32 ucr1, ucr2, ucr4;
 
 	ucr1 = imx_uart_readl(sport, UCR1);
 	ucr2 = imx_uart_readl(sport, UCR2);
+	ucr4 = imx_uart_readl(sport, UCR4);
 
 	if (sport->dma_is_enabled) {
 		ucr1 &= ~(UCR1_RXDMAEN | UCR1_ATDMAEN);
 	} else {
 		ucr1 &= ~UCR1_RRDYEN;
 		ucr2 &= ~UCR2_ATEN;
+		ucr4 &= ~UCR4_OREN;
 	}
 	imx_uart_writel(sport, ucr1, UCR1);
+	imx_uart_writel(sport, ucr4, UCR4);
 
 	ucr2 &= ~UCR2_RXEN;
 	imx_uart_writel(sport, ucr2, UCR2);
@@ -1544,7 +1547,7 @@ static void imx_uart_shutdown(struct uart_port *port)
 	imx_uart_writel(sport, ucr1, UCR1);
 
 	ucr4 = imx_uart_readl(sport, UCR4);
-	ucr4 &= ~(UCR4_OREN | UCR4_TCEN);
+	ucr4 &= ~UCR4_TCEN;
 	imx_uart_writel(sport, ucr4, UCR4);
 
 	spin_unlock_irqrestore(&sport->port.lock, flags);
-- 
2.34.1

[PATCH AUTOSEL 5.16 205/217] serial: pl010: Drop CR register reset on set_termios

[Sasha Levin]

From: Lukas Wunner <lukas@wunner.de>

[ Upstream commit 08a0c6dff91c965e39905cf200d22db989203ccb ]

pl010_set_termios() briefly resets the CR register to zero.

Where does this register write come from?

The PL010 driver's IRQ handler ambauart_int() originally modified the CR
register without holding the port spinlock.  ambauart_set_termios() also
modified that register.  To prevent concurrent read-modify-writes by the
IRQ handler and to prevent transmission while changing baudrate,
ambauart_set_termios() had to disable interrupts.  That is achieved by
writing zero to the CR register.

However in 2004 the PL010 driver was amended to acquire the port
spinlock in the IRQ handler, obviating the need to disable interrupts in
->set_termios():
https://git.kernel.org/history/history/c/157c0342e591

That rendered the CR register write obsolete.  Drop it.

Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/fcaff16e5b1abb4cc3da5a2879ac13f278b99ed0.1641128728.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/amba-pl010.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/tty/serial/amba-pl010.c b/drivers/tty/serial/amba-pl010.c
index e744b953ca346..47654073123d6 100644
--- a/drivers/tty/serial/amba-pl010.c
+++ b/drivers/tty/serial/amba-pl010.c
@@ -446,14 +446,11 @@ pl010_set_termios(struct uart_port *port, struct ktermios *termios,
 	if ((termios->c_cflag & CREAD) == 0)
 		uap->port.ignore_status_mask |= UART_DUMMY_RSR_RX;
 
-	/* first, disable everything */
 	old_cr = readb(uap->port.membase + UART010_CR) & ~UART010_CR_MSIE;
 
 	if (UART_ENABLE_MS(port, termios->c_cflag))
 		old_cr |= UART010_CR_MSIE;
 
-	writel(0, uap->port.membase + UART010_CR);
-
 	/* Set baud rate */
 	quot -= 1;
 	writel((quot & 0xf00) >> 8, uap->port.membase + UART010_LCRM);
-- 
2.34.1

[PATCH AUTOSEL 5.16 206/217] serial: pl011: Drop CR register reset on set_termios

[Sasha Levin]

From: Lukas Wunner <lukas@wunner.de>

[ Upstream commit e368cc656fd6d0075f1c3ab9676e2001451e3e04 ]

pl011_set_termios() briefly resets the CR register to zero, thereby
glitching DTR/RTS signals.  With rs485 this may result in the bus being
occupied for no reason.

Where does this register write originate from?

The PL011 driver was forked from the PL010 driver in 2004:
https://git.kernel.org/history/history/c/157c0342e591

Until this commit, the PL010 driver's IRQ handler ambauart_int()
modified the CR register without holding the port spinlock.

ambauart_set_termios() also modified that register.  To prevent
concurrent read-modify-writes by the IRQ handler and to prevent
transmission while changing baudrate, ambauart_set_termios() had to
disable interrupts.  On the PL010, that is achieved by writing zero to
the CR register.

However, on the PL011, interrupts are disabled in the IMSC register,
not in the CR register.

Additionally, the commit amended both the PL010 and PL011 driver to
acquire the port spinlock in the IRQ handler, obviating the need to
disable interrupts in ->set_termios().

So the CR register write is obsolete for two reasons.  Drop it.

Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/f49f945375f5ccb979893c49f1129f51651ac738.1641129062.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/amba-pl011.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 52518a606c06a..9b1b0d9bdf7be 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2105,9 +2105,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (port->rs485.flags & SER_RS485_ENABLED)
 		termios->c_cflag &= ~CRTSCTS;
 
-	/* first, disable everything */
 	old_cr = pl011_read(uap, REG_CR);
-	pl011_write(0, uap, REG_CR);
 
 	if (termios->c_cflag & CRTSCTS) {
 		if (old_cr & UART011_CR_RTS)
-- 
2.34.1

[PATCH AUTOSEL 5.16 207/217] serial: core: Keep mctrl register state and cached copy in sync

[Sasha Levin]

From: Lukas Wunner <lukas@wunner.de>

[ Upstream commit 93a770b7e16772530196674ffc79bb13fa927dc6 ]

struct uart_port contains a cached copy of the Modem Control signals.
It is used to skip register writes in uart_update_mctrl() if the new
signal state equals the old signal state.  It also avoids a register
read to obtain the current state of output signals.

When a uart_port is registered, uart_configure_port() changes signal
state but neglects to keep the cached copy in sync.  That may cause
a subsequent register write to be incorrectly skipped.  Fix it before
it trips somebody up.

This behavior has been present ever since the serial core was introduced
in 2002:
https://git.kernel.org/history/history/c/33c0d1b0c3eb

So far it was never an issue because the cached copy is initialized to 0
by kzalloc() and when uart_configure_port() is executed, at most DTR has
been set by uart_set_options() or sunsu_console_setup().  Therefore,
a stable designation seems unnecessary.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/bceeaba030b028ed810272d55d5fc6f3656ddddb.1641129752.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/serial_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 61e3dd0222af1..9e7e624a6c9db 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2393,7 +2393,8 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
 		 * We probably don't need a spinlock around this, but
 		 */
 		spin_lock_irqsave(&port->lock, flags);
-		port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
+		port->mctrl &= TIOCM_DTR;
+		port->ops->set_mctrl(port, port->mctrl);
 		spin_unlock_irqrestore(&port->lock, flags);
 
 		/*
-- 
2.34.1