[PATCH v4 00/10] tty: TX helpers

[PATCH v4 00/10] tty: TX helpers

[Jiri Slaby]

This series introduces uart_port_tx() + uart_port_tx_limited() TX
helpers. See PATCH 8/10 for the details. Comments welcome.

First the series performs simple cleanups, so that the later patches are
easier to follow.

Then it switches drivers to use them. First, to uart_port_tx() in 9/10
and then uart_port_tx_limited() in 10/10.

The diffstat of patches 9+10 is as follows:
 26 files changed, 145 insertions(+), 740 deletions(-)
which appears to be nice.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Johan Hovold <johan@kernel.org>
Cc: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Jiri Slaby (10):
  tty: serial: move and cleanup vt8500_tx_empty()
  tty: serial: clean up stop-tx part in altera_uart_tx_chars()
  tty: serial: altera_uart_{r,t}x_chars() need only uart_port
  tty: serial: extract lqasc_tx_ready() from lqasc_tx_chars()
  tty: serial: extract tx_ready() from __serial_lpc32xx_tx()
  tty: serial: switch mpc52xx_uart_int_{r,t}x_chars() to bool
  tty: serial: extract serial_omap_put_char() from transmit_chars()
  tty: serial: introduce transmit helpers
  tty: serial: use uart_port_tx() helper
  tty: serial: use uart_port_tx_limited()

 Documentation/driver-api/serial/driver.rst |  3 +
 drivers/tty/serial/21285.c                 | 32 ++-------
 drivers/tty/serial/altera_jtaguart.c       | 40 +++--------
 drivers/tty/serial/altera_uart.c           | 41 +++--------
 drivers/tty/serial/amba-pl010.c            | 32 ++-------
 drivers/tty/serial/apbuart.c               | 34 ++-------
 drivers/tty/serial/atmel_serial.c          | 28 ++------
 drivers/tty/serial/bcm63xx_uart.c          | 47 +++----------
 drivers/tty/serial/fsl_lpuart.c            | 30 ++------
 drivers/tty/serial/lantiq.c                | 44 +++---------
 drivers/tty/serial/lpc32xx_hs.c            | 39 +++--------
 drivers/tty/serial/mcf.c                   | 28 ++------
 drivers/tty/serial/mpc52xx_uart.c          | 49 +++----------
 drivers/tty/serial/mps2-uart.c             | 26 ++-----
 drivers/tty/serial/mux.c                   | 45 ++++--------
 drivers/tty/serial/mvebu-uart.c            | 38 ++--------
 drivers/tty/serial/mxs-auart.c             | 32 +++------
 drivers/tty/serial/omap-serial.c           | 46 ++++---------
 drivers/tty/serial/owl-uart.c              | 32 ++-------
 drivers/tty/serial/pxa.c                   | 33 ++-------
 drivers/tty/serial/rp2.c                   | 31 ++-------
 drivers/tty/serial/sa1100.c                | 34 ++-------
 drivers/tty/serial/serial_txx9.c           | 32 ++-------
 drivers/tty/serial/sifive.c                | 31 ++-------
 drivers/tty/serial/sprd_serial.c           | 33 ++-------
 drivers/tty/serial/st-asc.c                | 48 ++-----------
 drivers/tty/serial/vt8500_serial.c         | 41 +++--------
 include/linux/serial_core.h                | 80 ++++++++++++++++++++++
 28 files changed, 264 insertions(+), 765 deletions(-)

-- 
2.37.3

[PATCH v4 01/10] tty: serial: move and cleanup vt8500_tx_empty()

[Jiri Slaby]

Make vt8500_tx_empty() more readable by introducing a new local variable
and move the function before handle_tx(). That way we can reuse it in
there too.

Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v3] this is new in v3 -- extracted as a separate change from later
         patches

 drivers/tty/serial/vt8500_serial.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index 508ad7afa6de..10fbdb09965f 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -187,6 +187,13 @@ static void handle_rx(struct uart_port *port)
 	tty_flip_buffer_push(tport);
 }
 
+static unsigned int vt8500_tx_empty(struct uart_port *port)
+{
+	unsigned int idx = vt8500_read(port, VT8500_URFIDX) & 0x1f;
+
+	return idx < 16 ? TIOCSER_TEMT : 0;
+}
+
 static void handle_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
@@ -201,7 +208,7 @@ static void handle_tx(struct uart_port *port)
 		return;
 	}
 
-	while ((vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16) {
+	while (vt8500_tx_empty(port)) {
 		if (uart_circ_empty(xmit))
 			break;
 
@@ -260,12 +267,6 @@ static irqreturn_t vt8500_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static unsigned int vt8500_tx_empty(struct uart_port *port)
-{
-	return (vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16 ?
-						TIOCSER_TEMT : 0;
-}
-
 static unsigned int vt8500_get_mctrl(struct uart_port *port)
 {
 	unsigned int usr;
-- 
2.37.3

[PATCH v4 01/10] tty: serial: move and cleanup vt8500_tx_empty()

[Jiri Slaby]

Make vt8500_tx_empty() more readable by introducing a new local variable
and move the function before handle_tx(). That way we can reuse it in
there too.

Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v3] this is new in v3 -- extracted as a separate change from later
         patches

 drivers/tty/serial/vt8500_serial.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index 508ad7afa6de..10fbdb09965f 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -187,6 +187,13 @@ static void handle_rx(struct uart_port *port)
 	tty_flip_buffer_push(tport);
 }
 
+static unsigned int vt8500_tx_empty(struct uart_port *port)
+{
+	unsigned int idx = vt8500_read(port, VT8500_URFIDX) & 0x1f;
+
+	return idx < 16 ? TIOCSER_TEMT : 0;
+}
+
 static void handle_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
@@ -201,7 +208,7 @@ static void handle_tx(struct uart_port *port)
 		return;
 	}
 
-	while ((vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16) {
+	while (vt8500_tx_empty(port)) {
 		if (uart_circ_empty(xmit))
 			break;
 
@@ -260,12 +267,6 @@ static irqreturn_t vt8500_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static unsigned int vt8500_tx_empty(struct uart_port *port)
-{
-	return (vt8500_read(port, VT8500_URFIDX) & 0x1f) < 16 ?
-						TIOCSER_TEMT : 0;
-}
-
 static unsigned int vt8500_get_mctrl(struct uart_port *port)
 {
 	unsigned int usr;
-- 
2.37.3


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Re: [PATCH v4 01/10] tty: serial: move and cleanup vt8500_tx_empty()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 362 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> Make vt8500_tx_empty() more readable by introducing a new local variable
> and move the function before handle_tx(). That way we can reuse it in
> there too.
> 
> Cc: <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

Re: [PATCH v4 01/10] tty: serial: move and cleanup vt8500_tx_empty()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 362 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> Make vt8500_tx_empty() more readable by introducing a new local variable
> and move the function before handle_tx(). That way we can reuse it in
> there too.
> 
> Cc: <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]

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[PATCH v4 02/10] tty: serial: clean up stop-tx part in altera_uart_tx_chars()

[Jiri Slaby]

The "stop TX" path in altera_uart_tx_chars() is open-coded, so:
* use uart_circ_empty() to check if the buffer is empty, and
* when true, call altera_uart_stop_tx().

Cc: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/altera_uart.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index a38db2cb8dc1..4170e66601ec 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -272,10 +272,8 @@ static void altera_uart_tx_chars(struct altera_uart *pp)
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (xmit->head == xmit->tail) {
-		pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
-		altera_uart_update_ctrl_reg(pp);
-	}
+	if (uart_circ_empty(xmit))
+		altera_uart_stop_tx(port);
 }
 
 static irqreturn_t altera_uart_interrupt(int irq, void *data)
-- 
2.37.3

Re: [PATCH v4 02/10] tty: serial: clean up stop-tx part in altera_uart_tx_chars()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 372 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> The "stop TX" path in altera_uart_tx_chars() is open-coded, so:
> * use uart_circ_empty() to check if the buffer is empty, and
> * when true, call altera_uart_stop_tx().
> 
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

Re: [PATCH v4 02/10] tty: serial: clean up stop-tx part in altera_uart_tx_chars()

[Tobias Klauser]

On 2022-09-20 at 07:20:42 +0200, Jiri Slaby <jslaby@suse.cz> wrote:
> The "stop TX" path in altera_uart_tx_chars() is open-coded, so:
> * use uart_circ_empty() to check if the buffer is empty, and
> * when true, call altera_uart_stop_tx().
> 
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Acked-by: Tobias Klauser <tklauser@distanz.ch>

[PATCH v4 03/10] tty: serial: altera_uart_{r,t}x_chars() need only uart_port

[Jiri Slaby]

Both altera_uart_{r,t}x_chars() need only uart_port, not altera_uart. So
pass the former from altera_uart_interrupt() directly.

Apart it maybe saves a dereference, this makes the transition of
altera_uart_tx_chars() easier to follow in the next patch.

Cc: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/altera_uart.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 4170e66601ec..82f2790de28d 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -199,9 +199,8 @@ static void altera_uart_set_termios(struct uart_port *port,
 	 */
 }
 
-static void altera_uart_rx_chars(struct altera_uart *pp)
+static void altera_uart_rx_chars(struct uart_port *port)
 {
-	struct uart_port *port = &pp->port;
 	unsigned char ch, flag;
 	unsigned short status;
 
@@ -246,9 +245,8 @@ static void altera_uart_rx_chars(struct altera_uart *pp)
 	tty_flip_buffer_push(&port->state->port);
 }
 
-static void altera_uart_tx_chars(struct altera_uart *pp)
+static void altera_uart_tx_chars(struct uart_port *port)
 {
-	struct uart_port *port = &pp->port;
 	struct circ_buf *xmit = &port->state->xmit;
 
 	if (port->x_char) {
@@ -286,9 +284,9 @@ static irqreturn_t altera_uart_interrupt(int irq, void *data)
 
 	spin_lock(&port->lock);
 	if (isr & ALTERA_UART_STATUS_RRDY_MSK)
-		altera_uart_rx_chars(pp);
+		altera_uart_rx_chars(port);
 	if (isr & ALTERA_UART_STATUS_TRDY_MSK)
-		altera_uart_tx_chars(pp);
+		altera_uart_tx_chars(port);
 	spin_unlock(&port->lock);
 
 	return IRQ_RETVAL(isr);
-- 
2.37.3

Re: [PATCH v4 03/10] tty: serial: altera_uart_{r,t}x_chars() need only uart_port

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 463 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> Both altera_uart_{r,t}x_chars() need only uart_port, not altera_uart. So
> pass the former from altera_uart_interrupt() directly.
> 
> Apart it maybe saves a dereference, this makes the transition of
> altera_uart_tx_chars() easier to follow in the next patch.
> 
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

Re: [PATCH v4 03/10] tty: serial: altera_uart_{r,t}x_chars() need only uart_port

[Tobias Klauser]

On 2022-09-20 at 07:20:43 +0200, Jiri Slaby <jslaby@suse.cz> wrote:
> Both altera_uart_{r,t}x_chars() need only uart_port, not altera_uart. So
> pass the former from altera_uart_interrupt() directly.
> 
> Apart it maybe saves a dereference, this makes the transition of
> altera_uart_tx_chars() easier to follow in the next patch.
> 
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Acked-by: Tobias Klauser <tklauser@distanz.ch>

[PATCH v4 04/10] tty: serial: extract lqasc_tx_ready() from lqasc_tx_chars()

[Jiri Slaby]

The condition in lqasc_tx_chars()'s loop is barely readable. Extract it
to a separate function. This will make the cleanup in the next patches
easier too.

(Put it before lqasc_start_tx(), so that we can use it there later.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/lantiq.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/lantiq.c b/drivers/tty/serial/lantiq.c
index 6637b3caa6b7..6da1b7496c6c 100644
--- a/drivers/tty/serial/lantiq.c
+++ b/drivers/tty/serial/lantiq.c
@@ -139,6 +139,13 @@ lqasc_stop_tx(struct uart_port *port)
 	return;
 }
 
+static bool lqasc_tx_ready(struct uart_port *port)
+{
+	u32 fstat = __raw_readl(port->membase + LTQ_ASC_FSTAT);
+
+	return (fstat & ASCFSTAT_TXFREEMASK) >> ASCFSTAT_TXFREEOFF;
+}
+
 static void
 lqasc_start_tx(struct uart_port *port)
 {
@@ -228,8 +235,7 @@ lqasc_tx_chars(struct uart_port *port)
 		return;
 	}
 
-	while (((__raw_readl(port->membase + LTQ_ASC_FSTAT) &
-		ASCFSTAT_TXFREEMASK) >> ASCFSTAT_TXFREEOFF) != 0) {
+	while (lqasc_tx_ready(port)) {
 		if (port->x_char) {
 			writeb(port->x_char, port->membase + LTQ_ASC_TBUF);
 			port->icount.tx++;
-- 
2.37.3

Re: [PATCH v4 04/10] tty: serial: extract lqasc_tx_ready() from lqasc_tx_chars()

[Ilpo Järvinen]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> The condition in lqasc_tx_chars()'s loop is barely readable. Extract it
> to a separate function. This will make the cleanup in the next patches
> easier too.
> 
> (Put it before lqasc_start_tx(), so that we can use it there later.)
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> ---
> 
> Notes:
>     [v4] this is new in v4 -- extracted as a separate change
> 
>  drivers/tty/serial/lantiq.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/lantiq.c b/drivers/tty/serial/lantiq.c
> index 6637b3caa6b7..6da1b7496c6c 100644
> --- a/drivers/tty/serial/lantiq.c
> +++ b/drivers/tty/serial/lantiq.c
> @@ -139,6 +139,13 @@ lqasc_stop_tx(struct uart_port *port)
>  	return;
>  }
>  
> +static bool lqasc_tx_ready(struct uart_port *port)
> +{
> +	u32 fstat = __raw_readl(port->membase + LTQ_ASC_FSTAT);
> +
> +	return (fstat & ASCFSTAT_TXFREEMASK) >> ASCFSTAT_TXFREEOFF;

FIELD_GET(ASCFSTAT_TXFREEMASK, fstat)

> +}
> +
>  static void
>  lqasc_start_tx(struct uart_port *port)
>  {
> @@ -228,8 +235,7 @@ lqasc_tx_chars(struct uart_port *port)
>  		return;
>  	}
>  
> -	while (((__raw_readl(port->membase + LTQ_ASC_FSTAT) &
> -		ASCFSTAT_TXFREEMASK) >> ASCFSTAT_TXFREEOFF) != 0) {
> +	while (lqasc_tx_ready(port)) {
>  		if (port->x_char) {
>  			writeb(port->x_char, port->membase + LTQ_ASC_TBUF);
>  			port->icount.tx++;

There's similar construct in lqasc_console_putchar() that could take 
advantage of the same helper.

With FIELD_GET + the other place using the new helper, ASCFSTAT_TXFREEOFF 
can be dropped as well.


-- 
 i.

[PATCH v4 05/10] tty: serial: extract tx_ready() from __serial_lpc32xx_tx()

[Jiri Slaby]

The condition in __serial_lpc32xx_tx()'s loop is barely readable.
Extract it to a separate function. This will make the cleanup in the
next patches easier too.

Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/lpc32xx_hs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index 0d5ef7df27d0..ed47f4768338 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -278,6 +278,13 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
 
 static void serial_lpc32xx_stop_tx(struct uart_port *port);
 
+static bool serial_lpc32xx_tx_ready(struct uart_port *port)
+{
+	u32 level = readl(LPC32XX_HSUART_LEVEL(port->membase));
+
+	return LPC32XX_HSU_TX_LEV(level) < 64;
+}
+
 static void __serial_lpc32xx_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
@@ -293,8 +300,7 @@ static void __serial_lpc32xx_tx(struct uart_port *port)
 		goto exit_tx;
 
 	/* Transfer data */
-	while (LPC32XX_HSU_TX_LEV(readl(
-		LPC32XX_HSUART_LEVEL(port->membase))) < 64) {
+	while (serial_lpc32xx_tx_ready(port)) {
 		writel((u32) xmit->buf[xmit->tail],
 		       LPC32XX_HSUART_FIFO(port->membase));
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-- 
2.37.3

[PATCH v4 05/10] tty: serial: extract tx_ready() from __serial_lpc32xx_tx()

[Jiri Slaby]

The condition in __serial_lpc32xx_tx()'s loop is barely readable.
Extract it to a separate function. This will make the cleanup in the
next patches easier too.

Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/lpc32xx_hs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index 0d5ef7df27d0..ed47f4768338 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -278,6 +278,13 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
 
 static void serial_lpc32xx_stop_tx(struct uart_port *port);
 
+static bool serial_lpc32xx_tx_ready(struct uart_port *port)
+{
+	u32 level = readl(LPC32XX_HSUART_LEVEL(port->membase));
+
+	return LPC32XX_HSU_TX_LEV(level) < 64;
+}
+
 static void __serial_lpc32xx_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
@@ -293,8 +300,7 @@ static void __serial_lpc32xx_tx(struct uart_port *port)
 		goto exit_tx;
 
 	/* Transfer data */
-	while (LPC32XX_HSU_TX_LEV(readl(
-		LPC32XX_HSUART_LEVEL(port->membase))) < 64) {
+	while (serial_lpc32xx_tx_ready(port)) {
 		writel((u32) xmit->buf[xmit->tail],
 		       LPC32XX_HSUART_FIFO(port->membase));
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-- 
2.37.3


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Re: [PATCH v4 05/10] tty: serial: extract tx_ready() from __serial_lpc32xx_tx()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 501 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> The condition in __serial_lpc32xx_tx()'s loop is barely readable.
> Extract it to a separate function. This will make the cleanup in the
> next patches easier too.
> 
> Cc: Vladimir Zapolskiy <vz@mleia.com>
> Cc: <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

I noticed that wait_for_xmit_ready() uses < 32 for the similar check 
which seems fishy...


-- 
 i.

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]

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Re: [PATCH v4 05/10] tty: serial: extract tx_ready() from __serial_lpc32xx_tx()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 501 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> The condition in __serial_lpc32xx_tx()'s loop is barely readable.
> Extract it to a separate function. This will make the cleanup in the
> next patches easier too.
> 
> Cc: Vladimir Zapolskiy <vz@mleia.com>
> Cc: <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

I noticed that wait_for_xmit_ready() uses < 32 for the similar check 
which seems fishy...


-- 
 i.

[PATCH v4 06/10] tty: serial: switch mpc52xx_uart_int_{r,t}x_chars() to bool

[Jiri Slaby]

mpc52xx_uart_int_rx_chars() returns unsigned int.
mpc52xx_uart_int_tx_chars() returns int.

The both results are binary ORed to the "keepgoing" variable. Unify all
three to bool as the only interesting value is whether we should keep
looping (true/false).

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/mpc52xx_uart.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/mpc52xx_uart.c b/drivers/tty/serial/mpc52xx_uart.c
index 6f09b1cb3e1c..73362d4bc45d 100644
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -1364,7 +1364,7 @@ static const struct uart_ops mpc52xx_uart_ops = {
 /* Interrupt handling                                                       */
 /* ======================================================================== */
 
-static inline unsigned int
+static inline bool
 mpc52xx_uart_int_rx_chars(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
@@ -1425,7 +1425,7 @@ mpc52xx_uart_int_rx_chars(struct uart_port *port)
 	return psc_ops->raw_rx_rdy(port);
 }
 
-static inline int
+static inline bool
 mpc52xx_uart_int_tx_chars(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
@@ -1435,13 +1435,13 @@ mpc52xx_uart_int_tx_chars(struct uart_port *port)
 		psc_ops->write_char(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
-		return 1;
+		return true;
 	}
 
 	/* Nothing to do ? */
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 		mpc52xx_uart_stop_tx(port);
-		return 0;
+		return false;
 	}
 
 	/* Send chars */
@@ -1460,23 +1460,23 @@ mpc52xx_uart_int_tx_chars(struct uart_port *port)
 	/* Maybe we're done after all */
 	if (uart_circ_empty(xmit)) {
 		mpc52xx_uart_stop_tx(port);
-		return 0;
+		return false;
 	}
 
-	return 1;
+	return true;
 }
 
 static irqreturn_t
 mpc5xxx_uart_process_int(struct uart_port *port)
 {
 	unsigned long pass = ISR_PASS_LIMIT;
-	unsigned int keepgoing;
+	bool keepgoing;
 	u8 status;
 
 	/* While we have stuff to do, we continue */
 	do {
 		/* If we don't find anything to do, we stop */
-		keepgoing = 0;
+		keepgoing = false;
 
 		psc_ops->rx_clr_irq(port);
 		if (psc_ops->rx_rdy(port))
@@ -1495,7 +1495,7 @@ mpc5xxx_uart_process_int(struct uart_port *port)
 
 		/* Limit number of iteration */
 		if (!(--pass))
-			keepgoing = 0;
+			keepgoing = false;
 
 	} while (keepgoing);
 
-- 
2.37.3

Re: [PATCH v4 06/10] tty: serial: switch mpc52xx_uart_int_{r,t}x_chars() to bool

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 425 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> mpc52xx_uart_int_rx_chars() returns unsigned int.
> mpc52xx_uart_int_tx_chars() returns int.
> 
> The both results are binary ORed to the "keepgoing" variable. Unify all
> three to bool as the only interesting value is whether we should keep
> looping (true/false).
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

[PATCH v4 07/10] tty: serial: extract serial_omap_put_char() from transmit_chars()

[Jiri Slaby]

This non-trivial code is doubled in transmit_chars(), so it deserves its
own function. This will make next patches easier.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] this is new in v4 -- extracted as a separate change

 drivers/tty/serial/omap-serial.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index c87d85b901a7..b7b76e49115e 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -337,19 +337,24 @@ static void serial_omap_stop_rx(struct uart_port *port)
 	serial_out(up, UART_IER, up->ier);
 }
 
+static void serial_omap_put_char(struct uart_omap_port *up, unsigned char ch)
+{
+	serial_out(up, UART_TX, ch);
+
+	if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
+			!(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
+		up->rs485_tx_filter_count++;
+}
+
 static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
 {
 	struct circ_buf *xmit = &up->port.state->xmit;
 	int count;
 
 	if (up->port.x_char) {
-		serial_out(up, UART_TX, up->port.x_char);
+		serial_omap_put_char(up, up->port.x_char);
 		up->port.icount.tx++;
 		up->port.x_char = 0;
-		if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
-		    !(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
-			up->rs485_tx_filter_count++;
-
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
@@ -358,12 +363,9 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
 	}
 	count = up->port.fifosize / 4;
 	do {
-		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
+		serial_omap_put_char(up, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		up->port.icount.tx++;
-		if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
-		    !(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
-			up->rs485_tx_filter_count++;
 
 		if (uart_circ_empty(xmit))
 			break;
-- 
2.37.3

Re: [PATCH v4 07/10] tty: serial: extract serial_omap_put_char() from transmit_chars()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 284 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> This non-trivial code is doubled in transmit_chars(), so it deserves its
> own function. This will make next patches easier.
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

[PATCH v4 08/10] tty: serial: introduce transmit helpers

[Jiri Slaby]

Many serial drivers do the same thing:
* send x_char if set
* keep sending from the xmit circular buffer until either
  - the loop reaches the end of the xmit buffer
  - TX is stopped
  - HW fifo is full
* check for pending characters and:
  - wake up tty writers to fill for more data into xmit buffer
  - stop TX if there is nothing in the xmit buffer

The only differences are:
* how to write the character to the HW fifo
* the check of the end condition:
  - is the HW fifo full?
  - is limit of the written characters reached?

So unify the above into two helpers:
* uart_port_tx_limited() -- it performs the above taking the written
  characters limit into account, and
* uart_port_tx() -- the same as above, except it only checks the HW
  readiness, not the characters limit.

The HW specific operations (as stated as "differences" above) are passed
as arguments to the macros. They are:
* tx_ready -- returns true if HW can accept more data.
* put_char -- write a character to the device.
* tx_done -- when the write loop is done, perform arbitrary action
  before potential invocation of ops->stop_tx() happens.

Note that the above are macros. This means the code is generated in
place and the above 3 arguments are "inlined". I.e. no added penalty by
generating call instructions for every single character. Nor any
indirect calls. (As in some previous versions of this patchset.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] switch from helper generators to helpers similar to wait_event()
         [Arnd]

 Documentation/driver-api/serial/driver.rst |  3 +
 include/linux/serial_core.h                | 80 ++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst
index 23c6b956cd90..98d268555dcc 100644
--- a/Documentation/driver-api/serial/driver.rst
+++ b/Documentation/driver-api/serial/driver.rst
@@ -78,6 +78,9 @@ Other functions
            uart_get_lsr_info uart_handle_dcd_change uart_handle_cts_change
            uart_try_toggle_sysrq uart_get_console
 
+.. kernel-doc:: include/linux/serial_core.h
+   :identifiers: uart_port_tx_limited uart_port_tx
+
 Other notes
 -----------
 
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index de992585ea64..b8338a0a52ee 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -663,6 +663,86 @@ struct uart_driver {
 
 void uart_write_wakeup(struct uart_port *port);
 
+#define __uart_port_tx(uport, ch, tx_ready, put_char, tx_done, for_test,      \
+		for_post)						      \
+({									      \
+	struct uart_port *__port = (uport);				      \
+	struct circ_buf *xmit = &__port->state->xmit;			      \
+	unsigned int pending;						      \
+									      \
+	for (; (for_test) && (tx_ready); (for_post), __port->icount.tx++) {   \
+		if (__port->x_char) {					      \
+			(ch) = __port->x_char;				      \
+			(put_char);					      \
+			__port->x_char = 0;				      \
+			continue;					      \
+		}							      \
+									      \
+		if (uart_circ_empty(xmit) || uart_tx_stopped(__port))	      \
+			break;						      \
+									      \
+		(ch) = xmit->buf[xmit->tail];				      \
+		(put_char);						      \
+		xmit->tail = (xmit->tail + 1) % UART_XMIT_SIZE;		      \
+	}								      \
+									      \
+	(tx_done);							      \
+									      \
+	pending = uart_circ_chars_pending(xmit);			      \
+	if (pending < WAKEUP_CHARS) {					      \
+		uart_write_wakeup(__port);				      \
+									      \
+		if (pending == 0)					      \
+			__port->ops->stop_tx(__port);			      \
+	}								      \
+									      \
+	pending;							      \
+})
+
+/**
+ * uart_port_tx_limited -- transmit helper for uart_port with count limiting
+ * @port: uart port
+ * @ch: variable to store a character to be written to the HW
+ * @count: a limit of characters to send
+ * @tx_ready: can HW accept more data function
+ * @put_char: function to write a character
+ * @tx_done: function to call after the loop is done
+ *
+ * This helper transmits characters from the xmit buffer to the hardware using
+ * @put_char(). It does so until @count characters are sent and while @tx_ready
+ * evaluates to true.
+ *
+ * Returns: the number of characters in the xmit buffer when done.
+ *
+ * The expression in macro parameters shall be designed as follows:
+ *  * **tx_ready:** should evaluate to true if the HW can accept more data to
+ *    be sent. This parameter can be %true, which means the HW is always ready.
+ *  * **put_char:** shall write @ch to the device of @port.
+ *  * **tx_done:** when the write loop is done, this can perform arbitrary
+ *    action before potential invocation of ops->stop_tx() happens. If the
+ *    driver does not need to do anything, use e.g. ({}).
+ *
+ * For all of them, @port->lock is held, interrupts are locally disabled and
+ * the expressions must not sleep.
+ */
+#define uart_port_tx_limited(port, ch, count, tx_ready, put_char, tx_done) ({ \
+	unsigned int __count = (count);					      \
+	__uart_port_tx(port, ch, tx_ready, put_char, tx_done, __count,	      \
+			__count--);					      \
+})
+
+/**
+ * uart_port_tx -- transmit helper for uart_port
+ * @port: uart port
+ * @ch: variable to store a character to be written to the HW
+ * @tx_ready: can HW accept more data function
+ * @put_char: function to write a character
+ *
+ * See uart_port_tx_limited() for more details.
+ */
+#define uart_port_tx(port, ch, tx_ready, put_char)			\
+	__uart_port_tx(port, ch, tx_ready, put_char, ({}), true, ({}))
+
 /*
  * Baud rate helpers.
  */
-- 
2.37.3

Re: [PATCH v4 08/10] tty: serial: introduce transmit helpers

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 1615 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> Many serial drivers do the same thing:
> * send x_char if set
> * keep sending from the xmit circular buffer until either
>   - the loop reaches the end of the xmit buffer
>   - TX is stopped
>   - HW fifo is full
> * check for pending characters and:
>   - wake up tty writers to fill for more data into xmit buffer
>   - stop TX if there is nothing in the xmit buffer
> 
> The only differences are:
> * how to write the character to the HW fifo
> * the check of the end condition:
>   - is the HW fifo full?
>   - is limit of the written characters reached?
> 
> So unify the above into two helpers:
> * uart_port_tx_limited() -- it performs the above taking the written
>   characters limit into account, and
> * uart_port_tx() -- the same as above, except it only checks the HW
>   readiness, not the characters limit.
> 
> The HW specific operations (as stated as "differences" above) are passed
> as arguments to the macros. They are:
> * tx_ready -- returns true if HW can accept more data.
> * put_char -- write a character to the device.
> * tx_done -- when the write loop is done, perform arbitrary action
>   before potential invocation of ops->stop_tx() happens.
> 
> Note that the above are macros. This means the code is generated in
> place and the above 3 arguments are "inlined". I.e. no added penalty by
> generating call instructions for every single character. Nor any
> indirect calls. (As in some previous versions of this patchset.)
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

[PATCH v4 09/10] tty: serial: use uart_port_tx() helper

[Jiri Slaby]

uart_port_tx() is a new helper to send characters to the device. Use it
in these drivers.

Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v4] switch from DEFINE_UART_PORT_TX_HELPER() (helper generator) to
         uart_port_tx() (akin to wait_event())
    
    [v3] remove stray \n removal (Ilpo)

 drivers/tty/serial/altera_uart.c   | 29 ++++------------------
 drivers/tty/serial/atmel_serial.c  | 28 +++++----------------
 drivers/tty/serial/fsl_lpuart.c    | 30 ++++-------------------
 drivers/tty/serial/lantiq.c        | 36 +++------------------------
 drivers/tty/serial/lpc32xx_hs.c    | 33 +++----------------------
 drivers/tty/serial/mcf.c           | 28 +++++----------------
 drivers/tty/serial/mpc52xx_uart.c  | 39 +++---------------------------
 drivers/tty/serial/mps2-uart.c     | 26 +++-----------------
 drivers/tty/serial/mxs-auart.c     | 32 ++++++------------------
 drivers/tty/serial/owl-uart.c      | 32 +++---------------------
 drivers/tty/serial/sa1100.c        | 34 +++-----------------------
 drivers/tty/serial/vt8500_serial.c | 30 +++--------------------
 12 files changed, 58 insertions(+), 319 deletions(-)

diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 82f2790de28d..316074bb23e9 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -247,31 +247,12 @@ static void altera_uart_rx_chars(struct uart_port *port)
 
 static void altera_uart_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-
-	if (port->x_char) {
-		/* Send special char - probably flow control */
-		altera_uart_writel(port, port->x_char, ALTERA_UART_TXDATA_REG);
-		port->x_char = 0;
-		port->icount.tx++;
-		return;
-	}
-
-	while (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
-	       ALTERA_UART_STATUS_TRDY_MSK) {
-		if (xmit->head == xmit->tail)
-			break;
-		altera_uart_writel(port, xmit->buf[xmit->tail],
-		       ALTERA_UART_TXDATA_REG);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		altera_uart_stop_tx(port);
+	uart_port_tx(port, ch,
+		altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
+		                ALTERA_UART_STATUS_TRDY_MSK,
+		altera_uart_writel(port, ch, ALTERA_UART_TXDATA_REG));
 }
 
 static irqreturn_t altera_uart_interrupt(int irq, void *data)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index ab4a9dfae07d..0e2b59bec6ce 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -816,30 +816,14 @@ static void atmel_rx_chars(struct uart_port *port)
  */
 static void atmel_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	bool pending;
+	u8 ch;
 
-	if (port->x_char &&
-	    (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY)) {
-		atmel_uart_write_char(port, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
-		return;
-
-	while (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY) {
-		atmel_uart_write_char(port, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (!uart_circ_empty(xmit)) {
+	pending = uart_port_tx(port, ch,
+		atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY,
+		atmel_uart_write_char(port, ch));
+	if (pending) {
 		/* we still have characters to transmit, so we should continue
 		 * transmitting them when TX is ready, regardless of
 		 * mode or duplexity
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f21915015d67..e8a8c11b10a8 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -742,32 +742,12 @@ static int lpuart32_poll_get_char(struct uart_port *port)
 
 static inline void lpuart_transmit_buffer(struct lpuart_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
-
-	if (sport->port.x_char) {
-		writeb(sport->port.x_char, sport->port.membase + UARTDR);
-		sport->port.icount.tx++;
-		sport->port.x_char = 0;
-		return;
-	}
-
-	if (lpuart_stopped_or_empty(&sport->port)) {
-		lpuart_stop_tx(&sport->port);
-		return;
-	}
-
-	while (!uart_circ_empty(xmit) &&
-		(readb(sport->port.membase + UARTTCFIFO) < sport->txfifo_size)) {
-		writeb(xmit->buf[xmit->tail], sport->port.membase + UARTDR);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		sport->port.icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&sport->port);
+	struct uart_port *port = &sport->port;
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		lpuart_stop_tx(&sport->port);
+	uart_port_tx(port, ch,
+		readb(port->membase + UARTTCFIFO) < sport->txfifo_size,
+		writeb(ch, port->membase + UARTDR));
 }
 
 static inline void lpuart32_transmit_buffer(struct lpuart_port *sport)
diff --git a/drivers/tty/serial/lantiq.c b/drivers/tty/serial/lantiq.c
index 6da1b7496c6c..06e813a232c5 100644
--- a/drivers/tty/serial/lantiq.c
+++ b/drivers/tty/serial/lantiq.c
@@ -95,7 +95,6 @@
 #define ASCFSTAT_TXFREEMASK	0x3F000000
 #define ASCFSTAT_TXFREEOFF	24
 
-static void lqasc_tx_chars(struct uart_port *port);
 static struct ltq_uart_port *lqasc_port[MAXPORTS];
 static struct uart_driver lqasc_reg;
 
@@ -151,9 +150,12 @@ lqasc_start_tx(struct uart_port *port)
 {
 	unsigned long flags;
 	struct ltq_uart_port *ltq_port = to_ltq_uart_port(port);
+	u8 ch;
 
 	spin_lock_irqsave(&ltq_port->lock, flags);
-	lqasc_tx_chars(port);
+	uart_port_tx(port, ch,
+		lqasc_tx_ready(port),
+		writeb(ch, port->membase + LTQ_ASC_TBUF));
 	spin_unlock_irqrestore(&ltq_port->lock, flags);
 	return;
 }
@@ -226,36 +228,6 @@ lqasc_rx_chars(struct uart_port *port)
 	return 0;
 }
 
-static void
-lqasc_tx_chars(struct uart_port *port)
-{
-	struct circ_buf *xmit = &port->state->xmit;
-	if (uart_tx_stopped(port)) {
-		lqasc_stop_tx(port);
-		return;
-	}
-
-	while (lqasc_tx_ready(port)) {
-		if (port->x_char) {
-			writeb(port->x_char, port->membase + LTQ_ASC_TBUF);
-			port->icount.tx++;
-			port->x_char = 0;
-			continue;
-		}
-
-		if (uart_circ_empty(xmit))
-			break;
-
-		writeb(port->state->xmit.buf[port->state->xmit.tail],
-			port->membase + LTQ_ASC_TBUF);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-}
-
 static irqreturn_t
 lqasc_tx_int(int irq, void *_port)
 {
diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index ed47f4768338..b38fe4728c26 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -276,8 +276,6 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
 	tty_flip_buffer_push(tport);
 }
 
-static void serial_lpc32xx_stop_tx(struct uart_port *port);
-
 static bool serial_lpc32xx_tx_ready(struct uart_port *port)
 {
 	u32 level = readl(LPC32XX_HSUART_LEVEL(port->membase));
@@ -287,34 +285,11 @@ static bool serial_lpc32xx_tx_ready(struct uart_port *port)
 
 static void __serial_lpc32xx_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-
-	if (port->x_char) {
-		writel((u32)port->x_char, LPC32XX_HSUART_FIFO(port->membase));
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
-		goto exit_tx;
-
-	/* Transfer data */
-	while (serial_lpc32xx_tx_ready(port)) {
-		writel((u32) xmit->buf[xmit->tail],
-		       LPC32XX_HSUART_FIFO(port->membase));
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-exit_tx:
-	if (uart_circ_empty(xmit))
-		serial_lpc32xx_stop_tx(port);
+	uart_port_tx(port, ch,
+		serial_lpc32xx_tx_ready(port),
+		writel(ch, LPC32XX_HSUART_FIFO(port->membase)));
 }
 
 static irqreturn_t serial_lpc32xx_interrupt(int irq, void *dev_id)
diff --git a/drivers/tty/serial/mcf.c b/drivers/tty/serial/mcf.c
index b1cd9a76dd93..53b642ea46ba 100644
--- a/drivers/tty/serial/mcf.c
+++ b/drivers/tty/serial/mcf.c
@@ -327,29 +327,13 @@ static void mcf_rx_chars(struct mcf_uart *pp)
 static void mcf_tx_chars(struct mcf_uart *pp)
 {
 	struct uart_port *port = &pp->port;
-	struct circ_buf *xmit = &port->state->xmit;
-
-	if (port->x_char) {
-		/* Send special char - probably flow control */
-		writeb(port->x_char, port->membase + MCFUART_UTB);
-		port->x_char = 0;
-		port->icount.tx++;
-		return;
-	}
-
-	while (readb(port->membase + MCFUART_USR) & MCFUART_USR_TXREADY) {
-		if (uart_circ_empty(xmit))
-			break;
-		writeb(xmit->buf[xmit->tail], port->membase + MCFUART_UTB);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE -1);
-		port->icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	unsigned int pending;
+	u8 ch;
 
-	if (uart_circ_empty(xmit)) {
-		mcf_stop_tx(port);
+	pending = uart_port_tx(port, ch,
+		readb(port->membase + MCFUART_USR) & MCFUART_USR_TXREADY,
+		writeb(ch, port->membase + MCFUART_UTB));
+	if (!pending) {
 		/* Disable TX to negate RTS automatically */
 		if (port->rs485.flags & SER_RS485_ENABLED)
 			writeb(MCFUART_UCR_TXDISABLE,
diff --git a/drivers/tty/serial/mpc52xx_uart.c b/drivers/tty/serial/mpc52xx_uart.c
index 73362d4bc45d..384ca195e3d5 100644
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -1428,42 +1428,11 @@ mpc52xx_uart_int_rx_chars(struct uart_port *port)
 static inline bool
 mpc52xx_uart_int_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-
-	/* Process out of band chars */
-	if (port->x_char) {
-		psc_ops->write_char(port, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return true;
-	}
-
-	/* Nothing to do ? */
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mpc52xx_uart_stop_tx(port);
-		return false;
-	}
-
-	/* Send chars */
-	while (psc_ops->raw_tx_rdy(port)) {
-		psc_ops->write_char(port, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	}
-
-	/* Wake up */
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	/* Maybe we're done after all */
-	if (uart_circ_empty(xmit)) {
-		mpc52xx_uart_stop_tx(port);
-		return false;
-	}
+	u8 ch;
 
-	return true;
+	return uart_port_tx(port, ch,
+		psc_ops->raw_tx_rdy(port),
+		psc_ops->write_char(port, ch));
 }
 
 static irqreturn_t
diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
index 2e3e6cf16817..860d161fa594 100644
--- a/drivers/tty/serial/mps2-uart.c
+++ b/drivers/tty/serial/mps2-uart.c
@@ -129,29 +129,11 @@ static void mps2_uart_stop_tx(struct uart_port *port)
 
 static void mps2_uart_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-
-	while (!(mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)) {
-		if (port->x_char) {
-			mps2_uart_write8(port, port->x_char, UARTn_DATA);
-			port->x_char = 0;
-			port->icount.tx++;
-			continue;
-		}
-
-		if (uart_circ_empty(xmit) || uart_tx_stopped(port))
-			break;
-
-		mps2_uart_write8(port, xmit->buf[xmit->tail], UARTn_DATA);
-		xmit->tail = (xmit->tail + 1) % UART_XMIT_SIZE;
-		port->icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		mps2_uart_stop_tx(port);
+	uart_port_tx(port, ch,
+		mps2_uart_tx_empty(port),
+		mps2_uart_write8(port, ch, UARTn_DATA));
 }
 
 static void mps2_uart_start_tx(struct uart_port *port)
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index d21a4f3ef2fe..ef6e7bb6105c 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -569,6 +569,8 @@ static int mxs_auart_dma_tx(struct mxs_auart_port *s, int size)
 static void mxs_auart_tx_chars(struct mxs_auart_port *s)
 {
 	struct circ_buf *xmit = &s->port.state->xmit;
+	bool pending;
+	u8 ch;
 
 	if (auart_dma_enabled(s)) {
 		u32 i = 0;
@@ -603,31 +605,13 @@ static void mxs_auart_tx_chars(struct mxs_auart_port *s)
 		return;
 	}
 
-
-	while (!(mxs_read(s, REG_STAT) & AUART_STAT_TXFF)) {
-		if (s->port.x_char) {
-			s->port.icount.tx++;
-			mxs_write(s->port.x_char, s, REG_DATA);
-			s->port.x_char = 0;
-			continue;
-		}
-		if (!uart_circ_empty(xmit) && !uart_tx_stopped(&s->port)) {
-			s->port.icount.tx++;
-			mxs_write(xmit->buf[xmit->tail], s, REG_DATA);
-			xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		} else
-			break;
-	}
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&s->port);
-
-	if (uart_circ_empty(&(s->port.state->xmit)))
-		mxs_clr(AUART_INTR_TXIEN, s, REG_INTR);
-	else
+	pending = uart_port_tx(&s->port, ch,
+		!(mxs_read(s, REG_STAT) & AUART_STAT_TXFF),
+		mxs_write(ch, s, REG_DATA));
+	if (pending)
 		mxs_set(AUART_INTR_TXIEN, s, REG_INTR);
-
-	if (uart_tx_stopped(&s->port))
-		mxs_auart_stop_tx(&s->port);
+	else
+		mxs_clr(AUART_INTR_TXIEN, s, REG_INTR);
 }
 
 static void mxs_auart_rx_char(struct mxs_auart_port *s)
diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c
index fde39cc1145d..e99970a9437f 100644
--- a/drivers/tty/serial/owl-uart.c
+++ b/drivers/tty/serial/owl-uart.c
@@ -181,35 +181,11 @@ static void owl_uart_start_tx(struct uart_port *port)
 
 static void owl_uart_send_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int ch;
-
-	if (port->x_char) {
-		while (!(owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU))
-			cpu_relax();
-		owl_uart_write(port, port->x_char, OWL_UART_TXDAT);
-		port->icount.tx++;
-		port->x_char = 0;
-	}
-
-	if (uart_tx_stopped(port))
-		return;
-
-	while (!(owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU)) {
-		if (uart_circ_empty(xmit))
-			break;
+	u8 ch;
 
-		ch = xmit->buf[xmit->tail];
-		owl_uart_write(port, ch, OWL_UART_TXDAT);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (uart_circ_empty(xmit))
-		owl_uart_stop_tx(port);
+	uart_port_tx(port, ch,
+		!(owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU),
+		owl_uart_write(port, ch, OWL_UART_TXDAT));
 }
 
 static void owl_uart_receive_chars(struct uart_port *port)
diff --git a/drivers/tty/serial/sa1100.c b/drivers/tty/serial/sa1100.c
index dd9e3253cab4..55107bbc00ce 100644
--- a/drivers/tty/serial/sa1100.c
+++ b/drivers/tty/serial/sa1100.c
@@ -228,14 +228,7 @@ sa1100_rx_chars(struct sa1100_port *sport)
 
 static void sa1100_tx_chars(struct sa1100_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
-
-	if (sport->port.x_char) {
-		UART_PUT_CHAR(sport, sport->port.x_char);
-		sport->port.icount.tx++;
-		sport->port.x_char = 0;
-		return;
-	}
+	u8 ch;
 
 	/*
 	 * Check the modem control lines before
@@ -243,28 +236,9 @@ static void sa1100_tx_chars(struct sa1100_port *sport)
 	 */
 	sa1100_mctrl_check(sport);
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
-		sa1100_stop_tx(&sport->port);
-		return;
-	}
-
-	/*
-	 * Tried using FIFO (not checking TNF) for fifo fill:
-	 * still had the '4 bytes repeated' problem.
-	 */
-	while (UART_GET_UTSR1(sport) & UTSR1_TNF) {
-		UART_PUT_CHAR(sport, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		sport->port.icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&sport->port);
-
-	if (uart_circ_empty(xmit))
-		sa1100_stop_tx(&sport->port);
+	uart_port_tx(&sport->port, ch,
+			UART_GET_UTSR1(sport) & UTSR1_TNF,
+			UART_PUT_CHAR(sport, ch));
 }
 
 static irqreturn_t sa1100_int(int irq, void *dev_id)
diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index 10fbdb09965f..deedb6513160 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -196,33 +196,11 @@ static unsigned int vt8500_tx_empty(struct uart_port *port)
 
 static void handle_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	u8 ch;
 
-	if (port->x_char) {
-		writeb(port->x_char, port->membase + VT8500_TXFIFO);
-		port->icount.tx++;
-		port->x_char = 0;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		vt8500_stop_tx(port);
-		return;
-	}
-
-	while (vt8500_tx_empty(port)) {
-		if (uart_circ_empty(xmit))
-			break;
-
-		writeb(xmit->buf[xmit->tail], port->membase + VT8500_TXFIFO);
-
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (uart_circ_empty(xmit))
-		vt8500_stop_tx(port);
+	uart_port_tx(port, ch,
+		vt8500_tx_empty(port),
+		writeb(ch, port->membase + VT8500_TXFIFO));
 }
 
 static void vt8500_start_tx(struct uart_port *port)
-- 
2.37.3

Re: [PATCH v4 09/10] tty: serial: use uart_port_tx() helper

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2271 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> uart_port_tx() is a new helper to send characters to the device. Use it
> in these drivers.
> 
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Cc: Richard Genoud <richard.genoud@gmail.com>
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
> Cc: Vladimir Zapolskiy <vz@mleia.com>
> Cc: Liviu Dudau <liviu.dudau@arm.com>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: "Andreas Färber" <afaerber@suse.de>
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> ---

> diff --git a/drivers/tty/serial/mcf.c b/drivers/tty/serial/mcf.c
> index b1cd9a76dd93..53b642ea46ba 100644
> --- a/drivers/tty/serial/mcf.c
> +++ b/drivers/tty/serial/mcf.c
> @@ -327,29 +327,13 @@ static void mcf_rx_chars(struct mcf_uart *pp)
>  static void mcf_tx_chars(struct mcf_uart *pp)
>  {
>  	struct uart_port *port = &pp->port;
> -	struct circ_buf *xmit = &port->state->xmit;
> -
> -	if (port->x_char) {
> -		/* Send special char - probably flow control */
> -		writeb(port->x_char, port->membase + MCFUART_UTB);
> -		port->x_char = 0;
> -		port->icount.tx++;
> -		return;
> -	}
> -
> -	while (readb(port->membase + MCFUART_USR) & MCFUART_USR_TXREADY) {
> -		if (uart_circ_empty(xmit))
> -			break;
> -		writeb(xmit->buf[xmit->tail], port->membase + MCFUART_UTB);
> -		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE -1);
> -		port->icount.tx++;
> -	}
> -
> -	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> -		uart_write_wakeup(port);
> +	unsigned int pending;
> +	u8 ch;
>  
> -	if (uart_circ_empty(xmit)) {
> -		mcf_stop_tx(port);
> +	pending = uart_port_tx(port, ch,
> +		readb(port->membase + MCFUART_USR) & MCFUART_USR_TXREADY,
> +		writeb(ch, port->membase + MCFUART_UTB));
> +	if (!pending) {

Why unsigned int pending here and bool pending in the other cases?

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>


-- 
 i.

Re: [PATCH v4 09/10] tty: serial: use uart_port_tx() helper

[Jiri Slaby]

On 20. 09. 22, 10:54, Ilpo Järvinen wrote:
> On Tue, 20 Sep 2022, Jiri Slaby wrote:
> 
>> uart_port_tx() is a new helper to send characters to the device. Use it
>> in these drivers.
>>
>> Cc: Tobias Klauser <tklauser@distanz.ch>
>> Cc: Richard Genoud <richard.genoud@gmail.com>
>> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
>> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
>> Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
>> Cc: Vladimir Zapolskiy <vz@mleia.com>
>> Cc: Liviu Dudau <liviu.dudau@arm.com>
>> Cc: Sudeep Holla <sudeep.holla@arm.com>
>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>> Cc: Shawn Guo <shawnguo@kernel.org>
>> Cc: Sascha Hauer <s.hauer@pengutronix.de>
>> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
>> Cc: Fabio Estevam <festevam@gmail.com>
>> Cc: NXP Linux Team <linux-imx@nxp.com>
>> Cc: "Andreas Färber" <afaerber@suse.de>
>> Cc: Manivannan Sadhasivam <mani@kernel.org>
>> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
>> ---
> 
>> diff --git a/drivers/tty/serial/mcf.c b/drivers/tty/serial/mcf.c
>> index b1cd9a76dd93..53b642ea46ba 100644
>> --- a/drivers/tty/serial/mcf.c
>> +++ b/drivers/tty/serial/mcf.c
>> @@ -327,29 +327,13 @@ static void mcf_rx_chars(struct mcf_uart *pp)
>>   static void mcf_tx_chars(struct mcf_uart *pp)
>>   {
>>   	struct uart_port *port = &pp->port;
>> -	struct circ_buf *xmit = &port->state->xmit;
>> -
>> -	if (port->x_char) {
>> -		/* Send special char - probably flow control */
>> -		writeb(port->x_char, port->membase + MCFUART_UTB);
>> -		port->x_char = 0;
>> -		port->icount.tx++;
>> -		return;
>> -	}
>> -
>> -	while (readb(port->membase + MCFUART_USR) & MCFUART_USR_TXREADY) {
>> -		if (uart_circ_empty(xmit))
>> -			break;
>> -		writeb(xmit->buf[xmit->tail], port->membase + MCFUART_UTB);
>> -		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE -1);
>> -		port->icount.tx++;
>> -	}
>> -
>> -	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
>> -		uart_write_wakeup(port);
>> +	unsigned int pending;
>> +	u8 ch;
>>   
>> -	if (uart_circ_empty(xmit)) {
>> -		mcf_stop_tx(port);
>> +	pending = uart_port_tx(port, ch,
>> +		readb(port->membase + MCFUART_USR) & MCFUART_USR_TXREADY,
>> +		writeb(ch, port->membase + MCFUART_UTB));
>> +	if (!pending) {
> 
> Why unsigned int pending here and bool pending in the other cases?

Right, I somehow omitted that pending is not used anywhere else. This 
should be bool too, of course.

> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

thanks,
-- 
js
suse labs

[PATCH v4 10/10] tty: serial: use uart_port_tx_limited()

[Jiri Slaby]

uart_port_tx_limited() is a new helper to send characters to the device.
Use it in these drivers.

mux.c also needs to define tx_done(). But I'm not sure if the driver
really wants to wait for all the characters to dismiss from the HW fifo
at this code point. Hence I marked this as FIXME.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: "Pali Rohár" <pali@kernel.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: linux-riscv@lists.infradead.org
---

Notes:
    [v4] switch from DEFINE_UART_PORT_TX_HELPER_LIMITED() (helper generator)
         to uart_port_tx_limited() (akin to wait_event())

 drivers/tty/serial/21285.c           | 32 +++----------------
 drivers/tty/serial/altera_jtaguart.c | 40 ++++++-----------------
 drivers/tty/serial/amba-pl010.c      | 32 +++----------------
 drivers/tty/serial/apbuart.c         | 34 +++-----------------
 drivers/tty/serial/bcm63xx_uart.c    | 47 ++++++---------------------
 drivers/tty/serial/mux.c             | 45 ++++++++------------------
 drivers/tty/serial/mvebu-uart.c      | 38 +++-------------------
 drivers/tty/serial/omap-serial.c     | 32 +++----------------
 drivers/tty/serial/pxa.c             | 33 +++----------------
 drivers/tty/serial/rp2.c             | 31 ++++--------------
 drivers/tty/serial/serial_txx9.c     | 32 +++----------------
 drivers/tty/serial/sifive.c          | 31 +++---------------
 drivers/tty/serial/sprd_serial.c     | 33 +++----------------
 drivers/tty/serial/st-asc.c          | 48 +++-------------------------
 14 files changed, 87 insertions(+), 421 deletions(-)

diff --git a/drivers/tty/serial/21285.c b/drivers/tty/serial/21285.c
index 2f17bf4b221e..84c1e3e365c8 100644
--- a/drivers/tty/serial/21285.c
+++ b/drivers/tty/serial/21285.c
@@ -154,35 +154,13 @@ static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
 static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
-	struct circ_buf *xmit = &port->state->xmit;
-	int count = 256;
-
-	if (port->x_char) {
-		*CSR_UARTDR = port->x_char;
-		port->icount.tx++;
-		port->x_char = 0;
-		goto out;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		serial21285_stop_tx(port);
-		goto out;
-	}
-
-	do {
-		*CSR_UARTDR = xmit->buf[xmit->tail];
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0 && !(*CSR_UARTFLG & 0x20));
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		serial21285_stop_tx(port);
+	uart_port_tx_limited(port, ch, 256,
+		!(*CSR_UARTFLG & 0x20),
+		*CSR_UARTDR = ch,
+		({}));
 
- out:
 	return IRQ_HANDLED;
 }
 
diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
index 23f339757894..f224f5141726 100644
--- a/drivers/tty/serial/altera_jtaguart.c
+++ b/drivers/tty/serial/altera_jtaguart.c
@@ -137,39 +137,17 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
 {
 	struct uart_port *port = &pp->port;
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int pending, count;
-
-	if (port->x_char) {
-		/* Send special char - probably flow control */
-		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
-		port->x_char = 0;
-		port->icount.tx++;
-		return;
-	}
+	unsigned int space;
+	u8 ch;
 
-	pending = uart_circ_chars_pending(xmit);
-	if (pending > 0) {
-		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
-				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
-			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
-		if (count > pending)
-			count = pending;
-		if (count > 0) {
-			pending -= count;
-			while (count--) {
-				writel(xmit->buf[xmit->tail],
-				       port->membase + ALTERA_JTAGUART_DATA_REG);
-				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-				port->icount.tx++;
-			}
-			if (pending < WAKEUP_CHARS)
-				uart_write_wakeup(port);
-		}
-	}
+	space = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
+	space &= ALTERA_JTAGUART_CONTROL_WSPACE_MSK;
+	space >>= ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
 
-	if (pending == 0)
-		altera_jtaguart_stop_tx(port);
+	uart_port_tx_limited(port, ch, space,
+		true,
+		writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG),
+		({}));
 }
 
 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
diff --git a/drivers/tty/serial/amba-pl010.c b/drivers/tty/serial/amba-pl010.c
index af27fb8ec145..a98fae2ca422 100644
--- a/drivers/tty/serial/amba-pl010.c
+++ b/drivers/tty/serial/amba-pl010.c
@@ -164,34 +164,12 @@ static void pl010_rx_chars(struct uart_port *port)
 
 static void pl010_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int count;
+	u8 ch;
 
-	if (port->x_char) {
-		writel(port->x_char, port->membase + UART01x_DR);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		pl010_stop_tx(port);
-		return;
-	}
-
-	count = port->fifosize >> 1;
-	do {
-		writel(xmit->buf[xmit->tail], port->membase + UART01x_DR);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (uart_circ_empty(xmit))
-		pl010_stop_tx(port);
+	uart_port_tx_limited(port, ch, port->fifosize >> 1,
+		true,
+		writel(ch, port->membase + UART01x_DR),
+		({}));
 }
 
 static void pl010_modem_status(struct uart_amba_port *uap)
diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c
index 450f4edfda0f..915ee4b0d594 100644
--- a/drivers/tty/serial/apbuart.c
+++ b/drivers/tty/serial/apbuart.c
@@ -122,36 +122,12 @@ static void apbuart_rx_chars(struct uart_port *port)
 
 static void apbuart_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int count;
-
-	if (port->x_char) {
-		UART_PUT_CHAR(port, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		apbuart_stop_tx(port);
-		return;
-	}
-
-	/* amba: fill FIFO */
-	count = port->fifosize >> 1;
-	do {
-		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		apbuart_stop_tx(port);
+	uart_port_tx_limited(port, ch, port->fifosize >> 1,
+		true,
+		UART_PUT_CHAR(port, ch),
+		({}));
 }
 
 static irqreturn_t apbuart_int(int irq, void *dev_id)
diff --git a/drivers/tty/serial/bcm63xx_uart.c b/drivers/tty/serial/bcm63xx_uart.c
index 5d9737c2d1f2..62bc7244dc67 100644
--- a/drivers/tty/serial/bcm63xx_uart.c
+++ b/drivers/tty/serial/bcm63xx_uart.c
@@ -303,53 +303,24 @@ static void bcm_uart_do_rx(struct uart_port *port)
  */
 static void bcm_uart_do_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit;
-	unsigned int val, max_count;
-
-	if (port->x_char) {
-		bcm_uart_writel(port, port->x_char, UART_FIFO_REG);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_tx_stopped(port)) {
-		bcm_uart_stop_tx(port);
-		return;
-	}
-
-	xmit = &port->state->xmit;
-	if (uart_circ_empty(xmit))
-		goto txq_empty;
+	unsigned int val;
+	bool pending;
+	u8 ch;
 
 	val = bcm_uart_readl(port, UART_MCTL_REG);
 	val = (val & UART_MCTL_TXFIFOFILL_MASK) >> UART_MCTL_TXFIFOFILL_SHIFT;
-	max_count = port->fifosize - val;
-
-	while (max_count--) {
-		unsigned int c;
 
-		c = xmit->buf[xmit->tail];
-		bcm_uart_writel(port, c, UART_FIFO_REG);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (uart_circ_empty(xmit))
-		goto txq_empty;
-	return;
+	pending = uart_port_tx_limited(port, ch, port->fifosize - val,
+		true,
+		bcm_uart_writel(port, ch, UART_FIFO_REG),
+		({}));
+	if (pending)
+		return;
 
-txq_empty:
 	/* nothing to send, disable transmit interrupt */
 	val = bcm_uart_readl(port, UART_IR_REG);
 	val &= ~UART_TX_INT_MASK;
 	bcm_uart_writel(port, val, UART_IR_REG);
-	return;
 }
 
 /*
diff --git a/drivers/tty/serial/mux.c b/drivers/tty/serial/mux.c
index ed0e763f622a..85ce1e9af44a 100644
--- a/drivers/tty/serial/mux.c
+++ b/drivers/tty/serial/mux.c
@@ -171,6 +171,13 @@ static void mux_break_ctl(struct uart_port *port, int break_state)
 {
 }
 
+static void mux_tx_done(struct uart_port *port)
+{
+	/* FIXME js: really needs to wait? */
+	while (UART_GET_FIFO_CNT(port))
+		udelay(1);
+}
+
 /**
  * mux_write - Write chars to the mux fifo.
  * @port: Ptr to the uart_port.
@@ -180,39 +187,13 @@ static void mux_break_ctl(struct uart_port *port, int break_state)
  */
 static void mux_write(struct uart_port *port)
 {
-	int count;
-	struct circ_buf *xmit = &port->state->xmit;
-
-	if(port->x_char) {
-		UART_PUT_CHAR(port, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if(uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mux_stop_tx(port);
-		return;
-	}
-
-	count = (port->fifosize) - UART_GET_FIFO_CNT(port);
-	do {
-		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if(uart_circ_empty(xmit))
-			break;
-
-	} while(--count > 0);
-
-	while(UART_GET_FIFO_CNT(port)) 
-		udelay(1);
-
-	if(uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		mux_stop_tx(port);
+	uart_port_tx_limited(port, ch,
+		port->fifosize - UART_GET_FIFO_CNT(port),
+		true,
+		UART_PUT_CHAR(port, ch),
+		mux_tx_done(port));
 }
 
 /**
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index ba16e1da6bd3..7b566404cb33 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -335,40 +335,12 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status)
 
 static void mvebu_uart_tx_chars(struct uart_port *port, unsigned int status)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int count;
-	unsigned int st;
-
-	if (port->x_char) {
-		writel(port->x_char, port->membase + UART_TSH(port));
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mvebu_uart_stop_tx(port);
-		return;
-	}
-
-	for (count = 0; count < port->fifosize; count++) {
-		writel(xmit->buf[xmit->tail], port->membase + UART_TSH(port));
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-
-		if (uart_circ_empty(xmit))
-			break;
-
-		st = readl(port->membase + UART_STAT);
-		if (st & STAT_TX_FIFO_FUL)
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		mvebu_uart_stop_tx(port);
+	uart_port_tx_limited(port, ch, port->fifosize,
+		!(readl(port->membase + UART_STAT) & STAT_TX_FIFO_FUL),
+		writel(ch, port->membase + UART_TSH(port)),
+		({}));
 }
 
 static irqreturn_t mvebu_uart_isr(int irq, void *dev_id)
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b7b76e49115e..ccea746e1214 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -348,34 +348,12 @@ static void serial_omap_put_char(struct uart_omap_port *up, unsigned char ch)
 
 static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
-	int count;
+	u8 ch;
 
-	if (up->port.x_char) {
-		serial_omap_put_char(up, up->port.x_char);
-		up->port.icount.tx++;
-		up->port.x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial_omap_stop_tx(&up->port);
-		return;
-	}
-	count = up->port.fifosize / 4;
-	do {
-		serial_omap_put_char(up, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
-
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&up->port);
-
-	if (uart_circ_empty(xmit))
-		serial_omap_stop_tx(&up->port);
+	uart_port_tx_limited(&up->port, ch, up->port.fifosize / 4,
+		true,
+		serial_omap_put_char(up, ch),
+		({}));
 }
 
 static inline void serial_omap_enable_ier_thri(struct uart_omap_port *up)
diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index 2d25231fad84..444fa4b654ac 100644
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -174,35 +174,12 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status)
 
 static void transmit_chars(struct uart_pxa_port *up)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
-	int count;
+	u8 ch;
 
-	if (up->port.x_char) {
-		serial_out(up, UART_TX, up->port.x_char);
-		up->port.icount.tx++;
-		up->port.x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial_pxa_stop_tx(&up->port);
-		return;
-	}
-
-	count = up->port.fifosize / 2;
-	do {
-		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&up->port);
-
-
-	if (uart_circ_empty(xmit))
-		serial_pxa_stop_tx(&up->port);
+	uart_port_tx_limited(&up->port, ch, up->port.fifosize / 2,
+		true,
+		serial_out(up, UART_TX, ch),
+		({}));
 }
 
 static void serial_pxa_start_tx(struct uart_port *port)
diff --git a/drivers/tty/serial/rp2.c b/drivers/tty/serial/rp2.c
index b81afb06f1f4..749b873a5d99 100644
--- a/drivers/tty/serial/rp2.c
+++ b/drivers/tty/serial/rp2.c
@@ -427,32 +427,13 @@ static void rp2_rx_chars(struct rp2_uart_port *up)
 
 static void rp2_tx_chars(struct rp2_uart_port *up)
 {
-	u16 max_tx = FIFO_SIZE - readw(up->base + RP2_TX_FIFO_COUNT);
-	struct circ_buf *xmit = &up->port.state->xmit;
+	u8 ch;
 
-	if (uart_tx_stopped(&up->port)) {
-		rp2_uart_stop_tx(&up->port);
-		return;
-	}
-
-	for (; max_tx != 0; max_tx--) {
-		if (up->port.x_char) {
-			writeb(up->port.x_char, up->base + RP2_DATA_BYTE);
-			up->port.x_char = 0;
-			up->port.icount.tx++;
-			continue;
-		}
-		if (uart_circ_empty(xmit)) {
-			rp2_uart_stop_tx(&up->port);
-			break;
-		}
-		writeb(xmit->buf[xmit->tail], up->base + RP2_DATA_BYTE);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&up->port);
+	uart_port_tx_limited(&up->port, ch,
+		FIFO_SIZE - readw(up->base + RP2_TX_FIFO_COUNT),
+		true,
+		writeb(ch, up->base + RP2_DATA_BYTE),
+		({}));
 }
 
 static void rp2_ch_interrupt(struct rp2_uart_port *up)
diff --git a/drivers/tty/serial/serial_txx9.c b/drivers/tty/serial/serial_txx9.c
index e12f1dc18c38..eab387b01e36 100644
--- a/drivers/tty/serial/serial_txx9.c
+++ b/drivers/tty/serial/serial_txx9.c
@@ -321,34 +321,12 @@ receive_chars(struct uart_port *up, unsigned int *status)
 
 static inline void transmit_chars(struct uart_port *up)
 {
-	struct circ_buf *xmit = &up->state->xmit;
-	int count;
+	u8 ch;
 
-	if (up->x_char) {
-		sio_out(up, TXX9_SITFIFO, up->x_char);
-		up->icount.tx++;
-		up->x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(up)) {
-		serial_txx9_stop_tx(up);
-		return;
-	}
-
-	count = TXX9_SIO_TX_FIFO;
-	do {
-		sio_out(up, TXX9_SITFIFO, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(up);
-
-	if (uart_circ_empty(xmit))
-		serial_txx9_stop_tx(up);
+	uart_port_tx_limited(up, ch, TXX9_SIO_TX_FIFO,
+		true,
+		sio_out(up, TXX9_SITFIFO, ch),
+		({}));
 }
 
 static irqreturn_t serial_txx9_interrupt(int irq, void *dev_id)
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 4761f172103a..64cfd455f556 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -288,33 +288,12 @@ static void __ssp_transmit_char(struct sifive_serial_port *ssp, int ch)
  */
 static void __ssp_transmit_chars(struct sifive_serial_port *ssp)
 {
-	struct circ_buf *xmit = &ssp->port.state->xmit;
-	int count;
-
-	if (ssp->port.x_char) {
-		__ssp_transmit_char(ssp, ssp->port.x_char);
-		ssp->port.icount.tx++;
-		ssp->port.x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&ssp->port)) {
-		sifive_serial_stop_tx(&ssp->port);
-		return;
-	}
-	count = SIFIVE_TX_FIFO_DEPTH;
-	do {
-		__ssp_transmit_char(ssp, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		ssp->port.icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&ssp->port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		sifive_serial_stop_tx(&ssp->port);
+	uart_port_tx_limited(&ssp->port, ch, SIFIVE_TX_FIFO_DEPTH,
+		true,
+		__ssp_transmit_char(ssp, ch),
+		({}));
 }
 
 /**
diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 342a87967631..3f34f7bb7700 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -626,35 +626,12 @@ static inline void sprd_rx(struct uart_port *port)
 
 static inline void sprd_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int count;
-
-	if (port->x_char) {
-		serial_out(port, SPRD_TXD, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		sprd_stop_tx(port);
-		return;
-	}
-
-	count = THLD_TX_EMPTY;
-	do {
-		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		sprd_stop_tx(port);
+	uart_port_tx_limited(port, ch, THLD_TX_EMPTY,
+		true,
+		serial_out(port, SPRD_TXD, ch),
+		({}));
 }
 
 /* this handles the interrupt from one port */
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index fcecea689a0d..5215e6910f68 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -237,50 +237,12 @@ static inline unsigned asc_hw_txroom(struct uart_port *port)
  */
 static void asc_transmit_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int txroom;
-	unsigned char c;
-
-	txroom = asc_hw_txroom(port);
-
-	if ((txroom != 0) && port->x_char) {
-		c = port->x_char;
-		port->x_char = 0;
-		asc_out(port, ASC_TXBUF, c);
-		port->icount.tx++;
-		txroom = asc_hw_txroom(port);
-	}
-
-	if (uart_tx_stopped(port)) {
-		/*
-		 * We should try and stop the hardware here, but I
-		 * don't think the ASC has any way to do that.
-		 */
-		asc_disable_tx_interrupts(port);
-		return;
-	}
-
-	if (uart_circ_empty(xmit)) {
-		asc_disable_tx_interrupts(port);
-		return;
-	}
-
-	if (txroom == 0)
-		return;
-
-	do {
-		c = xmit->buf[xmit->tail];
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		asc_out(port, ASC_TXBUF, c);
-		port->icount.tx++;
-		txroom--;
-	} while ((txroom > 0) && (!uart_circ_empty(xmit)));
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		asc_disable_tx_interrupts(port);
+	uart_port_tx_limited(port, ch, asc_hw_txroom(port),
+		true,
+		asc_out(port, ASC_TXBUF, ch),
+		({}));
 }
 
 static void asc_receive_chars(struct uart_port *port)
-- 
2.37.3

[PATCH v4 10/10] tty: serial: use uart_port_tx_limited()

[Jiri Slaby]

uart_port_tx_limited() is a new helper to send characters to the device.
Use it in these drivers.

mux.c also needs to define tx_done(). But I'm not sure if the driver
really wants to wait for all the characters to dismiss from the HW fifo
at this code point. Hence I marked this as FIXME.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: "Pali Rohár" <pali@kernel.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: linux-riscv@lists.infradead.org
---

Notes:
    [v4] switch from DEFINE_UART_PORT_TX_HELPER_LIMITED() (helper generator)
         to uart_port_tx_limited() (akin to wait_event())

 drivers/tty/serial/21285.c           | 32 +++----------------
 drivers/tty/serial/altera_jtaguart.c | 40 ++++++-----------------
 drivers/tty/serial/amba-pl010.c      | 32 +++----------------
 drivers/tty/serial/apbuart.c         | 34 +++-----------------
 drivers/tty/serial/bcm63xx_uart.c    | 47 ++++++---------------------
 drivers/tty/serial/mux.c             | 45 ++++++++------------------
 drivers/tty/serial/mvebu-uart.c      | 38 +++-------------------
 drivers/tty/serial/omap-serial.c     | 32 +++----------------
 drivers/tty/serial/pxa.c             | 33 +++----------------
 drivers/tty/serial/rp2.c             | 31 ++++--------------
 drivers/tty/serial/serial_txx9.c     | 32 +++----------------
 drivers/tty/serial/sifive.c          | 31 +++---------------
 drivers/tty/serial/sprd_serial.c     | 33 +++----------------
 drivers/tty/serial/st-asc.c          | 48 +++-------------------------
 14 files changed, 87 insertions(+), 421 deletions(-)

diff --git a/drivers/tty/serial/21285.c b/drivers/tty/serial/21285.c
index 2f17bf4b221e..84c1e3e365c8 100644
--- a/drivers/tty/serial/21285.c
+++ b/drivers/tty/serial/21285.c
@@ -154,35 +154,13 @@ static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
 static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
-	struct circ_buf *xmit = &port->state->xmit;
-	int count = 256;
-
-	if (port->x_char) {
-		*CSR_UARTDR = port->x_char;
-		port->icount.tx++;
-		port->x_char = 0;
-		goto out;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		serial21285_stop_tx(port);
-		goto out;
-	}
-
-	do {
-		*CSR_UARTDR = xmit->buf[xmit->tail];
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0 && !(*CSR_UARTFLG & 0x20));
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		serial21285_stop_tx(port);
+	uart_port_tx_limited(port, ch, 256,
+		!(*CSR_UARTFLG & 0x20),
+		*CSR_UARTDR = ch,
+		({}));
 
- out:
 	return IRQ_HANDLED;
 }
 
diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
index 23f339757894..f224f5141726 100644
--- a/drivers/tty/serial/altera_jtaguart.c
+++ b/drivers/tty/serial/altera_jtaguart.c
@@ -137,39 +137,17 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
 {
 	struct uart_port *port = &pp->port;
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int pending, count;
-
-	if (port->x_char) {
-		/* Send special char - probably flow control */
-		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
-		port->x_char = 0;
-		port->icount.tx++;
-		return;
-	}
+	unsigned int space;
+	u8 ch;
 
-	pending = uart_circ_chars_pending(xmit);
-	if (pending > 0) {
-		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
-				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
-			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
-		if (count > pending)
-			count = pending;
-		if (count > 0) {
-			pending -= count;
-			while (count--) {
-				writel(xmit->buf[xmit->tail],
-				       port->membase + ALTERA_JTAGUART_DATA_REG);
-				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-				port->icount.tx++;
-			}
-			if (pending < WAKEUP_CHARS)
-				uart_write_wakeup(port);
-		}
-	}
+	space = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
+	space &= ALTERA_JTAGUART_CONTROL_WSPACE_MSK;
+	space >>= ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
 
-	if (pending == 0)
-		altera_jtaguart_stop_tx(port);
+	uart_port_tx_limited(port, ch, space,
+		true,
+		writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG),
+		({}));
 }
 
 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
diff --git a/drivers/tty/serial/amba-pl010.c b/drivers/tty/serial/amba-pl010.c
index af27fb8ec145..a98fae2ca422 100644
--- a/drivers/tty/serial/amba-pl010.c
+++ b/drivers/tty/serial/amba-pl010.c
@@ -164,34 +164,12 @@ static void pl010_rx_chars(struct uart_port *port)
 
 static void pl010_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int count;
+	u8 ch;
 
-	if (port->x_char) {
-		writel(port->x_char, port->membase + UART01x_DR);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		pl010_stop_tx(port);
-		return;
-	}
-
-	count = port->fifosize >> 1;
-	do {
-		writel(xmit->buf[xmit->tail], port->membase + UART01x_DR);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (uart_circ_empty(xmit))
-		pl010_stop_tx(port);
+	uart_port_tx_limited(port, ch, port->fifosize >> 1,
+		true,
+		writel(ch, port->membase + UART01x_DR),
+		({}));
 }
 
 static void pl010_modem_status(struct uart_amba_port *uap)
diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c
index 450f4edfda0f..915ee4b0d594 100644
--- a/drivers/tty/serial/apbuart.c
+++ b/drivers/tty/serial/apbuart.c
@@ -122,36 +122,12 @@ static void apbuart_rx_chars(struct uart_port *port)
 
 static void apbuart_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int count;
-
-	if (port->x_char) {
-		UART_PUT_CHAR(port, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		apbuart_stop_tx(port);
-		return;
-	}
-
-	/* amba: fill FIFO */
-	count = port->fifosize >> 1;
-	do {
-		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		apbuart_stop_tx(port);
+	uart_port_tx_limited(port, ch, port->fifosize >> 1,
+		true,
+		UART_PUT_CHAR(port, ch),
+		({}));
 }
 
 static irqreturn_t apbuart_int(int irq, void *dev_id)
diff --git a/drivers/tty/serial/bcm63xx_uart.c b/drivers/tty/serial/bcm63xx_uart.c
index 5d9737c2d1f2..62bc7244dc67 100644
--- a/drivers/tty/serial/bcm63xx_uart.c
+++ b/drivers/tty/serial/bcm63xx_uart.c
@@ -303,53 +303,24 @@ static void bcm_uart_do_rx(struct uart_port *port)
  */
 static void bcm_uart_do_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit;
-	unsigned int val, max_count;
-
-	if (port->x_char) {
-		bcm_uart_writel(port, port->x_char, UART_FIFO_REG);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_tx_stopped(port)) {
-		bcm_uart_stop_tx(port);
-		return;
-	}
-
-	xmit = &port->state->xmit;
-	if (uart_circ_empty(xmit))
-		goto txq_empty;
+	unsigned int val;
+	bool pending;
+	u8 ch;
 
 	val = bcm_uart_readl(port, UART_MCTL_REG);
 	val = (val & UART_MCTL_TXFIFOFILL_MASK) >> UART_MCTL_TXFIFOFILL_SHIFT;
-	max_count = port->fifosize - val;
-
-	while (max_count--) {
-		unsigned int c;
 
-		c = xmit->buf[xmit->tail];
-		bcm_uart_writel(port, c, UART_FIFO_REG);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
-
-	if (uart_circ_empty(xmit))
-		goto txq_empty;
-	return;
+	pending = uart_port_tx_limited(port, ch, port->fifosize - val,
+		true,
+		bcm_uart_writel(port, ch, UART_FIFO_REG),
+		({}));
+	if (pending)
+		return;
 
-txq_empty:
 	/* nothing to send, disable transmit interrupt */
 	val = bcm_uart_readl(port, UART_IR_REG);
 	val &= ~UART_TX_INT_MASK;
 	bcm_uart_writel(port, val, UART_IR_REG);
-	return;
 }
 
 /*
diff --git a/drivers/tty/serial/mux.c b/drivers/tty/serial/mux.c
index ed0e763f622a..85ce1e9af44a 100644
--- a/drivers/tty/serial/mux.c
+++ b/drivers/tty/serial/mux.c
@@ -171,6 +171,13 @@ static void mux_break_ctl(struct uart_port *port, int break_state)
 {
 }
 
+static void mux_tx_done(struct uart_port *port)
+{
+	/* FIXME js: really needs to wait? */
+	while (UART_GET_FIFO_CNT(port))
+		udelay(1);
+}
+
 /**
  * mux_write - Write chars to the mux fifo.
  * @port: Ptr to the uart_port.
@@ -180,39 +187,13 @@ static void mux_break_ctl(struct uart_port *port, int break_state)
  */
 static void mux_write(struct uart_port *port)
 {
-	int count;
-	struct circ_buf *xmit = &port->state->xmit;
-
-	if(port->x_char) {
-		UART_PUT_CHAR(port, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if(uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mux_stop_tx(port);
-		return;
-	}
-
-	count = (port->fifosize) - UART_GET_FIFO_CNT(port);
-	do {
-		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if(uart_circ_empty(xmit))
-			break;
-
-	} while(--count > 0);
-
-	while(UART_GET_FIFO_CNT(port)) 
-		udelay(1);
-
-	if(uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		mux_stop_tx(port);
+	uart_port_tx_limited(port, ch,
+		port->fifosize - UART_GET_FIFO_CNT(port),
+		true,
+		UART_PUT_CHAR(port, ch),
+		mux_tx_done(port));
 }
 
 /**
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index ba16e1da6bd3..7b566404cb33 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -335,40 +335,12 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status)
 
 static void mvebu_uart_tx_chars(struct uart_port *port, unsigned int status)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int count;
-	unsigned int st;
-
-	if (port->x_char) {
-		writel(port->x_char, port->membase + UART_TSH(port));
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mvebu_uart_stop_tx(port);
-		return;
-	}
-
-	for (count = 0; count < port->fifosize; count++) {
-		writel(xmit->buf[xmit->tail], port->membase + UART_TSH(port));
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-
-		if (uart_circ_empty(xmit))
-			break;
-
-		st = readl(port->membase + UART_STAT);
-		if (st & STAT_TX_FIFO_FUL)
-			break;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		mvebu_uart_stop_tx(port);
+	uart_port_tx_limited(port, ch, port->fifosize,
+		!(readl(port->membase + UART_STAT) & STAT_TX_FIFO_FUL),
+		writel(ch, port->membase + UART_TSH(port)),
+		({}));
 }
 
 static irqreturn_t mvebu_uart_isr(int irq, void *dev_id)
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b7b76e49115e..ccea746e1214 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -348,34 +348,12 @@ static void serial_omap_put_char(struct uart_omap_port *up, unsigned char ch)
 
 static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
-	int count;
+	u8 ch;
 
-	if (up->port.x_char) {
-		serial_omap_put_char(up, up->port.x_char);
-		up->port.icount.tx++;
-		up->port.x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial_omap_stop_tx(&up->port);
-		return;
-	}
-	count = up->port.fifosize / 4;
-	do {
-		serial_omap_put_char(up, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
-
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&up->port);
-
-	if (uart_circ_empty(xmit))
-		serial_omap_stop_tx(&up->port);
+	uart_port_tx_limited(&up->port, ch, up->port.fifosize / 4,
+		true,
+		serial_omap_put_char(up, ch),
+		({}));
 }
 
 static inline void serial_omap_enable_ier_thri(struct uart_omap_port *up)
diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index 2d25231fad84..444fa4b654ac 100644
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -174,35 +174,12 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status)
 
 static void transmit_chars(struct uart_pxa_port *up)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
-	int count;
+	u8 ch;
 
-	if (up->port.x_char) {
-		serial_out(up, UART_TX, up->port.x_char);
-		up->port.icount.tx++;
-		up->port.x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial_pxa_stop_tx(&up->port);
-		return;
-	}
-
-	count = up->port.fifosize / 2;
-	do {
-		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&up->port);
-
-
-	if (uart_circ_empty(xmit))
-		serial_pxa_stop_tx(&up->port);
+	uart_port_tx_limited(&up->port, ch, up->port.fifosize / 2,
+		true,
+		serial_out(up, UART_TX, ch),
+		({}));
 }
 
 static void serial_pxa_start_tx(struct uart_port *port)
diff --git a/drivers/tty/serial/rp2.c b/drivers/tty/serial/rp2.c
index b81afb06f1f4..749b873a5d99 100644
--- a/drivers/tty/serial/rp2.c
+++ b/drivers/tty/serial/rp2.c
@@ -427,32 +427,13 @@ static void rp2_rx_chars(struct rp2_uart_port *up)
 
 static void rp2_tx_chars(struct rp2_uart_port *up)
 {
-	u16 max_tx = FIFO_SIZE - readw(up->base + RP2_TX_FIFO_COUNT);
-	struct circ_buf *xmit = &up->port.state->xmit;
+	u8 ch;
 
-	if (uart_tx_stopped(&up->port)) {
-		rp2_uart_stop_tx(&up->port);
-		return;
-	}
-
-	for (; max_tx != 0; max_tx--) {
-		if (up->port.x_char) {
-			writeb(up->port.x_char, up->base + RP2_DATA_BYTE);
-			up->port.x_char = 0;
-			up->port.icount.tx++;
-			continue;
-		}
-		if (uart_circ_empty(xmit)) {
-			rp2_uart_stop_tx(&up->port);
-			break;
-		}
-		writeb(xmit->buf[xmit->tail], up->base + RP2_DATA_BYTE);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&up->port);
+	uart_port_tx_limited(&up->port, ch,
+		FIFO_SIZE - readw(up->base + RP2_TX_FIFO_COUNT),
+		true,
+		writeb(ch, up->base + RP2_DATA_BYTE),
+		({}));
 }
 
 static void rp2_ch_interrupt(struct rp2_uart_port *up)
diff --git a/drivers/tty/serial/serial_txx9.c b/drivers/tty/serial/serial_txx9.c
index e12f1dc18c38..eab387b01e36 100644
--- a/drivers/tty/serial/serial_txx9.c
+++ b/drivers/tty/serial/serial_txx9.c
@@ -321,34 +321,12 @@ receive_chars(struct uart_port *up, unsigned int *status)
 
 static inline void transmit_chars(struct uart_port *up)
 {
-	struct circ_buf *xmit = &up->state->xmit;
-	int count;
+	u8 ch;
 
-	if (up->x_char) {
-		sio_out(up, TXX9_SITFIFO, up->x_char);
-		up->icount.tx++;
-		up->x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(up)) {
-		serial_txx9_stop_tx(up);
-		return;
-	}
-
-	count = TXX9_SIO_TX_FIFO;
-	do {
-		sio_out(up, TXX9_SITFIFO, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(up);
-
-	if (uart_circ_empty(xmit))
-		serial_txx9_stop_tx(up);
+	uart_port_tx_limited(up, ch, TXX9_SIO_TX_FIFO,
+		true,
+		sio_out(up, TXX9_SITFIFO, ch),
+		({}));
 }
 
 static irqreturn_t serial_txx9_interrupt(int irq, void *dev_id)
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 4761f172103a..64cfd455f556 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -288,33 +288,12 @@ static void __ssp_transmit_char(struct sifive_serial_port *ssp, int ch)
  */
 static void __ssp_transmit_chars(struct sifive_serial_port *ssp)
 {
-	struct circ_buf *xmit = &ssp->port.state->xmit;
-	int count;
-
-	if (ssp->port.x_char) {
-		__ssp_transmit_char(ssp, ssp->port.x_char);
-		ssp->port.icount.tx++;
-		ssp->port.x_char = 0;
-		return;
-	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&ssp->port)) {
-		sifive_serial_stop_tx(&ssp->port);
-		return;
-	}
-	count = SIFIVE_TX_FIFO_DEPTH;
-	do {
-		__ssp_transmit_char(ssp, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		ssp->port.icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&ssp->port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		sifive_serial_stop_tx(&ssp->port);
+	uart_port_tx_limited(&ssp->port, ch, SIFIVE_TX_FIFO_DEPTH,
+		true,
+		__ssp_transmit_char(ssp, ch),
+		({}));
 }
 
 /**
diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 342a87967631..3f34f7bb7700 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -626,35 +626,12 @@ static inline void sprd_rx(struct uart_port *port)
 
 static inline void sprd_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int count;
-
-	if (port->x_char) {
-		serial_out(port, SPRD_TXD, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		sprd_stop_tx(port);
-		return;
-	}
-
-	count = THLD_TX_EMPTY;
-	do {
-		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		port->icount.tx++;
-		if (uart_circ_empty(xmit))
-			break;
-	} while (--count > 0);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		sprd_stop_tx(port);
+	uart_port_tx_limited(port, ch, THLD_TX_EMPTY,
+		true,
+		serial_out(port, SPRD_TXD, ch),
+		({}));
 }
 
 /* this handles the interrupt from one port */
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index fcecea689a0d..5215e6910f68 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -237,50 +237,12 @@ static inline unsigned asc_hw_txroom(struct uart_port *port)
  */
 static void asc_transmit_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	int txroom;
-	unsigned char c;
-
-	txroom = asc_hw_txroom(port);
-
-	if ((txroom != 0) && port->x_char) {
-		c = port->x_char;
-		port->x_char = 0;
-		asc_out(port, ASC_TXBUF, c);
-		port->icount.tx++;
-		txroom = asc_hw_txroom(port);
-	}
-
-	if (uart_tx_stopped(port)) {
-		/*
-		 * We should try and stop the hardware here, but I
-		 * don't think the ASC has any way to do that.
-		 */
-		asc_disable_tx_interrupts(port);
-		return;
-	}
-
-	if (uart_circ_empty(xmit)) {
-		asc_disable_tx_interrupts(port);
-		return;
-	}
-
-	if (txroom == 0)
-		return;
-
-	do {
-		c = xmit->buf[xmit->tail];
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		asc_out(port, ASC_TXBUF, c);
-		port->icount.tx++;
-		txroom--;
-	} while ((txroom > 0) && (!uart_circ_empty(xmit)));
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
+	u8 ch;
 
-	if (uart_circ_empty(xmit))
-		asc_disable_tx_interrupts(port);
+	uart_port_tx_limited(port, ch, asc_hw_txroom(port),
+		true,
+		asc_out(port, ASC_TXBUF, ch),
+		({}));
 }
 
 static void asc_receive_chars(struct uart_port *port)
-- 
2.37.3


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Re: [PATCH v4 10/10] tty: serial: use uart_port_tx_limited()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2712 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> uart_port_tx_limited() is a new helper to send characters to the device.
> Use it in these drivers.
> 
> mux.c also needs to define tx_done(). But I'm not sure if the driver
> really wants to wait for all the characters to dismiss from the HW fifo
> at this code point. Hence I marked this as FIXME.
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Florian Fainelli <f.fainelli@gmail.com>
> Cc: bcm-kernel-feedback-list@broadcom.com
> Cc: "Pali Rohár" <pali@kernel.org>
> Cc: Kevin Cernekee <cernekee@gmail.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Baolin Wang <baolin.wang7@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Cc: Patrice Chotard <patrice.chotard@foss.st.com>
> Cc: linux-riscv@lists.infradead.org

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

One improvement suggestion below.

> diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
> index 23f339757894..f224f5141726 100644
> --- a/drivers/tty/serial/altera_jtaguart.c
> +++ b/drivers/tty/serial/altera_jtaguart.c
> @@ -137,39 +137,17 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
>  static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
>  {
>  	struct uart_port *port = &pp->port;
> -	struct circ_buf *xmit = &port->state->xmit;
> -	unsigned int pending, count;
> -
> -	if (port->x_char) {
> -		/* Send special char - probably flow control */
> -		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
> -		port->x_char = 0;
> -		port->icount.tx++;
> -		return;
> -	}
> +	unsigned int space;
> +	u8 ch;
>  
> -	pending = uart_circ_chars_pending(xmit);
> -	if (pending > 0) {
> -		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
> -				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
> -			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
> -		if (count > pending)
> -			count = pending;
> -		if (count > 0) {
> -			pending -= count;
> -			while (count--) {
> -				writel(xmit->buf[xmit->tail],
> -				       port->membase + ALTERA_JTAGUART_DATA_REG);
> -				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> -				port->icount.tx++;
> -			}
> -			if (pending < WAKEUP_CHARS)
> -				uart_write_wakeup(port);
> -		}
> -	}
> +	space = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
> +	space &= ALTERA_JTAGUART_CONTROL_WSPACE_MSK;
> +	space >>= ALTERA_JTAGUART_CONTROL_WSPACE_OFF;

This is FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ...) & then allows 
killing ALTERA_JTAGUART_CONTROL_WSPACE_OFF. I'd probably do it in a 
separate patch though.


-- 
 i.

Re: [PATCH v4 10/10] tty: serial: use uart_port_tx_limited()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2712 bytes --]

On Tue, 20 Sep 2022, Jiri Slaby wrote:

> uart_port_tx_limited() is a new helper to send characters to the device.
> Use it in these drivers.
> 
> mux.c also needs to define tx_done(). But I'm not sure if the driver
> really wants to wait for all the characters to dismiss from the HW fifo
> at this code point. Hence I marked this as FIXME.
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Florian Fainelli <f.fainelli@gmail.com>
> Cc: bcm-kernel-feedback-list@broadcom.com
> Cc: "Pali Rohár" <pali@kernel.org>
> Cc: Kevin Cernekee <cernekee@gmail.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Baolin Wang <baolin.wang7@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Cc: Patrice Chotard <patrice.chotard@foss.st.com>
> Cc: linux-riscv@lists.infradead.org

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

One improvement suggestion below.

> diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
> index 23f339757894..f224f5141726 100644
> --- a/drivers/tty/serial/altera_jtaguart.c
> +++ b/drivers/tty/serial/altera_jtaguart.c
> @@ -137,39 +137,17 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
>  static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
>  {
>  	struct uart_port *port = &pp->port;
> -	struct circ_buf *xmit = &port->state->xmit;
> -	unsigned int pending, count;
> -
> -	if (port->x_char) {
> -		/* Send special char - probably flow control */
> -		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
> -		port->x_char = 0;
> -		port->icount.tx++;
> -		return;
> -	}
> +	unsigned int space;
> +	u8 ch;
>  
> -	pending = uart_circ_chars_pending(xmit);
> -	if (pending > 0) {
> -		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
> -				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
> -			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
> -		if (count > pending)
> -			count = pending;
> -		if (count > 0) {
> -			pending -= count;
> -			while (count--) {
> -				writel(xmit->buf[xmit->tail],
> -				       port->membase + ALTERA_JTAGUART_DATA_REG);
> -				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> -				port->icount.tx++;
> -			}
> -			if (pending < WAKEUP_CHARS)
> -				uart_write_wakeup(port);
> -		}
> -	}
> +	space = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
> +	space &= ALTERA_JTAGUART_CONTROL_WSPACE_MSK;
> +	space >>= ALTERA_JTAGUART_CONTROL_WSPACE_OFF;

This is FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ...) & then allows 
killing ALTERA_JTAGUART_CONTROL_WSPACE_OFF. I'd probably do it in a 
separate patch though.


-- 
 i.

[-- Attachment #2: Type: text/plain, Size: 161 bytes --]

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Re: [PATCH v4 10/10] tty: serial: use uart_port_tx_limited()

[Jiri Slaby]

On 20. 09. 22, 11:19, Ilpo Järvinen wrote:
> One improvement suggestion below.
> 
>> diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
>> index 23f339757894..f224f5141726 100644
>> --- a/drivers/tty/serial/altera_jtaguart.c
>> +++ b/drivers/tty/serial/altera_jtaguart.c
>> @@ -137,39 +137,17 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
>>   static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
...
>> +	space = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
>> +	space &= ALTERA_JTAGUART_CONTROL_WSPACE_MSK;
>> +	space >>= ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
> 
> This is FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ...) & then allows
> killing ALTERA_JTAGUART_CONTROL_WSPACE_OFF. I'd probably do it in a
> separate patch though.

Right. Prepared for v5.

thanks,
-- 
js
suse labs

Re: [PATCH v4 10/10] tty: serial: use uart_port_tx_limited()

[Jiri Slaby]

On 20. 09. 22, 11:19, Ilpo Järvinen wrote:
> One improvement suggestion below.
> 
>> diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
>> index 23f339757894..f224f5141726 100644
>> --- a/drivers/tty/serial/altera_jtaguart.c
>> +++ b/drivers/tty/serial/altera_jtaguart.c
>> @@ -137,39 +137,17 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
>>   static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
...
>> +	space = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG);
>> +	space &= ALTERA_JTAGUART_CONTROL_WSPACE_MSK;
>> +	space >>= ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
> 
> This is FIELD_GET(ALTERA_JTAGUART_CONTROL_WSPACE_MSK, ...) & then allows
> killing ALTERA_JTAGUART_CONTROL_WSPACE_OFF. I'd probably do it in a
> separate patch though.

Right. Prepared for v5.

thanks,
-- 
js
suse labs


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Re: [PATCH v4 00/10] tty: TX helpers

[Greg KH]

On Tue, Sep 20, 2022 at 07:20:40AM +0200, Jiri Slaby wrote:
> This series introduces uart_port_tx() + uart_port_tx_limited() TX
> helpers. See PATCH 8/10 for the details. Comments welcome.
> 
> First the series performs simple cleanups, so that the later patches are
> easier to follow.
> 
> Then it switches drivers to use them. First, to uart_port_tx() in 9/10
> and then uart_port_tx_limited() in 10/10.
> 
> The diffstat of patches 9+10 is as follows:
>  26 files changed, 145 insertions(+), 740 deletions(-)
> which appears to be nice.

I've queued up the first 7 patches here, as they were the preparation /
cleanup patches and deserved to go in no matter what.

thanks,

greg k-h