[PATCH v2 3/3] tty: serial: use DEFINE_UART_PORT_TX_HELPER_LIMITED()

From: Jiri Slaby
Date: Thu Sep 01 2022 - 07:07:34 EST

DEFINE_UART_PORT_TX_HELPER_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@xxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Florian Fainelli <f.fainelli@xxxxxxxxx>
Cc: bcm-kernel-feedback-list@xxxxxxxxxxxx
Cc: "Pali Rohár" <pali@xxxxxxxxxx>
Cc: Kevin Cernekee <cernekee@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Orson Zhai <orsonzhai@xxxxxxxxx>
Cc: Baolin Wang <baolin.wang7@xxxxxxxxx>
Cc: Chunyan Zhang <zhang.lyra@xxxxxxxxx>
Cc: Patrice Chotard <patrice.chotard@xxxxxxxxxxx>
Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
---
drivers/tty/serial/21285.c | 33 ++++--------------
drivers/tty/serial/altera_jtaguart.c | 42 ++++++-----------------
drivers/tty/serial/amba-pl010.c | 37 +++-----------------
drivers/tty/serial/apbuart.c | 36 ++++----------------
drivers/tty/serial/bcm63xx_uart.c | 47 +++++---------------------
drivers/tty/serial/mux.c | 46 ++++++++-----------------
drivers/tty/serial/mvebu-uart.c | 40 ++++------------------
drivers/tty/serial/omap-serial.c | 47 +++++++-------------------
drivers/tty/serial/pxa.c | 39 +++++-----------------
drivers/tty/serial/rp2.c | 36 ++++----------------
drivers/tty/serial/serial_txx9.c | 37 +++-----------------
drivers/tty/serial/sifive.c | 45 +++----------------------
drivers/tty/serial/sprd_serial.c | 38 +++------------------
drivers/tty/serial/st-asc.c | 50 ++++------------------------
14 files changed, 103 insertions(+), 470 deletions(-)

diff --git a/drivers/tty/serial/21285.c b/drivers/tty/serial/21285.c
index 7520cc02fd4d..a23401aa0847 100644
--- a/drivers/tty/serial/21285.c
+++ b/drivers/tty/serial/21285.c
@@ -151,38 +151,17 @@ static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
return IRQ_HANDLED;
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(serial21285_do_tx_chars, port, ch,
+ !(*CSR_UARTFLG & 0x20),
+ *CSR_UARTDR = ch,
+ ({}));
+
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);

- if (uart_circ_empty(xmit))
- serial21285_stop_tx(port);
+ serial21285_do_tx_chars(port, 256);

- out:
return IRQ_HANDLED;
}

diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
index cb791c5149a3..928ed419e969 100644
--- a/drivers/tty/serial/altera_jtaguart.c
+++ b/drivers/tty/serial/altera_jtaguart.c
@@ -134,42 +134,20 @@ static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
tty_flip_buffer_push(&port->state->port);
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(altera_jtaguart_do_tx_chars, port, ch,
+ true,
+ writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG),
+ ({}));
+
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;
- }
-
- 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);
- }
- }
+ unsigned int space;

- if (pending == 0)
- altera_jtaguart_stop_tx(port);
+ space = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
+ ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
+ ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
+ altera_jtaguart_do_tx_chars(port, space);
}

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 fae0b581ff42..cc95e5546b79 100644
--- a/drivers/tty/serial/amba-pl010.c
+++ b/drivers/tty/serial/amba-pl010.c
@@ -162,37 +162,10 @@ static void pl010_rx_chars(struct uart_port *port)
tty_flip_buffer_push(&port->state->port);
}

-static void pl010_tx_chars(struct uart_port *port)
-{
- struct circ_buf *xmit = &port->state->xmit;
- int count;
-
- 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);
-}
+static DEFINE_UART_PORT_TX_HELPER_LIMITED(pl010_tx_chars, port, ch,
+ true,
+ writel(ch, port->membase + UART01x_DR),
+ ({}));

static void pl010_modem_status(struct uart_amba_port *uap)
{
@@ -238,7 +211,7 @@ static irqreturn_t pl010_int(int irq, void *dev_id)
if (status & UART010_IIR_MIS)
pl010_modem_status(uap);
if (status & UART010_IIR_TIS)
- pl010_tx_chars(port);
+ pl010_tx_chars(port, port->fifosize >> 1);

if (pass_counter-- == 0)
break;
diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c
index 9ef82d870ff2..06c880ed7036 100644
--- a/drivers/tty/serial/apbuart.c
+++ b/drivers/tty/serial/apbuart.c
@@ -120,38 +120,14 @@ static void apbuart_rx_chars(struct uart_port *port)
tty_flip_buffer_push(&port->state->port);
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(apbuart_do_tx_chars, port, ch,
+ true,
+ UART_PUT_CHAR(port, ch),
+ ({}));
+
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);
-
- if (uart_circ_empty(xmit))
- apbuart_stop_tx(port);
+ apbuart_do_tx_chars(port, port->fifosize >> 1);
}

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 53b43174aa40..1b9f0cec3aa1 100644
--- a/drivers/tty/serial/bcm63xx_uart.c
+++ b/drivers/tty/serial/bcm63xx_uart.c
@@ -297,59 +297,30 @@ static void bcm_uart_do_rx(struct uart_port *port)
tty_flip_buffer_push(tty_port);
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(bcm_uart_tx, port, ch,
+ true,
+ bcm_uart_writel(port, ch, UART_FIFO_REG),
+ ({}));
+
/*
* fill tx fifo with chars to send, stop when fifo is about to be full
* or when all chars have been sent.
*/
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, pending;

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 = bcm_uart_tx(port, port->fifosize - val);
+ 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 0ba0f4d9459d..f65f694fdecd 100644
--- a/drivers/tty/serial/mux.c
+++ b/drivers/tty/serial/mux.c
@@ -171,6 +171,18 @@ 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);
+}
+
+static DEFINE_UART_PORT_TX_HELPER_LIMITED(mux_transmit, port, ch,
+ true,
+ UART_PUT_CHAR(port, ch),
+ mux_tx_done(port));
+
/**
* mux_write - Write chars to the mux fifo.
* @port: Ptr to the uart_port.
@@ -180,39 +192,7 @@ 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);
-
- if (uart_circ_empty(xmit))
- mux_stop_tx(port);
+ mux_transmit(port, port->fifosize - UART_GET_FIFO_CNT(port));
}

/**
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index 65eaecd10b7c..1dc0d9bcf797 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -333,42 +333,14 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status)
tty_flip_buffer_push(tport);
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(mvebu_uart_do_tx_chars, port, ch,
+ !(readl(port->membase + UART_STAT) & STAT_TX_FIFO_FUL),
+ writel(ch, port->membase + UART_TSH(port)),
+ ({}));
+
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);
-
- if (uart_circ_empty(xmit))
- mvebu_uart_stop_tx(port);
+ mvebu_uart_do_tx_chars(port, port->fifosize);
}

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 0aa666e247d5..a0ccde3b33e3 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -337,45 +337,22 @@ static void serial_omap_stop_rx(struct uart_port *port)
serial_out(up, UART_IER, up->ier);
}

-static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
+static void serial_omap_put_char(struct uart_port *port, unsigned char ch)
{
- struct circ_buf *xmit = &up->port.state->xmit;
- int count;
-
- if (up->port.x_char) {
- serial_out(up, UART_TX, 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)) {
- serial_omap_stop_tx(&up->port);
- return;
- }
- count = up->port.fifosize / 4;
- do {
- serial_out(up, UART_TX, 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;
- } while (--count > 0);
+ struct uart_omap_port *up = to_uart_omap_port(port);

- if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
- uart_write_wakeup(&up->port);
+ serial_out(up, UART_TX, ch);

- if (uart_circ_empty(xmit))
- serial_omap_stop_tx(&up->port);
+ if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
+ !(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
+ up->rs485_tx_filter_count++;
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(transmit_chars, port, ch,
+ true,
+ serial_omap_put_char(port, ch),
+ ({}));
+
static inline void serial_omap_enable_ier_thri(struct uart_omap_port *up)
{
if (!(up->ier & UART_IER_THRI)) {
@@ -573,7 +550,7 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id)
check_modem_status(up);
break;
case UART_IIR_THRI:
- transmit_chars(up, lsr);
+ transmit_chars(&up->port, up->port.fifosize / 4);
break;
case UART_IIR_RX_TIMEOUT:
case UART_IIR_RDI:
diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index 9309ffd87c8e..c1376e8adbf4 100644
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -172,39 +172,18 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status)
serial_out(up, UART_IER, up->ier);
}

-static void transmit_chars(struct uart_pxa_port *up)
+static void serial_pxa_put_char(struct uart_port *port, u8 ch)
{
- struct circ_buf *xmit = &up->port.state->xmit;
- int count;
-
- 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);
-
+ struct uart_pxa_port *up = (struct uart_pxa_port *)port;

- if (uart_circ_empty(xmit))
- serial_pxa_stop_tx(&up->port);
+ serial_out(up, UART_TX, ch);
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(transmit_chars, port, ch,
+ true,
+ serial_pxa_put_char(port, ch),
+ ({}));
+
static void serial_pxa_start_tx(struct uart_port *port)
{
struct uart_pxa_port *up = (struct uart_pxa_port *)port;
@@ -254,7 +233,7 @@ static inline irqreturn_t serial_pxa_irq(int irq, void *dev_id)
receive_chars(up, &lsr);
check_modem_status(up);
if (lsr & UART_LSR_THRE)
- transmit_chars(up);
+ transmit_chars(&up->port, up->port.fifosize / 2);
spin_unlock(&up->port.lock);
return IRQ_HANDLED;
}
diff --git a/drivers/tty/serial/rp2.c b/drivers/tty/serial/rp2.c
index 6689d8add8f7..8719022b189d 100644
--- a/drivers/tty/serial/rp2.c
+++ b/drivers/tty/serial/rp2.c
@@ -426,35 +426,10 @@ static void rp2_rx_chars(struct rp2_uart_port *up)
tty_flip_buffer_push(port);
}

-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;
-
- 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);
-}
+static DEFINE_UART_PORT_TX_HELPER_LIMITED(rp2_tx_chars, port, ch,
+ true,
+ writeb(ch, port_to_up(port)->base + RP2_DATA_BYTE),
+ ({}));

static void rp2_ch_interrupt(struct rp2_uart_port *up)
{
@@ -472,7 +447,8 @@ static void rp2_ch_interrupt(struct rp2_uart_port *up)
if (status & RP2_CHAN_STAT_RXDATA_m)
rp2_rx_chars(up);
if (status & RP2_CHAN_STAT_TXEMPTY_m)
- rp2_tx_chars(up);
+ rp2_tx_chars(&up->port,
+ FIFO_SIZE - readw(up->base + RP2_TX_FIFO_COUNT));
if (status & RP2_CHAN_STAT_MS_CHANGED_MASK)
wake_up_interruptible(&up->port.state->port.delta_msr_wait);

diff --git a/drivers/tty/serial/serial_txx9.c b/drivers/tty/serial/serial_txx9.c
index 228e380db080..855ad3b457f7 100644
--- a/drivers/tty/serial/serial_txx9.c
+++ b/drivers/tty/serial/serial_txx9.c
@@ -319,37 +319,10 @@ receive_chars(struct uart_port *up, unsigned int *status)
*status = disr;
}

-static inline void transmit_chars(struct uart_port *up)
-{
- struct circ_buf *xmit = &up->state->xmit;
- int count;
-
- 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);
-}
+static DEFINE_UART_PORT_TX_HELPER_LIMITED(transmit_chars, port, ch,
+ true,
+ sio_out(port, TXX9_SITFIFO, ch),
+ ({}));

static irqreturn_t serial_txx9_interrupt(int irq, void *dev_id)
{
@@ -371,7 +344,7 @@ static irqreturn_t serial_txx9_interrupt(int irq, void *dev_id)
if (status & TXX9_SIDISR_RDIS)
receive_chars(up, &status);
if (status & TXX9_SIDISR_TDIS)
- transmit_chars(up);
+ transmit_chars(up, TXX9_SIO_TX_FIFO);
/* Clear TX/RX Int. Status */
sio_mask(up, TXX9_SIDISR,
TXX9_SIDISR_TDIS | TXX9_SIDISR_RDIS |
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 5c3a07546a58..78180f936bf3 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -277,45 +277,10 @@ static void __ssp_transmit_char(struct sifive_serial_port *ssp, int ch)
__ssp_writel(ch, SIFIVE_SERIAL_TXDATA_OFFS, ssp);
}

-/**
- * __ssp_transmit_chars() - enqueue multiple bytes onto the TX FIFO
- * @ssp: pointer to a struct sifive_serial_port
- *
- * Transfer up to a TX FIFO size's worth of characters from the Linux serial
- * transmit buffer to the SiFive UART TX FIFO.
- *
- * Context: Any context. Expects @ssp->port.lock to be held by caller.
- */
-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);
-
- if (uart_circ_empty(xmit))
- sifive_serial_stop_tx(&ssp->port);
-}
+static DEFINE_UART_PORT_TX_HELPER_LIMITED(__ssp_transmit_chars, port, ch,
+ true,
+ __ssp_transmit_char(port_to_sifive_serial_port(port), ch),
+ ({}));

/**
* __ssp_enable_txwm() - enable transmit watermark interrupts
@@ -553,7 +518,7 @@ static irqreturn_t sifive_serial_irq(int irq, void *dev_id)
if (ip & SIFIVE_SERIAL_IP_RXWM_MASK)
__ssp_receive_chars(ssp);
if (ip & SIFIVE_SERIAL_IP_TXWM_MASK)
- __ssp_transmit_chars(ssp);
+ __ssp_transmit_chars(&ssp->port, SIFIVE_TX_FIFO_DEPTH);

spin_unlock(&ssp->port.lock);

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 4329b9c9cbf0..e217b7ab69af 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -624,38 +624,10 @@ static inline void sprd_rx(struct uart_port *port)
tty_flip_buffer_push(tty);
}

-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);
-
- if (uart_circ_empty(xmit))
- sprd_stop_tx(port);
-}
+static DEFINE_UART_PORT_TX_HELPER_LIMITED(sprd_tx, port, ch,
+ true,
+ serial_out(port, SPRD_TXD, ch),
+ ({}));

/* this handles the interrupt from one port */
static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
@@ -683,7 +655,7 @@ static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
sprd_rx(port);

if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
- sprd_tx(port);
+ sprd_tx(port, THLD_TX_EMPTY);

spin_unlock(&port->lock);

diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index cce42f4c9bc2..f5dd3fa4bf26 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -230,6 +230,11 @@ static inline unsigned asc_hw_txroom(struct uart_port *port)
return 0;
}

+static DEFINE_UART_PORT_TX_HELPER_LIMITED(asc_do_transmit_chars, port, ch,
+ true,
+ asc_out(port, ASC_TXBUF, ch),
+ ({}));
+
/*
* Start transmitting chars.
* This is called from both interrupt and task level.
@@ -237,50 +242,7 @@ 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);
-
- if (uart_circ_empty(xmit))
- asc_disable_tx_interrupts(port);
+ asc_do_transmit_chars(port, asc_hw_txroom(port));
}

static void asc_receive_chars(struct uart_port *port)
--
2.37.2