tty: serial: use uart_port_tx_limited()

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.

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>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221004104927.14361-4-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 43 deletions

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)