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, 9 insertions, 38 deletions

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;
 }
 
 /*