tty: serial: qcom-geni-serial: split out the FIFO tx code

qcom_geni_serial_handle_tx() is pretty big, let's move the code that
handles the actual writing of data to a separate function which makes
sense in preparation for introducing a dma variant of handle_tx().
Signed-off-by: NBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20221229155030.418800-10-brgl@bgdev.plSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -704,19 +704,48 @@ static void qcom_geni_serial_start_rx(struct uart_port *uport)
 	writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
 }
 
+static int qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
+					    unsigned int chunk)
+{
+	struct qcom_geni_serial_port *port = to_dev_port(uport);
+	struct circ_buf *xmit = &uport->state->xmit;
+	size_t remaining = chunk;
+	int i, tail = xmit->tail;
+
+	for (i = 0; i < chunk; ) {
+		unsigned int tx_bytes;
+		u8 buf[sizeof(u32)];
+		int c;
+
+		memset(buf, 0, sizeof(buf));
+		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
+
+		for (c = 0; c < tx_bytes ; c++) {
+			buf[c] = xmit->buf[tail++];
+			tail &= UART_XMIT_SIZE - 1;
+		}
+
+		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
+
+		i += tx_bytes;
+		uport->icount.tx += tx_bytes;
+		remaining -= tx_bytes;
+		port->tx_remaining -= tx_bytes;
+	}
+
+	return tail;
+}
+
 static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
 		bool active)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
 	struct circ_buf *xmit = &uport->state->xmit;
 	size_t avail;
-	size_t remaining;
 	size_t pending;
-	int i;
 	u32 status;
 	u32 irq_en;
 	unsigned int chunk;
-	int tail;
 
 	status = readl(uport->membase + SE_GENI_TX_FIFO_STATUS);
 
@@ -735,7 +764,6 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
 	avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
 	avail *= BYTES_PER_FIFO_WORD;
 
-	tail = xmit->tail;
 	chunk = min(avail, pending);
 	if (!chunk)
 		goto out_write_wakeup;
@@ -750,29 +778,7 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
 					uport->membase + SE_GENI_M_IRQ_EN);
 	}
 
-	remaining = chunk;
-	for (i = 0; i < chunk; ) {
-		unsigned int tx_bytes;
-		u8 buf[sizeof(u32)];
-		int c;
-
-		memset(buf, 0, sizeof(buf));
-		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
-
-		for (c = 0; c < tx_bytes ; c++) {
-			buf[c] = xmit->buf[tail++];
-			tail &= UART_XMIT_SIZE - 1;
-		}
-
-		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
-
-		i += tx_bytes;
-		uport->icount.tx += tx_bytes;
-		remaining -= tx_bytes;
-		port->tx_remaining -= tx_bytes;
-	}
-
-	xmit->tail = tail;
+	xmit->tail = qcom_geni_serial_send_chunk_fifo(uport, chunk);
 
 	/*
 	 * The tx fifo watermark is level triggered and latched. Though we had