linux-kernel - [PATCH v4 08/13] tty: serial: qcom-geni-serial: refactor qcom_geni_serial_handle

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Message-Id: <20221129110012.224685-9-brgl@bgdev.pl>
Date:   Tue, 29 Nov 2022 12:00:07 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Vinod Koul <vkoul@...nel.org>, Alex Elder <elder@...nel.org>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-serial@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v4 08/13] tty: serial: qcom-geni-serial: refactor qcom_geni_serial_handle_tx()

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

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().

Let's also shuffle the code a bit, drop unneeded variables and use
uart_xmit_advance() instead of handling tail->xmit manually.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/tty/serial/qcom_geni_serial.c | 55 +++++++++++++--------------
 1 file changed, 27 insertions(+), 28 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 68a1402fbe58..ece5b4d543fc 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -93,7 +93,7 @@
 #define IO_MACRO_IO2_IO3_SWAP		0x4640
 
 /* We always configure 4 bytes per FIFO word */
-#define BYTES_PER_FIFO_WORD		4
+#define BYTES_PER_FIFO_WORD		4U
 
 struct qcom_geni_private_data {
 	/* NOTE: earlycon port will have NULL here */
@@ -704,19 +704,41 @@ static void qcom_geni_serial_start_rx(struct uart_port *uport)
 	writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
 }
 
+static void 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;
+	unsigned int tx_bytes, remaining = chunk;
+	u8 buf[BYTES_PER_FIFO_WORD];
+	int c;
+
+	while (remaining) {
+		memset(buf, 0, sizeof(buf));
+		tx_bytes = min(remaining, BYTES_PER_FIFO_WORD);
+
+		for (c = 0; c < tx_bytes ; c++) {
+			buf[c] = xmit->buf[xmit->tail];
+			uart_xmit_advance(uport, 1);
+		}
+
+		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
+
+		remaining -= tx_bytes;
+		port->tx_remaining -= tx_bytes;
+	}
+}
+
 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 +757,6 @@ 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 +771,7 @@ 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;
+	qcom_geni_serial_send_chunk_fifo(uport, chunk);
 
 	/*
 	 * The tx fifo watermark is level triggered and latched. Though we had
-- 
2.37.2