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From: Rengarajan S <rengarajan.s@microchip.com>
To: <kumaravel.thiagarajan@microchip.com>,
	<tharunkumar.pasumarthi@microchip.com>, <gregkh@linuxfoundation.org>,
	<jirislaby@kernel.org>, <linux-serial@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <unglinuxdriver@microchip.com>
CC: <rengarajan.s@microchip.com>
Subject: [PATCH v1 tty] 8250: microchip: pci1xxxx: Refactor TX Burst code to use pre-existing APIs
Date: Thu, 22 Feb 2024 19:19:44 +0530
Message-ID: <20240222134944.1131952-1-rengarajan.s@microchip.com>
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Updated the TX Burst implementation by changing the circular buffer
processing with the pre-existing APIs in kernel. Also updated conditional
statements and alignment issues for better readability.

Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
---
 drivers/tty/serial/8250/8250_pci1xxxx.c | 39 ++++++++++++-------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
index 6cfeba058dba..84e0a0725f41 100644
--- a/drivers/tty/serial/8250/8250_pci1xxxx.c
+++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
@@ -374,7 +374,7 @@ static void pci1xxxx_rx_burst(struct uart_port *port, u32 uart_status)
 
 static void pci1xxxx_process_write_data(struct uart_port *port,
 					struct circ_buf *xmit,
-					int *data_empty_count,
+					u32 *data_empty_count,
 					u32 *valid_byte_count)
 {
 	u32 valid_burst_count = *valid_byte_count / UART_BURST_SIZE;
@@ -386,22 +386,24 @@ static void pci1xxxx_process_write_data(struct uart_port *port,
 	 * one byte at a time.
 	 */
 	while (valid_burst_count) {
-		if (*data_empty_count - UART_BURST_SIZE < 0)
+		if (*data_empty_count < UART_BURST_SIZE)
 			break;
-		if (xmit->tail > (UART_XMIT_SIZE - UART_BURST_SIZE))
+
+		if (CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE) <
+		    UART_BURST_SIZE)
 			break;
-		writel(*(unsigned int *)&xmit->buf[xmit->tail],
+
+		writel(*(u32 *)&xmit->buf[xmit->tail],
 		       port->membase + UART_TX_BURST_FIFO);
 		*valid_byte_count -= UART_BURST_SIZE;
 		*data_empty_count -= UART_BURST_SIZE;
 		valid_burst_count -= UART_BYTE_SIZE;
 
-		xmit->tail = (xmit->tail + UART_BURST_SIZE) &
-			     (UART_XMIT_SIZE - 1);
+		uart_xmit_advance(port, UART_BURST_SIZE);
 	}
 
 	while (*valid_byte_count) {
-		if (*data_empty_count - UART_BYTE_SIZE < 0)
+		if (*data_empty_count < UART_BYTE_SIZE)
 			break;
 		writeb(xmit->buf[xmit->tail], port->membase +
 		       UART_TX_BYTE_FIFO);
@@ -412,8 +414,7 @@ static void pci1xxxx_process_write_data(struct uart_port *port,
 		 * When the tail of the circular buffer is reached, the next
 		 * byte is transferred to the beginning of the buffer.
 		 */
-		xmit->tail = (xmit->tail + UART_BYTE_SIZE) &
-			     (UART_XMIT_SIZE - 1);
+		uart_xmit_advance(port, UART_BYTE_SIZE);
 
 		/*
 		 * If there are any pending burst count, data is handled by
@@ -434,16 +435,7 @@ static void pci1xxxx_tx_burst(struct uart_port *port, u32 uart_status)
 
 	xmit = &port->state->xmit;
 
-	if (port->x_char) {
-		writeb(port->x_char, port->membase + UART_TX);
-		port->icount.tx++;
-		port->x_char = 0;
-		return;
-	}
-
-	if ((uart_tx_stopped(port)) || (uart_circ_empty(xmit))) {
-		port->ops->stop_tx(port);
-	} else {
+	if (!(port->x_char)) {
 		data_empty_count = (pci1xxxx_read_burst_status(port) &
 				    UART_BST_STAT_TX_COUNT_MASK) >> 8;
 		do {
@@ -453,15 +445,22 @@ static void pci1xxxx_tx_burst(struct uart_port *port, u32 uart_status)
 						    &data_empty_count,
 						    &valid_byte_count);
 
-			port->icount.tx++;
 			if (uart_circ_empty(xmit))
 				break;
 		} while (data_empty_count && valid_byte_count);
+	} else {
+		writeb(port->x_char, port->membase + UART_TX);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
+	if ((uart_tx_stopped(port)) || (uart_circ_empty(xmit)))
+		port->ops->stop_tx(port);
+
 	 /*
 	  * With RPM enabled, we have to wait until the FIFO is empty before
 	  * the HW can go idle. So we get here once again with empty FIFO and
-- 
2.25.1