linux-kernel - [PATCH 3/7] serial: pch: decomission pch_uart_hal

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Message-Id: <20220503080808.28332-2-jslaby@suse.cz>
Date:   Tue,  3 May 2022 10:08:04 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3/7] serial: pch: decomission pch_uart_hal_write()

It's horrid and if we inline it into callers, we can get rid of a lot of
sugar around.

So:
* x_char handling becomes a single iowrite8.
* xmit->buf handling is a single loop simply writing characters one by
  one directly from the buf instead of complex cnt_to_end computations.
  Until the buf is empty or fifo size is reached.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/tty/serial/pch_uart.c | 46 ++++++++++-------------------------
 1 file changed, 13 insertions(+), 33 deletions(-)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 6cb631487383..4fcb6c144b54 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -550,18 +550,6 @@ static u8 pch_uart_hal_get_modem(struct eg20t_port *priv)
 	return (u8)msr;
 }
 
-static void pch_uart_hal_write(struct eg20t_port *priv,
-			      const unsigned char *buf, int tx_size)
-{
-	int i;
-	unsigned int thr;
-
-	for (i = 0; i < tx_size;) {
-		thr = buf[i++];
-		iowrite8(thr, priv->membase + PCH_UART_THR);
-	}
-}
-
 static int pch_uart_hal_read(struct eg20t_port *priv, unsigned char *buf,
 			     int rx_size)
 {
@@ -769,23 +757,21 @@ static void pch_dma_tx_complete(void *arg)
 	pch_uart_hal_enable_interrupt(priv, PCH_UART_HAL_TX_INT);
 }
 
-static int pop_tx(struct eg20t_port *priv, int size)
+static bool pop_tx(struct eg20t_port *priv, unsigned int size)
 {
-	int count = 0;
+	unsigned int count = 0;
 	struct uart_port *port = &priv->port;
 	struct circ_buf *xmit = &port->state->xmit;
 
-	if (uart_tx_stopped(port) || uart_circ_empty(xmit))
+	if (uart_tx_stopped(port))
 		goto pop_tx_end;
 
-	do {
-		int cnt_to_end =
-		    CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
-		int sz = min(size - count, cnt_to_end);
-		pch_uart_hal_write(priv, &xmit->buf[xmit->tail], sz);
-		xmit->tail = (xmit->tail + sz) & (UART_XMIT_SIZE - 1);
-		count += sz;
-	} while (!uart_circ_empty(xmit) && count < size);
+	while (!uart_circ_empty(xmit) && count < size) {
+		iowrite8(xmit->buf[xmit->tail], priv->membase + PCH_UART_THR);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		count++;
+	}
 
 pop_tx_end:
 	dev_dbg(priv->port.dev, "%d characters. Remained %d characters.(%lu)\n",
@@ -859,7 +845,6 @@ static unsigned int handle_tx(struct eg20t_port *priv)
 	struct uart_port *port = &priv->port;
 	struct circ_buf *xmit = &port->state->xmit;
 	int fifo_size;
-	int tx_size;
 	int size;
 	int tx_empty;
 
@@ -874,7 +859,7 @@ static unsigned int handle_tx(struct eg20t_port *priv)
 	fifo_size = max(priv->fifo_size, 1);
 	tx_empty = 1;
 	if (port->x_char) {
-		pch_uart_hal_write(priv, &port->x_char, 1);
+		iowrite8(port->x_char, priv->membase + PCH_UART_THR);
 		port->icount.tx++;
 		port->x_char = 0;
 		tx_empty = 0;
@@ -884,13 +869,8 @@ static unsigned int handle_tx(struct eg20t_port *priv)
 	size = min(xmit->head - xmit->tail, fifo_size);
 	if (size < 0)
 		size = fifo_size;
-	if (size) {
-		tx_size = pop_tx(priv, size);
-		if (tx_size > 0) {
-			port->icount.tx += tx_size;
-			tx_empty = 0;
-		}
-	}
+	if (size && pop_tx(priv, size))
+		tx_empty = 0;
 
 	priv->tx_empty = tx_empty;
 
@@ -935,7 +915,7 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
 	fifo_size = max(priv->fifo_size, 1);
 
 	if (port->x_char) {
-		pch_uart_hal_write(priv, &port->x_char, 1);
+		iowrite8(port->x_char, priv->membase + PCH_UART_THR);
 		port->icount.tx++;
 		port->x_char = 0;
 		fifo_size--;
-- 
2.36.0