linux-kernel - [PATCH v1 2/3] serial: liteuart: separate RX loop from poll timer

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Message-Id: <20221107171500.2537938-3-gsomlo@gmail.com>
Date:   Mon,  7 Nov 2022 12:14:59 -0500
From:   Gabriel Somlo <gsomlo@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-serial@...r.kernel.org, gregkh@...uxfoundation.org,
        jirislaby@...nel.org, kgugala@...micro.com, mholenko@...micro.com,
        joel@....id.au, david.abdurachmanov@...ive.com,
        florent@...oy-digital.fr
Subject: [PATCH v1 2/3] serial: liteuart: separate RX loop from poll timer

Move the character-receive (RX) loop to its own dedicated function,
and (for now) call that from the poll timer, liteuart_timer().

This is in preparation for adding IRQ support to the receive path.

Signed-off-by: Gabriel Somlo <gsomlo@...il.com>
---
 drivers/tty/serial/liteuart.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
index 4b9cca249828..90a29ed79bff 100644
--- a/drivers/tty/serial/liteuart.c
+++ b/drivers/tty/serial/liteuart.c
@@ -69,29 +69,34 @@ static struct uart_driver liteuart_driver = {
 #endif
 };
 
-static void liteuart_timer(struct timer_list *t)
+static void liteuart_rx_chars(struct uart_port *port)
 {
-	struct liteuart_port *uart = from_timer(uart, t, timer);
-	struct uart_port *port = &uart->port;
 	unsigned char __iomem *membase = port->membase;
-	unsigned int flg = TTY_NORMAL;
-	int ch;
-	unsigned long status;
+	unsigned int status;
+	unsigned char ch;
 
 	while ((status = !litex_read8(membase + OFF_RXEMPTY)) == 1) {
 		ch = litex_read8(membase + OFF_RXTX);
 		port->icount.rx++;
 
 		/* necessary for RXEMPTY to refresh its value */
-		litex_write8(membase + OFF_EV_PENDING, EV_TX | EV_RX);
+		litex_write8(membase + OFF_EV_PENDING, EV_RX);
 
 		/* no overflow bits in status */
 		if (!(uart_handle_sysrq_char(port, ch)))
-			uart_insert_char(port, status, 0, ch, flg);
-
-		tty_flip_buffer_push(&port->state->port);
+			uart_insert_char(port, status, 0, ch, TTY_NORMAL);
 	}
 
+	tty_flip_buffer_push(&port->state->port);
+}
+
+static void liteuart_timer(struct timer_list *t)
+{
+	struct liteuart_port *uart = from_timer(uart, t, timer);
+	struct uart_port *port = &uart->port;
+
+	liteuart_rx_chars(port);
+
 	mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
 }
 
-- 
2.37.3