linux-kernel - [PATCH 04/10] tty: xuartps: Add polled mode support for xuartps

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Date:	Thu, 17 Oct 2013 14:08:07 -0700
From:	Soren Brinkmann <soren.brinkmann@...inx.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Michal Simek <michal.simek@...inx.com>
Cc:	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	Vlad Lungu <vlad.lungu@...driver.com>,
	Soren Brinkmann <soren.brinkmann@...inx.com>
Subject: [PATCH 04/10] tty: xuartps: Add polled mode support for xuartps

From: Vlad Lungu <vlad.lungu@...driver.com>

This allows KDB/KGDB to run.

Signed-off-by: Vlad Lungu <vlad.lungu@...driver.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@...inx.com>
---
This is squashed from these original patches:
	tty: xuartps: Add polled mode support for xuartps

	This allows KDB/KGDB to run.
	There is a bug somewhere that blocks KDB when paging;
	set the LINES environment variable to a big value and
	scroll in your terminal.

	Signed-off-by: Vlad Lungu <vlad.lungu@...driver.com>

and

	tty: xuartps: Fix poll read

	This fixes the KDB paging issue.

	Signed-off-by: Vlad Lungu <vlad.lungu@...driver.com>

Additionally I fixed a few style issues.
---
 drivers/tty/serial/xilinx_uartps.c | 52 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 5d5557af4d22..62259f37ddda 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -775,6 +775,54 @@ static void xuartps_enable_ms(struct uart_port *port)
 	/* N/A */
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+static int xuartps_poll_get_char(struct uart_port *port)
+{
+	u32 imr;
+	int c;
+
+	/* Disable all interrupts */
+	imr = xuartps_readl(XUARTPS_IMR_OFFSET);
+	xuartps_writel(imr, XUARTPS_IDR_OFFSET);
+
+	/* Check if FIFO is empty */
+	if (xuartps_readl(XUARTPS_SR_OFFSET) & XUARTPS_SR_RXEMPTY)
+		c = NO_POLL_CHAR;
+	else /* Read a character */
+		c = (unsigned char) xuartps_readl(XUARTPS_FIFO_OFFSET);
+
+	/* Enable interrupts */
+	xuartps_writel(imr, XUARTPS_IER_OFFSET);
+
+	return c;
+}
+
+static void xuartps_poll_put_char(struct uart_port *port, unsigned char c)
+{
+	u32 imr;
+
+	/* Disable all interrupts */
+	imr = xuartps_readl(XUARTPS_IMR_OFFSET);
+	xuartps_writel(imr, XUARTPS_IDR_OFFSET);
+
+	/* Wait until FIFO is empty */
+	while (!(xuartps_readl(XUARTPS_SR_OFFSET) & XUARTPS_SR_TXEMPTY))
+		cpu_relax();
+
+	/* Write a character */
+	xuartps_writel(c, XUARTPS_FIFO_OFFSET);
+
+	/* Wait until FIFO is empty */
+	while (!(xuartps_readl(XUARTPS_SR_OFFSET) & XUARTPS_SR_TXEMPTY))
+		cpu_relax();
+
+	/* Enable interrupts */
+	xuartps_writel(imr, XUARTPS_IER_OFFSET);
+
+	return;
+}
+#endif
+
 /** The UART operations structure
  */
 static struct uart_ops xuartps_ops = {
@@ -807,6 +855,10 @@ static struct uart_ops xuartps_ops = {
 	.config_port	= xuartps_config_port,	/* Configure when driver
 						 * adds a xuartps port
 						 */
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_get_char	= xuartps_poll_get_char,
+	.poll_put_char	= xuartps_poll_put_char,
+#endif
 };
 
 static struct uart_port xuartps_port[2];
-- 
1.8.4.1

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