Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/kernel/drivers/tty/serial/8250/8250_fsl.c b/kernel/drivers/tty/serial/8250/8250_fsl.c
new file mode 100644
index 000000000..c0533a57e
--- /dev/null
+++ b/kernel/drivers/tty/serial/8250/8250_fsl.c
@@ -0,0 +1,62 @@
+#include <linux/serial_reg.h>
+#include <linux/serial_8250.h>
+
+#include "8250.h"
+
+/*
+ * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This isn't a full driver; it just provides an alternate IRQ
+ * handler to deal with an errata.  Everything else is just
+ * using the bog standard 8250 support.
+ *
+ * We follow code flow of serial8250_default_handle_irq() but add
+ * a check for a break and insert a dummy read on the Rx for the
+ * immediately following IRQ event.
+ *
+ * We re-use the already existing "bug handling" lsr_saved_flags
+ * field to carry the "what we just did" information from the one
+ * IRQ event to the next one.
+ */
+
+int fsl8250_handle_irq(struct uart_port *port)
+{
+	unsigned char lsr, orig_lsr;
+	unsigned long flags;
+	unsigned int iir;
+	struct uart_8250_port *up = up_to_u8250p(port);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	iir = port->serial_in(port, UART_IIR);
+	if (iir & UART_IIR_NO_INT) {
+		spin_unlock_irqrestore(&up->port.lock, flags);
+		return 0;
+	}
+
+	/* This is the WAR; if last event was BRK, then read and return */
+	if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) {
+		up->lsr_saved_flags &= ~UART_LSR_BI;
+		port->serial_in(port, UART_RX);
+		spin_unlock_irqrestore(&up->port.lock, flags);
+		return 1;
+	}
+
+	lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR);
+
+	if (lsr & (UART_LSR_DR | UART_LSR_BI))
+		lsr = serial8250_rx_chars(up, lsr);
+
+	serial8250_modem_status(up);
+
+	if (lsr & UART_LSR_THRE)
+		serial8250_tx_chars(up);
+
+	up->lsr_saved_flags = orig_lsr;
+	spin_unlock_irqrestore(&up->port.lock, flags);
+	return 1;
+}