linux-yocto: Add append for the 3.19 kernel

* Create the bbappend for the 3.19 kernel, add similar config as other
  linux-yocto appends
* Add the uartps fix, this is the patch backported from the Linux 4.0
  kernel

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>

2 files changed, 71 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-xlnx/3.19/tty-xuartps-Fix-RX-hang-and-TX-corruption-in-termios.patch b/recipes-kernel/linux/linux-xlnx/3.19/tty-xuartps-Fix-RX-hang-and-TX-corruption-in-termios.patch
new file mode 100644
index 00000000..8ae7b85a
--- /dev/null
+++ b/recipes-kernel/linux/linux-xlnx/3.19/tty-xuartps-Fix-RX-hang-and-TX-corruption-in-termios.patch
@@ -0,0 +1,62 @@
+From 6ecde472b0d943251f8f348155495391720b61b0 Mon Sep 17 00:00:00 2001
+From: Nathan Rossi <nathan.rossi@xilinx.com>
+Date: Fri, 16 Jan 2015 13:49:25 +0100
+Subject: [PATCH] tty: xuartps: Fix RX hang, and TX corruption in termios call
+
+The implementation of flushing the RX FIFO breaks in a number of cases,
+it is impossible to ensure an complete flush of the RX FIFO due to the
+hardware not allowing the use of the FIFOs when the receiver is disabled
+(Reading from the FIFO register does not remove it from the FIFO when
+the RX_EN=0 or RX_DIS=1). Additionally during an initial set_termios
+call where RX_DIS=1 causes a hang waiting forever for the RX FIFO to
+empty. On top of this the FIFO will be cleared by the use of the RXRST
+bits on the Control Register, making the RX flush pointless (as it does
+not preserve the data read anyway).
+
+Due to the TXRST the TX FIFO and transmitter can be interrupted during
+frame trasmission, causing corruption and additionally data lost in the
+FIFO. Most other serial drivers do not flush or clear the FIFOs during
+a termios configuration change and as such do not have issues with
+corruption. For this UART controller is it required that the TXRST/RXRST
+bit be flagged during the change, this means that the data in the FIFO
+will be dropped when changing configuration. In order to prevent data
+loss and corruption of the transmitted data, wait until the TX FIFO is
+empty before changing the configuration. The performance of this may
+cause the set_termios call to take a longer amount of time especially
+on lower baud rates, however it is comparable to the same performance
+hit that a console_write call costs.
+
+Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
+Acked-by: Anirudha Sarangi <anirudh@xilinx.com>
+Acked-by: Harini Katakam <harinik@xilinx.com>
+Signed-off-by: Michal Simek <michal.simek@xilinx.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Upstream-Status: Backport [Available in 4.0]
+---
+ drivers/tty/serial/xilinx_uartps.c |   10 ++++++----
+ 1 file changed, 6 insertions(+), 4 deletions(-)
+
+diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
+index 542bab3..cff531a 100644
+--- a/drivers/tty/serial/xilinx_uartps.c
++++ b/drivers/tty/serial/xilinx_uartps.c
+@@ -637,10 +637,12 @@ static void cdns_uart_set_termios(struct uart_port *port,
+ 
+        spin_lock_irqsave(&port->lock, flags);
+ 
+-       /* Empty the receive FIFO 1st before making changes */
+-       while ((cdns_uart_readl(CDNS_UART_SR_OFFSET) &
+-                CDNS_UART_SR_RXEMPTY) != CDNS_UART_SR_RXEMPTY) {
+-               cdns_uart_readl(CDNS_UART_FIFO_OFFSET);
++       /* Wait for the transmit FIFO to empty before making changes */
++       if (!(cdns_uart_readl(CDNS_UART_CR_OFFSET) & CDNS_UART_CR_TX_DIS)) {
++               while (!(cdns_uart_readl(CDNS_UART_SR_OFFSET) &
++                               CDNS_UART_SR_TXEMPTY)) {
++                       cpu_relax();
++               }
+        }
+ 
+        /* Disable the TX and RX to set baud rate */
+-- 
+1.7.10.4
+
diff --git a/recipes-kernel/linux/linux-yocto_3.19.bbappend b/recipes-kernel/linux/linux-yocto_3.19.bbappend
new file mode 100644
index 00000000..77f02833
--- /dev/null
+++ b/recipes-kernel/linux/linux-yocto_3.19.bbappend
@@ -0,0 +1,9 @@
+
+require linux-xilinx-configs.inc
+require linux-xilinx-machines.inc
+
+FILESEXTRAPATHS_prepend := "${THISDIR}/linux-xlnx/3.19:"
+SRC_URI_append_zynq += " \
+                file://tty-xuartps-Fix-RX-hang-and-TX-corruption-in-termios.patch \
+                "
+