bcm27xx: add linux 5.4 support

Tested on bcm2710 (Raspberry Pi 3B).

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/target/linux/bcm27xx/patches-5.4/950-0413-tty-amba-pl011-Add-un-throttle-support.patch b/target/linux/bcm27xx/patches-5.4/950-0413-tty-amba-pl011-Add-un-throttle-support.patch
new file mode 100644
index 0000000000..7777e2df96
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.4/950-0413-tty-amba-pl011-Add-un-throttle-support.patch
@@ -0,0 +1,61 @@
+From a3749ee48539fa832b1832cdcae26d34e5d20f00 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Fri, 24 Jan 2020 11:38:28 +0000
+Subject: [PATCH] tty: amba-pl011: Add un/throttle support
+
+The PL011 driver lacks throttle and unthrottle methods. As a result,
+sending more data to the Pi than it can immediately sink while CRTSCTS
+is enabled causes a NULL pointer to be followed.
+
+Add a throttle handler that disables the RX interrupts, and an
+unthrottle handler that reenables them.
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ drivers/tty/serial/amba-pl011.c | 28 ++++++++++++++++++++++++++++
+ 1 file changed, 28 insertions(+)
+
+--- a/drivers/tty/serial/amba-pl011.c
++++ b/drivers/tty/serial/amba-pl011.c
+@@ -1323,6 +1323,32 @@ static void pl011_start_tx(struct uart_p
+ 		pl011_start_tx_pio(uap);
+ }
+ 
++static void pl011_throttle(struct uart_port *port)
++{
++	struct uart_amba_port *uap =
++	    container_of(port, struct uart_amba_port, port);
++	unsigned long flags;
++
++	spin_lock_irqsave(&uap->port.lock, flags);
++	uap->im &= ~(UART011_RTIM | UART011_RXIM);
++	pl011_write(uap->im, uap, REG_IMSC);
++	spin_unlock_irqrestore(&uap->port.lock, flags);
++}
++
++static void pl011_unthrottle(struct uart_port *port)
++{
++	struct uart_amba_port *uap =
++	    container_of(port, struct uart_amba_port, port);
++	unsigned long flags;
++
++	spin_lock_irqsave(&uap->port.lock, flags);
++	uap->im |= UART011_RTIM;
++	if (!pl011_dma_rx_running(uap))
++	    uap->im |= UART011_RXIM;
++	pl011_write(uap->im, uap, REG_IMSC);
++	spin_unlock_irqrestore(&uap->port.lock, flags);
++}
++
+ static void pl011_stop_rx(struct uart_port *port)
+ {
+ 	struct uart_amba_port *uap =
+@@ -2164,6 +2190,8 @@ static const struct uart_ops amba_pl011_
+ 	.stop_tx	= pl011_stop_tx,
+ 	.start_tx	= pl011_start_tx,
+ 	.stop_rx	= pl011_stop_rx,
++	.throttle	= pl011_throttle,
++	.unthrottle	= pl011_unthrottle,
+ 	.enable_ms	= pl011_enable_ms,
+ 	.break_ctl	= pl011_break_ctl,
+ 	.startup	= pl011_startup,