3 files changed, 69 insertions, 0 deletions

diff --git a/drivers/tty/serial/8250_fsl.c b/drivers/tty/serial/8250_fsl.c
new file mode 100644
index 000000000000..f4d3c47b88e8
--- /dev/null
+++ b/drivers/tty/serial/8250_fsl.c
@@ -0,0 +1,63 @@
+#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 =
+                container_of(port, struct uart_8250_port, 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;
+}
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 705d2dc39c9a..fee9e04f42e7 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -97,6 +97,11 @@ config SERIAL_8250_PNP
           This builds standard PNP serial support. You may be able to
           disable this feature if you only need legacy serial support.
 
+config SERIAL_8250_FSL
+        bool
+        depends on SERIAL_8250 && PPC
+        default PPC
+
 config SERIAL_8250_HP300
         tristate
         depends on SERIAL_8250 && HP300
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index af57089ddb67..75eadb8d7178 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o
 obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554) += 8250_exar_st16c554.o
 obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o
 obj-$(CONFIG_SERIAL_8250_MCA) += 8250_mca.o
+obj-$(CONFIG_SERIAL_8250_FSL) += 8250_fsl.o
 obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o
 obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
 obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o