MIPS: JZ4740: Add serial support

The JZ4740 UART interface is almost 16550 compatible.
The UART module needs to be enabled by setting a bit in the FCR register
and it has support for receive timeout interrupts.  Instead of adding yet
another machine specific quirk to the 8250 serial driver we provide a
serial_out implementation which sets the required additional flags.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1403/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 53 insertions, 0 deletions

diff --git a/arch/mips/jz4740/serial.c b/arch/mips/jz4740/serial.c
new file mode 100644
index 000000000000..d23de45826d1
--- /dev/null
+++ b/arch/mips/jz4740/serial.c
@@ -0,0 +1,33 @@
+/*
+ *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
+ *  JZ4740 serial support
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ *  You should have received a copy of the  GNU General Public License along
+ *  with this program; if not, write  to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/io.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+
+void jz4740_serial_out(struct uart_port *p, int offset, int value)
+{
+        switch (offset) {
+        case UART_FCR:
+                value |= 0x10; /* Enable uart module */
+                break;
+        case UART_IER:
+                value |= (value & 0x4) << 2;
+                break;
+        default:
+                break;
+        }
+        writeb(value, p->membase + (offset << p->regshift));
+}
diff --git a/arch/mips/jz4740/serial.h b/arch/mips/jz4740/serial.h
new file mode 100644
index 000000000000..b9fe3ade0289
--- /dev/null
+++ b/arch/mips/jz4740/serial.h
@@ -0,0 +1,20 @@
+/*
+ *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
+ *  JZ4740 serial support
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ *  You should have received a copy of the  GNU General Public License along
+ *  with this program; if not, write  to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#ifndef __MIPS_JZ4740_SERIAL_H__
+
+void jz4740_serial_out(struct uart_port *p, int offset, int value);
+
+#endif