From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eddie Huang <eddie.huang@mediatek.com>
Subject: [PATCH 1/2] tty: serial: 8250_mtk: Add earlycon
Date: Thu, 18 Dec 2014 16:33:20 +0800
Message-ID: <1418891601-53769-2-git-send-email-eddie.huang@mediatek.com>
References: <1418891601-53769-1-git-send-email-eddie.huang@mediatek.com>
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To: Mark Rutland <mark.rutland@arm.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Matthias Brugger <matthias.bgg@gmail.com>
Cc: srv_heupstream@mediatek.com, Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Kumar Gala <galak@codeaurora.org>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Jiri Slaby <jslaby@suse.cz>, Eddie Huang <eddie.huang@mediatek.com>, Alan Cox <alan@linux.intel.com>, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Sascha Hauer <kernel@pengutronix.de>, yingjoe.chen@mediatek.com, yh.chen@mediatek.com
List-Id: devicetree@vger.kernel.org

Mediatek UART has highspeed register, but 8250_early.c doesn't
support this, so add earlycon in 8250_mtk.c

Signed-off-by: Eddie Huang <eddie.huang@mediatek.com>
---
 drivers/tty/serial/8250/8250_mtk.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index de7aae5..65dd569 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -23,6 +23,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/serial_8250.h>
 #include <linux/serial_reg.h>
+#include <linux/console.h>
 
 #include "8250.h"
 
@@ -289,6 +290,38 @@ static struct platform_driver mtk8250_platform_driver = {
 };
 module_platform_driver(mtk8250_platform_driver);
 
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+static void __init mtk8250_serial_putc(struct uart_port *port, int c)
+{
+	while ((readl(port->membase + (UART_LSR << 2)) & BOTH_EMPTY) !=
+		BOTH_EMPTY)
+		;
+	writel(c, port->membase + (UART_TX << 2));
+}
+
+static void __init early_mtk8250_write(struct console *console,
+					const char *s, unsigned int count)
+{
+	struct earlycon_device *dev = console->data;
+
+	uart_console_write(&dev->port, s, count, mtk8250_serial_putc);
+}
+
+static int __init early_mtk8250_setup(struct earlycon_device *device,
+					const char *options)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = early_mtk8250_write;
+
+	return 0;
+}
+
+EARLYCON_DECLARE(mtk8250, early_mtk8250_setup);
+OF_EARLYCON_DECLARE(mtk8250, "mediatek,mt6577-uart", early_mtk8250_setup);
+
 MODULE_AUTHOR("Matthias Brugger");
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Mediatek 8250 serial port driver");
-- 
1.8.1.1.dirty