linux-kernel - [PATCH 5/6] tty/serial: Add Spreadtrum's serial earlycon

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Date:	Mon, 29 Sep 2014 20:04:52 +0800
From:	zhang.lyra@...il.com
To:	catalin.marinas@....com, gregkh@...uxfoundation.org,
	ijc+devicetree@...lion.org.uk, jslaby@...e.cz,
	galak@...eaurora.org, broonie@...aro.org, mark.rutland@....com,
	m-karicheri2@...com, pawel.moll@....com, artagnon@...il.com,
	rrichter@...ium.com, robh+dt@...nel.org, will.deacon@....com,
	orsonzhai@...il.com, geng.ren@...eadtrum.com,
	zhizhou.zhang@...eadtrum.com
Cc:	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	"chunyan.zhang" <chunyan.zhang@...eadtrum.com>
Subject: [PATCH 5/6] tty/serial: Add Spreadtrum's serial earlycon

From: "chunyan.zhang" <chunyan.zhang@...eadtrum.com>

Adds earlycon support for the Spreadtrum's serial.

Signed-off-by: chunyan.zhang <chunyan.zhang@...eadtrum.com>
---
 drivers/tty/serial/Kconfig             |   12 ++++++
 drivers/tty/serial/Makefile            |    1 +
 drivers/tty/serial/serial_sprd_early.c |   64 ++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+)
 create mode 100644 drivers/tty/serial/serial_sprd_early.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 26cec64..ede16e6 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -85,6 +85,18 @@ config SERIAL_EARLYCON_ARM_SEMIHOST
 	  with "earlycon=smh" on the kernel command line. The console is
 	  enabled when early_param is processed.
 
+config SERIAL_EARLYCON_SPRD
+	bool "Early console using SPRD serial"
+	depends on ARM64
+	select SERIAL_CORE
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Support for early debug console using SPRD serial. This enables
+	  the console before standard serial driver is probed. This is enabled
+	  with "earlycon=serial_sprd" on the kernel command line. The console is
+	  enabled when early_param is processed.
+
 config SERIAL_SB1250_DUART
 	tristate "BCM1xxx on-chip DUART serial support"
 	depends on SIBYTE_SB1xxx_SOC=y
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 0080cc3..3ea9edc 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_SERIAL_21285) += 21285.o
 
 obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
 obj-$(CONFIG_SERIAL_EARLYCON_ARM_SEMIHOST) += earlycon-arm-semihost.o
+obj-$(CONFIG_SERIAL_EARLYCON_SPRD) += serial_sprd_early.o
 
 # These Sparc drivers have to appear before others such as 8250
 # which share ttySx minor node space.  Otherwise console device
diff --git a/drivers/tty/serial/serial_sprd_early.c b/drivers/tty/serial/serial_sprd_early.c
new file mode 100644
index 0000000..059e109
--- /dev/null
+++ b/drivers/tty/serial/serial_sprd_early.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2012 Spreadtrum Communications Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/serial_core.h>
+#include <linux/of.h>
+
+/*offset*/
+#define ARM_UART_TXD	0x0000
+#define ARM_UART_RXD	0x0004
+#define ARM_UART_STS0	0x0008
+#define ARM_UART_STS1	0x000C
+#define ARM_UART_IEN	0x0010
+#define ARM_UART_ICLR	0x0014
+#define ARM_UART_CTL0	0x0018
+#define ARM_UART_CTL1	0x001C
+#define ARM_UART_CTL2	0x0020
+#define ARM_UART_CLKD0	0x0024
+#define ARM_UART_CLKD1	0x0028
+#define ARM_UART_STS2	0x002C
+
+/*line status */
+#define UART_LSR_TX_OVER	(0x1<<15)
+
+static void serial_sprd_putc(struct uart_port *port, int c)
+{
+	while (!(readl(port->membase + ARM_UART_STS0) & UART_LSR_TX_OVER))
+		;
+	writeb(c, port->membase + ARM_UART_TXD);
+}
+
+static void serial_sprd_early_write(struct console *con, const char *s,
+				    unsigned n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, serial_sprd_putc);
+}
+
+static int __init serial_sprd_early_console_setup(
+				struct earlycon_device *device,
+				const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = serial_sprd_early_write;
+	return 0;
+}
+EARLYCON_DECLARE(serial_sprd, serial_sprd_early_console_setup);
+OF_EARLYCON_DECLARE(serial_sprd, "sprd,serial",
+		    serial_sprd_early_console_setup);
-- 
1.7.9.5

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