1 files changed, 152 insertions, 0 deletions
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
new file mode 100644
index 000000000000..4f27f788ac6f
--- /dev/null
+++ b/drivers/tty/serial/earlycon.c
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ * Author: Rob Herring <robh@kernel.org>
+ *
+ * Based on 8250 earlycon:
+ * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
+ *	Bjorn Helgaas <bjorn.helgaas@hp.com>
+ *
+ * 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.
+ */
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/serial_core.h>
+
+#ifdef CONFIG_FIX_EARLYCON_MEM
+#include <asm/fixmap.h>
+#endif
+
+#include <asm/serial.h>
+
+static struct console early_con = {
+	.name =		"uart", /* 8250 console switch requires this name */
+	.flags =	CON_PRINTBUFFER | CON_BOOT,
+	.index =	-1,
+};
+
+static struct earlycon_device early_console_dev = {
+	.con = &early_con,
+};
+
+static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
+{
+	void __iomem *base;
+#ifdef CONFIG_FIX_EARLYCON_MEM
+	set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
+	base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
+	base += paddr & ~PAGE_MASK;
+#else
+	base = ioremap(paddr, size);
+#endif
+	if (!base)
+		pr_err("%s: Couldn't map 0x%llx\n", __func__,
+		       (unsigned long long)paddr);
+
+	return base;
+}
+
+static int __init parse_options(struct earlycon_device *device,
+				char *options)
+{
+	struct uart_port *port = &device->port;
+	int mmio, mmio32, length, ret;
+	unsigned long addr;
+
+	if (!options)
+		return -ENODEV;
+
+	mmio = !strncmp(options, "mmio,", 5);
+	mmio32 = !strncmp(options, "mmio32,", 7);
+	if (mmio || mmio32) {
+		port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32);
+		options += mmio ? 5 : 7;
+		ret = kstrtoul(options, 0, &addr);
+		if (ret)
+			return ret;
+		port->mapbase = addr;
+		if (mmio32)
+			port->regshift = 2;
+	} else if (!strncmp(options, "io,", 3)) {
+		port->iotype = UPIO_PORT;
+		options += 3;
+		ret = kstrtoul(options, 0, &addr);
+		if (ret)
+			return ret;
+		port->iobase = addr;
+		mmio = 0;
+	} else if (!strncmp(options, "0x", 2)) {
+		port->iotype = UPIO_MEM;
+		ret = kstrtoul(options, 0, &addr);
+		if (ret)
+			return ret;
+		port->mapbase = addr;
+	} else {
+		return -EINVAL;
+	}
+
+	port->uartclk = BASE_BAUD * 16;
+
+	options = strchr(options, ',');
+	if (options) {
+		options++;
+		ret = kstrtouint(options, 0, &device->baud);
+		if (ret)
+			return ret;
+		length = min(strcspn(options, " ") + 1,
+			     (size_t)(sizeof(device->options)));
+		strlcpy(device->options, options, length);
+	}
+
+	if (mmio || mmio32)
+		pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
+			mmio32 ? "32" : "",
+			(unsigned long long)port->mapbase,
+			device->options);
+	else
+		pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
+			port->iobase,
+			device->options);
+
+	return 0;
+}
+
+int __init setup_earlycon(char *buf, const char *match,
+			  int (*setup)(struct earlycon_device *, const char *))
+{
+	int err;
+	size_t len;
+	struct uart_port *port = &early_console_dev.port;
+
+	if (!buf || !match || !setup)
+		return 0;
+
+	len = strlen(match);
+	if (strncmp(buf, match, len))
+		return 0;
+	if (buf[len] && (buf[len] != ','))
+		return 0;
+
+	buf += len + 1;
+
+	err = parse_options(&early_console_dev, buf);
+	/* On parsing error, pass the options buf to the setup function */
+	if (!err)
+		buf = NULL;
+
+	if (port->mapbase)
+		port->membase = earlycon_map(port->mapbase, 64);
+
+	early_console_dev.con->data = &early_console_dev;
+	err = setup(&early_console_dev, buf);
+	if (err < 0)
+		return err;
+	if (!early_console_dev.con->write)
+		return -ENODEV;
+
+	register_console(early_console_dev.con);
+	return 0;
+}