Blackfin arch: Initial patch to add earlyprintk support

This allows debugging of problems which happen eary in the kernel
boot process (after bootargs are parsed, but before serial subsystem
is fully initialized)

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 161 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/early_printk.c b/arch/blackfin/kernel/early_printk.c
new file mode 100644
index 00000000000..9bf61706694
--- /dev/null
+++ b/arch/blackfin/kernel/early_printk.c
@@ -0,0 +1,161 @@
+/*
+ * File:         arch/blackfin/kernel/early_printk.c
+ * Based on:     arch/x86_64/kernel/early_printk.c
+ * Author:       Robin Getz <rgetz@blackfin.uclinux.org
+ *
+ * Created:      14Aug2007
+ * Description:  allow a console to be used for early printk
+ *
+ * Modified:
+ *               Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Bugs:         Enter bugs at http://blackfin.uclinux.org/
+ *
+ * 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.
+ *
+ * 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/init.h>
+#include <linux/serial_core.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <asm/blackfin.h>
+#include <asm/irq_handler.h>
+#include <asm/early_printk.h>
+
+#ifdef CONFIG_SERIAL_BFIN
+extern struct console *bfin_earlyserial_init(unsigned int port,
+						unsigned int cflag);
+#endif
+
+static struct console *early_console;
+
+/* Default console
+ * Port n == ttyBFn
+ * cflags == UART output modes
+ */
+#define DEFAULT_PORT 0
+#define DEFAULT_CFLAG CS8|B57600
+
+#ifdef CONFIG_SERIAL_CORE
+/* What should get here is "0,57600" */
+static struct console * __init earlyserial_init(char *buf)
+{
+	int baud, bit;
+	char parity;
+	unsigned int serial_port = DEFAULT_PORT;
+	unsigned int cflag = DEFAULT_CFLAG;
+
+	serial_port = simple_strtoul(buf, &buf, 10);
+	buf++;
+
+	cflag = 0;
+	baud = simple_strtoul(buf, &buf, 10);
+	switch (baud) {
+	case 1200:
+		cflag |= B1200;
+		break;
+	case 2400:
+		cflag |= B2400;
+		break;
+	case 4800:
+		cflag |= B4800;
+		break;
+	case 9600:
+		cflag |= B9600;
+		break;
+	case 19200:
+		cflag |= B19200;
+		break;
+	case 38400:
+		cflag |= B38400;
+		break;
+	case 115200:
+		cflag |= B115200;
+		break;
+	default:
+		cflag |= B57600;
+	}
+
+	parity = buf[0];
+	buf++;
+	switch (parity) {
+	case 'e':
+		cflag |= PARENB;
+		break;
+	case 'o':
+		cflag |= PARODD;
+		break;
+	}
+
+	bit = simple_strtoul(buf, &buf, 10);
+	switch (bit) {
+	case 5:
+		cflag |= CS5;
+		break;
+	case 6:
+		cflag |= CS5;
+		break;
+	case 7:
+		cflag |= CS5;
+		break;
+	default:
+		cflag |= CS8;
+	}
+
+#ifdef CONFIG_SERIAL_BFIN
+	return bfin_earlyserial_init(serial_port, cflag);
+#else
+	return NULL;
+#endif
+
+}
+#endif
+
+int __init setup_early_printk(char *buf)
+{
+
+	/* Crashing in here would be really bad, so check both the var
+	   and the pointer before we start using it
+	 */
+	if (!buf)
+		return 0;
+
+	if (!*buf)
+		return 0;
+
+	if (early_console != NULL)
+		return 0;
+
+#ifdef CONFIG_SERIAL_BFIN
+	/* Check for Blackfin Serial */
+	if (!strncmp(buf, "serial,uart", 11)) {
+		buf += 11;
+		early_console = earlyserial_init(buf);
+	}
+#endif
+#ifdef CONFIG_FB
+		/* TODO: add framebuffer console support */
+#endif
+
+	if (likely(early_console)) {
+		early_console->flags |= CON_BOOT;
+
+		register_console(early_console);
+		printk(KERN_INFO "early printk enabled on %s%d\n",
+			early_console->name,
+			early_console->index);
+	}
+
+	return 0;
+}
+
+early_param("earlyprintk", setup_early_printk);