1 files changed, 113 insertions, 0 deletions
diff --git a/arch/blackfin/kernel/shadow_console.c b/arch/blackfin/kernel/shadow_console.c
new file mode 100644
index 00000000000..8b8c7107a16
--- /dev/null
+++ b/arch/blackfin/kernel/shadow_console.c
@@ -0,0 +1,113 @@
+/*
+ * manage a small early shadow of the log buffer which we can pass between the
+ * bootloader so early crash messages are communicated properly and easily
+ *
+ * Copyright 2009 Analog Devices Inc.
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <asm/blackfin.h>
+#include <asm/irq_handler.h>
+#include <asm/early_printk.h>
+
+#define SHADOW_CONSOLE_START		(0x500)
+#define SHADOW_CONSOLE_END		(0x1000)
+#define SHADOW_CONSOLE_MAGIC_LOC	(0x4F0)
+#define SHADOW_CONSOLE_MAGIC		(0xDEADBEEF)
+
+static __initdata char *shadow_console_buffer = (char *)SHADOW_CONSOLE_START;
+
+__init void early_shadow_write(struct console *con, const char *s,
+				unsigned int n)
+{
+	unsigned int i;
+	/*
+	 * save 2 bytes for the double null at the end
+	 * once we fail on a long line, make sure we don't write a short line afterwards
+	 */
+	if ((shadow_console_buffer + n) <= (char *)(SHADOW_CONSOLE_END - 2)) {
+		/* can't use memcpy - it may not be relocated yet */
+		for (i = 0; i <= n; i++)
+			shadow_console_buffer[i] = s[i];
+		shadow_console_buffer += n;
+		shadow_console_buffer[0] = 0;
+		shadow_console_buffer[1] = 0;
+	} else
+		shadow_console_buffer = (char *)SHADOW_CONSOLE_END;
+}
+
+static __initdata struct console early_shadow_console = {
+	.name = "early_shadow",
+	.write = early_shadow_write,
+	.flags = CON_BOOT | CON_PRINTBUFFER,
+	.index = -1,
+	.device = 0,
+};
+
+__init int shadow_console_enabled(void)
+{
+	return early_shadow_console.flags & CON_ENABLED;
+}
+
+__init void mark_shadow_error(void)
+{
+	int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
+	loc[0] = SHADOW_CONSOLE_MAGIC;
+	loc[1] = SHADOW_CONSOLE_START;
+}
+
+__init void enable_shadow_console(void)
+{
+	if (!shadow_console_enabled()) {
+		register_console(&early_shadow_console);
+		/* for now, assume things are going to fail */
+		mark_shadow_error();
+	}
+}
+
+static __init int disable_shadow_console(void)
+{
+	/*
+	 * by the time pure_initcall runs, the standard console is enabled,
+	 * and the early_console is off, so unset the magic numbers
+	 * unregistering the console is taken care of in common code (See
+	 * ./kernel/printk:disable_boot_consoles() )
+	 */
+	int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
+
+	loc[0] = 0;
+
+	return 0;
+}
+pure_initcall(disable_shadow_console);
+
+/*
+ * since we can't use printk, dump numbers (as hex), n = # bits
+ */
+__init void early_shadow_reg(unsigned long reg, unsigned int n)
+{
+	/*
+	 * can't use any "normal" kernel features, since thay
+	 * may not be relocated to their execute address yet
+	 */
+	int i;
+	char ascii[11] = " 0x";
+
+	n = n / 4;
+	reg = reg << ((8 - n) * 4);
+	n += 3;
+
+	for (i = 3; i <= n ; i++) {
+		ascii[i] = hex_asc_lo(reg >> 28);
+		reg <<= 4;
+	}
+	early_shadow_write(NULL, ascii, n);
+
+}