MIPS: ralink: add a bootrom dumper module

This patch adds a trivial driver that allows userland to extract the bootrom of
a SoC via debugfs.
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/8002/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/ralink/Makefile

@@ -18,3 +18,5 @@ obj-$(CONFIG_SOC_RT3883) += rt3883.o
 obj-$(CONFIG_SOC_MT7620) += mt7620.o
 
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
+
+obj-$(CONFIG_DEBUG_FS) += bootrom.o

arch/mips/ralink/bootrom.c

+/*
+ * 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.
+ *
+ * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#define BOOTROM_OFFSET	0x10118000
+#define BOOTROM_SIZE	0x8000
+
+static void __iomem *membase = (void __iomem *) KSEG1ADDR(BOOTROM_OFFSET);
+
+static int bootrom_show(struct seq_file *s, void *unused)
+{
+	seq_write(s, membase, BOOTROM_SIZE);
+
+	return 0;
+}
+
+static int bootrom_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, bootrom_show, NULL);
+}
+
+static const struct file_operations bootrom_file_ops = {
+	.open		= bootrom_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int bootrom_setup(void)
+{
+	if (!debugfs_create_file("bootrom", 0444,
+			NULL, NULL, &bootrom_file_ops)) {
+		pr_err("Failed to create bootrom debugfs file\n");
+
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+postcore_initcall(bootrom_setup);