1 files changed, 94 insertions, 0 deletions
diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c
new file mode 100644
index 000000000000..0019d3ec18dd
--- /dev/null
+++ b/drivers/firmware/google/coreboot_table.c
@@ -0,0 +1,94 @@
+/*
+ * coreboot_table.c
+ *
+ * Module providing coreboot table access.
+ *
+ * Copyright 2017 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2.0 as published by
+ * the Free Software Foundation.
+ *
+ * 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/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "coreboot_table.h"
+
+struct coreboot_table_entry {
+	u32 tag;
+	u32 size;
+};
+
+static struct coreboot_table_header __iomem *ptr_header;
+
+/*
+ * This function parses the coreboot table for an entry that contains the base
+ * address of the given entry tag. The coreboot table consists of a header
+ * directly followed by a number of small, variable-sized entries, which each
+ * contain an identifying tag and their length as the first two fields.
+ */
+int coreboot_table_find(int tag, void *data, size_t data_size)
+{
+	struct coreboot_table_header header;
+	struct coreboot_table_entry entry;
+	void *ptr_entry;
+	int i;
+
+	if (!ptr_header)
+		return -EPROBE_DEFER;
+
+	memcpy_fromio(&header, ptr_header, sizeof(header));
+
+	if (strncmp(header.signature, "LBIO", sizeof(header.signature))) {
+		pr_warn("coreboot_table: coreboot table missing or corrupt!\n");
+		return -ENODEV;
+	}
+
+	ptr_entry = (void *)ptr_header + header.header_bytes;
+
+	for (i = 0; i < header.table_entries; i++) {
+		memcpy_fromio(&entry, ptr_entry, sizeof(entry));
+		if (entry.tag == tag) {
+			if (data_size < entry.size)
+				return -EINVAL;
+
+			memcpy_fromio(data, ptr_entry, entry.size);
+
+			return 0;
+		}
+
+		ptr_entry += entry.size;
+	}
+
+	return -ENOENT;
+}
+EXPORT_SYMBOL(coreboot_table_find);
+
+int coreboot_table_init(void __iomem *ptr)
+{
+	ptr_header = ptr;
+
+	return 0;
+}
+EXPORT_SYMBOL(coreboot_table_init);
+
+int coreboot_table_exit(void)
+{
+	if (ptr_header)
+		iounmap(ptr_header);
+
+	return 0;
+}
+EXPORT_SYMBOL(coreboot_table_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");