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/*
* 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");
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