firmware: Google VPD: import lib_vpd source files

/*

 * vpd_decode.c

 *

 * Google VPD decoding routines.

 *

 * 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/export.h>

#include "vpd_decode.h"

static int vpd_decode_len(const s32 max_len, const u8 *in,

			  s32 *length, s32 *decoded_len)

{

	u8 more;

	int i = 0;

	if (!length || !decoded_len)

		return VPD_FAIL;

	*length = 0;

	do {

		if (i >= max_len)

			return VPD_FAIL;

		more = in[i] & 0x80;

		*length <<= 7;

		*length |= in[i] & 0x7f;

		++i;

	} while (more);

	*decoded_len = i;

	return VPD_OK;

}

int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed,

		      vpd_decode_callback callback, void *callback_arg)

{

	int type;

	int res;

	s32 key_len;

	s32 value_len;

	s32 decoded_len;

	const u8 *key;

	const u8 *value;

	/* type */

	if (*consumed >= max_len)

		return VPD_FAIL;

	type = input_buf[*consumed];

	switch (type) {

	case VPD_TYPE_INFO:

	case VPD_TYPE_STRING:

		(*consumed)++;

		/* key */

		res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed],

				     &key_len, &decoded_len);

		if (res != VPD_OK || *consumed + decoded_len >= max_len)

			return VPD_FAIL;

		*consumed += decoded_len;

		key = &input_buf[*consumed];

		*consumed += key_len;

		/* value */

		res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed],

				     &value_len, &decoded_len);

		if (res != VPD_OK || *consumed + decoded_len > max_len)

			return VPD_FAIL;

		*consumed += decoded_len;

		value = &input_buf[*consumed];

		*consumed += value_len;

		if (type == VPD_TYPE_STRING)

			return callback(key, key_len, value, value_len,

					callback_arg);

		break;

	default:

		return VPD_FAIL;

	}

	return VPD_OK;

}

/*

 * vpd_decode.h

 *

 * Google VPD decoding routines.

 *

 * 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.

 */

#ifndef __VPD_DECODE_H

#define __VPD_DECODE_H

#include <linux/types.h>

enum {

	VPD_OK = 0,

	VPD_FAIL,

};

enum {

	VPD_TYPE_TERMINATOR = 0,

	VPD_TYPE_STRING,

	VPD_TYPE_INFO                = 0xfe,

	VPD_TYPE_IMPLICIT_TERMINATOR = 0xff,

};

/* Callback for vpd_decode_string to invoke. */

typedef int vpd_decode_callback(const u8 *key, s32 key_len,

				const u8 *value, s32 value_len,

				void *arg);

/*

 * vpd_decode_string

 *

 * Given the encoded string, this function invokes callback with extracted

 * (key, value). The *consumed will be plused the number of bytes consumed in

 * this function.

 *

 * The input_buf points to the first byte of the input buffer.

 *

 * The *consumed starts from 0, which is actually the next byte to be decoded.

 * It can be non-zero to be used in multiple calls.

 *

 * If one entry is successfully decoded, sends it to callback and returns the

 * result.

 */

int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed,

		      vpd_decode_callback callback, void *callback_arg);

#endif  /* __VPD_DECODE_H */