tpm_buff.c

/*
 * Copyright (c) 2019 Apertus Solutions, LLC
 *
 * Author(s):
 *      Daniel P. Smith <dpsmith@apertussolutions.com>
 *
 */

#ifdef LINUX_KERNEL

#include <linux/types.h>
#include <linux/string.h>

#elif defined LINUX_USERSPACE

#include <stdint.h>
#include <string.h>
#include <sys/types.h>

#endif

#include "tpm.h"
#include "tpmbuff.h"
#include "tpm_common.h"

#define STATIC_TIS_BUFFER_SIZE		1024

#define TPM_CRB_DATA_BUFFER_OFFSET	0x80
#define TPM_CRB_DATA_BUFFER_SIZE	3966

u8 *tpmb_reserve(struct tpmbuff *b)
{
	if (b->locked)
		return NULL;

	b->len = sizeof(struct tpm_header);
	b->locked = 1;
	b->data = b->head + b->len;
	b->tail = b->data;

	return b->head;
}

void tpmb_free(struct tpmbuff *b)
{
	memset(b->head, 0, b->len);

	b->len = 0;
	b->locked = 0;
	b->data = NULL;
	b->tail = NULL;
}

u8 *tpmb_put(struct tpmbuff *b, size_t size)
{
	u8 *tail = b->tail;

	if ((b->len + size) > b->truesize)
		return NULL; /* TODO: add overflow buffer support */

	b->tail += size;
	b->len += size;

	return tail;
}

size_t tpmb_trim(struct tpmbuff *b, size_t size)
{
	if (b->len < size)
		size = b->len;

	/* TODO: add overflow buffer support */

	b->tail -= size;
	b->len -= size;

	return size;
}

size_t tpmb_size(struct tpmbuff *b)
{
	return b->len;
}

static u8 tis_buff[STATIC_TIS_BUFFER_SIZE];
static struct tpmbuff tpm_buff;

struct tpmbuff *alloc_tpmbuff(enum tpm_hw_intf intf, u8 locality)
{
	struct tpmbuff *b = &tpm_buff;

	switch (intf) {
	case TPM_TIS:
		if (b->head)
			goto reset;

		b->head = (u8 *)&tis_buff;
		b->truesize = STATIC_TIS_BUFFER_SIZE;
		break;
	case TPM_CRB:
		b->head = (u8 *)(uintptr_t)(TPM_MMIO_BASE + (locality << 12)
			       + TPM_CRB_DATA_BUFFER_OFFSET);
		b->truesize = TPM_CRB_DATA_BUFFER_SIZE;
		break;
	default:
		return NULL;
	}

reset:
	b->len = 0;
	b->locked = 0;
	b->data = NULL;
	b->tail = NULL;
	b->end = b->head + (b->truesize - 1);

	return b;
}

void free_tpmbuff(struct tpmbuff *b, enum tpm_hw_intf intf)
{
	switch (intf) {
	case TPM_TIS:
		b->head = NULL;
		break;
	case TPM_CRB:
		b->head = NULL;
		break;
	default:
		break;
	}
}