include/shared_mem.h

/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/*
 * Shared memory interface for Chrome EC.
 *
 * This is intended to supply a relatively large block of memory for use by a
 * task for a relatively short amount of time.  For example, verified boot may
 * need a buffer to hold signature data during a verification operation.  It is
 * NOT intended for allocating long-term buffers; those should in general be
 * static variables allocated at compile-time.  It is NOT a full-featured
 * replacement for malloc() / free().
 */

#ifndef __CROS_EC_SHARED_MEM_H
#define __CROS_EC_SHARED_MEM_H

#include "common.h"

/**
 * Initializes the module.
 */
int shared_mem_init(void);

/**
 * Returns the maximum amount of shared memory which can be acquired, in
 * bytes.
 */
int shared_mem_size(void);

/**
 * Acquires a shared memory area of the requested size in bytes.
 *
 * @param size		Number of bytes requested
 * @param dest_ptr	If successful, set on return to the start of the
 *			granted memory buffer.
 *
 * @return EC_SUCCESS if successful, EC_ERROR_BUSY if buffer in use, or
 * other non-zero error code.
 */
int shared_mem_acquire(int size, char **dest_ptr);

/**
 * Releases a shared memory area previously allocated via shared_mem_acquire().
 */
void shared_mem_release(void *ptr);

#endif  /* __CROS_EC_SHARED_MEM_H */