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/* Copyright (c) 2012 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 module for Chrome EC */
#include "config.h"
#include "link_defs.h"
#include "shared_mem.h"
#include "system.h"
static int buf_in_use;
int shared_mem_size(void)
{
/* Use all the RAM we can. The shared memory buffer is the
* last thing allocated from the start of RAM, so we can use
* everything up to the jump data at the end of RAM. */
return system_usable_ram_end() - (uint32_t)__shared_mem_buf;
}
int shared_mem_acquire(int size, int wait, char **dest_ptr)
{
if (size > shared_mem_size() || size <= 0)
return EC_ERROR_INVAL;
/* TODO: if task_start() hasn't been called, fail immediately
* if not available. */
/* TODO: wait if requested; for now, we fail immediately if
* not available. */
if (buf_in_use)
return EC_ERROR_BUSY;
/* TODO: atomically acquire buf_in_use. */
buf_in_use = 1;
*dest_ptr = __shared_mem_buf;
return EC_SUCCESS;
}
void shared_mem_release(void *ptr)
{
/* TODO: use event to wake up a previously-blocking acquire */
buf_in_use = 0;
}
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