gcip-kernel-driver/include/gcip/gcip-mem-pool.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * A simple memory allocator to help allocating reserved memory pools.
 *
 * Copyright (C) 2022 Google LLC
 */

#ifndef __GCIP_MEM_POOL_H__
#define __GCIP_MEM_POOL_H__

#include <linux/device.h>
#include <linux/genalloc.h>
#include <linux/types.h>

struct gcip_mem_pool {
	struct device *dev;
	struct gen_pool *gen_pool;
	unsigned long base_addr;
	size_t granule;
};

/*
 * Initializes the memory pool object.
 *
 * @pool: The memory pool object to be initialized.
 * @dev: Used for logging only.
 * @base_addr: The base address of the pool. Must be greater than 0 and a multiple of @granule.
 * @size: The size of the pool. @size should be a multiple of @granule.
 * @granule: The granule when invoking the allocator. Should be a power of 2.
 *
 * Returns 0 on success, a negative errno otherwise.
 *
 * Call gcip_mem_pool_exit() to release the resources of @pool.
 */
int gcip_mem_pool_init(struct gcip_mem_pool *pool, struct device *dev, unsigned long base_addr,
		       size_t size, size_t granule);
/*
 * Releases resources of @pool.
 *
 * Note: you must release (by calling gcip_mem_pool_free) all allocations before calling this
 * function.
 */
void gcip_mem_pool_exit(struct gcip_mem_pool *pool);

/*
 * Allocates and returns the allocated address.
 *
 * @size: Size to be allocated.
 *
 * Returns the allocated address. Returns 0 on allocation failure.
 */
unsigned long gcip_mem_pool_alloc(struct gcip_mem_pool *pool, size_t size);
/*
 * Returns the address previously allocated by gcip_mem_pool_alloc().
 *
 * The size and address must match what previously passed to / returned by gcip_mem_pool_alloc().
 */
void gcip_mem_pool_free(struct gcip_mem_pool *pool, unsigned long addr, size_t size);

/*
 * Returns the offset between @addr and @base_addr passed to gcip_mem_pool_init().
 *
 * @addr must be a value returned by gcip_mem_pool_alloc().
 */
static inline size_t gcip_mem_pool_offset(struct gcip_mem_pool *pool, unsigned long addr)
{
	return addr - pool->base_addr;
}

#endif /* __GCIP_MEM_POOL_H__ */