linux-imx

// SPDX-License-Identifier: GPL-2.0-only

/*

 * Basic general purpose allocator for managing special purpose

 * memory, for example, memory that is not managed by the regular

 * kmalloc/kfree interface.  Uses for this includes on-device special

 * memory, uncached memory etc.

 *

 * It is safe to use the allocator in NMI handlers and other special

 * unblockable contexts that could otherwise deadlock on locks.  This

 * is implemented by using atomic operations and retries on any

 * conflicts.  The disadvantage is that there may be livelocks in

 * extreme cases.  For better scalability, one allocator can be used

 * for each CPU.

 *

 * The lockless operation only works if there is enough memory

 * available.  If new memory is added to the pool a lock has to be

 * still taken.  So any user relying on locklessness has to ensure

 * that sufficient memory is preallocated.

 *

 * The basic atomic operation of this allocator is cmpxchg on long.

 * On architectures that don't have NMI-safe cmpxchg implementation,

 * the allocator can NOT be used in NMI handler.  So code uses the

 * allocator in NMI handler should depend on

 * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.

 *

 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>

 */

​

#include <linux/slab.h>

#include <linux/export.h>

#include <linux/bitmap.h>

#include <linux/rculist.h>

#include <linux/interrupt.h>

#include <linux/genalloc.h>

#include <linux/of_device.h>

#include <linux/vmalloc.h>

​

static inline size_t chunk_size(const struct gen_pool_chunk *chunk)

{

    return chunk->end_addr - chunk->start_addr + 1;

}

​

static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)

{

    unsigned long val, nval;

​

    nval = *addr;

    do {

        val = nval;

        if (val & mask_to_set)

            return -EBUSY;

        cpu_relax();

    } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);

​

    return 0;

}

​

static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)

{

    unsigned long val, nval;

​

    nval = *addr;

    do {