dma-contiguous.c

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/*
 * Contiguous Memory Allocator for DMA mapping framework
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Written by:
 *  Marek Szyprowski <[email protected]>
 *  Michal Nazarewicz <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License or (at your optional) any later version of the license.
 */

#define pr_fmt(fmt) "cma: " fmt

#ifdef CONFIG_CMA_DEBUG
#ifndef DEBUG
#  define DEBUG
#endif
#endif

#include <asm/page.h>
#include <asm/dma-contiguous.h>

#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/page-isolation.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/mm_types.h>
#include <linux/dma-contiguous.h>

struct cma {
    unsigned long   base_pfn;
    unsigned long   count;
    unsigned long   *bitmap;
};

struct cma *dma_contiguous_default_area;

#ifdef CONFIG_CMA_SIZE_MBYTES
#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
#else
#define CMA_SIZE_MBYTES 0
#endif

/*
 * Default global CMA area size can be defined in kernel's .config.
 * This is usefull mainly for distro maintainers to create a kernel
 * that works correctly for most supported systems.
 * The size can be set in bytes or as a percentage of the total memory
 * in the system.
 *
 * Users, who want to set the size of global CMA area for their system
 * should use cma= kernel parameter.
 */
static const unsigned long size_bytes = CMA_SIZE_MBYTES * SZ_1M;
static long size_cmdline = -1;

static int __init early_cma(char *p)
{
    pr_debug("%s(%s)\n", __func__, p);
    size_cmdline = memparse(p, &p);
    return 0;
}
early_param("cma", early_cma);

#ifdef CONFIG_CMA_SIZE_PERCENTAGE

static unsigned long __init __maybe_unused cma_early_percent_memory(void)
{
    struct memblock_region *reg;
    unsigned long total_pages = 0;

    /*
     * We cannot use memblock_phys_mem_size() here, because
     * memblock_analyze() has not been called yet.
     */
    for_each_memblock(memory, reg)
        total_pages += memblock_region_memory_end_pfn(reg) -
                   memblock_region_memory_base_pfn(reg);

    return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
}

#else

static inline __maybe_unused unsigned long cma_early_percent_memory(void)
{
    return 0;
}

#endif

void __init dma_contiguous_reserve(phys_addr_t limit)
{
    unsigned long selected_size = 0;

    pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);

    if (size_cmdline != -1) {
        selected_size = size_cmdline;
    } else {
#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
        selected_size = size_bytes;
#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
        selected_size = cma_early_percent_memory();
#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
        selected_size = min(size_bytes, cma_early_percent_memory());
#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
        selected_size = max(size_bytes, cma_early_percent_memory());
#endif
    }

    if (selected_size) {
        pr_debug("%s: reserving %ld MiB for global area\n", __func__,
             selected_size / SZ_1M);

        dma_declare_contiguous(NULL, selected_size, 0, limit);
    }
};

static DEFINE_MUTEX(cma_mutex);

static __init int cma_activate_area(unsigned long base_pfn, unsigned long count)
{
    unsigned long pfn = base_pfn;
    unsigned i = count >> pageblock_order;
    struct zone *zone;

    WARN_ON_ONCE(!pfn_valid(pfn));
    zone = page_zone(pfn_to_page(pfn));

    do {
        unsigned j;
        base_pfn = pfn;
        for (j = pageblock_nr_pages; j; --j, pfn++) {
            WARN_ON_ONCE(!pfn_valid(pfn));
            if (page_zone(pfn_to_page(pfn)) != zone)
                return -EINVAL;
        }
        init_cma_reserved_pageblock(pfn_to_page(base_pfn));
    } while (--i);
    return 0;
}

static __init struct cma *cma_create_area(unsigned long base_pfn,
                     unsigned long count)
{
    int bitmap_size = BITS_TO_LONGS(count) * sizeof(long);
    struct cma *cma;
    int ret = -ENOMEM;

    pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count);

    cma = kmalloc(sizeof *cma, GFP_KERNEL);
    if (!cma)
        return ERR_PTR(-ENOMEM);

    cma->base_pfn = base_pfn;
    cma->count = count;
    cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);

    if (!cma->bitmap)
        goto no_mem;

    ret = cma_activate_area(base_pfn, count);
    if (ret)
        goto error;

    pr_debug("%s: returned %p\n", __func__, (void *)cma);
    return cma;

error:
    kfree(cma->bitmap);
no_mem:
    kfree(cma);
    return ERR_PTR(ret);
}

static struct cma_reserved {
    phys_addr_t start;
    unsigned long size;
    struct device *dev;
} cma_reserved[MAX_CMA_AREAS] __initdata;
static unsigned cma_reserved_count __initdata;

static int __init cma_init_reserved_areas(void)
{
    struct cma_reserved *r = cma_reserved;
    unsigned i = cma_reserved_count;

    pr_debug("%s()\n", __func__);

    for (; i; --i, ++r) {
        struct cma *cma;
        cma = cma_create_area(PFN_DOWN(r->start),
                      r->size >> PAGE_SHIFT);
        if (!IS_ERR(cma))
            dev_set_cma_area(r->dev, cma);
    }
    return 0;
}
core_initcall(cma_init_reserved_areas);

int __init dma_declare_contiguous(struct device *dev, unsigned long size,
                  phys_addr_t base, phys_addr_t limit)
{
    struct cma_reserved *r = &cma_reserved[cma_reserved_count];
    unsigned long alignment;

    pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__,
         (unsigned long)size, (unsigned long)base,
         (unsigned long)limit);

    /* Sanity checks */
    if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) {
        pr_err("Not enough slots for CMA reserved regions!\n");
        return -ENOSPC;
    }

    if (!size)
        return -EINVAL;

    /* Sanitise input arguments */
    alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
    base = ALIGN(base, alignment);
    size = ALIGN(size, alignment);
    limit &= ~(alignment - 1);

    /* Reserve memory */
    if (base) {
        if (memblock_is_region_reserved(base, size) ||
            memblock_reserve(base, size) < 0) {
            base = -EBUSY;
            goto err;
        }
    } else {
        /*
         * Use __memblock_alloc_base() since
         * memblock_alloc_base() panic()s.
         */
        phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
        if (!addr) {
            base = -ENOMEM;
            goto err;
        } else if (addr + size > ~(unsigned long)0) {
            memblock_free(addr, size);
            base = -EINVAL;
            goto err;
        } else {
            base = addr;
        }
    }

    /*
     * Each reserved area must be initialised later, when more kernel
     * subsystems (like slab allocator) are available.
     */
    r->start = base;
    r->size = size;
    r->dev = dev;
    cma_reserved_count++;
    pr_info("CMA: reserved %ld MiB at %08lx\n", size / SZ_1M,
        (unsigned long)base);

    /* Architecture specific contiguous memory fixup. */
    dma_contiguous_early_fixup(base, size);
    return 0;
err:
    pr_err("CMA: failed to reserve %ld MiB\n", size / SZ_1M);
    return base;
}

struct page *dma_alloc_from_contiguous(struct device *dev, int count,
                       unsigned int align)
{
    unsigned long mask, pfn, pageno, start = 0;
    struct cma *cma = dev_get_cma_area(dev);
    struct page *page = NULL;
    int ret;

    if (!cma || !cma->count)
        return NULL;

    if (align > CONFIG_CMA_ALIGNMENT)
        align = CONFIG_CMA_ALIGNMENT;

    pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
         count, align);

    if (!count)
        return NULL;

    mask = (1 << align) - 1;

    mutex_lock(&cma_mutex);

    for (;;) {
        pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
                            start, count, mask);
        if (pageno >= cma->count)
            break;

        pfn = cma->base_pfn + pageno;
        ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
        if (ret == 0) {
            bitmap_set(cma->bitmap, pageno, count);
            page = pfn_to_page(pfn);
            break;
        } else if (ret != -EBUSY) {
            break;
        }
        pr_debug("%s(): memory range at %p is busy, retrying\n",
             __func__, pfn_to_page(pfn));
        /* try again with a bit different memory target */
        start = pageno + mask + 1;
    }

    mutex_unlock(&cma_mutex);
    pr_debug("%s(): returned %p\n", __func__, page);
    return page;
}

bool dma_release_from_contiguous(struct device *dev, struct page *pages,
                 int count)
{
    struct cma *cma = dev_get_cma_area(dev);
    unsigned long pfn;

    if (!cma || !pages)
        return false;

    pr_debug("%s(page %p)\n", __func__, (void *)pages);

    pfn = page_to_pfn(pages);

    if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
        return false;

    VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);

    mutex_lock(&cma_mutex);
    bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
    free_contig_range(pfn, count);
    mutex_unlock(&cma_mutex);

    return true;
}