/*
 * Contiguous Memory Allocator for DMA mapping framework
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Written by:
 *      Marek Szyprowski <m.szyprowski@samsung.com>
 *      Michal Nazarewicz <mina86@mina86.com>
 *
 * 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/slab.h>
#include <linux/swap.h>
#include <linux/mm_types.h>
#include <linux/dma-contiguous.h>

#ifndef SZ_1M
#define SZ_1M (1 << 20)
#endif

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

/**
 * dma_contiguous_reserve() - reserve area for contiguous memory handling
 * @limit: End address of the reserved memory (optional, 0 for any).
 *
 * This function reserves memory from early allocator. It should be
 * called by arch specific code once the early allocator (memblock or bootmem)
 * has been activated and all other subsystems have already allocated/reserved
 * memory.
 */
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);

/**
 * dma_declare_contiguous() - reserve area for contiguous memory handling
 *                            for particular device
 * @dev:   Pointer to device structure.
 * @size:  Size of the reserved memory.
 * @base:  Start address of the reserved memory (optional, 0 for any).
 * @limit: End address of the reserved memory (optional, 0 for any).
 *
 * This function reserves memory for specified device. It should be
 * called by board specific code when early allocator (memblock or bootmem)
 * is still activate.
 */
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;
}

/**
 * dma_alloc_from_contiguous() - allocate pages from contiguous area
 * @dev:   Pointer to device for which the allocation is performed.
 * @count: Requested number of pages.
 * @align: Requested alignment of pages (in PAGE_SIZE order).
 *
 * This function allocates memory buffer for specified device. It uses
 * device specific contiguous memory area if available or the default
 * global one. Requires architecture specific get_dev_cma_area() helper
 * function.
 */
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);
        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) {
                        ret = -ENOMEM;
                        goto error;
                }

                pfn = cma->base_pfn + pageno;
                ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
                if (ret == 0) {
                        bitmap_set(cma->bitmap, pageno, count);
                        break;
                } else if (ret != -EBUSY) {
                        goto error;
                }
                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__, pfn_to_page(pfn));
        return pfn_to_page(pfn);
error:
        mutex_unlock(&cma_mutex);
        return NULL;
}

/**
 * dma_release_from_contiguous() - release allocated pages
 * @dev:   Pointer to device for which the pages were allocated.
 * @pages: Allocated pages.
 * @count: Number of allocated pages.
 *
 * This function releases memory allocated by dma_alloc_from_contiguous().
 * It returns false when provided pages do not belong to contiguous area and
 * true otherwise.
 */
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;
}