// SPDX-License-Identifier: GPL-2.0-only
/*
 * DMA Pool allocator
 *
 * Copyright 2001 David Brownell
 * Copyright 2007 Intel Corporation
 *   Author: Matthew Wilcox <willy@linux.intel.com>
 *
 * This allocator returns small blocks of a given size which are DMA-able by
 * the given device.  It uses the dma_alloc_coherent page allocator to get
 * new pages, then splits them up into blocks of the required size.
 * Many older drivers still have their own code to do this.
 *
 * The current design of this allocator is fairly simple.  The pool is
 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
 * allocated pages.  Each page in the page_list is split into blocks of at
 * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
 * list of free blocks across all pages.  Used blocks aren't tracked, but we
 * keep a count of how many are currently allocated from each page.
 */

#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/poison.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/wait.h>

#ifdef CONFIG_SLUB_DEBUG_ON
#define DMAPOOL_DEBUG 1
#endif

struct dma_block {
        struct dma_block *next_block;
        dma_addr_t dma;
};

struct dma_pool {               /* the pool */
        struct list_head page_list;
        spinlock_t lock;
        struct dma_block *next_block;
        size_t nr_blocks;
        size_t nr_active;
        size_t nr_pages;
        struct device *dev;
        unsigned int size;
        unsigned int allocation;
        unsigned int boundary;
        int node;
        char name[32];
        struct list_head pools;
};

struct dma_page {               /* cacheable header for 'allocation' bytes */
        struct list_head page_list;
        void *vaddr;
        dma_addr_t dma;
};

static DEFINE_MUTEX(pools_lock);
static DEFINE_MUTEX(pools_reg_lock);

static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dma_pool *pool;
        unsigned size;

        size = sysfs_emit(buf, "poolinfo - 0.1\n");

        mutex_lock(&pools_lock);
        list_for_each_entry(pool, &dev->dma_pools, pools) {
                /* per-pool info, no real statistics yet */
                size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n",
                                      pool->name, pool->nr_active,
                                      pool->nr_blocks, pool->size,
                                      pool->nr_pages);
        }
        mutex_unlock(&pools_lock);

        return size;
}

static DEVICE_ATTR_RO(pools);

#ifdef DMAPOOL_DEBUG
static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
                             gfp_t mem_flags)
{
        u8 *data = (void *)block;
        int i;

        for (i = sizeof(struct dma_block); i < pool->size; i++) {
                if (data[i] == POOL_POISON_FREED)
                        continue;
                dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__,
                        pool->name, block);

                /*
                 * Dump the first 4 bytes even if they are not
                 * POOL_POISON_FREED
                 */
                print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
                                data, pool->size, 1);
                break;
        }

        if (!want_init_on_alloc(mem_flags))
                memset(block, POOL_POISON_ALLOCATED, pool->size);
}

static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
{
        struct dma_page *page;

        list_for_each_entry(page, &pool->page_list, page_list) {
                if (dma < page->dma)
                        continue;
                if ((dma - page->dma) < pool->allocation)
                        return page;
        }
        return NULL;
}

static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
{
        struct dma_block *block = pool->next_block;
        struct dma_page *page;

        page = pool_find_page(pool, dma);
        if (!page) {
                dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
                        __func__, pool->name, vaddr, &dma);
                return true;
        }

        while (block) {
                if (block != vaddr) {
                        block = block->next_block;
                        continue;
                }
                dev_err(pool->dev, "%s %s, dma %pad already free\n",
                        __func__, pool->name, &dma);
                return true;
        }

        memset(vaddr, POOL_POISON_FREED, pool->size);
        return false;
}

static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
{
        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
}
#else
static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
                             gfp_t mem_flags)
{
}

static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
{
        if (want_init_on_free())
                memset(vaddr, 0, pool->size);
        return false;
}

static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
{
}
#endif

static struct dma_block *pool_block_pop(struct dma_pool *pool)
{
        struct dma_block *block = pool->next_block;

        if (block) {
                pool->next_block = block->next_block;
                pool->nr_active++;
        }
        return block;
}

static void pool_block_push(struct dma_pool *pool, struct dma_block *block,
                            dma_addr_t dma)
{
        block->dma = dma;
        block->next_block = pool->next_block;
        pool->next_block = block;
}


/**
 * dma_pool_create_node - Creates a pool of coherent DMA memory blocks.
 * @name: name of pool, for diagnostics
 * @dev: device that will be doing the DMA
 * @size: size of the blocks in this pool.
 * @align: alignment requirement for blocks; must be a power of two
 * @boundary: returned blocks won't cross this power of two boundary
 * @node: optional NUMA node to allocate structs 'dma_pool' and 'dma_page' on
 * Context: not in_interrupt()
 *
 * Given one of these pools, dma_pool_alloc()
 * may be used to allocate memory.  Such memory will all have coherent
 * DMA mappings, accessible by the device and its driver without using
 * cache flushing primitives.  The actual size of blocks allocated may be
 * larger than requested because of alignment.
 *
 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 * cross that size boundary.  This is useful for devices which have
 * addressing restrictions on individual DMA transfers, such as not crossing
 * boundaries of 4KBytes.
 *
 * Return: a dma allocation pool with the requested characteristics, or
 * %NULL if one can't be created.
 */
struct dma_pool *dma_pool_create_node(const char *name, struct device *dev,
                size_t size, size_t align, size_t boundary, int node)
{
        struct dma_pool *retval;
        size_t allocation;
        bool empty;

        if (!dev)
                return NULL;

        if (align == 0)
                align = 1;
        else if (align & (align - 1))
                return NULL;

        if (size == 0 || size > INT_MAX)
                return NULL;
        if (size < sizeof(struct dma_block))
                size = sizeof(struct dma_block);

        size = ALIGN(size, align);
        allocation = max_t(size_t, size, PAGE_SIZE);

        if (!boundary)
                boundary = allocation;
        else if ((boundary < size) || (boundary & (boundary - 1)))
                return NULL;

        boundary = min(boundary, allocation);

        retval = kzalloc_node(sizeof(*retval), GFP_KERNEL, node);
        if (!retval)
                return retval;

        strscpy(retval->name, name, sizeof(retval->name));

        retval->dev = dev;

        INIT_LIST_HEAD(&retval->page_list);
        spin_lock_init(&retval->lock);
        retval->size = size;
        retval->boundary = boundary;
        retval->allocation = allocation;
        retval->node = node;
        INIT_LIST_HEAD(&retval->pools);

        /*
         * pools_lock ensures that the ->dma_pools list does not get corrupted.
         * pools_reg_lock ensures that there is not a race between
         * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
         * when the first invocation of dma_pool_create() failed on
         * device_create_file() and the second assumes that it has been done (I
         * know it is a short window).
         */
        mutex_lock(&pools_reg_lock);
        mutex_lock(&pools_lock);
        empty = list_empty(&dev->dma_pools);
        list_add(&retval->pools, &dev->dma_pools);
        mutex_unlock(&pools_lock);
        if (empty) {
                int err;

                err = device_create_file(dev, &dev_attr_pools);
                if (err) {
                        mutex_lock(&pools_lock);
                        list_del(&retval->pools);
                        mutex_unlock(&pools_lock);
                        mutex_unlock(&pools_reg_lock);
                        kfree(retval);
                        return NULL;
                }
        }
        mutex_unlock(&pools_reg_lock);
        return retval;
}
EXPORT_SYMBOL(dma_pool_create_node);

static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
{
        unsigned int next_boundary = pool->boundary, offset = 0;
        struct dma_block *block, *first = NULL, *last = NULL;

        pool_init_page(pool, page);
        while (offset + pool->size <= pool->allocation) {
                if (offset + pool->size > next_boundary) {
                        offset = next_boundary;
                        next_boundary += pool->boundary;
                        continue;
                }

                block = page->vaddr + offset;
                block->dma = page->dma + offset;
                block->next_block = NULL;

                if (last)
                        last->next_block = block;
                else
                        first = block;
                last = block;

                offset += pool->size;
                pool->nr_blocks++;
        }

        last->next_block = pool->next_block;
        pool->next_block = first;

        list_add(&page->page_list, &pool->page_list);
        pool->nr_pages++;
}

static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
{
        struct dma_page *page;

        page = kmalloc_node(sizeof(*page), mem_flags, pool->node);
        if (!page)
                return NULL;

        page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
                                         &page->dma, mem_flags);
        if (!page->vaddr) {
                kfree(page);
                return NULL;
        }

        return page;
}

/**
 * dma_pool_destroy - destroys a pool of dma memory blocks.
 * @pool: dma pool that will be destroyed
 * Context: !in_interrupt()
 *
 * Caller guarantees that no more memory from the pool is in use,
 * and that nothing will try to use the pool after this call.
 */
void dma_pool_destroy(struct dma_pool *pool)
{
        struct dma_page *page, *tmp;
        bool empty, busy = false;

        if (unlikely(!pool))
                return;

        mutex_lock(&pools_reg_lock);
        mutex_lock(&pools_lock);
        list_del(&pool->pools);
        empty = list_empty(&pool->dev->dma_pools);
        mutex_unlock(&pools_lock);
        if (empty)
                device_remove_file(pool->dev, &dev_attr_pools);
        mutex_unlock(&pools_reg_lock);

        if (pool->nr_active) {
                dev_err(pool->dev, "%s %s busy\n", __func__, pool->name);
                busy = true;
        }

        list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
                if (!busy)
                        dma_free_coherent(pool->dev, pool->allocation,
                                          page->vaddr, page->dma);
                list_del(&page->page_list);
                kfree(page);
        }

        kfree(pool);
}
EXPORT_SYMBOL(dma_pool_destroy);

/**
 * dma_pool_alloc - get a block of coherent memory
 * @pool: dma pool that will produce the block
 * @mem_flags: GFP_* bitmask
 * @handle: pointer to dma address of block
 *
 * Return: the kernel virtual address of a currently unused block,
 * and reports its dma address through the handle.
 * If such a memory block can't be allocated, %NULL is returned.
 */
void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
                     dma_addr_t *handle)
{
        struct dma_block *block;
        struct dma_page *page;
        unsigned long flags;

        might_alloc(mem_flags);

        spin_lock_irqsave(&pool->lock, flags);
        block = pool_block_pop(pool);
        if (!block) {
                /*
                 * pool_alloc_page() might sleep, so temporarily drop
                 * &pool->lock
                 */
                spin_unlock_irqrestore(&pool->lock, flags);

                page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
                if (!page)
                        return NULL;

                spin_lock_irqsave(&pool->lock, flags);
                pool_initialise_page(pool, page);
                block = pool_block_pop(pool);
        }
        spin_unlock_irqrestore(&pool->lock, flags);

        *handle = block->dma;
        pool_check_block(pool, block, mem_flags);
        if (want_init_on_alloc(mem_flags))
                memset(block, 0, pool->size);

        return block;
}
EXPORT_SYMBOL(dma_pool_alloc);

/**
 * dma_pool_free - put block back into dma pool
 * @pool: the dma pool holding the block
 * @vaddr: virtual address of block
 * @dma: dma address of block
 *
 * Caller promises neither device nor driver will again touch this block
 * unless it is first re-allocated.
 */
void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
{
        struct dma_block *block = vaddr;
        unsigned long flags;

        spin_lock_irqsave(&pool->lock, flags);
        if (!pool_block_err(pool, vaddr, dma)) {
                pool_block_push(pool, block, dma);
                pool->nr_active--;
        }
        spin_unlock_irqrestore(&pool->lock, flags);
}
EXPORT_SYMBOL(dma_pool_free);

/*
 * Managed DMA pool
 */
static void dmam_pool_release(struct device *dev, void *res)
{
        struct dma_pool *pool = *(struct dma_pool **)res;

        dma_pool_destroy(pool);
}

static int dmam_pool_match(struct device *dev, void *res, void *match_data)
{
        return *(struct dma_pool **)res == match_data;
}

/**
 * dmam_pool_create - Managed dma_pool_create()
 * @name: name of pool, for diagnostics
 * @dev: device that will be doing the DMA
 * @size: size of the blocks in this pool.
 * @align: alignment requirement for blocks; must be a power of two
 * @allocation: returned blocks won't cross this boundary (or zero)
 *
 * Managed dma_pool_create().  DMA pool created with this function is
 * automatically destroyed on driver detach.
 *
 * Return: a managed dma allocation pool with the requested
 * characteristics, or %NULL if one can't be created.
 */
struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
                                  size_t size, size_t align, size_t allocation)
{
        struct dma_pool **ptr, *pool;

        ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return NULL;

        pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
        if (pool)
                devres_add(dev, ptr);
        else
                devres_free(ptr);

        return pool;
}
EXPORT_SYMBOL(dmam_pool_create);

/**
 * dmam_pool_destroy - Managed dma_pool_destroy()
 * @pool: dma pool that will be destroyed
 *
 * Managed dma_pool_destroy().
 */
void dmam_pool_destroy(struct dma_pool *pool)
{
        struct device *dev = pool->dev;

        WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
}
EXPORT_SYMBOL(dmam_pool_destroy);