// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2012 ARM Ltd.
 * Copyright (C) 2020 Google LLC
 */
#include <linux/cma.h>
#include <linux/debugfs.h>
#include <linux/dma-map-ops.h>
#include <linux/dma-direct.h>
#include <linux/init.h>
#include <linux/genalloc.h>
#include <linux/set_memory.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

static struct gen_pool *atomic_pool_dma __ro_after_init;
static unsigned long pool_size_dma;
static struct gen_pool *atomic_pool_dma32 __ro_after_init;
static unsigned long pool_size_dma32;
static struct gen_pool *atomic_pool_kernel __ro_after_init;
static unsigned long pool_size_kernel;

/* Size can be defined by the coherent_pool command line */
static size_t atomic_pool_size;

/* Dynamic background expansion when the atomic pool is near capacity */
static struct work_struct atomic_pool_work;

static int __init early_coherent_pool(char *p)
{
        atomic_pool_size = memparse(p, &p);
        return 0;
}
early_param("coherent_pool", early_coherent_pool);

static void __init dma_atomic_pool_debugfs_init(void)
{
        struct dentry *root;

        root = debugfs_create_dir("dma_pools", NULL);
        debugfs_create_ulong("pool_size_dma", 0400, root, &pool_size_dma);
        debugfs_create_ulong("pool_size_dma32", 0400, root, &pool_size_dma32);
        debugfs_create_ulong("pool_size_kernel", 0400, root, &pool_size_kernel);
}

static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
{
        if (gfp & __GFP_DMA)
                pool_size_dma += size;
        else if (gfp & __GFP_DMA32)
                pool_size_dma32 += size;
        else
                pool_size_kernel += size;
}

static bool cma_in_zone(gfp_t gfp)
{
        unsigned long size;
        phys_addr_t end;
        struct cma *cma;

        cma = dev_get_cma_area(NULL);
        if (!cma)
                return false;

        size = cma_get_size(cma);
        if (!size)
                return false;

        /* CMA can't cross zone boundaries, see cma_activate_area() */
        end = cma_get_base(cma) + size - 1;
        if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
                return end <= zone_dma_limit;
        if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
                return end <= max(DMA_BIT_MASK(32), zone_dma_limit);
        return true;
}

static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
                              gfp_t gfp)
{
        unsigned int order;
        struct page *page = NULL;
        void *addr;
        int ret = -ENOMEM;

        /* Cannot allocate larger than MAX_PAGE_ORDER */
        order = min(get_order(pool_size), MAX_PAGE_ORDER);

        do {
                pool_size = 1 << (PAGE_SHIFT + order);
                if (cma_in_zone(gfp))
                        page = dma_alloc_from_contiguous(NULL, 1 << order,
                                                         order, false);
                if (!page)
                        page = alloc_pages(gfp | __GFP_NOWARN, order);
        } while (!page && order-- > 0);
        if (!page)
                goto out;

        arch_dma_prep_coherent(page, pool_size);

#ifdef CONFIG_DMA_DIRECT_REMAP
        addr = dma_common_contiguous_remap(page, pool_size,
                        pgprot_decrypted(pgprot_dmacoherent(PAGE_KERNEL)),
                        __builtin_return_address(0));
        if (!addr)
                goto free_page;
#else
        addr = page_to_virt(page);
#endif
        /*
         * Memory in the atomic DMA pools must be unencrypted, the pools do not
         * shrink so no re-encryption occurs in dma_direct_free().
         */
        ret = set_memory_decrypted((unsigned long)page_to_virt(page),
                                   1 << order);
        if (ret)
                goto remove_mapping;
        ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
                                pool_size, NUMA_NO_NODE);
        if (ret)
                goto encrypt_mapping;

        dma_atomic_pool_size_add(gfp, pool_size);
        return 0;

encrypt_mapping:
        ret = set_memory_encrypted((unsigned long)page_to_virt(page),
                                   1 << order);
        if (WARN_ON_ONCE(ret)) {
                /* Decrypt succeeded but encrypt failed, purposely leak */
                goto out;
        }
remove_mapping:
#ifdef CONFIG_DMA_DIRECT_REMAP
        dma_common_free_remap(addr, pool_size);
free_page:
        __free_pages(page, order);
#endif
out:
        return ret;
}

static void atomic_pool_resize(struct gen_pool *pool, gfp_t gfp)
{
        if (pool && gen_pool_avail(pool) < atomic_pool_size)
                atomic_pool_expand(pool, gen_pool_size(pool), gfp);
}

static void atomic_pool_work_fn(struct work_struct *work)
{
        if (IS_ENABLED(CONFIG_ZONE_DMA))
                atomic_pool_resize(atomic_pool_dma,
                                   GFP_KERNEL | GFP_DMA);
        if (IS_ENABLED(CONFIG_ZONE_DMA32))
                atomic_pool_resize(atomic_pool_dma32,
                                   GFP_KERNEL | GFP_DMA32);
        atomic_pool_resize(atomic_pool_kernel, GFP_KERNEL);
}

static __init struct gen_pool *__dma_atomic_pool_init(size_t pool_size,
                                                      gfp_t gfp)
{
        struct gen_pool *pool;
        int ret;

        pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
        if (!pool)
                return NULL;

        gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL);

        ret = atomic_pool_expand(pool, pool_size, gfp);
        if (ret) {
                gen_pool_destroy(pool);
                pr_err("DMA: failed to allocate %zu KiB %pGg pool for atomic allocation\n",
                       pool_size >> 10, &gfp);
                return NULL;
        }

        pr_info("DMA: preallocated %zu KiB %pGg pool for atomic allocations\n",
                gen_pool_size(pool) >> 10, &gfp);
        return pool;
}

#ifdef CONFIG_ZONE_DMA32
#define has_managed_dma32 has_managed_zone(ZONE_DMA32)
#else
#define has_managed_dma32 false
#endif

static int __init dma_atomic_pool_init(void)
{
        int ret = 0;

        /*
         * If coherent_pool was not used on the command line, default the pool
         * sizes to 128KB per 1GB of memory, min 128KB, max MAX_PAGE_ORDER.
         */
        if (!atomic_pool_size) {
                unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
                pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
                atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
        }
        INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);

        /* All memory might be in the DMA zone(s) to begin with */
        if (has_managed_zone(ZONE_NORMAL)) {
                atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
                                                    GFP_KERNEL);
                if (!atomic_pool_kernel)
                        ret = -ENOMEM;
        }
        if (has_managed_dma()) {
                atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
                                                GFP_KERNEL | GFP_DMA);
                if (!atomic_pool_dma)
                        ret = -ENOMEM;
        }
        if (has_managed_dma32) {
                atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
                                                GFP_KERNEL | GFP_DMA32);
                if (!atomic_pool_dma32)
                        ret = -ENOMEM;
        }

        dma_atomic_pool_debugfs_init();
        return ret;
}
postcore_initcall(dma_atomic_pool_init);

static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)
{
        if (prev == NULL) {
                if (gfp & GFP_DMA)
                        return atomic_pool_dma ?: atomic_pool_dma32 ?: atomic_pool_kernel;
                if (gfp & GFP_DMA32)
                        return atomic_pool_dma32 ?: atomic_pool_dma ?: atomic_pool_kernel;
                return atomic_pool_kernel ?: atomic_pool_dma32 ?: atomic_pool_dma;
        }
        if (prev == atomic_pool_kernel)
                return atomic_pool_dma32 ? atomic_pool_dma32 : atomic_pool_dma;
        if (prev == atomic_pool_dma32)
                return atomic_pool_dma;
        return NULL;
}

static struct page *__dma_alloc_from_pool(struct device *dev, size_t size,
                struct gen_pool *pool, void **cpu_addr,
                bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
{
        unsigned long addr;
        phys_addr_t phys;

        addr = gen_pool_alloc(pool, size);
        if (!addr)
                return NULL;

        phys = gen_pool_virt_to_phys(pool, addr);
        if (phys_addr_ok && !phys_addr_ok(dev, phys, size)) {
                gen_pool_free(pool, addr, size);
                return NULL;
        }

        if (gen_pool_avail(pool) < atomic_pool_size)
                schedule_work(&atomic_pool_work);

        *cpu_addr = (void *)addr;
        memset(*cpu_addr, 0, size);
        return pfn_to_page(__phys_to_pfn(phys));
}

struct page *dma_alloc_from_pool(struct device *dev, size_t size,
                void **cpu_addr, gfp_t gfp,
                bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
{
        struct gen_pool *pool = NULL;
        struct page *page;
        bool pool_found = false;

        while ((pool = dma_guess_pool(pool, gfp))) {
                pool_found = true;
                page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
                                             phys_addr_ok);
                if (page)
                        return page;
        }

        if (pool_found)
                WARN(!(gfp & __GFP_NOWARN), "DMA pool exhausted for %s\n", dev_name(dev));
        else
                WARN(1, "Failed to get suitable pool for %s\n", dev_name(dev));
        return NULL;
}

bool dma_free_from_pool(struct device *dev, void *start, size_t size)
{
        struct gen_pool *pool = NULL;

        while ((pool = dma_guess_pool(pool, 0))) {
                if (!gen_pool_has_addr(pool, (unsigned long)start, size))
                        continue;
                gen_pool_free(pool, (unsigned long)start, size);
                return true;
        }

        return false;
}