kernel/dma/remap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2012 ARM Ltd.
   4  * Copyright (c) 2014 The Linux Foundation
   5  */
   6 #include <linux/dma-direct.h>
   7 #include <linux/dma-noncoherent.h>
   8 #include <linux/dma-contiguous.h>
   9 #include <linux/init.h>
  10 #include <linux/genalloc.h>
  11 #include <linux/slab.h>
  12 #include <linux/vmalloc.h>
  13
  14 struct page **dma_common_find_pages(void *cpu_addr)
  15 {
  16         struct vm_struct *area = find_vm_area(cpu_addr);
  17
  18         if (!area || area->flags != VM_DMA_COHERENT)
  19                 return NULL;
  20         return area->pages;
  21 }
  22
  23 static struct vm_struct *__dma_common_pages_remap(struct page **pages,
  24                         size_t size, pgprot_t prot, const void *caller)
  25 {
  26         struct vm_struct *area;
  27
  28         area = get_vm_area_caller(size, VM_DMA_COHERENT, caller);
  29         if (!area)
  30                 return NULL;
  31
  32         if (map_vm_area(area, prot, pages)) {
  33                 vunmap(area->addr);
  34                 return NULL;
  35         }
  36
  37         return area;
  38 }
  39
  40 /*
  41  * Remaps an array of PAGE_SIZE pages into another vm_area.
  42  * Cannot be used in non-sleeping contexts
  43  */
  44 void *dma_common_pages_remap(struct page **pages, size_t size,
  45                          pgprot_t prot, const void *caller)
  46 {
  47         struct vm_struct *area;
  48
  49         area = __dma_common_pages_remap(pages, size, prot, caller);
  50         if (!area)
  51                 return NULL;
  52
  53         area->pages = pages;
  54
  55         return area->addr;
  56 }
  57
  58 /*
  59  * Remaps an allocated contiguous region into another vm_area.
  60  * Cannot be used in non-sleeping contexts
  61  */
  62 void *dma_common_contiguous_remap(struct page *page, size_t size,
  63                         pgprot_t prot, const void *caller)
  64 {
  65         int i;
  66         struct page **pages;
  67         struct vm_struct *area;
  68
  69         pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
  70         if (!pages)
  71                 return NULL;
  72
  73         for (i = 0; i < (size >> PAGE_SHIFT); i++)
  74                 pages[i] = nth_page(page, i);
  75
  76         area = __dma_common_pages_remap(pages, size, prot, caller);
  77
  78         kfree(pages);
  79
  80         if (!area)
  81                 return NULL;
  82         return area->addr;
  83 }
  84
  85 /*
  86  * Unmaps a range previously mapped by dma_common_*_remap
  87  */
  88 void dma_common_free_remap(void *cpu_addr, size_t size)
  89 {
  90         struct vm_struct *area = find_vm_area(cpu_addr);
  91
  92         if (!area || area->flags != VM_DMA_COHERENT) {
  93                 WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
  94                 return;
  95         }
  96
  97         unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
  98         vunmap(cpu_addr);
  99 }
 100
 101 #ifdef CONFIG_DMA_DIRECT_REMAP
 102 static struct gen_pool *atomic_pool __ro_after_init;
 103
 104 #define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
 105 static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;
 106
 107 static int __init early_coherent_pool(char *p)
 108 {
 109         atomic_pool_size = memparse(p, &p);
 110         return 0;
 111 }
 112 early_param("coherent_pool", early_coherent_pool);
 113
 114 static gfp_t dma_atomic_pool_gfp(void)
 115 {
 116         if (IS_ENABLED(CONFIG_ZONE_DMA))
 117                 return GFP_DMA;
 118         if (IS_ENABLED(CONFIG_ZONE_DMA32))
 119                 return GFP_DMA32;
 120         return GFP_KERNEL;
 121 }
 122
 123 static int __init dma_atomic_pool_init(void)
 124 {
 125         unsigned int pool_size_order = get_order(atomic_pool_size);
 126         unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
 127         struct page *page;
 128         void *addr;
 129         int ret;
 130
 131         if (dev_get_cma_area(NULL))
 132                 page = dma_alloc_from_contiguous(NULL, nr_pages,
 133                                                  pool_size_order, false);
 134         else
 135                 page = alloc_pages(dma_atomic_pool_gfp(), pool_size_order);
 136         if (!page)
 137                 goto out;
 138
 139         arch_dma_prep_coherent(page, atomic_pool_size);
 140
 141         atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
 142         if (!atomic_pool)
 143                 goto free_page;
 144
 145         addr = dma_common_contiguous_remap(page, atomic_pool_size,
 146                                            pgprot_dmacoherent(PAGE_KERNEL),
 147                                            __builtin_return_address(0));
 148         if (!addr)
 149                 goto destroy_genpool;
 150
 151         ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
 152                                 page_to_phys(page), atomic_pool_size, -1);
 153         if (ret)
 154                 goto remove_mapping;
 155         gen_pool_set_algo(atomic_pool, gen_pool_first_fit_order_align, NULL);
 156
 157         pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n",
 158                 atomic_pool_size / 1024);
 159         return 0;
 160
 161 remove_mapping:
 162         dma_common_free_remap(addr, atomic_pool_size);
 163 destroy_genpool:
 164         gen_pool_destroy(atomic_pool);
 165         atomic_pool = NULL;
 166 free_page:
 167         if (!dma_release_from_contiguous(NULL, page, nr_pages))
 168                 __free_pages(page, pool_size_order);
 169 out:
 170         pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n",
 171                 atomic_pool_size / 1024);
 172         return -ENOMEM;
 173 }
 174 postcore_initcall(dma_atomic_pool_init);
 175
 176 bool dma_in_atomic_pool(void *start, size_t size)
 177 {
 178         if (unlikely(!atomic_pool))
 179                 return false;
 180
 181         return gen_pool_has_addr(atomic_pool, (unsigned long)start, size);
 182 }
 183
 184 void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
 185 {
 186         unsigned long val;
 187         void *ptr = NULL;
 188
 189         if (!atomic_pool) {
 190                 WARN(1, "coherent pool not initialised!\n");
 191                 return NULL;
 192         }
 193
 194         val = gen_pool_alloc(atomic_pool, size);
 195         if (val) {
 196                 phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
 197
 198                 *ret_page = pfn_to_page(__phys_to_pfn(phys));
 199                 ptr = (void *)val;
 200                 memset(ptr, 0, size);
 201         }
 202
 203         return ptr;
 204 }
 205
 206 bool dma_free_from_pool(void *start, size_t size)
 207 {
 208         if (!dma_in_atomic_pool(start, size))
 209                 return false;
 210         gen_pool_free(atomic_pool, (unsigned long)start, size);
 211         return true;
 212 }
 213 #endif /* CONFIG_DMA_DIRECT_REMAP */