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   1 /*
   2  * Copyright (C) 2008 Advanced Micro Devices, Inc.
   3  *
   4  * Author: Joerg Roedel <joerg.roedel@amd.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  18  */
  19
  20 #include <linux/dma-debug.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/types.h>
  23 #include <linux/list.h>
  24 #include <linux/slab.h>
  25
  26 #define HASH_SIZE       1024ULL
  27 #define HASH_FN_SHIFT   13
  28 #define HASH_FN_MASK    (HASH_SIZE - 1)
  29
  30 enum {
  31         dma_debug_single,
  32         dma_debug_page,
  33         dma_debug_sg,
  34         dma_debug_coherent,
  35 };
  36
  37 struct dma_debug_entry {
  38         struct list_head list;
  39         struct device    *dev;
  40         int              type;
  41         phys_addr_t      paddr;
  42         u64              dev_addr;
  43         u64              size;
  44         int              direction;
  45         int              sg_call_ents;
  46         int              sg_mapped_ents;
  47 };
  48
  49 struct hash_bucket {
  50         struct list_head list;
  51         spinlock_t lock;
  52 } __cacheline_aligned_in_smp;
  53
  54 /* Hash list to save the allocated dma addresses */
  55 static struct hash_bucket dma_entry_hash[HASH_SIZE];
  56 /* List of pre-allocated dma_debug_entry's */
  57 static LIST_HEAD(free_entries);
  58 /* Lock for the list above */
  59 static DEFINE_SPINLOCK(free_entries_lock);
  60
  61 /* Global disable flag - will be set in case of an error */
  62 static bool global_disable __read_mostly;
  63
  64 static u32 num_free_entries;
  65 static u32 min_free_entries;
  66
  67 /* number of preallocated entries requested by kernel cmdline */
  68 static u32 req_entries;
  69
  70 /*
  71  * Hash related functions
  72  *
  73  * Every DMA-API request is saved into a struct dma_debug_entry. To
  74  * have quick access to these structs they are stored into a hash.
  75  */
  76 static int hash_fn(struct dma_debug_entry *entry)
  77 {
  78         /*
  79          * Hash function is based on the dma address.
  80          * We use bits 20-27 here as the index into the hash
  81          */
  82         return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
  83 }
  84
  85 /*
  86  * Request exclusive access to a hash bucket for a given dma_debug_entry.
  87  */
  88 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
  89                                            unsigned long *flags)
  90 {
  91         int idx = hash_fn(entry);
  92         unsigned long __flags;
  93
  94         spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
  95         *flags = __flags;
  96         return &dma_entry_hash[idx];
  97 }
  98
  99 /*
 100  * Give up exclusive access to the hash bucket
 101  */
 102 static void put_hash_bucket(struct hash_bucket *bucket,
 103                             unsigned long *flags)
 104 {
 105         unsigned long __flags = *flags;
 106
 107         spin_unlock_irqrestore(&bucket->lock, __flags);
 108 }
 109
 110 /*
 111  * Search a given entry in the hash bucket list
 112  */
 113 static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
 114                                                 struct dma_debug_entry *ref)
 115 {
 116         struct dma_debug_entry *entry;
 117
 118         list_for_each_entry(entry, &bucket->list, list) {
 119                 if ((entry->dev_addr == ref->dev_addr) &&
 120                     (entry->dev == ref->dev))
 121                         return entry;
 122         }
 123
 124         return NULL;
 125 }
 126
 127 /*
 128  * Add an entry to a hash bucket
 129  */
 130 static void hash_bucket_add(struct hash_bucket *bucket,
 131                             struct dma_debug_entry *entry)
 132 {
 133         list_add_tail(&entry->list, &bucket->list);
 134 }
 135
 136 /*
 137  * Remove entry from a hash bucket list
 138  */
 139 static void hash_bucket_del(struct dma_debug_entry *entry)
 140 {
 141         list_del(&entry->list);
 142 }
 143
 144 /*
 145  * Wrapper function for adding an entry to the hash.
 146  * This function takes care of locking itself.
 147  */
 148 static void add_dma_entry(struct dma_debug_entry *entry)
 149 {
 150         struct hash_bucket *bucket;
 151         unsigned long flags;
 152
 153         bucket = get_hash_bucket(entry, &flags);
 154         hash_bucket_add(bucket, entry);
 155         put_hash_bucket(bucket, &flags);
 156 }
 157
 158 /* struct dma_entry allocator
 159  *
 160  * The next two functions implement the allocator for
 161  * struct dma_debug_entries.
 162  */
 163 static struct dma_debug_entry *dma_entry_alloc(void)
 164 {
 165         struct dma_debug_entry *entry = NULL;
 166         unsigned long flags;
 167
 168         spin_lock_irqsave(&free_entries_lock, flags);
 169
 170         if (list_empty(&free_entries)) {
 171                 printk(KERN_ERR "DMA-API: debugging out of memory "
 172                                 "- disabling\n");
 173                 global_disable = true;
 174                 goto out;
 175         }
 176
 177         entry = list_entry(free_entries.next, struct dma_debug_entry, list);
 178         list_del(&entry->list);
 179         memset(entry, 0, sizeof(*entry));
 180
 181         num_free_entries -= 1;
 182         if (num_free_entries < min_free_entries)
 183                 min_free_entries = num_free_entries;
 184
 185 out:
 186         spin_unlock_irqrestore(&free_entries_lock, flags);
 187
 188         return entry;
 189 }
 190
 191 static void dma_entry_free(struct dma_debug_entry *entry)
 192 {
 193         unsigned long flags;
 194
 195         /*
 196          * add to beginning of the list - this way the entries are
 197          * more likely cache hot when they are reallocated.
 198          */
 199         spin_lock_irqsave(&free_entries_lock, flags);
 200         list_add(&entry->list, &free_entries);
 201         num_free_entries += 1;
 202         spin_unlock_irqrestore(&free_entries_lock, flags);
 203 }
 204
 205 /*
 206  * DMA-API debugging init code
 207  *
 208  * The init code does two things:
 209  *   1. Initialize core data structures
 210  *   2. Preallocate a given number of dma_debug_entry structs
 211  */
 212
 213 static int prealloc_memory(u32 num_entries)
 214 {
 215         struct dma_debug_entry *entry, *next_entry;
 216         int i;
 217
 218         for (i = 0; i < num_entries; ++i) {
 219                 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 220                 if (!entry)
 221                         goto out_err;
 222
 223                 list_add_tail(&entry->list, &free_entries);
 224         }
 225
 226         num_free_entries = num_entries;
 227         min_free_entries = num_entries;
 228
 229         printk(KERN_INFO "DMA-API: preallocated %d debug entries\n",
 230                         num_entries);
 231
 232         return 0;
 233
 234 out_err:
 235
 236         list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
 237                 list_del(&entry->list);
 238                 kfree(entry);
 239         }
 240
 241         return -ENOMEM;
 242 }
 243
 244 /*
 245  * Let the architectures decide how many entries should be preallocated.
 246  */
 247 void dma_debug_init(u32 num_entries)
 248 {
 249         int i;
 250
 251         if (global_disable)
 252                 return;
 253
 254         for (i = 0; i < HASH_SIZE; ++i) {
 255                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
 256                 dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
 257         }
 258
 259         if (req_entries)
 260                 num_entries = req_entries;
 261
 262         if (prealloc_memory(num_entries) != 0) {
 263                 printk(KERN_ERR "DMA-API: debugging out of memory error "
 264                                 "- disabled\n");
 265                 global_disable = true;
 266
 267                 return;
 268         }
 269
 270         printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");
 271 }
 272
 273 static __init int dma_debug_cmdline(char *str)
 274 {
 275         if (!str)
 276                 return -EINVAL;
 277
 278         if (strncmp(str, "off", 3) == 0) {
 279                 printk(KERN_INFO "DMA-API: debugging disabled on kernel "
 280                                  "command line\n");
 281                 global_disable = true;
 282         }
 283
 284         return 0;
 285 }
 286
 287 static __init int dma_debug_entries_cmdline(char *str)
 288 {
 289         int res;
 290
 291         if (!str)
 292                 return -EINVAL;
 293
 294         res = get_option(&str, &req_entries);
 295
 296         if (!res)
 297                 req_entries = 0;
 298
 299         return 0;
 300 }
 301
 302 __setup("dma_debug=", dma_debug_cmdline);
 303 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
 304