2 * Copyright (C) 2008 Advanced Micro Devices, Inc.
4 * Author: Joerg Roedel <joerg.roedel@amd.com>
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.
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.
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
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>
26 #define HASH_SIZE 1024ULL
27 #define HASH_FN_SHIFT 13
28 #define HASH_FN_MASK (HASH_SIZE - 1)
37 struct dma_debug_entry {
38 struct list_head list;
50 struct list_head list;
52 } __cacheline_aligned_in_smp;
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);
61 /* Global disable flag - will be set in case of an error */
62 static bool global_disable __read_mostly;
64 static u32 num_free_entries;
65 static u32 min_free_entries;
68 * Hash related functions
70 * Every DMA-API request is saved into a struct dma_debug_entry. To
71 * have quick access to these structs they are stored into a hash.
73 static int hash_fn(struct dma_debug_entry *entry)
76 * Hash function is based on the dma address.
77 * We use bits 20-27 here as the index into the hash
79 return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
83 * Request exclusive access to a hash bucket for a given dma_debug_entry.
85 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
88 int idx = hash_fn(entry);
89 unsigned long __flags;
91 spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
93 return &dma_entry_hash[idx];
97 * Give up exclusive access to the hash bucket
99 static void put_hash_bucket(struct hash_bucket *bucket,
100 unsigned long *flags)
102 unsigned long __flags = *flags;
104 spin_unlock_irqrestore(&bucket->lock, __flags);
108 * Search a given entry in the hash bucket list
110 static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
111 struct dma_debug_entry *ref)
113 struct dma_debug_entry *entry;
115 list_for_each_entry(entry, &bucket->list, list) {
116 if ((entry->dev_addr == ref->dev_addr) &&
117 (entry->dev == ref->dev))
125 * Add an entry to a hash bucket
127 static void hash_bucket_add(struct hash_bucket *bucket,
128 struct dma_debug_entry *entry)
130 list_add_tail(&entry->list, &bucket->list);
134 * Remove entry from a hash bucket list
136 static void hash_bucket_del(struct dma_debug_entry *entry)
138 list_del(&entry->list);
142 * Wrapper function for adding an entry to the hash.
143 * This function takes care of locking itself.
145 static void add_dma_entry(struct dma_debug_entry *entry)
147 struct hash_bucket *bucket;
150 bucket = get_hash_bucket(entry, &flags);
151 hash_bucket_add(bucket, entry);
152 put_hash_bucket(bucket, &flags);
155 /* struct dma_entry allocator
157 * The next two functions implement the allocator for
158 * struct dma_debug_entries.
160 static struct dma_debug_entry *dma_entry_alloc(void)
162 struct dma_debug_entry *entry = NULL;
165 spin_lock_irqsave(&free_entries_lock, flags);
167 if (list_empty(&free_entries)) {
168 printk(KERN_ERR "DMA-API: debugging out of memory "
170 global_disable = true;
174 entry = list_entry(free_entries.next, struct dma_debug_entry, list);
175 list_del(&entry->list);
176 memset(entry, 0, sizeof(*entry));
178 num_free_entries -= 1;
179 if (num_free_entries < min_free_entries)
180 min_free_entries = num_free_entries;
183 spin_unlock_irqrestore(&free_entries_lock, flags);
188 static void dma_entry_free(struct dma_debug_entry *entry)
193 * add to beginning of the list - this way the entries are
194 * more likely cache hot when they are reallocated.
196 spin_lock_irqsave(&free_entries_lock, flags);
197 list_add(&entry->list, &free_entries);
198 num_free_entries += 1;
199 spin_unlock_irqrestore(&free_entries_lock, flags);
203 * DMA-API debugging init code
205 * The init code does two things:
206 * 1. Initialize core data structures
207 * 2. Preallocate a given number of dma_debug_entry structs
210 static int prealloc_memory(u32 num_entries)
212 struct dma_debug_entry *entry, *next_entry;
215 for (i = 0; i < num_entries; ++i) {
216 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
220 list_add_tail(&entry->list, &free_entries);
223 num_free_entries = num_entries;
224 min_free_entries = num_entries;
226 printk(KERN_INFO "DMA-API: preallocated %d debug entries\n",
233 list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
234 list_del(&entry->list);
242 * Let the architectures decide how many entries should be preallocated.
244 void dma_debug_init(u32 num_entries)
251 for (i = 0; i < HASH_SIZE; ++i) {
252 INIT_LIST_HEAD(&dma_entry_hash[i].list);
253 dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
256 if (prealloc_memory(num_entries) != 0) {
257 printk(KERN_ERR "DMA-API: debugging out of memory error "
259 global_disable = true;
264 printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");