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587 giacomo 1
#include <linuxcomp.h>
2
 
3
#include <linux/pci.h>
4
#include <linux/slab.h>
5
#include <linux/module.h>
6
 
7
/*
8
 * Pool allocator ... wraps the pci_alloc_consistent page allocator, so
9
 * small blocks are easily used by drivers for bus mastering controllers.
10
 * This should probably be sharing the guts of the slab allocator.
11
 */
12
 
13
struct pci_pool {       /* the pool */
14
        struct list_head        page_list;
15
        spinlock_t              lock;
16
        size_t                  blocks_per_page;
17
        size_t                  size;
18
        struct pci_dev          *dev;
19
        size_t                  allocation;
20
        char                    name [32];
21
        wait_queue_head_t       waitq;
22
        struct list_head        pools;
23
};
24
 
25
struct pci_page {       /* cacheable header for 'allocation' bytes */
26
        struct list_head        page_list;
27
        void                    *vaddr;
28
        dma_addr_t              dma;
29
        unsigned                in_use;
30
        unsigned long           bitmap [0];
31
};
32
 
33
#define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
34
#define POOL_POISON_FREED       0xa7    /* !inuse */
35
#define POOL_POISON_ALLOCATED   0xa9    /* !initted */
36
 
37
static DECLARE_MUTEX (pools_lock);
38
 
39
static ssize_t
40
show_pools (struct device *dev, char *buf)
41
{
42
        struct pci_dev          *pdev;
43
        unsigned                temp, size;
44
        char                    *next;
45
        struct list_head        *i, *j;
46
 
47
        pdev = container_of (dev, struct pci_dev, dev);
48
        next = buf;
49
        size = PAGE_SIZE;
50
 
51
        temp = snprintf26(next, size, "poolinfo - 0.1\n");
52
        size -= temp;
53
        next += temp;
54
 
55
        down (&pools_lock);
56
        list_for_each (i, &pdev->pools) {
57
                struct pci_pool *pool;
58
                unsigned        pages = 0, blocks = 0;
59
 
60
                pool = list_entry (i, struct pci_pool, pools);
61
 
62
                list_for_each (j, &pool->page_list) {
63
                        struct pci_page *page;
64
 
65
                        page = list_entry (j, struct pci_page, page_list);
66
                        pages++;
67
                        blocks += page->in_use;
68
                }
69
 
70
                /* per-pool info, no real statistics yet */
71
                temp = snprintf26(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
72
                                pool->name,
73
                                blocks, (unsigned int)(pages * pool->blocks_per_page),
74
                                (unsigned int)(pool->size), pages);
75
                size -= temp;
76
                next += temp;
77
        }
78
        up (&pools_lock);
79
 
80
        return PAGE_SIZE - size;
81
}
82
static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);
83
 
84
/**
85
 * pci_pool_create - Creates a pool of pci consistent memory blocks, for dma.
86
 * @name: name of pool, for diagnostics
87
 * @pdev: pci device that will be doing the DMA
88
 * @size: size of the blocks in this pool.
89
 * @align: alignment requirement for blocks; must be a power of two
90
 * @allocation: returned blocks won't cross this boundary (or zero)
91
 * Context: !in_interrupt()
92
 *
93
 * Returns a pci allocation pool with the requested characteristics, or
94
 * null if one can't be created.  Given one of these pools, pci_pool_alloc()
95
 * may be used to allocate memory.  Such memory will all have "consistent"
96
 * DMA mappings, accessible by the device and its driver without using
97
 * cache flushing primitives.  The actual size of blocks allocated may be
98
 * larger than requested because of alignment.
99
 *
100
 * If allocation is nonzero, objects returned from pci_pool_alloc() won't
101
 * cross that size boundary.  This is useful for devices which have
102
 * addressing restrictions on individual DMA transfers, such as not crossing
103
 * boundaries of 4KBytes.
104
 */
105
struct pci_pool *
106
pci_pool_create (const char *name, struct pci_dev *pdev,
107
        size_t size, size_t align, size_t allocation)
108
{
109
        struct pci_pool         *retval;
110
 
111
        if (align == 0)
112
                align = 1;
113
        if (size == 0)
114
                return 0;
115
        else if (size < align)
116
                size = align;
117
        else if ((size % align) != 0) {
118
                size += align + 1;
119
                size &= ~(align - 1);
120
        }
121
 
122
        if (allocation == 0) {
123
                if (PAGE_SIZE < size)
124
                        allocation = size;
125
                else
126
                        allocation = PAGE_SIZE;
127
                // FIXME: round up for less fragmentation
128
        } else if (allocation < size)
129
                return 0;
130
 
131
        if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL)))
132
                return retval;
133
 
134
        strlcpy (retval->name, name, sizeof retval->name);
135
 
136
        retval->dev = pdev;
137
 
138
        INIT_LIST_HEAD (&retval->page_list);
139
        spin_lock_init (&retval->lock);
140
        retval->size = size;
141
        retval->allocation = allocation;
142
        retval->blocks_per_page = allocation / size;
143
        init_waitqueue_head (&retval->waitq);
144
 
145
        if (pdev) {
146
                down (&pools_lock);
147
                if (list_empty (&pdev->pools))
148
                        device_create_file (&pdev->dev, &dev_attr_pools);
149
                /* note:  not currently insisting "name" be unique */
150
                list_add (&retval->pools, &pdev->pools);
151
                up (&pools_lock);
152
        } else
153
                INIT_LIST_HEAD (&retval->pools);
154
 
155
        return retval;
156
}
157
 
158
 
159
static struct pci_page *
160
pool_alloc_page (struct pci_pool *pool, int mem_flags)
161
{
162
        struct pci_page *page;
163
        int             mapsize;
164
 
165
        mapsize = pool->blocks_per_page;
166
        mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
167
        mapsize *= sizeof (long);
168
 
169
        page = (struct pci_page *) kmalloc (mapsize + sizeof *page, mem_flags);
170
        if (!page)
171
                return 0;
172
        page->vaddr = pci_alloc_consistent (pool->dev,
173
                                            pool->allocation,
174
                                            &page->dma);
175
        if (page->vaddr) {
176
                memset (page->bitmap, 0xff, mapsize);   // bit set == free
177
#ifdef  CONFIG_DEBUG_SLAB
178
                memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
179
#endif
180
                list_add (&page->page_list, &pool->page_list);
181
                page->in_use = 0;
182
        } else {
183
                kfree (page);
184
                page = 0;
185
        }
186
        return page;
187
}
188
 
189
 
190
static inline int
191
is_page_busy (int blocks, unsigned long *bitmap)
192
{
193
        while (blocks > 0) {
194
                if (*bitmap++ != ~0UL)
195
                        return 1;
196
                blocks -= BITS_PER_LONG;
197
        }
198
        return 0;
199
}
200
 
201
static void
202
pool_free_page (struct pci_pool *pool, struct pci_page *page)
203
{
204
        dma_addr_t      dma = page->dma;
205
 
206
#ifdef  CONFIG_DEBUG_SLAB
207
        memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
208
#endif
209
        pci_free_consistent (pool->dev, pool->allocation, page->vaddr, dma);
210
        list_del (&page->page_list);
211
        kfree (page);
212
}
213
 
214
 
215
/**
216
 * pci_pool_destroy - destroys a pool of pci memory blocks.
217
 * @pool: pci pool that will be destroyed
218
 * Context: !in_interrupt()
219
 *
220
 * Caller guarantees that no more memory from the pool is in use,
221
 * and that nothing will try to use the pool after this call.
222
 */
223
void
224
pci_pool_destroy (struct pci_pool *pool)
225
{
226
        down (&pools_lock);
227
        list_del (&pool->pools);
228
        if (pool->dev && list_empty (&pool->dev->pools))
229
                device_remove_file (&pool->dev->dev, &dev_attr_pools);
230
        up (&pools_lock);
231
 
232
        while (!list_empty (&pool->page_list)) {
233
                struct pci_page         *page;
234
                page = list_entry (pool->page_list.next,
235
                                struct pci_page, page_list);
236
                if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
237
                        printk (KERN_ERR "pci_pool_destroy %s/%s, %p busy\n",
238
                                pool->dev ? pci_name(pool->dev) : NULL,
239
                                pool->name, page->vaddr);
240
                        /* leak the still-in-use consistent memory */
241
                        list_del (&page->page_list);
242
                        kfree (page);
243
                } else
244
                        pool_free_page (pool, page);
245
        }
246
 
247
        kfree (pool);
248
}
249
 
250
 
251
/**
252
 * pci_pool_alloc - get a block of consistent memory
253
 * @pool: pci pool that will produce the block
254
 * @mem_flags: SLAB_KERNEL or SLAB_ATOMIC
255
 * @handle: pointer to dma address of block
256
 *
257
 * This returns the kernel virtual address of a currently unused block,
258
 * and reports its dma address through the handle.
259
 * If such a memory block can't be allocated, null is returned.
260
 */
261
void *
262
pci_pool_alloc (struct pci_pool *pool, int mem_flags, dma_addr_t *handle)
263
{
264
        unsigned long           flags;
265
        struct list_head        *entry;
266
        struct pci_page         *page;
267
        int                     map, block;
268
        size_t                  offset;
269
        void                    *retval;
270
 
271
restart:
272
        spin_lock_irqsave (&pool->lock, flags);
273
        list_for_each (entry, &pool->page_list) {
274
                int             i;
275
                page = list_entry (entry, struct pci_page, page_list);
276
                /* only cachable accesses here ... */
277
                for (map = 0, i = 0;
278
                                i < pool->blocks_per_page;
279
                                i += BITS_PER_LONG, map++) {
280
                        if (page->bitmap [map] == 0)
281
                                continue;
282
                        block = ffz (~ page->bitmap [map]);
283
                        if ((i + block) < pool->blocks_per_page) {
284
                                clear_bit (block, &page->bitmap [map]);
285
                                offset = (BITS_PER_LONG * map) + block;
286
                                offset *= pool->size;
287
                                goto ready;
288
                        }
289
                }
290
        }
291
        if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {
292
                if (mem_flags == SLAB_KERNEL) {
293
                        DECLARE_WAITQUEUE (wait, current);
294
 
295
                        //current->state = TASK_INTERRUPTIBLE;
296
                        add_wait_queue (&pool->waitq, &wait);
297
                        spin_unlock_irqrestore (&pool->lock, flags);
298
 
299
                        schedule_timeout (POOL_TIMEOUT_JIFFIES);
300
 
301
                        remove_wait_queue (&pool->waitq, &wait);
302
                        goto restart;
303
                }
304
                retval = 0;
305
                goto done;
306
        }
307
 
308
        clear_bit (0, &page->bitmap [0]);
309
        offset = 0;
310
ready:
311
        page->in_use++;
312
        retval = offset + page->vaddr;
313
        *handle = offset + page->dma;
314
#ifdef  CONFIG_DEBUG_SLAB
315
        memset (retval, POOL_POISON_ALLOCATED, pool->size);
316
#endif
317
done:
318
        spin_unlock_irqrestore (&pool->lock, flags);
319
        return retval;
320
}
321
 
322
 
323
static struct pci_page *
324
pool_find_page (struct pci_pool *pool, dma_addr_t dma)
325
{
326
        unsigned long           flags;
327
        struct list_head        *entry;
328
        struct pci_page         *page;
329
 
330
        spin_lock_irqsave (&pool->lock, flags);
331
        list_for_each (entry, &pool->page_list) {
332
                page = list_entry (entry, struct pci_page, page_list);
333
                if (dma < page->dma)
334
                        continue;
335
                if (dma < (page->dma + pool->allocation))
336
                        goto done;
337
        }
338
        page = 0;
339
done:
340
        spin_unlock_irqrestore (&pool->lock, flags);
341
        return page;
342
}
343
 
344
 
345
/**
346
 * pci_pool_free - put block back into pci pool
347
 * @pool: the pci pool holding the block
348
 * @vaddr: virtual address of block
349
 * @dma: dma address of block
350
 *
351
 * Caller promises neither device nor driver will again touch this block
352
 * unless it is first re-allocated.
353
 */
354
void
355
pci_pool_free (struct pci_pool *pool, void *vaddr, dma_addr_t dma)
356
{
357
        struct pci_page         *page;
358
        unsigned long           flags;
359
        int                     map, block;
360
 
361
        if ((page = pool_find_page (pool, dma)) == 0) {
362
                printk (KERN_ERR "pci_pool_free %s/%s, %p/%lx (bad dma)\n",
363
                        pool->dev ? pci_name(pool->dev) : NULL,
364
                        pool->name, vaddr, (unsigned long) dma);
365
                return;
366
        }
367
 
368
        block = dma - page->dma;
369
        block /= pool->size;
370
        map = block / BITS_PER_LONG;
371
        block %= BITS_PER_LONG;
372
 
373
#ifdef  CONFIG_DEBUG_SLAB
374
        if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
375
                printk (KERN_ERR "pci_pool_free %s/%s, %p (bad vaddr)/%Lx\n",
376
                        pool->dev ? pci_name(pool->dev) : NULL,
377
                        pool->name, vaddr, (unsigned long long) dma);
378
                return;
379
        }
380
        if (page->bitmap [map] & (1UL << block)) {
381
                printk (KERN_ERR "pci_pool_free %s/%s, dma %Lx already free\n",
382
                        pool->dev ? pci_name(pool->dev) : NULL,
383
                        pool->name, (unsigned long long)dma);
384
                return;
385
        }
386
        memset (vaddr, POOL_POISON_FREED, pool->size);
387
#endif
388
 
389
        spin_lock_irqsave (&pool->lock, flags);
390
        page->in_use--;
391
        set_bit (block, &page->bitmap [map]);
392
        if (waitqueue_active (&pool->waitq))
393
                wake_up (&pool->waitq);
394
        /*
395
         * Resist a temptation to do
396
         *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
397
         * it is not interrupt safe. Better have empty pages hang around.
398
         */
399
        spin_unlock_irqrestore (&pool->lock, flags);
400
}
401
 
402
 
403
EXPORT_SYMBOL (pci_pool_create);
404
EXPORT_SYMBOL (pci_pool_destroy);
405
EXPORT_SYMBOL (pci_pool_alloc);
406
EXPORT_SYMBOL (pci_pool_free);