1 /*
2 * scsi_dma.c Copyright (C) 2000 Eric Youngdale
3 *
4 * mid-level SCSI DMA bounce buffer allocator
5 *
6 */
7
8 #define __NO_VERSION__
9 #include <linux/config.h>
10 #include <linux/module.h>
11 #include <linux/blk.h>
12
13
14 #include "scsi.h"
15 #include "hosts.h"
16 #include "constants.h"
17
18 #ifdef CONFIG_KMOD
19 #include <linux/kmod.h>
20 #endif
21
22 /*
23 * PAGE_SIZE must be a multiple of the sector size (512). True
24 * for all reasonably recent architectures (even the VAX...).
25 */
26 #define SECTOR_SIZE 512
27 #define SECTORS_PER_PAGE (PAGE_SIZE/SECTOR_SIZE)
28
29 #if SECTORS_PER_PAGE <= 8
30 typedef unsigned char FreeSectorBitmap;
31 #elif SECTORS_PER_PAGE <= 32
32 typedef unsigned int FreeSectorBitmap;
33 #else
34 #error You lose.
35 #endif
36
37 /*
38 * Used for access to internal allocator used for DMA safe buffers.
39 */
40 static spinlock_t allocator_request_lock = SPIN_LOCK_UNLOCKED;
41
42 static FreeSectorBitmap *dma_malloc_freelist = NULL;
43 static int need_isa_bounce_buffers;
44 static unsigned int dma_sectors = 0;
45 unsigned int scsi_dma_free_sectors = 0;
46 unsigned int scsi_need_isa_buffer = 0;
47 static unsigned char **dma_malloc_pages = NULL;
48
49 /*
50 * Function: scsi_malloc
51 *
52 * Purpose: Allocate memory from the DMA-safe pool.
53 *
54 * Arguments: len - amount of memory we need.
55 *
56 * Lock status: No locks assumed to be held. This function is SMP-safe.
57 *
58 * Returns: Pointer to memory block.
59 *
60 * Notes: Prior to the new queue code, this function was not SMP-safe.
61 * This function can only allocate in units of sectors
62 * (i.e. 512 bytes).
63 *
64 * We cannot use the normal system allocator becuase we need
65 * to be able to guarantee that we can process a complete disk
66 * I/O request without touching the system allocator. Think
67 * about it - if the system were heavily swapping, and tried to
68 * write out a block of memory to disk, and the SCSI code needed
69 * to allocate more memory in order to be able to write the
70 * data to disk, you would wedge the system.
71 */
72 void *scsi_malloc(unsigned int len)
73 {
74 unsigned int nbits, mask;
75 unsigned long flags;
76
77 int i, j;
78 if (len % SECTOR_SIZE != 0 || len > PAGE_SIZE)
79 return NULL;
80
81 nbits = len >> 9;
82 mask = (1 << nbits) - 1;
83
84 spin_lock_irqsave(&allocator_request_lock, flags);
85
86 for (i = 0; i < dma_sectors / SECTORS_PER_PAGE; i++)
87 for (j = 0; j <= SECTORS_PER_PAGE - nbits; j++) {
88 if ((dma_malloc_freelist[i] & (mask << j)) == 0) {
89 dma_malloc_freelist[i] |= (mask << j);
90 scsi_dma_free_sectors -= nbits;
91 #ifdef DEBUG
92 SCSI_LOG_MLQUEUE(3, printk("SMalloc: %d %p [From:%p]\n", len, dma_malloc_pages[i] + (j << 9)));
93 printk("SMalloc: %d %p [From:%p]\n", len, dma_malloc_pages[i] + (j << 9));
94 #endif
95 spin_unlock_irqrestore(&allocator_request_lock, flags);
96 return (void *) ((unsigned long) dma_malloc_pages[i] + (j << 9));
97 }
98 }
99 spin_unlock_irqrestore(&allocator_request_lock, flags);
100 return NULL; /* Nope. No more */
101 }
102
103 /*
104 * Function: scsi_free
105 *
106 * Purpose: Free memory into the DMA-safe pool.
107 *
108 * Arguments: ptr - data block we are freeing.
109 * len - size of block we are freeing.
110 *
111 * Lock status: No locks assumed to be held. This function is SMP-safe.
112 *
113 * Returns: Nothing
114 *
115 * Notes: This function *must* only be used to free memory
116 * allocated from scsi_malloc().
117 *
118 * Prior to the new queue code, this function was not SMP-safe.
119 * This function can only allocate in units of sectors
120 * (i.e. 512 bytes).
121 */
122 int scsi_free(void *obj, unsigned int len)
123 {
124 unsigned int page, sector, nbits, mask;
125 unsigned long flags;
126
127 #ifdef DEBUG
128 unsigned long ret = 0;
129
130 #ifdef __mips__
131 __asm__ __volatile__("move\t%0,$31":"=r"(ret));
132 #else
133 ret = __builtin_return_address(0);
134 #endif
135 printk("scsi_free %p %d\n", obj, len);
136 SCSI_LOG_MLQUEUE(3, printk("SFree: %p %d\n", obj, len));
137 #endif
138
139 spin_lock_irqsave(&allocator_request_lock, flags);
140
141 for (page = 0; page < dma_sectors / SECTORS_PER_PAGE; page++) {
142 unsigned long page_addr = (unsigned long) dma_malloc_pages[page];
143 if ((unsigned long) obj >= page_addr &&
144 (unsigned long) obj < page_addr + PAGE_SIZE) {
145 sector = (((unsigned long) obj) - page_addr) >> 9;
146
147 nbits = len >> 9;
148 mask = (1 << nbits) - 1;
149
150 if (sector + nbits > SECTORS_PER_PAGE)
151 panic("scsi_free:Bad memory alignment");
152
153 if ((dma_malloc_freelist[page] &
154 (mask << sector)) != (mask << sector)) {
155 #ifdef DEBUG
156 printk("scsi_free(obj=%p, len=%d) called from %08lx\n",
157 obj, len, ret);
158 #endif
159 panic("scsi_free:Trying to free unused memory");
160 }
161 scsi_dma_free_sectors += nbits;
162 dma_malloc_freelist[page] &= ~(mask << sector);
163 spin_unlock_irqrestore(&allocator_request_lock, flags);
164 return 0;
165 }
166 }
167 panic("scsi_free:Bad offset");
168 }
169
170
171 /*
172 * Function: scsi_resize_dma_pool
173 *
174 * Purpose: Ensure that the DMA pool is sufficiently large to be
175 * able to guarantee that we can always process I/O requests
176 * without calling the system allocator.
177 *
178 * Arguments: None.
179 *
180 * Lock status: No locks assumed to be held. This function is SMP-safe.
181 *
182 * Returns: Nothing
183 *
184 * Notes: Prior to the new queue code, this function was not SMP-safe.
185 * Go through the device list and recompute the most appropriate
186 * size for the dma pool. Then grab more memory (as required).
187 */
188 void scsi_resize_dma_pool(void)
189 {
190 int i, k;
191 unsigned long size;
192 unsigned long flags;
193 struct Scsi_Host *shpnt;
194 struct Scsi_Host *host = NULL;
195 Scsi_Device *SDpnt;
196 FreeSectorBitmap *new_dma_malloc_freelist = NULL;
197 unsigned int new_dma_sectors = 0;
198 unsigned int new_need_isa_buffer = 0;
199 unsigned char **new_dma_malloc_pages = NULL;
200 int out_of_space = 0;
201
202 spin_lock_irqsave(&allocator_request_lock, flags);
203
204 if (!scsi_hostlist) {
205 /*
206 * Free up the DMA pool.
207 */
208 if (scsi_dma_free_sectors != dma_sectors)
209 panic("SCSI DMA pool memory leak %d %d\n", scsi_dma_free_sectors, dma_sectors);
210
211 for (i = 0; i < dma_sectors / SECTORS_PER_PAGE; i++)
212 free_pages((unsigned long) dma_malloc_pages[i], 0);
213 if (dma_malloc_pages)
214 kfree((char *) dma_malloc_pages);
215 dma_malloc_pages = NULL;
216 if (dma_malloc_freelist)
217 kfree((char *) dma_malloc_freelist);
218 dma_malloc_freelist = NULL;
219 dma_sectors = 0;
220 scsi_dma_free_sectors = 0;
221 spin_unlock_irqrestore(&allocator_request_lock, flags);
222 return;
223 }
224 /* Next, check to see if we need to extend the DMA buffer pool */
225
226 new_dma_sectors = 2 * SECTORS_PER_PAGE; /* Base value we use */
227
228 if (__pa(high_memory) - 1 > ISA_DMA_THRESHOLD)
229 need_isa_bounce_buffers = 1;
230 else
231 need_isa_bounce_buffers = 0;
232
233 if (scsi_devicelist)
234 for (shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
235 new_dma_sectors += SECTORS_PER_PAGE; /* Increment for each host */
236
237 for (host = scsi_hostlist; host; host = host->next) {
238 for (SDpnt = host->host_queue; SDpnt; SDpnt = SDpnt->next) {
239 /*
240 * sd and sr drivers allocate scatterlists.
241 * sr drivers may allocate for each command 1x2048 or 2x1024 extra
242 * buffers for 2k sector size and 1k fs.
243 * sg driver allocates buffers < 4k.
244 * st driver does not need buffers from the dma pool.
245 * estimate 4k buffer/command for devices of unknown type (should panic).
246 */
247 if (SDpnt->type == TYPE_WORM || SDpnt->type == TYPE_ROM ||
248 SDpnt->type == TYPE_DISK || SDpnt->type == TYPE_MOD) {
249 int nents = host->sg_tablesize;
250 #ifdef DMA_CHUNK_SIZE
251 /* If the architecture does DMA sg merging, make sure
252 we count with at least 64 entries even for HBAs
253 which handle very few sg entries. */
254 if (nents < 64) nents = 64;
255 #endif
256 new_dma_sectors += ((nents *
257 sizeof(struct scatterlist) + 511) >> 9) *
258 SDpnt->queue_depth;
259 if (SDpnt->type == TYPE_WORM || SDpnt->type == TYPE_ROM)
260 new_dma_sectors += (2048 >> 9) * SDpnt->queue_depth;
261 } else if (SDpnt->type == TYPE_SCANNER ||
262 SDpnt->type == TYPE_PROCESSOR ||
263 SDpnt->type == TYPE_COMM ||
264 SDpnt->type == TYPE_MEDIUM_CHANGER ||
265 SDpnt->type == TYPE_ENCLOSURE) {
266 new_dma_sectors += (4096 >> 9) * SDpnt->queue_depth;
267 } else {
268 if (SDpnt->type != TYPE_TAPE) {
269 printk("resize_dma_pool: unknown device type %d\n", SDpnt->type);
270 new_dma_sectors += (4096 >> 9) * SDpnt->queue_depth;
271 }
272 }
273
274 if (host->unchecked_isa_dma &&
275 need_isa_bounce_buffers &&
276 SDpnt->type != TYPE_TAPE) {
277 new_dma_sectors += (PAGE_SIZE >> 9) * host->sg_tablesize *
278 SDpnt->queue_depth;
279 new_need_isa_buffer++;
280 }
281 }
282 }
283
284 #ifdef DEBUG_INIT
285 printk("resize_dma_pool: needed dma sectors = %d\n", new_dma_sectors);
286 #endif
287
288 /* limit DMA memory to 32MB: */
289 new_dma_sectors = (new_dma_sectors + 15) & 0xfff0;
290
291 /*
292 * We never shrink the buffers - this leads to
293 * race conditions that I would rather not even think
294 * about right now.
295 */
296 #if 0 /* Why do this? No gain and risks out_of_space */
297 if (new_dma_sectors < dma_sectors)
298 new_dma_sectors = dma_sectors;
299 #endif
300 if (new_dma_sectors <= dma_sectors) {
301 spin_unlock_irqrestore(&allocator_request_lock, flags);
302 return; /* best to quit while we are in front */
303 }
304
305 for (k = 0; k < 20; ++k) { /* just in case */
306 out_of_space = 0;
307 size = (new_dma_sectors / SECTORS_PER_PAGE) *
308 sizeof(FreeSectorBitmap);
309 new_dma_malloc_freelist = (FreeSectorBitmap *)
310 kmalloc(size, GFP_ATOMIC);
311 if (new_dma_malloc_freelist) {
312 memset(new_dma_malloc_freelist, 0, size);
313 size = (new_dma_sectors / SECTORS_PER_PAGE) *
314 sizeof(*new_dma_malloc_pages);
315 new_dma_malloc_pages = (unsigned char **)
316 kmalloc(size, GFP_ATOMIC);
317 if (!new_dma_malloc_pages) {
318 size = (new_dma_sectors / SECTORS_PER_PAGE) *
319 sizeof(FreeSectorBitmap);
320 kfree((char *) new_dma_malloc_freelist);
321 out_of_space = 1;
322 } else {
323 memset(new_dma_malloc_pages, 0, size);
324 }
325 } else
326 out_of_space = 1;
327
328 if ((!out_of_space) && (new_dma_sectors > dma_sectors)) {
329 for (i = dma_sectors / SECTORS_PER_PAGE;
330 i < new_dma_sectors / SECTORS_PER_PAGE; i++) {
331 new_dma_malloc_pages[i] = (unsigned char *)
332 __get_free_pages(GFP_ATOMIC | GFP_DMA, 0);
333 if (!new_dma_malloc_pages[i])
334 break;
335 }
336 if (i != new_dma_sectors / SECTORS_PER_PAGE) { /* clean up */
337 int k = i;
338
339 out_of_space = 1;
340 for (i = 0; i < k; ++i)
341 free_pages((unsigned long) new_dma_malloc_pages[i], 0);
342 }
343 }
344 if (out_of_space) { /* try scaling down new_dma_sectors request */
345 printk("scsi::resize_dma_pool: WARNING, dma_sectors=%u, "
346 "wanted=%u, scaling\n", dma_sectors, new_dma_sectors);
347 if (new_dma_sectors < (8 * SECTORS_PER_PAGE))
348 break; /* pretty well hopeless ... */
349 new_dma_sectors = (new_dma_sectors * 3) / 4;
350 new_dma_sectors = (new_dma_sectors + 15) & 0xfff0;
351 if (new_dma_sectors <= dma_sectors)
352 break; /* stick with what we have got */
353 } else
354 break; /* found space ... */
355 } /* end of for loop */
356 if (out_of_space) {
357 spin_unlock_irqrestore(&allocator_request_lock, flags);
358 scsi_need_isa_buffer = new_need_isa_buffer; /* some useful info */
359 printk(" WARNING, not enough memory, pool not expanded\n");
360 return;
361 }
362 /* When we dick with the actual DMA list, we need to
363 * protect things
364 */
365 if (dma_malloc_freelist) {
366 size = (dma_sectors / SECTORS_PER_PAGE) * sizeof(FreeSectorBitmap);
367 memcpy(new_dma_malloc_freelist, dma_malloc_freelist, size);
368 kfree((char *) dma_malloc_freelist);
369 }
370 dma_malloc_freelist = new_dma_malloc_freelist;
371
372 if (dma_malloc_pages) {
373 size = (dma_sectors / SECTORS_PER_PAGE) * sizeof(*dma_malloc_pages);
374 memcpy(new_dma_malloc_pages, dma_malloc_pages, size);
375 kfree((char *) dma_malloc_pages);
376 }
377 scsi_dma_free_sectors += new_dma_sectors - dma_sectors;
378 dma_malloc_pages = new_dma_malloc_pages;
379 dma_sectors = new_dma_sectors;
380 scsi_need_isa_buffer = new_need_isa_buffer;
381
382 spin_unlock_irqrestore(&allocator_request_lock, flags);
383
384 #ifdef DEBUG_INIT
385 printk("resize_dma_pool: dma free sectors = %d\n", scsi_dma_free_sectors);
386 printk("resize_dma_pool: dma sectors = %d\n", dma_sectors);
387 printk("resize_dma_pool: need isa buffers = %d\n", scsi_need_isa_buffer);
388 #endif
389 }
390
391 /*
392 * Function: scsi_init_minimal_dma_pool
393 *
394 * Purpose: Allocate a minimal (1-page) DMA pool.
395 *
396 * Arguments: None.
397 *
398 * Lock status: No locks assumed to be held. This function is SMP-safe.
399 *
400 * Returns: Nothing
401 *
402 * Notes:
403 */
404 int scsi_init_minimal_dma_pool(void)
405 {
406 unsigned long size;
407 unsigned long flags;
408 int has_space = 0;
409
410 spin_lock_irqsave(&allocator_request_lock, flags);
411
412 dma_sectors = PAGE_SIZE / SECTOR_SIZE;
413 scsi_dma_free_sectors = dma_sectors;
414 /*
415 * Set up a minimal DMA buffer list - this will be used during scan_scsis
416 * in some cases.
417 */
418
419 /* One bit per sector to indicate free/busy */
420 size = (dma_sectors / SECTORS_PER_PAGE) * sizeof(FreeSectorBitmap);
421 dma_malloc_freelist = (FreeSectorBitmap *)
422 kmalloc(size, GFP_ATOMIC);
423 if (dma_malloc_freelist) {
424 memset(dma_malloc_freelist, 0, size);
425 /* One pointer per page for the page list */
426 dma_malloc_pages = (unsigned char **) kmalloc(
427 (dma_sectors / SECTORS_PER_PAGE) * sizeof(*dma_malloc_pages),
428 GFP_ATOMIC);
429 if (dma_malloc_pages) {
430 memset(dma_malloc_pages, 0, size);
431 dma_malloc_pages[0] = (unsigned char *)
432 __get_free_pages(GFP_ATOMIC | GFP_DMA, 0);
433 if (dma_malloc_pages[0])
434 has_space = 1;
435 }
436 }
437 if (!has_space) {
438 if (dma_malloc_freelist) {
439 kfree((char *) dma_malloc_freelist);
440 if (dma_malloc_pages)
441 kfree((char *) dma_malloc_pages);
442 }
443 spin_unlock_irqrestore(&allocator_request_lock, flags);
444 printk("scsi::init_module: failed, out of memory\n");
445 return 1;
446 }
447
448 spin_unlock_irqrestore(&allocator_request_lock, flags);
449 return 0;
450 }
451
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