1 /*
2 * comedi_buf.c
3 *
4 * COMEDI - Linux Control and Measurement Device Interface
5 * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22 #include "comedidev.h"
23 #include "comedi_internal.h"
24
25 #ifdef PAGE_KERNEL_NOCACHE
26 #define COMEDI_PAGE_PROTECTION PAGE_KERNEL_NOCACHE
27 #else
28 #define COMEDI_PAGE_PROTECTION PAGE_KERNEL
29 #endif
30
__comedi_buf_free(struct comedi_device * dev,struct comedi_subdevice * s,unsigned n_pages)31 static void __comedi_buf_free(struct comedi_device *dev,
32 struct comedi_subdevice *s,
33 unsigned n_pages)
34 {
35 struct comedi_async *async = s->async;
36 struct comedi_buf_page *buf;
37 unsigned i;
38
39 if (async->prealloc_buf) {
40 vunmap(async->prealloc_buf);
41 async->prealloc_buf = NULL;
42 async->prealloc_bufsz = 0;
43 }
44
45 if (!async->buf_page_list)
46 return;
47
48 for (i = 0; i < n_pages; ++i) {
49 buf = &async->buf_page_list[i];
50 if (buf->virt_addr) {
51 clear_bit(PG_reserved,
52 &(virt_to_page(buf->virt_addr)->flags));
53 if (s->async_dma_dir != DMA_NONE) {
54 #ifdef CONFIG_HAS_DMA
55 dma_free_coherent(dev->hw_dev,
56 PAGE_SIZE,
57 buf->virt_addr,
58 buf->dma_addr);
59 #endif
60 } else {
61 free_page((unsigned long)buf->virt_addr);
62 }
63 }
64 }
65 vfree(async->buf_page_list);
66 async->buf_page_list = NULL;
67 async->n_buf_pages = 0;
68 }
69
__comedi_buf_alloc(struct comedi_device * dev,struct comedi_subdevice * s,unsigned n_pages)70 static void __comedi_buf_alloc(struct comedi_device *dev,
71 struct comedi_subdevice *s,
72 unsigned n_pages)
73 {
74 struct comedi_async *async = s->async;
75 struct page **pages = NULL;
76 struct comedi_buf_page *buf;
77 unsigned i;
78
79 if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {
80 dev_err(dev->class_dev,
81 "dma buffer allocation not supported\n");
82 return;
83 }
84
85 async->buf_page_list = vzalloc(sizeof(*buf) * n_pages);
86 if (async->buf_page_list)
87 pages = vmalloc(sizeof(struct page *) * n_pages);
88
89 if (!pages)
90 return;
91
92 for (i = 0; i < n_pages; i++) {
93 buf = &async->buf_page_list[i];
94 if (s->async_dma_dir != DMA_NONE)
95 #ifdef CONFIG_HAS_DMA
96 buf->virt_addr = dma_alloc_coherent(dev->hw_dev,
97 PAGE_SIZE,
98 &buf->dma_addr,
99 GFP_KERNEL |
100 __GFP_COMP);
101 #else
102 break;
103 #endif
104 else
105 buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);
106 if (!buf->virt_addr)
107 break;
108
109 set_bit(PG_reserved, &(virt_to_page(buf->virt_addr)->flags));
110
111 pages[i] = virt_to_page(buf->virt_addr);
112 }
113
114 /* vmap the prealloc_buf if all the pages were allocated */
115 if (i == n_pages)
116 async->prealloc_buf = vmap(pages, n_pages, VM_MAP,
117 COMEDI_PAGE_PROTECTION);
118
119 vfree(pages);
120 }
121
comedi_buf_alloc(struct comedi_device * dev,struct comedi_subdevice * s,unsigned long new_size)122 int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
123 unsigned long new_size)
124 {
125 struct comedi_async *async = s->async;
126
127 /* Round up new_size to multiple of PAGE_SIZE */
128 new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;
129
130 /* if no change is required, do nothing */
131 if (async->prealloc_buf && async->prealloc_bufsz == new_size)
132 return 0;
133
134 /* deallocate old buffer */
135 __comedi_buf_free(dev, s, async->n_buf_pages);
136
137 /* allocate new buffer */
138 if (new_size) {
139 unsigned n_pages = new_size >> PAGE_SHIFT;
140
141 __comedi_buf_alloc(dev, s, n_pages);
142
143 if (!async->prealloc_buf) {
144 /* allocation failed */
145 __comedi_buf_free(dev, s, n_pages);
146 return -ENOMEM;
147 }
148 async->n_buf_pages = n_pages;
149 }
150 async->prealloc_bufsz = new_size;
151
152 return 0;
153 }
154
comedi_buf_reset(struct comedi_async * async)155 void comedi_buf_reset(struct comedi_async *async)
156 {
157 async->buf_write_alloc_count = 0;
158 async->buf_write_count = 0;
159 async->buf_read_alloc_count = 0;
160 async->buf_read_count = 0;
161
162 async->buf_write_ptr = 0;
163 async->buf_read_ptr = 0;
164
165 async->cur_chan = 0;
166 async->scan_progress = 0;
167 async->munge_chan = 0;
168 async->munge_count = 0;
169 async->munge_ptr = 0;
170
171 async->events = 0;
172 }
173
comedi_buf_write_n_available(struct comedi_async * async)174 static unsigned int comedi_buf_write_n_available(struct comedi_async *async)
175 {
176 unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
177
178 return free_end - async->buf_write_alloc_count;
179 }
180
__comedi_buf_write_alloc(struct comedi_async * async,unsigned int nbytes,int strict)181 static unsigned int __comedi_buf_write_alloc(struct comedi_async *async,
182 unsigned int nbytes,
183 int strict)
184 {
185 unsigned int available = comedi_buf_write_n_available(async);
186
187 if (nbytes > available)
188 nbytes = strict ? 0 : available;
189
190 async->buf_write_alloc_count += nbytes;
191
192 /*
193 * ensure the async buffer 'counts' are read and updated
194 * before we write data to the write-alloc'ed buffer space
195 */
196 smp_mb();
197
198 return nbytes;
199 }
200
201 /* allocates chunk for the writer from free buffer space */
comedi_buf_write_alloc(struct comedi_async * async,unsigned int nbytes)202 unsigned int comedi_buf_write_alloc(struct comedi_async *async,
203 unsigned int nbytes)
204 {
205 return __comedi_buf_write_alloc(async, nbytes, 0);
206 }
207 EXPORT_SYMBOL_GPL(comedi_buf_write_alloc);
208
209 /*
210 * munging is applied to data by core as it passes between user
211 * and kernel space
212 */
comedi_buf_munge(struct comedi_async * async,unsigned int num_bytes)213 static unsigned int comedi_buf_munge(struct comedi_async *async,
214 unsigned int num_bytes)
215 {
216 struct comedi_subdevice *s = async->subdevice;
217 unsigned int count = 0;
218 const unsigned num_sample_bytes = bytes_per_sample(s);
219
220 if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {
221 async->munge_count += num_bytes;
222 count = num_bytes;
223 } else {
224 /* don't munge partial samples */
225 num_bytes -= num_bytes % num_sample_bytes;
226 while (count < num_bytes) {
227 int block_size = num_bytes - count;
228 unsigned int buf_end;
229
230 buf_end = async->prealloc_bufsz - async->munge_ptr;
231 if (block_size > buf_end)
232 block_size = buf_end;
233
234 s->munge(s->device, s,
235 async->prealloc_buf + async->munge_ptr,
236 block_size, async->munge_chan);
237
238 /*
239 * ensure data is munged in buffer before the
240 * async buffer munge_count is incremented
241 */
242 smp_wmb();
243
244 async->munge_chan += block_size / num_sample_bytes;
245 async->munge_chan %= async->cmd.chanlist_len;
246 async->munge_count += block_size;
247 async->munge_ptr += block_size;
248 async->munge_ptr %= async->prealloc_bufsz;
249 count += block_size;
250 }
251 }
252
253 return count;
254 }
255
comedi_buf_write_n_allocated(struct comedi_async * async)256 unsigned int comedi_buf_write_n_allocated(struct comedi_async *async)
257 {
258 return async->buf_write_alloc_count - async->buf_write_count;
259 }
260
261 /* transfers a chunk from writer to filled buffer space */
comedi_buf_write_free(struct comedi_async * async,unsigned int nbytes)262 unsigned int comedi_buf_write_free(struct comedi_async *async,
263 unsigned int nbytes)
264 {
265 unsigned int allocated = comedi_buf_write_n_allocated(async);
266
267 if (nbytes > allocated)
268 nbytes = allocated;
269
270 async->buf_write_count += nbytes;
271 async->buf_write_ptr += nbytes;
272 comedi_buf_munge(async, async->buf_write_count - async->munge_count);
273 if (async->buf_write_ptr >= async->prealloc_bufsz)
274 async->buf_write_ptr %= async->prealloc_bufsz;
275
276 return nbytes;
277 }
278 EXPORT_SYMBOL_GPL(comedi_buf_write_free);
279
comedi_buf_read_n_available(struct comedi_async * async)280 unsigned int comedi_buf_read_n_available(struct comedi_async *async)
281 {
282 unsigned num_bytes;
283
284 if (!async)
285 return 0;
286
287 num_bytes = async->munge_count - async->buf_read_count;
288
289 /*
290 * ensure the async buffer 'counts' are read before we
291 * attempt to read data from the buffer
292 */
293 smp_rmb();
294
295 return num_bytes;
296 }
297 EXPORT_SYMBOL_GPL(comedi_buf_read_n_available);
298
299 /* allocates a chunk for the reader from filled (and munged) buffer space */
comedi_buf_read_alloc(struct comedi_async * async,unsigned int nbytes)300 unsigned int comedi_buf_read_alloc(struct comedi_async *async,
301 unsigned int nbytes)
302 {
303 unsigned int available;
304
305 available = async->munge_count - async->buf_read_alloc_count;
306 if (nbytes > available)
307 nbytes = available;
308
309 async->buf_read_alloc_count += nbytes;
310
311 /*
312 * ensure the async buffer 'counts' are read before we
313 * attempt to read data from the read-alloc'ed buffer space
314 */
315 smp_rmb();
316
317 return nbytes;
318 }
319 EXPORT_SYMBOL_GPL(comedi_buf_read_alloc);
320
comedi_buf_read_n_allocated(struct comedi_async * async)321 static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async)
322 {
323 return async->buf_read_alloc_count - async->buf_read_count;
324 }
325
326 /* transfers control of a chunk from reader to free buffer space */
comedi_buf_read_free(struct comedi_async * async,unsigned int nbytes)327 unsigned int comedi_buf_read_free(struct comedi_async *async,
328 unsigned int nbytes)
329 {
330 unsigned int allocated;
331
332 /*
333 * ensure data has been read out of buffer before
334 * the async read count is incremented
335 */
336 smp_mb();
337
338 allocated = comedi_buf_read_n_allocated(async);
339 if (nbytes > allocated)
340 nbytes = allocated;
341
342 async->buf_read_count += nbytes;
343 async->buf_read_ptr += nbytes;
344 async->buf_read_ptr %= async->prealloc_bufsz;
345 return nbytes;
346 }
347 EXPORT_SYMBOL_GPL(comedi_buf_read_free);
348
comedi_buf_put(struct comedi_async * async,short x)349 int comedi_buf_put(struct comedi_async *async, short x)
350 {
351 unsigned int n = __comedi_buf_write_alloc(async, sizeof(short), 1);
352
353 if (n < sizeof(short)) {
354 async->events |= COMEDI_CB_ERROR;
355 return 0;
356 }
357 *(short *)(async->prealloc_buf + async->buf_write_ptr) = x;
358 comedi_buf_write_free(async, sizeof(short));
359 return 1;
360 }
361 EXPORT_SYMBOL_GPL(comedi_buf_put);
362
comedi_buf_get(struct comedi_async * async,short * x)363 int comedi_buf_get(struct comedi_async *async, short *x)
364 {
365 unsigned int n = comedi_buf_read_n_available(async);
366
367 if (n < sizeof(short))
368 return 0;
369 comedi_buf_read_alloc(async, sizeof(short));
370 *x = *(short *)(async->prealloc_buf + async->buf_read_ptr);
371 comedi_buf_read_free(async, sizeof(short));
372 return 1;
373 }
374 EXPORT_SYMBOL_GPL(comedi_buf_get);
375
comedi_buf_memcpy_to(struct comedi_async * async,unsigned int offset,const void * data,unsigned int num_bytes)376 void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
377 const void *data, unsigned int num_bytes)
378 {
379 unsigned int write_ptr = async->buf_write_ptr + offset;
380
381 if (write_ptr >= async->prealloc_bufsz)
382 write_ptr %= async->prealloc_bufsz;
383
384 while (num_bytes) {
385 unsigned int block_size;
386
387 if (write_ptr + num_bytes > async->prealloc_bufsz)
388 block_size = async->prealloc_bufsz - write_ptr;
389 else
390 block_size = num_bytes;
391
392 memcpy(async->prealloc_buf + write_ptr, data, block_size);
393
394 data += block_size;
395 num_bytes -= block_size;
396
397 write_ptr = 0;
398 }
399 }
400 EXPORT_SYMBOL_GPL(comedi_buf_memcpy_to);
401
comedi_buf_memcpy_from(struct comedi_async * async,unsigned int offset,void * dest,unsigned int nbytes)402 void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
403 void *dest, unsigned int nbytes)
404 {
405 void *src;
406 unsigned int read_ptr = async->buf_read_ptr + offset;
407
408 if (read_ptr >= async->prealloc_bufsz)
409 read_ptr %= async->prealloc_bufsz;
410
411 while (nbytes) {
412 unsigned int block_size;
413
414 src = async->prealloc_buf + read_ptr;
415
416 if (nbytes >= async->prealloc_bufsz - read_ptr)
417 block_size = async->prealloc_bufsz - read_ptr;
418 else
419 block_size = nbytes;
420
421 memcpy(dest, src, block_size);
422 nbytes -= block_size;
423 dest += block_size;
424 read_ptr = 0;
425 }
426 }
427 EXPORT_SYMBOL_GPL(comedi_buf_memcpy_from);
428