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1/*
2 * Register cache access API - rbtree caching support
3 *
4 * Copyright 2011 Wolfson Microelectronics plc
5 *
6 * Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/debugfs.h>
14#include <linux/device.h>
15#include <linux/rbtree.h>
16#include <linux/seq_file.h>
17#include <linux/slab.h>
18
19#include "internal.h"
20
21static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
22 unsigned int value);
23static int regcache_rbtree_exit(struct regmap *map);
24
25struct regcache_rbtree_node {
26 /* block of adjacent registers */
27 void *block;
28 /* Which registers are present */
29 long *cache_present;
30 /* base register handled by this block */
31 unsigned int base_reg;
32 /* number of registers available in the block */
33 unsigned int blklen;
34 /* the actual rbtree node holding this block */
35 struct rb_node node;
36} __attribute__ ((packed));
37
38struct regcache_rbtree_ctx {
39 struct rb_root root;
40 struct regcache_rbtree_node *cached_rbnode;
41};
42
43static inline void regcache_rbtree_get_base_top_reg(
44 struct regmap *map,
45 struct regcache_rbtree_node *rbnode,
46 unsigned int *base, unsigned int *top)
47{
48 *base = rbnode->base_reg;
49 *top = rbnode->base_reg + ((rbnode->blklen - 1) * map->reg_stride);
50}
51
52static unsigned int regcache_rbtree_get_register(struct regmap *map,
53 struct regcache_rbtree_node *rbnode, unsigned int idx)
54{
55 return regcache_get_val(map, rbnode->block, idx);
56}
57
58static void regcache_rbtree_set_register(struct regmap *map,
59 struct regcache_rbtree_node *rbnode,
60 unsigned int idx, unsigned int val)
61{
62 set_bit(idx, rbnode->cache_present);
63 regcache_set_val(map, rbnode->block, idx, val);
64}
65
66static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
67 unsigned int reg)
68{
69 struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
70 struct rb_node *node;
71 struct regcache_rbtree_node *rbnode;
72 unsigned int base_reg, top_reg;
73
74 rbnode = rbtree_ctx->cached_rbnode;
75 if (rbnode) {
76 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
77 &top_reg);
78 if (reg >= base_reg && reg <= top_reg)
79 return rbnode;
80 }
81
82 node = rbtree_ctx->root.rb_node;
83 while (node) {
84 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
85 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
86 &top_reg);
87 if (reg >= base_reg && reg <= top_reg) {
88 rbtree_ctx->cached_rbnode = rbnode;
89 return rbnode;
90 } else if (reg > top_reg) {
91 node = node->rb_right;
92 } else if (reg < base_reg) {
93 node = node->rb_left;
94 }
95 }
96
97 return NULL;
98}
99
100static int regcache_rbtree_insert(struct regmap *map, struct rb_root *root,
101 struct regcache_rbtree_node *rbnode)
102{
103 struct rb_node **new, *parent;
104 struct regcache_rbtree_node *rbnode_tmp;
105 unsigned int base_reg_tmp, top_reg_tmp;
106 unsigned int base_reg;
107
108 parent = NULL;
109 new = &root->rb_node;
110 while (*new) {
111 rbnode_tmp = rb_entry(*new, struct regcache_rbtree_node, node);
112 /* base and top registers of the current rbnode */
113 regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
114 &top_reg_tmp);
115 /* base register of the rbnode to be added */
116 base_reg = rbnode->base_reg;
117 parent = *new;
118 /* if this register has already been inserted, just return */
119 if (base_reg >= base_reg_tmp &&
120 base_reg <= top_reg_tmp)
121 return 0;
122 else if (base_reg > top_reg_tmp)
123 new = &((*new)->rb_right);
124 else if (base_reg < base_reg_tmp)
125 new = &((*new)->rb_left);
126 }
127
128 /* insert the node into the rbtree */
129 rb_link_node(&rbnode->node, parent, new);
130 rb_insert_color(&rbnode->node, root);
131
132 return 1;
133}
134
135#ifdef CONFIG_DEBUG_FS
136static int rbtree_show(struct seq_file *s, void *ignored)
137{
138 struct regmap *map = s->private;
139 struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
140 struct regcache_rbtree_node *n;
141 struct rb_node *node;
142 unsigned int base, top;
143 size_t mem_size;
144 int nodes = 0;
145 int registers = 0;
146 int this_registers, average;
147
148 map->lock(map->lock_arg);
149
150 mem_size = sizeof(*rbtree_ctx);
151
152 for (node = rb_first(&rbtree_ctx->root); node != NULL;
153 node = rb_next(node)) {
154 n = rb_entry(node, struct regcache_rbtree_node, node);
155 mem_size += sizeof(*n);
156 mem_size += (n->blklen * map->cache_word_size);
157 mem_size += BITS_TO_LONGS(n->blklen) * sizeof(long);
158
159 regcache_rbtree_get_base_top_reg(map, n, &base, &top);
160 this_registers = ((top - base) / map->reg_stride) + 1;
161 seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
162
163 nodes++;
164 registers += this_registers;
165 }
166
167 if (nodes)
168 average = registers / nodes;
169 else
170 average = 0;
171
172 seq_printf(s, "%d nodes, %d registers, average %d registers, used %zu bytes\n",
173 nodes, registers, average, mem_size);
174
175 map->unlock(map->lock_arg);
176
177 return 0;
178}
179
180static int rbtree_open(struct inode *inode, struct file *file)
181{
182 return single_open(file, rbtree_show, inode->i_private);
183}
184
185static const struct file_operations rbtree_fops = {
186 .open = rbtree_open,
187 .read = seq_read,
188 .llseek = seq_lseek,
189 .release = single_release,
190};
191
192static void rbtree_debugfs_init(struct regmap *map)
193{
194 debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
195}
196#endif
197
198static int regcache_rbtree_init(struct regmap *map)
199{
200 struct regcache_rbtree_ctx *rbtree_ctx;
201 int i;
202 int ret;
203
204 map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
205 if (!map->cache)
206 return -ENOMEM;
207
208 rbtree_ctx = map->cache;
209 rbtree_ctx->root = RB_ROOT;
210 rbtree_ctx->cached_rbnode = NULL;
211
212 for (i = 0; i < map->num_reg_defaults; i++) {
213 ret = regcache_rbtree_write(map,
214 map->reg_defaults[i].reg,
215 map->reg_defaults[i].def);
216 if (ret)
217 goto err;
218 }
219
220 return 0;
221
222err:
223 regcache_rbtree_exit(map);
224 return ret;
225}
226
227static int regcache_rbtree_exit(struct regmap *map)
228{
229 struct rb_node *next;
230 struct regcache_rbtree_ctx *rbtree_ctx;
231 struct regcache_rbtree_node *rbtree_node;
232
233 /* if we've already been called then just return */
234 rbtree_ctx = map->cache;
235 if (!rbtree_ctx)
236 return 0;
237
238 /* free up the rbtree */
239 next = rb_first(&rbtree_ctx->root);
240 while (next) {
241 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
242 next = rb_next(&rbtree_node->node);
243 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
244 kfree(rbtree_node->cache_present);
245 kfree(rbtree_node->block);
246 kfree(rbtree_node);
247 }
248
249 /* release the resources */
250 kfree(map->cache);
251 map->cache = NULL;
252
253 return 0;
254}
255
256static int regcache_rbtree_read(struct regmap *map,
257 unsigned int reg, unsigned int *value)
258{
259 struct regcache_rbtree_node *rbnode;
260 unsigned int reg_tmp;
261
262 rbnode = regcache_rbtree_lookup(map, reg);
263 if (rbnode) {
264 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
265 if (!test_bit(reg_tmp, rbnode->cache_present))
266 return -ENOENT;
267 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
268 } else {
269 return -ENOENT;
270 }
271
272 return 0;
273}
274
275
276static int regcache_rbtree_insert_to_block(struct regmap *map,
277 struct regcache_rbtree_node *rbnode,
278 unsigned int base_reg,
279 unsigned int top_reg,
280 unsigned int reg,
281 unsigned int value)
282{
283 unsigned int blklen;
284 unsigned int pos, offset;
285 unsigned long *present;
286 u8 *blk;
287
288 blklen = (top_reg - base_reg) / map->reg_stride + 1;
289 pos = (reg - base_reg) / map->reg_stride;
290 offset = (rbnode->base_reg - base_reg) / map->reg_stride;
291
292 blk = krealloc(rbnode->block,
293 blklen * map->cache_word_size,
294 GFP_KERNEL);
295 if (!blk)
296 return -ENOMEM;
297
298 if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
299 present = krealloc(rbnode->cache_present,
300 BITS_TO_LONGS(blklen) * sizeof(*present),
301 GFP_KERNEL);
302 if (!present) {
303 kfree(blk);
304 return -ENOMEM;
305 }
306
307 memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
308 (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
309 * sizeof(*present));
310 } else {
311 present = rbnode->cache_present;
312 }
313
314 /* insert the register value in the correct place in the rbnode block */
315 if (pos == 0) {
316 memmove(blk + offset * map->cache_word_size,
317 blk, rbnode->blklen * map->cache_word_size);
318 bitmap_shift_left(present, present, offset, blklen);
319 }
320
321 /* update the rbnode block, its size and the base register */
322 rbnode->block = blk;
323 rbnode->blklen = blklen;
324 rbnode->base_reg = base_reg;
325 rbnode->cache_present = present;
326
327 regcache_rbtree_set_register(map, rbnode, pos, value);
328 return 0;
329}
330
331static struct regcache_rbtree_node *
332regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
333{
334 struct regcache_rbtree_node *rbnode;
335 const struct regmap_range *range;
336 int i;
337
338 rbnode = kzalloc(sizeof(*rbnode), GFP_KERNEL);
339 if (!rbnode)
340 return NULL;
341
342 /* If there is a read table then use it to guess at an allocation */
343 if (map->rd_table) {
344 for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
345 if (regmap_reg_in_range(reg,
346 &map->rd_table->yes_ranges[i]))
347 break;
348 }
349
350 if (i != map->rd_table->n_yes_ranges) {
351 range = &map->rd_table->yes_ranges[i];
352 rbnode->blklen = (range->range_max - range->range_min) /
353 map->reg_stride + 1;
354 rbnode->base_reg = range->range_min;
355 }
356 }
357
358 if (!rbnode->blklen) {
359 rbnode->blklen = 1;
360 rbnode->base_reg = reg;
361 }
362
363 rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
364 GFP_KERNEL);
365 if (!rbnode->block)
366 goto err_free;
367
368 rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
369 sizeof(*rbnode->cache_present),
370 GFP_KERNEL);
371 if (!rbnode->cache_present)
372 goto err_free_block;
373
374 return rbnode;
375
376err_free_block:
377 kfree(rbnode->block);
378err_free:
379 kfree(rbnode);
380 return NULL;
381}
382
383static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
384 unsigned int value)
385{
386 struct regcache_rbtree_ctx *rbtree_ctx;
387 struct regcache_rbtree_node *rbnode, *rbnode_tmp;
388 struct rb_node *node;
389 unsigned int reg_tmp;
390 int ret;
391
392 rbtree_ctx = map->cache;
393
394 /* if we can't locate it in the cached rbnode we'll have
395 * to traverse the rbtree looking for it.
396 */
397 rbnode = regcache_rbtree_lookup(map, reg);
398 if (rbnode) {
399 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
400 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
401 } else {
402 unsigned int base_reg, top_reg;
403 unsigned int new_base_reg, new_top_reg;
404 unsigned int min, max;
405 unsigned int max_dist;
406 unsigned int dist, best_dist = UINT_MAX;
407
408 max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
409 map->cache_word_size;
410 if (reg < max_dist)
411 min = 0;
412 else
413 min = reg - max_dist;
414 max = reg + max_dist;
415
416 /* look for an adjacent register to the one we are about to add */
417 node = rbtree_ctx->root.rb_node;
418 while (node) {
419 rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
420 node);
421
422 regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
423 &base_reg, &top_reg);
424
425 if (base_reg <= max && top_reg >= min) {
426 if (reg < base_reg)
427 dist = base_reg - reg;
428 else if (reg > top_reg)
429 dist = reg - top_reg;
430 else
431 dist = 0;
432 if (dist < best_dist) {
433 rbnode = rbnode_tmp;
434 best_dist = dist;
435 new_base_reg = min(reg, base_reg);
436 new_top_reg = max(reg, top_reg);
437 }
438 }
439
440 /*
441 * Keep looking, we want to choose the closest block,
442 * otherwise we might end up creating overlapping
443 * blocks, which breaks the rbtree.
444 */
445 if (reg < base_reg)
446 node = node->rb_left;
447 else if (reg > top_reg)
448 node = node->rb_right;
449 else
450 break;
451 }
452
453 if (rbnode) {
454 ret = regcache_rbtree_insert_to_block(map, rbnode,
455 new_base_reg,
456 new_top_reg, reg,
457 value);
458 if (ret)
459 return ret;
460 rbtree_ctx->cached_rbnode = rbnode;
461 return 0;
462 }
463
464 /* We did not manage to find a place to insert it in
465 * an existing block so create a new rbnode.
466 */
467 rbnode = regcache_rbtree_node_alloc(map, reg);
468 if (!rbnode)
469 return -ENOMEM;
470 regcache_rbtree_set_register(map, rbnode,
471 reg - rbnode->base_reg, value);
472 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
473 rbtree_ctx->cached_rbnode = rbnode;
474 }
475
476 return 0;
477}
478
479static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
480 unsigned int max)
481{
482 struct regcache_rbtree_ctx *rbtree_ctx;
483 struct rb_node *node;
484 struct regcache_rbtree_node *rbnode;
485 unsigned int base_reg, top_reg;
486 unsigned int start, end;
487 int ret;
488
489 rbtree_ctx = map->cache;
490 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
491 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
492
493 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
494 &top_reg);
495 if (base_reg > max)
496 break;
497 if (top_reg < min)
498 continue;
499
500 if (min > base_reg)
501 start = (min - base_reg) / map->reg_stride;
502 else
503 start = 0;
504
505 if (max < top_reg)
506 end = (max - base_reg) / map->reg_stride + 1;
507 else
508 end = rbnode->blklen;
509
510 ret = regcache_sync_block(map, rbnode->block,
511 rbnode->cache_present,
512 rbnode->base_reg, start, end);
513 if (ret != 0)
514 return ret;
515 }
516
517 return regmap_async_complete(map);
518}
519
520static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
521 unsigned int max)
522{
523 struct regcache_rbtree_ctx *rbtree_ctx;
524 struct regcache_rbtree_node *rbnode;
525 struct rb_node *node;
526 unsigned int base_reg, top_reg;
527 unsigned int start, end;
528
529 rbtree_ctx = map->cache;
530 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
531 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
532
533 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
534 &top_reg);
535 if (base_reg > max)
536 break;
537 if (top_reg < min)
538 continue;
539
540 if (min > base_reg)
541 start = (min - base_reg) / map->reg_stride;
542 else
543 start = 0;
544
545 if (max < top_reg)
546 end = (max - base_reg) / map->reg_stride + 1;
547 else
548 end = rbnode->blklen;
549
550 bitmap_clear(rbnode->cache_present, start, end - start);
551 }
552
553 return 0;
554}
555
556struct regcache_ops regcache_rbtree_ops = {
557 .type = REGCACHE_RBTREE,
558 .name = "rbtree",
559 .init = regcache_rbtree_init,
560 .exit = regcache_rbtree_exit,
561#ifdef CONFIG_DEBUG_FS
562 .debugfs_init = rbtree_debugfs_init,
563#endif
564 .read = regcache_rbtree_read,
565 .write = regcache_rbtree_write,
566 .sync = regcache_rbtree_sync,
567 .drop = regcache_rbtree_drop,
568};