1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // Register cache access API - rbtree caching support
4 //
5 // Copyright 2011 Wolfson Microelectronics plc
6 //
7 // Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
8
9 #include <linux/debugfs.h>
10 #include <linux/device.h>
11 #include <linux/rbtree.h>
12 #include <linux/seq_file.h>
13 #include <linux/slab.h>
14
15 #include "internal.h"
16
17 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
18 unsigned int value);
19 static int regcache_rbtree_exit(struct regmap *map);
20
21 struct regcache_rbtree_node {
22 /* block of adjacent registers */
23 void *block;
24 /* Which registers are present */
25 unsigned long *cache_present;
26 /* base register handled by this block */
27 unsigned int base_reg;
28 /* number of registers available in the block */
29 unsigned int blklen;
30 /* the actual rbtree node holding this block */
31 struct rb_node node;
32 };
33
34 struct regcache_rbtree_ctx {
35 struct rb_root root;
36 struct regcache_rbtree_node *cached_rbnode;
37 };
38
regcache_rbtree_get_base_top_reg(struct regmap * map,struct regcache_rbtree_node * rbnode,unsigned int * base,unsigned int * top)39 static inline void regcache_rbtree_get_base_top_reg(
40 struct regmap *map,
41 struct regcache_rbtree_node *rbnode,
42 unsigned int *base, unsigned int *top)
43 {
44 *base = rbnode->base_reg;
45 *top = rbnode->base_reg + ((rbnode->blklen - 1) * map->reg_stride);
46 }
47
regcache_rbtree_get_register(struct regmap * map,struct regcache_rbtree_node * rbnode,unsigned int idx)48 static unsigned int regcache_rbtree_get_register(struct regmap *map,
49 struct regcache_rbtree_node *rbnode, unsigned int idx)
50 {
51 return regcache_get_val(map, rbnode->block, idx);
52 }
53
regcache_rbtree_set_register(struct regmap * map,struct regcache_rbtree_node * rbnode,unsigned int idx,unsigned int val)54 static void regcache_rbtree_set_register(struct regmap *map,
55 struct regcache_rbtree_node *rbnode,
56 unsigned int idx, unsigned int val)
57 {
58 set_bit(idx, rbnode->cache_present);
59 regcache_set_val(map, rbnode->block, idx, val);
60 }
61
regcache_rbtree_lookup(struct regmap * map,unsigned int reg)62 static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
63 unsigned int reg)
64 {
65 struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
66 struct rb_node *node;
67 struct regcache_rbtree_node *rbnode;
68 unsigned int base_reg, top_reg;
69
70 rbnode = rbtree_ctx->cached_rbnode;
71 if (rbnode) {
72 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
73 &top_reg);
74 if (reg >= base_reg && reg <= top_reg)
75 return rbnode;
76 }
77
78 node = rbtree_ctx->root.rb_node;
79 while (node) {
80 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
81 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
82 &top_reg);
83 if (reg >= base_reg && reg <= top_reg) {
84 rbtree_ctx->cached_rbnode = rbnode;
85 return rbnode;
86 } else if (reg > top_reg) {
87 node = node->rb_right;
88 } else if (reg < base_reg) {
89 node = node->rb_left;
90 }
91 }
92
93 return NULL;
94 }
95
regcache_rbtree_insert(struct regmap * map,struct rb_root * root,struct regcache_rbtree_node * rbnode)96 static int regcache_rbtree_insert(struct regmap *map, struct rb_root *root,
97 struct regcache_rbtree_node *rbnode)
98 {
99 struct rb_node **new, *parent;
100 struct regcache_rbtree_node *rbnode_tmp;
101 unsigned int base_reg_tmp, top_reg_tmp;
102 unsigned int base_reg;
103
104 parent = NULL;
105 new = &root->rb_node;
106 while (*new) {
107 rbnode_tmp = rb_entry(*new, struct regcache_rbtree_node, node);
108 /* base and top registers of the current rbnode */
109 regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
110 &top_reg_tmp);
111 /* base register of the rbnode to be added */
112 base_reg = rbnode->base_reg;
113 parent = *new;
114 /* if this register has already been inserted, just return */
115 if (base_reg >= base_reg_tmp &&
116 base_reg <= top_reg_tmp)
117 return 0;
118 else if (base_reg > top_reg_tmp)
119 new = &((*new)->rb_right);
120 else if (base_reg < base_reg_tmp)
121 new = &((*new)->rb_left);
122 }
123
124 /* insert the node into the rbtree */
125 rb_link_node(&rbnode->node, parent, new);
126 rb_insert_color(&rbnode->node, root);
127
128 return 1;
129 }
130
131 #ifdef CONFIG_DEBUG_FS
rbtree_show(struct seq_file * s,void * ignored)132 static int rbtree_show(struct seq_file *s, void *ignored)
133 {
134 struct regmap *map = s->private;
135 struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
136 struct regcache_rbtree_node *n;
137 struct rb_node *node;
138 unsigned int base, top;
139 size_t mem_size;
140 int nodes = 0;
141 int registers = 0;
142 int this_registers, average;
143
144 map->lock(map->lock_arg);
145
146 mem_size = sizeof(*rbtree_ctx);
147
148 for (node = rb_first(&rbtree_ctx->root); node != NULL;
149 node = rb_next(node)) {
150 n = rb_entry(node, struct regcache_rbtree_node, node);
151 mem_size += sizeof(*n);
152 mem_size += (n->blklen * map->cache_word_size);
153 mem_size += BITS_TO_LONGS(n->blklen) * sizeof(long);
154
155 regcache_rbtree_get_base_top_reg(map, n, &base, &top);
156 this_registers = ((top - base) / map->reg_stride) + 1;
157 seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
158
159 nodes++;
160 registers += this_registers;
161 }
162
163 if (nodes)
164 average = registers / nodes;
165 else
166 average = 0;
167
168 seq_printf(s, "%d nodes, %d registers, average %d registers, used %zu bytes\n",
169 nodes, registers, average, mem_size);
170
171 map->unlock(map->lock_arg);
172
173 return 0;
174 }
175
176 DEFINE_SHOW_ATTRIBUTE(rbtree);
177
rbtree_debugfs_init(struct regmap * map)178 static void rbtree_debugfs_init(struct regmap *map)
179 {
180 debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
181 }
182 #endif
183
regcache_rbtree_init(struct regmap * map)184 static int regcache_rbtree_init(struct regmap *map)
185 {
186 struct regcache_rbtree_ctx *rbtree_ctx;
187 int i;
188 int ret;
189
190 map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
191 if (!map->cache)
192 return -ENOMEM;
193
194 rbtree_ctx = map->cache;
195 rbtree_ctx->root = RB_ROOT;
196 rbtree_ctx->cached_rbnode = NULL;
197
198 for (i = 0; i < map->num_reg_defaults; i++) {
199 ret = regcache_rbtree_write(map,
200 map->reg_defaults[i].reg,
201 map->reg_defaults[i].def);
202 if (ret)
203 goto err;
204 }
205
206 return 0;
207
208 err:
209 regcache_rbtree_exit(map);
210 return ret;
211 }
212
regcache_rbtree_exit(struct regmap * map)213 static int regcache_rbtree_exit(struct regmap *map)
214 {
215 struct rb_node *next;
216 struct regcache_rbtree_ctx *rbtree_ctx;
217 struct regcache_rbtree_node *rbtree_node;
218
219 /* if we've already been called then just return */
220 rbtree_ctx = map->cache;
221 if (!rbtree_ctx)
222 return 0;
223
224 /* free up the rbtree */
225 next = rb_first(&rbtree_ctx->root);
226 while (next) {
227 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
228 next = rb_next(&rbtree_node->node);
229 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
230 kfree(rbtree_node->cache_present);
231 kfree(rbtree_node->block);
232 kfree(rbtree_node);
233 }
234
235 /* release the resources */
236 kfree(map->cache);
237 map->cache = NULL;
238
239 return 0;
240 }
241
regcache_rbtree_read(struct regmap * map,unsigned int reg,unsigned int * value)242 static int regcache_rbtree_read(struct regmap *map,
243 unsigned int reg, unsigned int *value)
244 {
245 struct regcache_rbtree_node *rbnode;
246 unsigned int reg_tmp;
247
248 rbnode = regcache_rbtree_lookup(map, reg);
249 if (rbnode) {
250 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
251 if (!test_bit(reg_tmp, rbnode->cache_present))
252 return -ENOENT;
253 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
254 } else {
255 return -ENOENT;
256 }
257
258 return 0;
259 }
260
261
regcache_rbtree_insert_to_block(struct regmap * map,struct regcache_rbtree_node * rbnode,unsigned int base_reg,unsigned int top_reg,unsigned int reg,unsigned int value)262 static int regcache_rbtree_insert_to_block(struct regmap *map,
263 struct regcache_rbtree_node *rbnode,
264 unsigned int base_reg,
265 unsigned int top_reg,
266 unsigned int reg,
267 unsigned int value)
268 {
269 unsigned int blklen;
270 unsigned int pos, offset;
271 unsigned long *present;
272 u8 *blk;
273
274 blklen = (top_reg - base_reg) / map->reg_stride + 1;
275 pos = (reg - base_reg) / map->reg_stride;
276 offset = (rbnode->base_reg - base_reg) / map->reg_stride;
277
278 blk = krealloc(rbnode->block,
279 blklen * map->cache_word_size,
280 map->alloc_flags);
281 if (!blk)
282 return -ENOMEM;
283
284 rbnode->block = blk;
285
286 if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
287 present = krealloc(rbnode->cache_present,
288 BITS_TO_LONGS(blklen) * sizeof(*present),
289 map->alloc_flags);
290 if (!present)
291 return -ENOMEM;
292
293 memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
294 (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
295 * sizeof(*present));
296 } else {
297 present = rbnode->cache_present;
298 }
299
300 /* insert the register value in the correct place in the rbnode block */
301 if (pos == 0) {
302 memmove(blk + offset * map->cache_word_size,
303 blk, rbnode->blklen * map->cache_word_size);
304 bitmap_shift_left(present, present, offset, blklen);
305 }
306
307 /* update the rbnode block, its size and the base register */
308 rbnode->blklen = blklen;
309 rbnode->base_reg = base_reg;
310 rbnode->cache_present = present;
311
312 regcache_rbtree_set_register(map, rbnode, pos, value);
313 return 0;
314 }
315
316 static struct regcache_rbtree_node *
regcache_rbtree_node_alloc(struct regmap * map,unsigned int reg)317 regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
318 {
319 struct regcache_rbtree_node *rbnode;
320 const struct regmap_range *range;
321 int i;
322
323 rbnode = kzalloc(sizeof(*rbnode), map->alloc_flags);
324 if (!rbnode)
325 return NULL;
326
327 /* If there is a read table then use it to guess at an allocation */
328 if (map->rd_table) {
329 for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
330 if (regmap_reg_in_range(reg,
331 &map->rd_table->yes_ranges[i]))
332 break;
333 }
334
335 if (i != map->rd_table->n_yes_ranges) {
336 range = &map->rd_table->yes_ranges[i];
337 rbnode->blklen = (range->range_max - range->range_min) /
338 map->reg_stride + 1;
339 rbnode->base_reg = range->range_min;
340 }
341 }
342
343 if (!rbnode->blklen) {
344 rbnode->blklen = 1;
345 rbnode->base_reg = reg;
346 }
347
348 rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
349 map->alloc_flags);
350 if (!rbnode->block)
351 goto err_free;
352
353 rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
354 sizeof(*rbnode->cache_present),
355 map->alloc_flags);
356 if (!rbnode->cache_present)
357 goto err_free_block;
358
359 return rbnode;
360
361 err_free_block:
362 kfree(rbnode->block);
363 err_free:
364 kfree(rbnode);
365 return NULL;
366 }
367
regcache_rbtree_write(struct regmap * map,unsigned int reg,unsigned int value)368 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
369 unsigned int value)
370 {
371 struct regcache_rbtree_ctx *rbtree_ctx;
372 struct regcache_rbtree_node *rbnode, *rbnode_tmp;
373 struct rb_node *node;
374 unsigned int reg_tmp;
375 int ret;
376
377 rbtree_ctx = map->cache;
378
379 /* if we can't locate it in the cached rbnode we'll have
380 * to traverse the rbtree looking for it.
381 */
382 rbnode = regcache_rbtree_lookup(map, reg);
383 if (rbnode) {
384 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
385 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
386 } else {
387 unsigned int base_reg, top_reg;
388 unsigned int new_base_reg, new_top_reg;
389 unsigned int min, max;
390 unsigned int max_dist;
391 unsigned int dist, best_dist = UINT_MAX;
392
393 max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
394 map->cache_word_size;
395 if (reg < max_dist)
396 min = 0;
397 else
398 min = reg - max_dist;
399 max = reg + max_dist;
400
401 /* look for an adjacent register to the one we are about to add */
402 node = rbtree_ctx->root.rb_node;
403 while (node) {
404 rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
405 node);
406
407 regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
408 &base_reg, &top_reg);
409
410 if (base_reg <= max && top_reg >= min) {
411 if (reg < base_reg)
412 dist = base_reg - reg;
413 else if (reg > top_reg)
414 dist = reg - top_reg;
415 else
416 dist = 0;
417 if (dist < best_dist) {
418 rbnode = rbnode_tmp;
419 best_dist = dist;
420 new_base_reg = min(reg, base_reg);
421 new_top_reg = max(reg, top_reg);
422 }
423 }
424
425 /*
426 * Keep looking, we want to choose the closest block,
427 * otherwise we might end up creating overlapping
428 * blocks, which breaks the rbtree.
429 */
430 if (reg < base_reg)
431 node = node->rb_left;
432 else if (reg > top_reg)
433 node = node->rb_right;
434 else
435 break;
436 }
437
438 if (rbnode) {
439 ret = regcache_rbtree_insert_to_block(map, rbnode,
440 new_base_reg,
441 new_top_reg, reg,
442 value);
443 if (ret)
444 return ret;
445 rbtree_ctx->cached_rbnode = rbnode;
446 return 0;
447 }
448
449 /* We did not manage to find a place to insert it in
450 * an existing block so create a new rbnode.
451 */
452 rbnode = regcache_rbtree_node_alloc(map, reg);
453 if (!rbnode)
454 return -ENOMEM;
455 regcache_rbtree_set_register(map, rbnode,
456 (reg - rbnode->base_reg) / map->reg_stride,
457 value);
458 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
459 rbtree_ctx->cached_rbnode = rbnode;
460 }
461
462 return 0;
463 }
464
regcache_rbtree_sync(struct regmap * map,unsigned int min,unsigned int max)465 static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
466 unsigned int max)
467 {
468 struct regcache_rbtree_ctx *rbtree_ctx;
469 struct rb_node *node;
470 struct regcache_rbtree_node *rbnode;
471 unsigned int base_reg, top_reg;
472 unsigned int start, end;
473 int ret;
474
475 map->async = true;
476
477 rbtree_ctx = map->cache;
478 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
479 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
480
481 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
482 &top_reg);
483 if (base_reg > max)
484 break;
485 if (top_reg < min)
486 continue;
487
488 if (min > base_reg)
489 start = (min - base_reg) / map->reg_stride;
490 else
491 start = 0;
492
493 if (max < top_reg)
494 end = (max - base_reg) / map->reg_stride + 1;
495 else
496 end = rbnode->blklen;
497
498 ret = regcache_sync_block(map, rbnode->block,
499 rbnode->cache_present,
500 rbnode->base_reg, start, end);
501 if (ret != 0)
502 return ret;
503 }
504
505 map->async = false;
506
507 return regmap_async_complete(map);
508 }
509
regcache_rbtree_drop(struct regmap * map,unsigned int min,unsigned int max)510 static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
511 unsigned int max)
512 {
513 struct regcache_rbtree_ctx *rbtree_ctx;
514 struct regcache_rbtree_node *rbnode;
515 struct rb_node *node;
516 unsigned int base_reg, top_reg;
517 unsigned int start, end;
518
519 rbtree_ctx = map->cache;
520 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
521 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
522
523 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
524 &top_reg);
525 if (base_reg > max)
526 break;
527 if (top_reg < min)
528 continue;
529
530 if (min > base_reg)
531 start = (min - base_reg) / map->reg_stride;
532 else
533 start = 0;
534
535 if (max < top_reg)
536 end = (max - base_reg) / map->reg_stride + 1;
537 else
538 end = rbnode->blklen;
539
540 bitmap_clear(rbnode->cache_present, start, end - start);
541 }
542
543 return 0;
544 }
545
546 struct regcache_ops regcache_rbtree_ops = {
547 .type = REGCACHE_RBTREE,
548 .name = "rbtree",
549 .init = regcache_rbtree_init,
550 .exit = regcache_rbtree_exit,
551 #ifdef CONFIG_DEBUG_FS
552 .debugfs_init = rbtree_debugfs_init,
553 #endif
554 .read = regcache_rbtree_read,
555 .write = regcache_rbtree_write,
556 .sync = regcache_rbtree_sync,
557 .drop = regcache_rbtree_drop,
558 };
559