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
17static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
18 unsigned int value);
19static int regcache_rbtree_exit(struct regmap *map);
20
21struct 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
34struct regcache_rbtree_ctx {
35 struct rb_root root;
36 struct regcache_rbtree_node *cached_rbnode;
37};
38
39static 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
48static 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, base: rbnode->block, idx);
52}
53
54static 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(nr: idx, addr: rbnode->cache_present);
59 regcache_set_val(map, base: rbnode->block, idx, val);
60}
61
62static 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: &base_reg,
73 top: &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: &base_reg,
82 top: &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
96static 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: rbnode_tmp, base: &base_reg_tmp,
110 top: &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(node: &rbnode->node, parent, rb_link: new);
126 rb_insert_color(&rbnode->node, root);
127
128 return 1;
129}
130
131#ifdef CONFIG_DEBUG_FS
132static 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, rbnode: n, base: &base, top: &top);
156 this_registers = ((top - base) / map->reg_stride) + 1;
157 seq_printf(m: s, fmt: "%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(m: s, fmt: "%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
176DEFINE_SHOW_ATTRIBUTE(rbtree);
177
178static void rbtree_debugfs_init(struct regmap *map)
179{
180 debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
181}
182#endif
183
184static 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, map->alloc_flags);
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 reg: map->reg_defaults[i].reg,
201 value: map->reg_defaults[i].def);
202 if (ret)
203 goto err;
204 }
205
206 return 0;
207
208err:
209 regcache_rbtree_exit(map);
210 return ret;
211}
212
213static 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(objp: rbtree_node->cache_present);
231 kfree(objp: rbtree_node->block);
232 kfree(objp: rbtree_node);
233 }
234
235 /* release the resources */
236 kfree(objp: map->cache);
237 map->cache = NULL;
238
239 return 0;
240}
241
242static 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, idx: reg_tmp);
254 } else {
255 return -ENOENT;
256 }
257
258 return 0;
259}
260
261
262static 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_array(rbnode->block, blklen, map->cache_word_size, map->alloc_flags);
279 if (!blk)
280 return -ENOMEM;
281
282 rbnode->block = blk;
283
284 if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
285 present = krealloc_array(rbnode->cache_present,
286 BITS_TO_LONGS(blklen), sizeof(*present),
287 map->alloc_flags);
288 if (!present)
289 return -ENOMEM;
290
291 memset(s: present + BITS_TO_LONGS(rbnode->blklen), c: 0,
292 n: (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
293 * sizeof(*present));
294 } else {
295 present = rbnode->cache_present;
296 }
297
298 /* insert the register value in the correct place in the rbnode block */
299 if (pos == 0) {
300 memmove(dest: blk + offset * map->cache_word_size,
301 src: blk, count: rbnode->blklen * map->cache_word_size);
302 bitmap_shift_left(dst: present, src: present, shift: offset, nbits: blklen);
303 }
304
305 /* update the rbnode block, its size and the base register */
306 rbnode->blklen = blklen;
307 rbnode->base_reg = base_reg;
308 rbnode->cache_present = present;
309
310 regcache_rbtree_set_register(map, rbnode, idx: pos, val: value);
311 return 0;
312}
313
314static struct regcache_rbtree_node *
315regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
316{
317 struct regcache_rbtree_node *rbnode;
318 const struct regmap_range *range;
319 int i;
320
321 rbnode = kzalloc(sizeof(*rbnode), map->alloc_flags);
322 if (!rbnode)
323 return NULL;
324
325 /* If there is a read table then use it to guess at an allocation */
326 if (map->rd_table) {
327 for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
328 if (regmap_reg_in_range(reg,
329 range: &map->rd_table->yes_ranges[i]))
330 break;
331 }
332
333 if (i != map->rd_table->n_yes_ranges) {
334 range = &map->rd_table->yes_ranges[i];
335 rbnode->blklen = (range->range_max - range->range_min) /
336 map->reg_stride + 1;
337 rbnode->base_reg = range->range_min;
338 }
339 }
340
341 if (!rbnode->blklen) {
342 rbnode->blklen = 1;
343 rbnode->base_reg = reg;
344 }
345
346 rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
347 map->alloc_flags);
348 if (!rbnode->block)
349 goto err_free;
350
351 rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
352 sizeof(*rbnode->cache_present),
353 map->alloc_flags);
354 if (!rbnode->cache_present)
355 goto err_free_block;
356
357 return rbnode;
358
359err_free_block:
360 kfree(objp: rbnode->block);
361err_free:
362 kfree(objp: rbnode);
363 return NULL;
364}
365
366static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
367 unsigned int value)
368{
369 struct regcache_rbtree_ctx *rbtree_ctx;
370 struct regcache_rbtree_node *rbnode, *rbnode_tmp;
371 struct rb_node *node;
372 unsigned int reg_tmp;
373 int ret;
374
375 rbtree_ctx = map->cache;
376
377 /* if we can't locate it in the cached rbnode we'll have
378 * to traverse the rbtree looking for it.
379 */
380 rbnode = regcache_rbtree_lookup(map, reg);
381 if (rbnode) {
382 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
383 regcache_rbtree_set_register(map, rbnode, idx: reg_tmp, val: value);
384 } else {
385 unsigned int base_reg, top_reg;
386 unsigned int new_base_reg, new_top_reg;
387 unsigned int min, max;
388 unsigned int max_dist;
389 unsigned int dist, best_dist = UINT_MAX;
390
391 max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
392 map->cache_word_size;
393 if (reg < max_dist)
394 min = 0;
395 else
396 min = reg - max_dist;
397 max = reg + max_dist;
398
399 /* look for an adjacent register to the one we are about to add */
400 node = rbtree_ctx->root.rb_node;
401 while (node) {
402 rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
403 node);
404
405 regcache_rbtree_get_base_top_reg(map, rbnode: rbnode_tmp,
406 base: &base_reg, top: &top_reg);
407
408 if (base_reg <= max && top_reg >= min) {
409 if (reg < base_reg)
410 dist = base_reg - reg;
411 else if (reg > top_reg)
412 dist = reg - top_reg;
413 else
414 dist = 0;
415 if (dist < best_dist) {
416 rbnode = rbnode_tmp;
417 best_dist = dist;
418 new_base_reg = min(reg, base_reg);
419 new_top_reg = max(reg, top_reg);
420 }
421 }
422
423 /*
424 * Keep looking, we want to choose the closest block,
425 * otherwise we might end up creating overlapping
426 * blocks, which breaks the rbtree.
427 */
428 if (reg < base_reg)
429 node = node->rb_left;
430 else if (reg > top_reg)
431 node = node->rb_right;
432 else
433 break;
434 }
435
436 if (rbnode) {
437 ret = regcache_rbtree_insert_to_block(map, rbnode,
438 base_reg: new_base_reg,
439 top_reg: new_top_reg, reg,
440 value);
441 if (ret)
442 return ret;
443 rbtree_ctx->cached_rbnode = rbnode;
444 return 0;
445 }
446
447 /* We did not manage to find a place to insert it in
448 * an existing block so create a new rbnode.
449 */
450 rbnode = regcache_rbtree_node_alloc(map, reg);
451 if (!rbnode)
452 return -ENOMEM;
453 regcache_rbtree_set_register(map, rbnode,
454 idx: (reg - rbnode->base_reg) / map->reg_stride,
455 val: value);
456 regcache_rbtree_insert(map, root: &rbtree_ctx->root, rbnode);
457 rbtree_ctx->cached_rbnode = rbnode;
458 }
459
460 return 0;
461}
462
463static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
464 unsigned int max)
465{
466 struct regcache_rbtree_ctx *rbtree_ctx;
467 struct rb_node *node;
468 struct regcache_rbtree_node *rbnode;
469 unsigned int base_reg, top_reg;
470 unsigned int start, end;
471 int ret;
472
473 map->async = true;
474
475 rbtree_ctx = map->cache;
476 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
477 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
478
479 regcache_rbtree_get_base_top_reg(map, rbnode, base: &base_reg,
480 top: &top_reg);
481 if (base_reg > max)
482 break;
483 if (top_reg < min)
484 continue;
485
486 if (min > base_reg)
487 start = (min - base_reg) / map->reg_stride;
488 else
489 start = 0;
490
491 if (max < top_reg)
492 end = (max - base_reg) / map->reg_stride + 1;
493 else
494 end = rbnode->blklen;
495
496 ret = regcache_sync_block(map, block: rbnode->block,
497 cache_present: rbnode->cache_present,
498 block_base: rbnode->base_reg, start, end);
499 if (ret != 0)
500 return ret;
501 }
502
503 map->async = false;
504
505 return regmap_async_complete(map);
506}
507
508static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
509 unsigned int max)
510{
511 struct regcache_rbtree_ctx *rbtree_ctx;
512 struct regcache_rbtree_node *rbnode;
513 struct rb_node *node;
514 unsigned int base_reg, top_reg;
515 unsigned int start, end;
516
517 rbtree_ctx = map->cache;
518 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
519 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
520
521 regcache_rbtree_get_base_top_reg(map, rbnode, base: &base_reg,
522 top: &top_reg);
523 if (base_reg > max)
524 break;
525 if (top_reg < min)
526 continue;
527
528 if (min > base_reg)
529 start = (min - base_reg) / map->reg_stride;
530 else
531 start = 0;
532
533 if (max < top_reg)
534 end = (max - base_reg) / map->reg_stride + 1;
535 else
536 end = rbnode->blklen;
537
538 bitmap_clear(map: rbnode->cache_present, start, nbits: end - start);
539 }
540
541 return 0;
542}
543
544struct regcache_ops regcache_rbtree_ops = {
545 .type = REGCACHE_RBTREE,
546 .name = "rbtree",
547 .init = regcache_rbtree_init,
548 .exit = regcache_rbtree_exit,
549#ifdef CONFIG_DEBUG_FS
550 .debugfs_init = rbtree_debugfs_init,
551#endif
552 .read = regcache_rbtree_read,
553 .write = regcache_rbtree_write,
554 .sync = regcache_rbtree_sync,
555 .drop = regcache_rbtree_drop,
556};
557