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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 = container_of(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 = container_of(*new, struct regcache_rbtree_node,
112 node);
113 /* base and top registers of the current rbnode */
114 regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
115 &top_reg_tmp);
116 /* base register of the rbnode to be added */
117 base_reg = rbnode->base_reg;
118 parent = *new;
119 /* if this register has already been inserted, just return */
120 if (base_reg >= base_reg_tmp &&
121 base_reg <= top_reg_tmp)
122 return 0;
123 else if (base_reg > top_reg_tmp)
124 new = &((*new)->rb_right);
125 else if (base_reg < base_reg_tmp)
126 new = &((*new)->rb_left);
127 }
128
129 /* insert the node into the rbtree */
130 rb_link_node(&rbnode->node, parent, new);
131 rb_insert_color(&rbnode->node, root);
132
133 return 1;
134}
135
136#ifdef CONFIG_DEBUG_FS
137static int rbtree_show(struct seq_file *s, void *ignored)
138{
139 struct regmap *map = s->private;
140 struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
141 struct regcache_rbtree_node *n;
142 struct rb_node *node;
143 unsigned int base, top;
144 size_t mem_size;
145 int nodes = 0;
146 int registers = 0;
147 int this_registers, average;
148
149 map->lock(map->lock_arg);
150
151 mem_size = sizeof(*rbtree_ctx);
152
153 for (node = rb_first(&rbtree_ctx->root); node != NULL;
154 node = rb_next(node)) {
155 n = container_of(node, struct regcache_rbtree_node, node);
156 mem_size += sizeof(*n);
157 mem_size += (n->blklen * map->cache_word_size);
158 mem_size += BITS_TO_LONGS(n->blklen) * sizeof(long);
159
160 regcache_rbtree_get_base_top_reg(map, n, &base, &top);
161 this_registers = ((top - base) / map->reg_stride) + 1;
162 seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
163
164 nodes++;
165 registers += this_registers;
166 }
167
168 if (nodes)
169 average = registers / nodes;
170 else
171 average = 0;
172
173 seq_printf(s, "%d nodes, %d registers, average %d registers, used %zu bytes\n",
174 nodes, registers, average, mem_size);
175
176 map->unlock(map->lock_arg);
177
178 return 0;
179}
180
181static int rbtree_open(struct inode *inode, struct file *file)
182{
183 return single_open(file, rbtree_show, inode->i_private);
184}
185
186static const struct file_operations rbtree_fops = {
187 .open = rbtree_open,
188 .read = seq_read,
189 .llseek = seq_lseek,
190 .release = single_release,
191};
192
193static void rbtree_debugfs_init(struct regmap *map)
194{
195 debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
196}
197#endif
198
199static int regcache_rbtree_init(struct regmap *map)
200{
201 struct regcache_rbtree_ctx *rbtree_ctx;
202 int i;
203 int ret;
204
205 map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
206 if (!map->cache)
207 return -ENOMEM;
208
209 rbtree_ctx = map->cache;
210 rbtree_ctx->root = RB_ROOT;
211 rbtree_ctx->cached_rbnode = NULL;
212
213 for (i = 0; i < map->num_reg_defaults; i++) {
214 ret = regcache_rbtree_write(map,
215 map->reg_defaults[i].reg,
216 map->reg_defaults[i].def);
217 if (ret)
218 goto err;
219 }
220
221 return 0;
222
223err:
224 regcache_rbtree_exit(map);
225 return ret;
226}
227
228static int regcache_rbtree_exit(struct regmap *map)
229{
230 struct rb_node *next;
231 struct regcache_rbtree_ctx *rbtree_ctx;
232 struct regcache_rbtree_node *rbtree_node;
233
234 /* if we've already been called then just return */
235 rbtree_ctx = map->cache;
236 if (!rbtree_ctx)
237 return 0;
238
239 /* free up the rbtree */
240 next = rb_first(&rbtree_ctx->root);
241 while (next) {
242 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
243 next = rb_next(&rbtree_node->node);
244 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
245 kfree(rbtree_node->cache_present);
246 kfree(rbtree_node->block);
247 kfree(rbtree_node);
248 }
249
250 /* release the resources */
251 kfree(map->cache);
252 map->cache = NULL;
253
254 return 0;
255}
256
257static int regcache_rbtree_read(struct regmap *map,
258 unsigned int reg, unsigned int *value)
259{
260 struct regcache_rbtree_node *rbnode;
261 unsigned int reg_tmp;
262
263 rbnode = regcache_rbtree_lookup(map, reg);
264 if (rbnode) {
265 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
266 if (!test_bit(reg_tmp, rbnode->cache_present))
267 return -ENOENT;
268 *value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
269 } else {
270 return -ENOENT;
271 }
272
273 return 0;
274}
275
276
277static int regcache_rbtree_insert_to_block(struct regmap *map,
278 struct regcache_rbtree_node *rbnode,
279 unsigned int base_reg,
280 unsigned int top_reg,
281 unsigned int reg,
282 unsigned int value)
283{
284 unsigned int blklen;
285 unsigned int pos, offset;
286 unsigned long *present;
287 u8 *blk;
288
289 blklen = (top_reg - base_reg) / map->reg_stride + 1;
290 pos = (reg - base_reg) / map->reg_stride;
291 offset = (rbnode->base_reg - base_reg) / map->reg_stride;
292
293 blk = krealloc(rbnode->block,
294 blklen * map->cache_word_size,
295 GFP_KERNEL);
296 if (!blk)
297 return -ENOMEM;
298
299 if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
300 present = krealloc(rbnode->cache_present,
301 BITS_TO_LONGS(blklen) * sizeof(*present),
302 GFP_KERNEL);
303 if (!present) {
304 kfree(blk);
305 return -ENOMEM;
306 }
307
308 memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
309 (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
310 * sizeof(*present));
311 } else {
312 present = rbnode->cache_present;
313 }
314
315 /* insert the register value in the correct place in the rbnode block */
316 if (pos == 0) {
317 memmove(blk + offset * map->cache_word_size,
318 blk, rbnode->blklen * map->cache_word_size);
319 bitmap_shift_left(present, present, offset, blklen);
320 }
321
322 /* update the rbnode block, its size and the base register */
323 rbnode->block = blk;
324 rbnode->blklen = blklen;
325 rbnode->base_reg = base_reg;
326 rbnode->cache_present = present;
327
328 regcache_rbtree_set_register(map, rbnode, pos, value);
329 return 0;
330}
331
332static struct regcache_rbtree_node *
333regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
334{
335 struct regcache_rbtree_node *rbnode;
336 const struct regmap_range *range;
337 int i;
338
339 rbnode = kzalloc(sizeof(*rbnode), GFP_KERNEL);
340 if (!rbnode)
341 return NULL;
342
343 /* If there is a read table then use it to guess at an allocation */
344 if (map->rd_table) {
345 for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
346 if (regmap_reg_in_range(reg,
347 &map->rd_table->yes_ranges[i]))
348 break;
349 }
350
351 if (i != map->rd_table->n_yes_ranges) {
352 range = &map->rd_table->yes_ranges[i];
353 rbnode->blklen = (range->range_max - range->range_min) /
354 map->reg_stride + 1;
355 rbnode->base_reg = range->range_min;
356 }
357 }
358
359 if (!rbnode->blklen) {
360 rbnode->blklen = 1;
361 rbnode->base_reg = reg;
362 }
363
364 rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
365 GFP_KERNEL);
366 if (!rbnode->block)
367 goto err_free;
368
369 rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
370 sizeof(*rbnode->cache_present),
371 GFP_KERNEL);
372 if (!rbnode->cache_present)
373 goto err_free_block;
374
375 return rbnode;
376
377err_free_block:
378 kfree(rbnode->block);
379err_free:
380 kfree(rbnode);
381 return NULL;
382}
383
384static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
385 unsigned int value)
386{
387 struct regcache_rbtree_ctx *rbtree_ctx;
388 struct regcache_rbtree_node *rbnode, *rbnode_tmp;
389 struct rb_node *node;
390 unsigned int reg_tmp;
391 int ret;
392
393 rbtree_ctx = map->cache;
394
395 /* if we can't locate it in the cached rbnode we'll have
396 * to traverse the rbtree looking for it.
397 */
398 rbnode = regcache_rbtree_lookup(map, reg);
399 if (rbnode) {
400 reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
401 regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
402 } else {
403 unsigned int base_reg, top_reg;
404 unsigned int new_base_reg, new_top_reg;
405 unsigned int min, max;
406 unsigned int max_dist;
407 unsigned int dist, best_dist = UINT_MAX;
408
409 max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
410 map->cache_word_size;
411 if (reg < max_dist)
412 min = 0;
413 else
414 min = reg - max_dist;
415 max = reg + max_dist;
416
417 /* look for an adjacent register to the one we are about to add */
418 node = rbtree_ctx->root.rb_node;
419 while (node) {
420 rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
421 node);
422
423 regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
424 &base_reg, &top_reg);
425
426 if (base_reg <= max && top_reg >= min) {
427 if (reg < base_reg)
428 dist = base_reg - reg;
429 else if (reg > top_reg)
430 dist = reg - top_reg;
431 else
432 dist = 0;
433 if (dist < best_dist) {
434 rbnode = rbnode_tmp;
435 best_dist = dist;
436 new_base_reg = min(reg, base_reg);
437 new_top_reg = max(reg, top_reg);
438 }
439 }
440
441 /*
442 * Keep looking, we want to choose the closest block,
443 * otherwise we might end up creating overlapping
444 * blocks, which breaks the rbtree.
445 */
446 if (reg < base_reg)
447 node = node->rb_left;
448 else if (reg > top_reg)
449 node = node->rb_right;
450 else
451 break;
452 }
453
454 if (rbnode) {
455 ret = regcache_rbtree_insert_to_block(map, rbnode,
456 new_base_reg,
457 new_top_reg, reg,
458 value);
459 if (ret)
460 return ret;
461 rbtree_ctx->cached_rbnode = rbnode;
462 return 0;
463 }
464
465 /* We did not manage to find a place to insert it in
466 * an existing block so create a new rbnode.
467 */
468 rbnode = regcache_rbtree_node_alloc(map, reg);
469 if (!rbnode)
470 return -ENOMEM;
471 regcache_rbtree_set_register(map, rbnode,
472 reg - rbnode->base_reg, value);
473 regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
474 rbtree_ctx->cached_rbnode = rbnode;
475 }
476
477 return 0;
478}
479
480static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
481 unsigned int max)
482{
483 struct regcache_rbtree_ctx *rbtree_ctx;
484 struct rb_node *node;
485 struct regcache_rbtree_node *rbnode;
486 unsigned int base_reg, top_reg;
487 unsigned int start, end;
488 int ret;
489
490 rbtree_ctx = map->cache;
491 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
492 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
493
494 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
495 &top_reg);
496 if (base_reg > max)
497 break;
498 if (top_reg < min)
499 continue;
500
501 if (min > base_reg)
502 start = (min - base_reg) / map->reg_stride;
503 else
504 start = 0;
505
506 if (max < top_reg)
507 end = (max - base_reg) / map->reg_stride + 1;
508 else
509 end = rbnode->blklen;
510
511 ret = regcache_sync_block(map, rbnode->block,
512 rbnode->cache_present,
513 rbnode->base_reg, start, end);
514 if (ret != 0)
515 return ret;
516 }
517
518 return regmap_async_complete(map);
519}
520
521static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
522 unsigned int max)
523{
524 struct regcache_rbtree_ctx *rbtree_ctx;
525 struct regcache_rbtree_node *rbnode;
526 struct rb_node *node;
527 unsigned int base_reg, top_reg;
528 unsigned int start, end;
529
530 rbtree_ctx = map->cache;
531 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
532 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
533
534 regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
535 &top_reg);
536 if (base_reg > max)
537 break;
538 if (top_reg < min)
539 continue;
540
541 if (min > base_reg)
542 start = (min - base_reg) / map->reg_stride;
543 else
544 start = 0;
545
546 if (max < top_reg)
547 end = (max - base_reg) / map->reg_stride + 1;
548 else
549 end = rbnode->blklen;
550
551 bitmap_clear(rbnode->cache_present, start, end - start);
552 }
553
554 return 0;
555}
556
557struct regcache_ops regcache_rbtree_ops = {
558 .type = REGCACHE_RBTREE,
559 .name = "rbtree",
560 .init = regcache_rbtree_init,
561 .exit = regcache_rbtree_exit,
562#ifdef CONFIG_DEBUG_FS
563 .debugfs_init = rbtree_debugfs_init,
564#endif
565 .read = regcache_rbtree_read,
566 .write = regcache_rbtree_write,
567 .sync = regcache_rbtree_sync,
568 .drop = regcache_rbtree_drop,
569};