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(rbnode->blklen * map->cache_word_size,
365				GFP_KERNEL);
366	if (!rbnode->block)
367		goto err_free;
368
369	rbnode->cache_present = kzalloc(BITS_TO_LONGS(rbnode->blklen) *
370		sizeof(*rbnode->cache_present), 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
407		max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
408			map->cache_word_size;
409		if (reg < max_dist)
410			min = 0;
411		else
412			min = reg - max_dist;
413		max = reg + max_dist;
414
415		/* look for an adjacent register to the one we are about to add */
416		for (node = rb_first(&rbtree_ctx->root); node;
417		     node = rb_next(node)) {
418			rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
419					      node);
420
421			regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
422				&base_reg, &top_reg);
423
424			if (base_reg <= max && top_reg >= min) {
425				new_base_reg = min(reg, base_reg);
426				new_top_reg = max(reg, top_reg);
427			} else {
428				continue;
429			}
430
431			ret = regcache_rbtree_insert_to_block(map, rbnode_tmp,
432							      new_base_reg,
433							      new_top_reg, reg,
434							      value);
435			if (ret)
436				return ret;
437			rbtree_ctx->cached_rbnode = rbnode_tmp;
438			return 0;
439		}
440
441		/* We did not manage to find a place to insert it in
442		 * an existing block so create a new rbnode.
443		 */
444		rbnode = regcache_rbtree_node_alloc(map, reg);
445		if (!rbnode)
446			return -ENOMEM;
447		regcache_rbtree_set_register(map, rbnode,
448					     reg - rbnode->base_reg, value);
449		regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
450		rbtree_ctx->cached_rbnode = rbnode;
451	}
452
453	return 0;
454}
455
456static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
457				unsigned int max)
458{
459	struct regcache_rbtree_ctx *rbtree_ctx;
460	struct rb_node *node;
461	struct regcache_rbtree_node *rbnode;
462	unsigned int base_reg, top_reg;
463	unsigned int start, end;
464	int ret;
465
466	rbtree_ctx = map->cache;
467	for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
468		rbnode = rb_entry(node, struct regcache_rbtree_node, node);
469
470		regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
471			&top_reg);
472		if (base_reg > max)
473			break;
474		if (top_reg < min)
475			continue;
476
477		if (min > base_reg)
478			start = (min - base_reg) / map->reg_stride;
479		else
480			start = 0;
481
482		if (max < top_reg)
483			end = (max - base_reg) / map->reg_stride + 1;
484		else
485			end = rbnode->blklen;
486
487		ret = regcache_sync_block(map, rbnode->block,
488					  rbnode->cache_present,
489					  rbnode->base_reg, start, end);
490		if (ret != 0)
491			return ret;
492	}
493
494	return regmap_async_complete(map);
495}
496
497static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
498				unsigned int max)
499{
500	struct regcache_rbtree_ctx *rbtree_ctx;
501	struct regcache_rbtree_node *rbnode;
502	struct rb_node *node;
503	unsigned int base_reg, top_reg;
504	unsigned int start, end;
505
506	rbtree_ctx = map->cache;
507	for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
508		rbnode = rb_entry(node, struct regcache_rbtree_node, node);
509
510		regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
511			&top_reg);
512		if (base_reg > max)
513			break;
514		if (top_reg < min)
515			continue;
516
517		if (min > base_reg)
518			start = (min - base_reg) / map->reg_stride;
519		else
520			start = 0;
521
522		if (max < top_reg)
523			end = (max - base_reg) / map->reg_stride + 1;
524		else
525			end = rbnode->blklen;
526
527		bitmap_clear(rbnode->cache_present, start, end - start);
528	}
529
530	return 0;
531}
532
533struct regcache_ops regcache_rbtree_ops = {
534	.type = REGCACHE_RBTREE,
535	.name = "rbtree",
536	.init = regcache_rbtree_init,
537	.exit = regcache_rbtree_exit,
538#ifdef CONFIG_DEBUG_FS
539	.debugfs_init = rbtree_debugfs_init,
540#endif
541	.read = regcache_rbtree_read,
542	.write = regcache_rbtree_write,
543	.sync = regcache_rbtree_sync,
544	.drop = regcache_rbtree_drop,
545};
546