regcache-rbtree.c revision c5713004b304e89c8c5117d8f226d5a1603571dc 
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/slab.h>
14#include <linux/rbtree.h>
15
16#include "internal.h"
17
18static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
19				 unsigned int value);
20
21struct regcache_rbtree_node {
22	/* the actual rbtree node holding this block */
23	struct rb_node node;
24	/* base register handled by this block */
25	unsigned int base_reg;
26	/* block of adjacent registers */
27	void *block;
28	/* number of registers available in the block */
29	unsigned int blklen;
30} __attribute__ ((packed));
31
32struct regcache_rbtree_ctx {
33	struct rb_root root;
34	struct regcache_rbtree_node *cached_rbnode;
35};
36
37static inline void regcache_rbtree_get_base_top_reg(
38	struct regcache_rbtree_node *rbnode,
39	unsigned int *base, unsigned int *top)
40{
41	*base = rbnode->base_reg;
42	*top = rbnode->base_reg + rbnode->blklen - 1;
43}
44
45static unsigned int regcache_rbtree_get_register(
46	struct regcache_rbtree_node *rbnode, unsigned int idx,
47	unsigned int word_size)
48{
49	return regcache_get_val(rbnode->block, idx, word_size);
50}
51
52static void regcache_rbtree_set_register(struct regcache_rbtree_node *rbnode,
53					 unsigned int idx, unsigned int val,
54					 unsigned int word_size)
55{
56	regcache_set_val(rbnode->block, idx, val, word_size);
57}
58
59static struct regcache_rbtree_node *regcache_rbtree_lookup(
60	struct rb_root *root, unsigned int reg)
61{
62	struct rb_node *node;
63	struct regcache_rbtree_node *rbnode;
64	unsigned int base_reg, top_reg;
65
66	node = root->rb_node;
67	while (node) {
68		rbnode = container_of(node, struct regcache_rbtree_node, node);
69		regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
70		if (reg >= base_reg && reg <= top_reg)
71			return rbnode;
72		else if (reg > top_reg)
73			node = node->rb_right;
74		else if (reg < base_reg)
75			node = node->rb_left;
76	}
77
78	return NULL;
79}
80
81static int regcache_rbtree_insert(struct rb_root *root,
82				  struct regcache_rbtree_node *rbnode)
83{
84	struct rb_node **new, *parent;
85	struct regcache_rbtree_node *rbnode_tmp;
86	unsigned int base_reg_tmp, top_reg_tmp;
87	unsigned int base_reg;
88
89	parent = NULL;
90	new = &root->rb_node;
91	while (*new) {
92		rbnode_tmp = container_of(*new, struct regcache_rbtree_node,
93					  node);
94		/* base and top registers of the current rbnode */
95		regcache_rbtree_get_base_top_reg(rbnode_tmp, &base_reg_tmp,
96						 &top_reg_tmp);
97		/* base register of the rbnode to be added */
98		base_reg = rbnode->base_reg;
99		parent = *new;
100		/* if this register has already been inserted, just return */
101		if (base_reg >= base_reg_tmp &&
102		    base_reg <= top_reg_tmp)
103			return 0;
104		else if (base_reg > top_reg_tmp)
105			new = &((*new)->rb_right);
106		else if (base_reg < base_reg_tmp)
107			new = &((*new)->rb_left);
108	}
109
110	/* insert the node into the rbtree */
111	rb_link_node(&rbnode->node, parent, new);
112	rb_insert_color(&rbnode->node, root);
113
114	return 1;
115}
116
117static int regcache_rbtree_init(struct regmap *map)
118{
119	struct regcache_rbtree_ctx *rbtree_ctx;
120	int i;
121	int ret;
122
123	map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
124	if (!map->cache)
125		return -ENOMEM;
126
127	rbtree_ctx = map->cache;
128	rbtree_ctx->root = RB_ROOT;
129	rbtree_ctx->cached_rbnode = NULL;
130
131	for (i = 0; i < map->num_reg_defaults; i++) {
132		ret = regcache_rbtree_write(map,
133					    map->reg_defaults[i].reg,
134					    map->reg_defaults[i].def);
135		if (ret)
136			goto err;
137	}
138
139	return 0;
140
141err:
142	regcache_exit(map);
143	return ret;
144}
145
146static int regcache_rbtree_exit(struct regmap *map)
147{
148	struct rb_node *next;
149	struct regcache_rbtree_ctx *rbtree_ctx;
150	struct regcache_rbtree_node *rbtree_node;
151
152	/* if we've already been called then just return */
153	rbtree_ctx = map->cache;
154	if (!rbtree_ctx)
155		return 0;
156
157	/* free up the rbtree */
158	next = rb_first(&rbtree_ctx->root);
159	while (next) {
160		rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
161		next = rb_next(&rbtree_node->node);
162		rb_erase(&rbtree_node->node, &rbtree_ctx->root);
163		kfree(rbtree_node->block);
164		kfree(rbtree_node);
165	}
166
167	/* release the resources */
168	kfree(map->cache);
169	map->cache = NULL;
170
171	return 0;
172}
173
174static int regcache_rbtree_read(struct regmap *map,
175				unsigned int reg, unsigned int *value)
176{
177	struct regcache_rbtree_ctx *rbtree_ctx;
178	struct regcache_rbtree_node *rbnode;
179	unsigned int base_reg, top_reg;
180	unsigned int reg_tmp;
181
182	rbtree_ctx = map->cache;
183	/* look up the required register in the cached rbnode */
184	rbnode = rbtree_ctx->cached_rbnode;
185	if (rbnode) {
186		regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
187		if (reg >= base_reg && reg <= top_reg) {
188			reg_tmp = reg - base_reg;
189			*value = regcache_rbtree_get_register(rbnode, reg_tmp,
190							      map->cache_word_size);
191			return 0;
192		}
193	}
194	/* if we can't locate it in the cached rbnode we'll have
195	 * to traverse the rbtree looking for it.
196	 */
197	rbnode = regcache_rbtree_lookup(&rbtree_ctx->root, reg);
198	if (rbnode) {
199		reg_tmp = reg - rbnode->base_reg;
200		*value = regcache_rbtree_get_register(rbnode, reg_tmp,
201						      map->cache_word_size);
202		rbtree_ctx->cached_rbnode = rbnode;
203	} else {
204		/* uninitialized registers default to 0 */
205		*value = 0;
206	}
207
208	return 0;
209}
210
211
212static int regcache_rbtree_insert_to_block(struct regcache_rbtree_node *rbnode,
213					   unsigned int pos, unsigned int reg,
214					   unsigned int value, unsigned int word_size)
215{
216	u8 *blk;
217
218	blk = krealloc(rbnode->block,
219		       (rbnode->blklen + 1) * word_size, GFP_KERNEL);
220	if (!blk)
221		return -ENOMEM;
222
223	/* insert the register value in the correct place in the rbnode block */
224	memmove(blk + (pos + 1) * word_size,
225		blk + pos * word_size,
226		(rbnode->blklen - pos) * word_size);
227
228	/* update the rbnode block, its size and the base register */
229	rbnode->block = blk;
230	rbnode->blklen++;
231	if (!pos)
232		rbnode->base_reg = reg;
233
234	regcache_rbtree_set_register(rbnode, pos, value, word_size);
235	return 0;
236}
237
238static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
239				 unsigned int value)
240{
241	struct regcache_rbtree_ctx *rbtree_ctx;
242	struct regcache_rbtree_node *rbnode, *rbnode_tmp;
243	struct rb_node *node;
244	unsigned int val;
245	unsigned int reg_tmp;
246	unsigned int base_reg, top_reg;
247	unsigned int pos;
248	int i;
249	int ret;
250
251	rbtree_ctx = map->cache;
252	/* look up the required register in the cached rbnode */
253	rbnode = rbtree_ctx->cached_rbnode;
254	if (rbnode) {
255		regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
256		if (reg >= base_reg && reg <= top_reg) {
257			reg_tmp = reg - base_reg;
258			val = regcache_rbtree_get_register(rbnode, reg_tmp,
259							   map->cache_word_size);
260			if (val == value)
261				return 0;
262			regcache_rbtree_set_register(rbnode, reg_tmp, value,
263						     map->cache_word_size);
264			return 0;
265		}
266	}
267	/* if we can't locate it in the cached rbnode we'll have
268	 * to traverse the rbtree looking for it.
269	 */
270	rbnode = regcache_rbtree_lookup(&rbtree_ctx->root, reg);
271	if (rbnode) {
272		reg_tmp = reg - rbnode->base_reg;
273		val = regcache_rbtree_get_register(rbnode, reg_tmp,
274						   map->cache_word_size);
275		if (val == value)
276			return 0;
277		regcache_rbtree_set_register(rbnode, reg_tmp, value,
278					     map->cache_word_size);
279		rbtree_ctx->cached_rbnode = rbnode;
280	} else {
281		/* bail out early, no need to create the rbnode yet */
282		if (!value)
283			return 0;
284		/* look for an adjacent register to the one we are about to add */
285		for (node = rb_first(&rbtree_ctx->root); node;
286		     node = rb_next(node)) {
287			rbnode_tmp = rb_entry(node, struct regcache_rbtree_node, node);
288			for (i = 0; i < rbnode_tmp->blklen; i++) {
289				reg_tmp = rbnode_tmp->base_reg + i;
290				if (abs(reg_tmp - reg) != 1)
291					continue;
292				/* decide where in the block to place our register */
293				if (reg_tmp + 1 == reg)
294					pos = i + 1;
295				else
296					pos = i;
297				ret = regcache_rbtree_insert_to_block(rbnode_tmp, pos,
298								      reg, value,
299								      map->cache_word_size);
300				if (ret)
301					return ret;
302				rbtree_ctx->cached_rbnode = rbnode_tmp;
303				return 0;
304			}
305		}
306		/* we did not manage to find a place to insert it in an existing
307		 * block so create a new rbnode with a single register in its block.
308		 * This block will get populated further if any other adjacent
309		 * registers get modified in the future.
310		 */
311		rbnode = kzalloc(sizeof *rbnode, GFP_KERNEL);
312		if (!rbnode)
313			return -ENOMEM;
314		rbnode->blklen = 1;
315		rbnode->base_reg = reg;
316		rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
317					GFP_KERNEL);
318		if (!rbnode->block) {
319			kfree(rbnode);
320			return -ENOMEM;
321		}
322		regcache_rbtree_set_register(rbnode, 0, value, map->cache_word_size);
323		regcache_rbtree_insert(&rbtree_ctx->root, rbnode);
324		rbtree_ctx->cached_rbnode = rbnode;
325	}
326
327	return 0;
328}
329
330static int regcache_rbtree_sync(struct regmap *map)
331{
332	struct regcache_rbtree_ctx *rbtree_ctx;
333	struct rb_node *node;
334	struct regcache_rbtree_node *rbnode;
335	unsigned int regtmp;
336	unsigned int val, def;
337	int ret;
338	int i;
339
340	rbtree_ctx = map->cache;
341	for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
342		rbnode = rb_entry(node, struct regcache_rbtree_node, node);
343		for (i = 0; i < rbnode->blklen; i++) {
344			regtmp = rbnode->base_reg + i;
345			val = regcache_rbtree_get_register(rbnode, i,
346							   map->cache_word_size);
347			ret = regcache_lookup_reg(map, i);
348			if (ret < 0)
349				def = 0;
350			else
351				def = map->reg_defaults[ret].def;
352			if (val == def)
353				continue;
354			map->cache_bypass = 1;
355			ret = regmap_write(map, regtmp, val);
356			map->cache_bypass = 0;
357			if (ret)
358				return ret;
359			dev_dbg(map->dev, "Synced register %#x, value %#x\n",
360				regtmp, val);
361		}
362	}
363
364	return 0;
365}
366
367struct regcache_ops regcache_rbtree_ops = {
368	.type = REGCACHE_RBTREE,
369	.name = "rbtree",
370	.init = regcache_rbtree_init,
371	.exit = regcache_rbtree_exit,
372	.read = regcache_rbtree_read,
373	.write = regcache_rbtree_write,
374	.sync = regcache_rbtree_sync
375};
376