2 * Register cache access API - rbtree caching support
4 * Copyright 2011 Wolfson Microelectronics plc
6 * Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
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.
13 #include <linux/slab.h>
14 #include <linux/rbtree.h>
18 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
21 struct regcache_rbtree_node {
22 /* the actual rbtree node holding this block */
24 /* base register handled by this block */
25 unsigned int base_reg;
26 /* block of adjacent registers */
28 /* number of registers available in the block */
30 } __attribute__ ((packed));
32 struct regcache_rbtree_ctx {
34 struct regcache_rbtree_node *cached_rbnode;
37 static inline void regcache_rbtree_get_base_top_reg(
38 struct regcache_rbtree_node *rbnode,
39 unsigned int *base, unsigned int *top)
41 *base = rbnode->base_reg;
42 *top = rbnode->base_reg + rbnode->blklen - 1;
45 static unsigned int regcache_rbtree_get_register(
46 struct regcache_rbtree_node *rbnode, unsigned int idx,
47 unsigned int word_size)
49 return regcache_get_val(rbnode->block, idx, word_size);
52 static void regcache_rbtree_set_register(struct regcache_rbtree_node *rbnode,
53 unsigned int idx, unsigned int val,
54 unsigned int word_size)
56 regcache_set_val(rbnode->block, idx, val, word_size);
59 static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
62 struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
64 struct regcache_rbtree_node *rbnode;
65 unsigned int base_reg, top_reg;
67 rbnode = rbtree_ctx->cached_rbnode;
69 regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
70 if (reg >= base_reg && reg <= top_reg)
74 node = rbtree_ctx->root.rb_node;
76 rbnode = container_of(node, struct regcache_rbtree_node, node);
77 regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
78 if (reg >= base_reg && reg <= top_reg) {
79 rbtree_ctx->cached_rbnode = rbnode;
81 } else if (reg > top_reg) {
82 node = node->rb_right;
83 } else if (reg < base_reg) {
91 static int regcache_rbtree_insert(struct rb_root *root,
92 struct regcache_rbtree_node *rbnode)
94 struct rb_node **new, *parent;
95 struct regcache_rbtree_node *rbnode_tmp;
96 unsigned int base_reg_tmp, top_reg_tmp;
97 unsigned int base_reg;
100 new = &root->rb_node;
102 rbnode_tmp = container_of(*new, struct regcache_rbtree_node,
104 /* base and top registers of the current rbnode */
105 regcache_rbtree_get_base_top_reg(rbnode_tmp, &base_reg_tmp,
107 /* base register of the rbnode to be added */
108 base_reg = rbnode->base_reg;
110 /* if this register has already been inserted, just return */
111 if (base_reg >= base_reg_tmp &&
112 base_reg <= top_reg_tmp)
114 else if (base_reg > top_reg_tmp)
115 new = &((*new)->rb_right);
116 else if (base_reg < base_reg_tmp)
117 new = &((*new)->rb_left);
120 /* insert the node into the rbtree */
121 rb_link_node(&rbnode->node, parent, new);
122 rb_insert_color(&rbnode->node, root);
127 static int regcache_rbtree_init(struct regmap *map)
129 struct regcache_rbtree_ctx *rbtree_ctx;
133 map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
137 rbtree_ctx = map->cache;
138 rbtree_ctx->root = RB_ROOT;
139 rbtree_ctx->cached_rbnode = NULL;
141 for (i = 0; i < map->num_reg_defaults; i++) {
142 ret = regcache_rbtree_write(map,
143 map->reg_defaults[i].reg,
144 map->reg_defaults[i].def);
156 static int regcache_rbtree_exit(struct regmap *map)
158 struct rb_node *next;
159 struct regcache_rbtree_ctx *rbtree_ctx;
160 struct regcache_rbtree_node *rbtree_node;
162 /* if we've already been called then just return */
163 rbtree_ctx = map->cache;
167 /* free up the rbtree */
168 next = rb_first(&rbtree_ctx->root);
170 rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
171 next = rb_next(&rbtree_node->node);
172 rb_erase(&rbtree_node->node, &rbtree_ctx->root);
173 kfree(rbtree_node->block);
177 /* release the resources */
184 static int regcache_rbtree_read(struct regmap *map,
185 unsigned int reg, unsigned int *value)
187 struct regcache_rbtree_node *rbnode;
188 unsigned int reg_tmp;
190 rbnode = regcache_rbtree_lookup(map, reg);
192 reg_tmp = reg - rbnode->base_reg;
193 *value = regcache_rbtree_get_register(rbnode, reg_tmp,
194 map->cache_word_size);
203 static int regcache_rbtree_insert_to_block(struct regcache_rbtree_node *rbnode,
204 unsigned int pos, unsigned int reg,
205 unsigned int value, unsigned int word_size)
209 blk = krealloc(rbnode->block,
210 (rbnode->blklen + 1) * word_size, GFP_KERNEL);
214 /* insert the register value in the correct place in the rbnode block */
215 memmove(blk + (pos + 1) * word_size,
216 blk + pos * word_size,
217 (rbnode->blklen - pos) * word_size);
219 /* update the rbnode block, its size and the base register */
223 rbnode->base_reg = reg;
225 regcache_rbtree_set_register(rbnode, pos, value, word_size);
229 static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
232 struct regcache_rbtree_ctx *rbtree_ctx;
233 struct regcache_rbtree_node *rbnode, *rbnode_tmp;
234 struct rb_node *node;
236 unsigned int reg_tmp;
241 rbtree_ctx = map->cache;
242 /* if we can't locate it in the cached rbnode we'll have
243 * to traverse the rbtree looking for it.
245 rbnode = regcache_rbtree_lookup(map, reg);
247 reg_tmp = reg - rbnode->base_reg;
248 val = regcache_rbtree_get_register(rbnode, reg_tmp,
249 map->cache_word_size);
252 regcache_rbtree_set_register(rbnode, reg_tmp, value,
253 map->cache_word_size);
255 /* look for an adjacent register to the one we are about to add */
256 for (node = rb_first(&rbtree_ctx->root); node;
257 node = rb_next(node)) {
258 rbnode_tmp = rb_entry(node, struct regcache_rbtree_node, node);
259 for (i = 0; i < rbnode_tmp->blklen; i++) {
260 reg_tmp = rbnode_tmp->base_reg + i;
261 if (abs(reg_tmp - reg) != 1)
263 /* decide where in the block to place our register */
264 if (reg_tmp + 1 == reg)
268 ret = regcache_rbtree_insert_to_block(rbnode_tmp, pos,
270 map->cache_word_size);
273 rbtree_ctx->cached_rbnode = rbnode_tmp;
277 /* we did not manage to find a place to insert it in an existing
278 * block so create a new rbnode with a single register in its block.
279 * This block will get populated further if any other adjacent
280 * registers get modified in the future.
282 rbnode = kzalloc(sizeof *rbnode, GFP_KERNEL);
286 rbnode->base_reg = reg;
287 rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
289 if (!rbnode->block) {
293 regcache_rbtree_set_register(rbnode, 0, value, map->cache_word_size);
294 regcache_rbtree_insert(&rbtree_ctx->root, rbnode);
295 rbtree_ctx->cached_rbnode = rbnode;
301 static int regcache_rbtree_sync(struct regmap *map)
303 struct regcache_rbtree_ctx *rbtree_ctx;
304 struct rb_node *node;
305 struct regcache_rbtree_node *rbnode;
311 rbtree_ctx = map->cache;
312 for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
313 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
314 for (i = 0; i < rbnode->blklen; i++) {
315 regtmp = rbnode->base_reg + i;
316 val = regcache_rbtree_get_register(rbnode, i,
317 map->cache_word_size);
319 /* Is this the hardware default? If so skip. */
320 ret = regcache_lookup_reg(map, i);
321 if (ret > 0 && val == map->reg_defaults[ret].def)
324 map->cache_bypass = 1;
325 ret = _regmap_write(map, regtmp, val);
326 map->cache_bypass = 0;
329 dev_dbg(map->dev, "Synced register %#x, value %#x\n",
337 struct regcache_ops regcache_rbtree_ops = {
338 .type = REGCACHE_RBTREE,
340 .init = regcache_rbtree_init,
341 .exit = regcache_rbtree_exit,
342 .read = regcache_rbtree_read,
343 .write = regcache_rbtree_write,
344 .sync = regcache_rbtree_sync