regcache-rbtree.c
// SPDX-License-Identifier: GPL-2.0
//
// Register cache access API - rbtree caching support
//
// Copyright 2011 Wolfson Microelectronics plc
//
// Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/rbtree.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include "internal.h"
static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
unsigned int value);
static int regcache_rbtree_exit(struct regmap *map);
struct regcache_rbtree_node {
/* block of adjacent registers */
void *block;
/* Which registers are present */
long *cache_present;
/* base register handled by this block */
unsigned int base_reg;
/* number of registers available in the block */
unsigned int blklen;
/* the actual rbtree node holding this block */
struct rb_node node;
};
struct regcache_rbtree_ctx {
struct rb_root root;
struct regcache_rbtree_node *cached_rbnode;
};
static inline void regcache_rbtree_get_base_top_reg(
struct regmap *map,
struct regcache_rbtree_node *rbnode,
unsigned int *base, unsigned int *top)
{
*base = rbnode->base_reg;
*top = rbnode->base_reg + ((rbnode->blklen - 1) * map->reg_stride);
}
static unsigned int regcache_rbtree_get_register(struct regmap *map,
struct regcache_rbtree_node *rbnode, unsigned int idx)
{
return regcache_get_val(map, rbnode->block, idx);
}
static void regcache_rbtree_set_register(struct regmap *map,
struct regcache_rbtree_node *rbnode,
unsigned int idx, unsigned int val)
{
set_bit(idx, rbnode->cache_present);
regcache_set_val(map, rbnode->block, idx, val);
}
static struct regcache_rbtree_node *regcache_rbtree_lookup(struct regmap *map,
unsigned int reg)
{
struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
struct rb_node *node;
struct regcache_rbtree_node *rbnode;
unsigned int base_reg, top_reg;
rbnode = rbtree_ctx->cached_rbnode;
if (rbnode) {
regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
&top_reg);
if (reg >= base_reg && reg <= top_reg)
return rbnode;
}
node = rbtree_ctx->root.rb_node;
while (node) {
rbnode = rb_entry(node, struct regcache_rbtree_node, node);
regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
&top_reg);
if (reg >= base_reg && reg <= top_reg) {
rbtree_ctx->cached_rbnode = rbnode;
return rbnode;
} else if (reg > top_reg) {
node = node->rb_right;
} else if (reg < base_reg) {
node = node->rb_left;
}
}
return NULL;
}
static int regcache_rbtree_insert(struct regmap *map, struct rb_root *root,
struct regcache_rbtree_node *rbnode)
{
struct rb_node **new, *parent;
struct regcache_rbtree_node *rbnode_tmp;
unsigned int base_reg_tmp, top_reg_tmp;
unsigned int base_reg;
parent = NULL;
new = &root->rb_node;
while (*new) {
rbnode_tmp = rb_entry(*new, struct regcache_rbtree_node, node);
/* base and top registers of the current rbnode */
regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
&top_reg_tmp);
/* base register of the rbnode to be added */
base_reg = rbnode->base_reg;
parent = *new;
/* if this register has already been inserted, just return */
if (base_reg >= base_reg_tmp &&
base_reg <= top_reg_tmp)
return 0;
else if (base_reg > top_reg_tmp)
new = &((*new)->rb_right);
else if (base_reg < base_reg_tmp)
new = &((*new)->rb_left);
}
/* insert the node into the rbtree */
rb_link_node(&rbnode->node, parent, new);
rb_insert_color(&rbnode->node, root);
return 1;
}
#ifdef CONFIG_DEBUG_FS
static int rbtree_show(struct seq_file *s, void *ignored)
{
struct regmap *map = s->private;
struct regcache_rbtree_ctx *rbtree_ctx = map->cache;
struct regcache_rbtree_node *n;
struct rb_node *node;
unsigned int base, top;
size_t mem_size;
int nodes = 0;
int registers = 0;
int this_registers, average;
map->lock(map->lock_arg);
mem_size = sizeof(*rbtree_ctx);
for (node = rb_first(&rbtree_ctx->root); node != NULL;
node = rb_next(node)) {
n = rb_entry(node, struct regcache_rbtree_node, node);
mem_size += sizeof(*n);
mem_size += (n->blklen * map->cache_word_size);
mem_size += BITS_TO_LONGS(n->blklen) * sizeof(long);
regcache_rbtree_get_base_top_reg(map, n, &base, &top);
this_registers = ((top - base) / map->reg_stride) + 1;
seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
nodes++;
registers += this_registers;
}
if (nodes)
average = registers / nodes;
else
average = 0;
seq_printf(s, "%d nodes, %d registers, average %d registers, used %zu bytes\n",
nodes, registers, average, mem_size);
map->unlock(map->lock_arg);
return 0;
}
DEFINE_SHOW_ATTRIBUTE(rbtree);
static void rbtree_debugfs_init(struct regmap *map)
{
debugfs_create_file("rbtree", 0400, map->debugfs, map, &rbtree_fops);
}
#endif
static int regcache_rbtree_init(struct regmap *map)
{
struct regcache_rbtree_ctx *rbtree_ctx;
int i;
int ret;
map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
if (!map->cache)
return -ENOMEM;
rbtree_ctx = map->cache;
rbtree_ctx->root = RB_ROOT;
rbtree_ctx->cached_rbnode = NULL;
for (i = 0; i < map->num_reg_defaults; i++) {
ret = regcache_rbtree_write(map,
map->reg_defaults[i].reg,
map->reg_defaults[i].def);
if (ret)
goto err;
}
return 0;
err:
regcache_rbtree_exit(map);
return ret;
}
static int regcache_rbtree_exit(struct regmap *map)
{
struct rb_node *next;
struct regcache_rbtree_ctx *rbtree_ctx;
struct regcache_rbtree_node *rbtree_node;
/* if we've already been called then just return */
rbtree_ctx = map->cache;
if (!rbtree_ctx)
return 0;
/* free up the rbtree */
next = rb_first(&rbtree_ctx->root);
while (next) {
rbtree_node = rb_entry(next, struct regcache_rbtree_node, node);
next = rb_next(&rbtree_node->node);
rb_erase(&rbtree_node->node, &rbtree_ctx->root);
kfree(rbtree_node->cache_present);
kfree(rbtree_node->block);
kfree(rbtree_node);
}
/* release the resources */
kfree(map->cache);
map->cache = NULL;
return 0;
}
static int regcache_rbtree_read(struct regmap *map,
unsigned int reg, unsigned int *value)
{
struct regcache_rbtree_node *rbnode;
unsigned int reg_tmp;
rbnode = regcache_rbtree_lookup(map, reg);
if (rbnode) {
reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
if (!test_bit(reg_tmp, rbnode->cache_present))
return -ENOENT;
*value = regcache_rbtree_get_register(map, rbnode, reg_tmp);
} else {
return -ENOENT;
}
return 0;
}
static int regcache_rbtree_insert_to_block(struct regmap *map,
struct regcache_rbtree_node *rbnode,
unsigned int base_reg,
unsigned int top_reg,
unsigned int reg,
unsigned int value)
{
unsigned int blklen;
unsigned int pos, offset;
unsigned long *present;
u8 *blk;
blklen = (top_reg - base_reg) / map->reg_stride + 1;
pos = (reg - base_reg) / map->reg_stride;
offset = (rbnode->base_reg - base_reg) / map->reg_stride;
blk = krealloc(rbnode->block,
blklen * map->cache_word_size,
GFP_KERNEL);
if (!blk)
return -ENOMEM;
rbnode->block = blk;
if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
present = krealloc(rbnode->cache_present,
BITS_TO_LONGS(blklen) * sizeof(*present),
GFP_KERNEL);
if (!present)
return -ENOMEM;
memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
(BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
* sizeof(*present));
} else {
present = rbnode->cache_present;
}
/* insert the register value in the correct place in the rbnode block */
if (pos == 0) {
memmove(blk + offset * map->cache_word_size,
blk, rbnode->blklen * map->cache_word_size);
bitmap_shift_left(present, present, offset, blklen);
}
/* update the rbnode block, its size and the base register */
rbnode->blklen = blklen;
rbnode->base_reg = base_reg;
rbnode->cache_present = present;
regcache_rbtree_set_register(map, rbnode, pos, value);
return 0;
}
static struct regcache_rbtree_node *
regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
{
struct regcache_rbtree_node *rbnode;
const struct regmap_range *range;
int i;
rbnode = kzalloc(sizeof(*rbnode), GFP_KERNEL);
if (!rbnode)
return NULL;
/* If there is a read table then use it to guess at an allocation */
if (map->rd_table) {
for (i = 0; i < map->rd_table->n_yes_ranges; i++) {
if (regmap_reg_in_range(reg,
&map->rd_table->yes_ranges[i]))
break;
}
if (i != map->rd_table->n_yes_ranges) {
range = &map->rd_table->yes_ranges[i];
rbnode->blklen = (range->range_max - range->range_min) /
map->reg_stride + 1;
rbnode->base_reg = range->range_min;
}
}
if (!rbnode->blklen) {
rbnode->blklen = 1;
rbnode->base_reg = reg;
}
rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
GFP_KERNEL);
if (!rbnode->block)
goto err_free;
rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
sizeof(*rbnode->cache_present),
GFP_KERNEL);
if (!rbnode->cache_present)
goto err_free_block;
return rbnode;
err_free_block:
kfree(rbnode->block);
err_free:
kfree(rbnode);
return NULL;
}
static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
unsigned int value)
{
struct regcache_rbtree_ctx *rbtree_ctx;
struct regcache_rbtree_node *rbnode, *rbnode_tmp;
struct rb_node *node;
unsigned int reg_tmp;
int ret;
rbtree_ctx = map->cache;
/* if we can't locate it in the cached rbnode we'll have
* to traverse the rbtree looking for it.
*/
rbnode = regcache_rbtree_lookup(map, reg);
if (rbnode) {
reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
regcache_rbtree_set_register(map, rbnode, reg_tmp, value);
} else {
unsigned int base_reg, top_reg;
unsigned int new_base_reg, new_top_reg;
unsigned int min, max;
unsigned int max_dist;
unsigned int dist, best_dist = UINT_MAX;
max_dist = map->reg_stride * sizeof(*rbnode_tmp) /
map->cache_word_size;
if (reg < max_dist)
min = 0;
else
min = reg - max_dist;
max = reg + max_dist;
/* look for an adjacent register to the one we are about to add */
node = rbtree_ctx->root.rb_node;
while (node) {
rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
node);
regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
&base_reg, &top_reg);
if (base_reg <= max && top_reg >= min) {
if (reg < base_reg)
dist = base_reg - reg;
else if (reg > top_reg)
dist = reg - top_reg;
else
dist = 0;
if (dist < best_dist) {
rbnode = rbnode_tmp;
best_dist = dist;
new_base_reg = min(reg, base_reg);
new_top_reg = max(reg, top_reg);
}
}
/*
* Keep looking, we want to choose the closest block,
* otherwise we might end up creating overlapping
* blocks, which breaks the rbtree.
*/
if (reg < base_reg)
node = node->rb_left;
else if (reg > top_reg)
node = node->rb_right;
else
break;
}
if (rbnode) {
ret = regcache_rbtree_insert_to_block(map, rbnode,
new_base_reg,
new_top_reg, reg,
value);
if (ret)
return ret;
rbtree_ctx->cached_rbnode = rbnode;
return 0;
}
/* We did not manage to find a place to insert it in
* an existing block so create a new rbnode.
*/
rbnode = regcache_rbtree_node_alloc(map, reg);
if (!rbnode)
return -ENOMEM;
regcache_rbtree_set_register(map, rbnode,
reg - rbnode->base_reg, value);
regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
rbtree_ctx->cached_rbnode = rbnode;
}
return 0;
}
static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
unsigned int max)
{
struct regcache_rbtree_ctx *rbtree_ctx;
struct rb_node *node;
struct regcache_rbtree_node *rbnode;
unsigned int base_reg, top_reg;
unsigned int start, end;
int ret;
rbtree_ctx = map->cache;
for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
rbnode = rb_entry(node, struct regcache_rbtree_node, node);
regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
&top_reg);
if (base_reg > max)
break;
if (top_reg < min)
continue;
if (min > base_reg)
start = (min - base_reg) / map->reg_stride;
else
start = 0;
if (max < top_reg)
end = (max - base_reg) / map->reg_stride + 1;
else
end = rbnode->blklen;
ret = regcache_sync_block(map, rbnode->block,
rbnode->cache_present,
rbnode->base_reg, start, end);
if (ret != 0)
return ret;
}
return regmap_async_complete(map);
}
static int regcache_rbtree_drop(struct regmap *map, unsigned int min,
unsigned int max)
{
struct regcache_rbtree_ctx *rbtree_ctx;
struct regcache_rbtree_node *rbnode;
struct rb_node *node;
unsigned int base_reg, top_reg;
unsigned int start, end;
rbtree_ctx = map->cache;
for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
rbnode = rb_entry(node, struct regcache_rbtree_node, node);
regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
&top_reg);
if (base_reg > max)
break;
if (top_reg < min)
continue;
if (min > base_reg)
start = (min - base_reg) / map->reg_stride;
else
start = 0;
if (max < top_reg)
end = (max - base_reg) / map->reg_stride + 1;
else
end = rbnode->blklen;
bitmap_clear(rbnode->cache_present, start, end - start);
}
return 0;
}
struct regcache_ops regcache_rbtree_ops = {
.type = REGCACHE_RBTREE,
.name = "rbtree",
.init = regcache_rbtree_init,
.exit = regcache_rbtree_exit,
#ifdef CONFIG_DEBUG_FS
.debugfs_init = rbtree_debugfs_init,
#endif
.read = regcache_rbtree_read,
.write = regcache_rbtree_write,
.sync = regcache_rbtree_sync,
.drop = regcache_rbtree_drop,
};