// SPDX-License-Identifier: GPL-2.0
//
// Register cache access API - flat caching support
//
// Copyright 2012 Wolfson Microelectronics plc
//
// Author: Mark Brown <broonie@opensource.wolfsonmicro.com>

#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/limits.h>
#include <linux/overflow.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include "internal.h"

static inline unsigned int regcache_flat_get_index(const struct regmap *map,
                                                   unsigned int reg)
{
        return regcache_get_index_by_order(map, reg);
}

struct regcache_flat_data {
        unsigned long *valid;
        unsigned int data[];
};

static int regcache_flat_init(struct regmap *map)
{
        unsigned int cache_size;
        struct regcache_flat_data *cache;

        if (!map || map->reg_stride_order < 0 || !map->max_register_is_set)
                return -EINVAL;

        cache_size = regcache_flat_get_index(map, map->max_register) + 1;
        cache = kzalloc_flex(*cache, data, cache_size, map->alloc_flags);
        if (!cache)
                return -ENOMEM;

        cache->valid = bitmap_zalloc(cache_size, map->alloc_flags);
        if (!cache->valid)
                goto err_free;

        map->cache = cache;

        return 0;

err_free:
        kfree(cache);
        return -ENOMEM;
}

static int regcache_flat_exit(struct regmap *map)
{
        struct regcache_flat_data *cache = map->cache;

        if (cache)
                bitmap_free(cache->valid);

        kfree(cache);
        map->cache = NULL;

        return 0;
}

static int regcache_flat_populate(struct regmap *map)
{
        struct regcache_flat_data *cache = map->cache;
        unsigned int i;

        for (i = 0; i < map->num_reg_defaults; i++) {
                unsigned int reg = map->reg_defaults[i].reg;
                unsigned int index = regcache_flat_get_index(map, reg);

                cache->data[index] = map->reg_defaults[i].def;
                __set_bit(index, cache->valid);
        }

        if (map->reg_default_cb) {
                dev_dbg(map->dev,
                        "Populating regcache_flat using reg_default_cb callback\n");

                for (i = 0; i <= map->max_register; i += map->reg_stride) {
                        unsigned int index = regcache_flat_get_index(map, i);
                        unsigned int value;

                        if (test_bit(index, cache->valid))
                                continue;

                        if (map->reg_default_cb(map->dev, i, &value))
                                continue;

                        cache->data[index] = value;
                        __set_bit(index, cache->valid);
                }
        }

        return 0;
}

static int regcache_flat_read(struct regmap *map,
                              unsigned int reg, unsigned int *value)
{
        struct regcache_flat_data *cache = map->cache;
        unsigned int index = regcache_flat_get_index(map, reg);

        /* legacy behavior: ignore validity, but warn the user */
        if (unlikely(!test_bit(index, cache->valid)))
                dev_warn_once(map->dev,
                        "using zero-initialized flat cache, this may cause unexpected behavior");

        *value = cache->data[index];

        return 0;
}

static int regcache_flat_sparse_read(struct regmap *map,
                                     unsigned int reg, unsigned int *value)
{
        struct regcache_flat_data *cache = map->cache;
        unsigned int index = regcache_flat_get_index(map, reg);

        if (unlikely(!test_bit(index, cache->valid)))
                return -ENOENT;

        *value = cache->data[index];

        return 0;
}

static int regcache_flat_write(struct regmap *map, unsigned int reg,
                               unsigned int value)
{
        struct regcache_flat_data *cache = map->cache;
        unsigned int index = regcache_flat_get_index(map, reg);

        cache->data[index] = value;
        __set_bit(index, cache->valid);

        return 0;
}

static int regcache_flat_drop(struct regmap *map, unsigned int min,
                              unsigned int max)
{
        struct regcache_flat_data *cache = map->cache;
        unsigned int bitmap_min = regcache_flat_get_index(map, min);
        unsigned int bitmap_max = regcache_flat_get_index(map, max);

        bitmap_clear(cache->valid, bitmap_min, bitmap_max + 1 - bitmap_min);

        return 0;
}

struct regcache_ops regcache_flat_ops = {
        .type = REGCACHE_FLAT,
        .name = "flat",
        .init = regcache_flat_init,
        .exit = regcache_flat_exit,
        .populate = regcache_flat_populate,
        .read = regcache_flat_read,
        .write = regcache_flat_write,
};

struct regcache_ops regcache_flat_sparse_ops = {
        .type = REGCACHE_FLAT_S,
        .name = "flat-sparse",
        .init = regcache_flat_init,
        .exit = regcache_flat_exit,
        .populate = regcache_flat_populate,
        .read = regcache_flat_sparse_read,
        .write = regcache_flat_write,
        .drop = regcache_flat_drop,
};