/*
 * Register cache access API
 *
 * Copyright 2011 Wolfson Microelectronics plc
 *
 * Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/bsearch.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/sort.h>

#include "trace.h"
#include "internal.h"

static const struct regcache_ops *cache_types[] = {
        &regcache_rbtree_ops,
#if IS_ENABLED(CONFIG_REGCACHE_COMPRESSED)
        &regcache_lzo_ops,
#endif
        &regcache_flat_ops,
};

static int regcache_hw_init(struct regmap *map)
{
        int i, j;
        int ret;
        int count;
        unsigned int reg, val;
        void *tmp_buf;

        if (!map->num_reg_defaults_raw)
                return -EINVAL;

        /* calculate the size of reg_defaults */
        for (count = 0, i = 0; i < map->num_reg_defaults_raw; i++)
                if (regmap_readable(map, i * map->reg_stride) &&
                    !regmap_volatile(map, i * map->reg_stride))
                        count++;

        /* all registers are unreadable or volatile, so just bypass */
        if (!count) {
                map->cache_bypass = true;
                return 0;
        }

        map->num_reg_defaults = count;
        map->reg_defaults = kmalloc_array(count, sizeof(struct reg_default),
                                          GFP_KERNEL);
        if (!map->reg_defaults)
                return -ENOMEM;

        if (!map->reg_defaults_raw) {
                bool cache_bypass = map->cache_bypass;
                dev_warn(map->dev, "No cache defaults, reading back from HW\n");

                /* Bypass the cache access till data read from HW */
                map->cache_bypass = true;
                tmp_buf = kmalloc(map->cache_size_raw, GFP_KERNEL);
                if (!tmp_buf) {
                        ret = -ENOMEM;
                        goto err_free;
                }
                ret = regmap_raw_read(map, 0, tmp_buf,
                                      map->cache_size_raw);
                map->cache_bypass = cache_bypass;
                if (ret == 0) {
                        map->reg_defaults_raw = tmp_buf;
                        map->cache_free = 1;
                } else {
                        kfree(tmp_buf);
                }
        }

        /* fill the reg_defaults */
        for (i = 0, j = 0; i < map->num_reg_defaults_raw; i++) {
                reg = i * map->reg_stride;

                if (!regmap_readable(map, reg))
                        continue;

                if (regmap_volatile(map, reg))
                        continue;

                if (map->reg_defaults_raw) {
                        val = regcache_get_val(map, map->reg_defaults_raw, i);
                } else {
                        bool cache_bypass = map->cache_bypass;

                        map->cache_bypass = true;
                        ret = regmap_read(map, reg, &val);
                        map->cache_bypass = cache_bypass;
                        if (ret != 0) {
                                dev_err(map->dev, "Failed to read %d: %d\n",
                                        reg, ret);
                                goto err_free;
                        }
                }

                map->reg_defaults[j].reg = reg;
                map->reg_defaults[j].def = val;
                j++;
        }

        return 0;

err_free:
        kfree(map->reg_defaults);

        return ret;
}

int regcache_init(struct regmap *map, const struct regmap_config *config)
{
        int ret;
        int i;
        void *tmp_buf;

        if (map->cache_type == REGCACHE_NONE) {
                if (config->reg_defaults || config->num_reg_defaults_raw)
                        dev_warn(map->dev,
                                 "No cache used with register defaults set!\n");

                map->cache_bypass = true;
                return 0;
        }

        if (config->reg_defaults && !config->num_reg_defaults) {
                dev_err(map->dev,
                         "Register defaults are set without the number!\n");
                return -EINVAL;
        }

        for (i = 0; i < config->num_reg_defaults; i++)
                if (config->reg_defaults[i].reg % map->reg_stride)
                        return -EINVAL;

        for (i = 0; i < ARRAY_SIZE(cache_types); i++)
                if (cache_types[i]->type == map->cache_type)
                        break;

        if (i == ARRAY_SIZE(cache_types)) {
                dev_err(map->dev, "Could not match compress type: %d\n",
                        map->cache_type);
                return -EINVAL;
        }

        map->num_reg_defaults = config->num_reg_defaults;
        map->num_reg_defaults_raw = config->num_reg_defaults_raw;
        map->reg_defaults_raw = config->reg_defaults_raw;
        map->cache_word_size = DIV_ROUND_UP(config->val_bits, 8);
        map->cache_size_raw = map->cache_word_size * config->num_reg_defaults_raw;

        map->cache = NULL;
        map->cache_ops = cache_types[i];

        if (!map->cache_ops->read ||
            !map->cache_ops->write ||
            !map->cache_ops->name)
                return -EINVAL;

        /* We still need to ensure that the reg_defaults
         * won't vanish from under us.  We'll need to make
         * a copy of it.
         */
        if (config->reg_defaults) {
                tmp_buf = kmemdup(config->reg_defaults, map->num_reg_defaults *
                                  sizeof(struct reg_default), GFP_KERNEL);
                if (!tmp_buf)
                        return -ENOMEM;
                map->reg_defaults = tmp_buf;
        } else if (map->num_reg_defaults_raw) {
                /* Some devices such as PMICs don't have cache defaults,
                 * we cope with this by reading back the HW registers and
                 * crafting the cache defaults by hand.
                 */
                ret = regcache_hw_init(map);
                if (ret < 0)
                        return ret;
                if (map->cache_bypass)
                        return 0;
        }

        if (!map->max_register)
                map->max_register = map->num_reg_defaults_raw;

        if (map->cache_ops->init) {
                dev_dbg(map->dev, "Initializing %s cache\n",
                        map->cache_ops->name);
                ret = map->cache_ops->init(map);
                if (ret)
                        goto err_free;
        }
        return 0;

err_free:
        kfree(map->reg_defaults);
        if (map->cache_free)
                kfree(map->reg_defaults_raw);

        return ret;
}

void regcache_exit(struct regmap *map)
{
        if (map->cache_type == REGCACHE_NONE)
                return;

        BUG_ON(!map->cache_ops);

        kfree(map->reg_defaults);
        if (map->cache_free)
                kfree(map->reg_defaults_raw);

        if (map->cache_ops->exit) {
                dev_dbg(map->dev, "Destroying %s cache\n",
                        map->cache_ops->name);
                map->cache_ops->exit(map);
        }
}

/**
 * regcache_read - Fetch the value of a given register from the cache.
 *
 * @map: map to configure.
 * @reg: The register index.
 * @value: The value to be returned.
 *
 * Return a negative value on failure, 0 on success.
 */
int regcache_read(struct regmap *map,
                  unsigned int reg, unsigned int *value)
{
        int ret;

        if (map->cache_type == REGCACHE_NONE)
                return -ENOSYS;

        BUG_ON(!map->cache_ops);

        if (!regmap_volatile(map, reg)) {
                ret = map->cache_ops->read(map, reg, value);

                if (ret == 0)
                        trace_regmap_reg_read_cache(map, reg, *value);

                return ret;
        }

        return -EINVAL;
}

/**
 * regcache_write - Set the value of a given register in the cache.
 *
 * @map: map to configure.
 * @reg: The register index.
 * @value: The new register value.
 *
 * Return a negative value on failure, 0 on success.
 */
int regcache_write(struct regmap *map,
                   unsigned int reg, unsigned int value)
{
        if (map->cache_type == REGCACHE_NONE)
                return 0;

        BUG_ON(!map->cache_ops);

        if (!regmap_volatile(map, reg))
                return map->cache_ops->write(map, reg, value);

        return 0;
}

static bool regcache_reg_needs_sync(struct regmap *map, unsigned int reg,
                                    unsigned int val)
{
        int ret;

        /* If we don't know the chip just got reset, then sync everything. */
        if (!map->no_sync_defaults)
                return true;

        /* Is this the hardware default?  If so skip. */
        ret = regcache_lookup_reg(map, reg);
        if (ret >= 0 && val == map->reg_defaults[ret].def)
                return false;
        return true;
}

static int regcache_default_sync(struct regmap *map, unsigned int min,
                                 unsigned int max)
{
        unsigned int reg;

        for (reg = min; reg <= max; reg += map->reg_stride) {
                unsigned int val;
                int ret;

                if (regmap_volatile(map, reg) ||
                    !regmap_writeable(map, reg))
                        continue;

                ret = regcache_read(map, reg, &val);
                if (ret)
                        return ret;

                if (!regcache_reg_needs_sync(map, reg, val))
                        continue;

                map->cache_bypass = true;
                ret = _regmap_write(map, reg, val);
                map->cache_bypass = false;
                if (ret) {
                        dev_err(map->dev, "Unable to sync register %#x. %d\n",
                                reg, ret);
                        return ret;
                }
                dev_dbg(map->dev, "Synced register %#x, value %#x\n", reg, val);
        }

        return 0;
}

/**
 * regcache_sync - Sync the register cache with the hardware.
 *
 * @map: map to configure.
 *
 * Any registers that should not be synced should be marked as
 * volatile.  In general drivers can choose not to use the provided
 * syncing functionality if they so require.
 *
 * Return a negative value on failure, 0 on success.
 */
int regcache_sync(struct regmap *map)
{
        int ret = 0;
        unsigned int i;
        const char *name;
        bool bypass;

        BUG_ON(!map->cache_ops);

        map->lock(map->lock_arg);
        /* Remember the initial bypass state */
        bypass = map->cache_bypass;
        dev_dbg(map->dev, "Syncing %s cache\n",
                map->cache_ops->name);
        name = map->cache_ops->name;
        trace_regcache_sync(map, name, "start");

        if (!map->cache_dirty)
                goto out;

        map->async = true;

        /* Apply any patch first */
        map->cache_bypass = true;
        for (i = 0; i < map->patch_regs; i++) {
                ret = _regmap_write(map, map->patch[i].reg, map->patch[i].def);
                if (ret != 0) {
                        dev_err(map->dev, "Failed to write %x = %x: %d\n",
                                map->patch[i].reg, map->patch[i].def, ret);
                        goto out;
                }
        }
        map->cache_bypass = false;

        if (map->cache_ops->sync)
                ret = map->cache_ops->sync(map, 0, map->max_register);
        else
                ret = regcache_default_sync(map, 0, map->max_register);

        if (ret == 0)
                map->cache_dirty = false;

out:
        /* Restore the bypass state */
        map->async = false;
        map->cache_bypass = bypass;
        map->no_sync_defaults = false;
        map->unlock(map->lock_arg);

        regmap_async_complete(map);

        trace_regcache_sync(map, name, "stop");

        return ret;
}
EXPORT_SYMBOL_GPL(regcache_sync);

/**
 * regcache_sync_region - Sync part  of the register cache with the hardware.
 *
 * @map: map to sync.
 * @min: first register to sync
 * @max: last register to sync
 *
 * Write all non-default register values in the specified region to
 * the hardware.
 *
 * Return a negative value on failure, 0 on success.
 */
int regcache_sync_region(struct regmap *map, unsigned int min,
                         unsigned int max)
{
        int ret = 0;
        const char *name;
        bool bypass;

        BUG_ON(!map->cache_ops);

        map->lock(map->lock_arg);

        /* Remember the initial bypass state */
        bypass = map->cache_bypass;

        name = map->cache_ops->name;
        dev_dbg(map->dev, "Syncing %s cache from %d-%d\n", name, min, max);

        trace_regcache_sync(map, name, "start region");

        if (!map->cache_dirty)
                goto out;

        map->async = true;

        if (map->cache_ops->sync)
                ret = map->cache_ops->sync(map, min, max);
        else
                ret = regcache_default_sync(map, min, max);

out:
        /* Restore the bypass state */
        map->cache_bypass = bypass;
        map->async = false;
        map->no_sync_defaults = false;
        map->unlock(map->lock_arg);

        regmap_async_complete(map);

        trace_regcache_sync(map, name, "stop region");

        return ret;
}
EXPORT_SYMBOL_GPL(regcache_sync_region);

/**
 * regcache_drop_region - Discard part of the register cache
 *
 * @map: map to operate on
 * @min: first register to discard
 * @max: last register to discard
 *
 * Discard part of the register cache.
 *
 * Return a negative value on failure, 0 on success.
 */
int regcache_drop_region(struct regmap *map, unsigned int min,
                         unsigned int max)
{
        int ret = 0;

        if (!map->cache_ops || !map->cache_ops->drop)
                return -EINVAL;

        map->lock(map->lock_arg);

        trace_regcache_drop_region(map, min, max);

        ret = map->cache_ops->drop(map, min, max);

        map->unlock(map->lock_arg);

        return ret;
}
EXPORT_SYMBOL_GPL(regcache_drop_region);

/**
 * regcache_cache_only - Put a register map into cache only mode
 *
 * @map: map to configure
 * @enable: flag if changes should be written to the hardware
 *
 * When a register map is marked as cache only writes to the register
 * map API will only update the register cache, they will not cause
 * any hardware changes.  This is useful for allowing portions of
 * drivers to act as though the device were functioning as normal when
 * it is disabled for power saving reasons.
 */
void regcache_cache_only(struct regmap *map, bool enable)
{
        map->lock(map->lock_arg);
        WARN_ON(map->cache_bypass && enable);
        map->cache_only = enable;
        trace_regmap_cache_only(map, enable);
        map->unlock(map->lock_arg);
}
EXPORT_SYMBOL_GPL(regcache_cache_only);

/**
 * regcache_mark_dirty - Indicate that HW registers were reset to default values
 *
 * @map: map to mark
 *
 * Inform regcache that the device has been powered down or reset, so that
 * on resume, regcache_sync() knows to write out all non-default values
 * stored in the cache.
 *
 * If this function is not called, regcache_sync() will assume that
 * the hardware state still matches the cache state, modulo any writes that
 * happened when cache_only was true.
 */
void regcache_mark_dirty(struct regmap *map)
{
        map->lock(map->lock_arg);
        map->cache_dirty = true;
        map->no_sync_defaults = true;
        map->unlock(map->lock_arg);
}
EXPORT_SYMBOL_GPL(regcache_mark_dirty);

/**
 * regcache_cache_bypass - Put a register map into cache bypass mode
 *
 * @map: map to configure
 * @enable: flag if changes should not be written to the cache
 *
 * When a register map is marked with the cache bypass option, writes
 * to the register map API will only update the hardware and not the
 * the cache directly.  This is useful when syncing the cache back to
 * the hardware.
 */
void regcache_cache_bypass(struct regmap *map, bool enable)
{
        map->lock(map->lock_arg);
        WARN_ON(map->cache_only && enable);
        map->cache_bypass = enable;
        trace_regmap_cache_bypass(map, enable);
        map->unlock(map->lock_arg);
}
EXPORT_SYMBOL_GPL(regcache_cache_bypass);

bool regcache_set_val(struct regmap *map, void *base, unsigned int idx,
                      unsigned int val)
{
        if (regcache_get_val(map, base, idx) == val)
                return true;

        /* Use device native format if possible */
        if (map->format.format_val) {
                map->format.format_val(base + (map->cache_word_size * idx),
                                       val, 0);
                return false;
        }

        switch (map->cache_word_size) {
        case 1: {
                u8 *cache = base;

                cache[idx] = val;
                break;
        }
        case 2: {
                u16 *cache = base;

                cache[idx] = val;
                break;
        }
        case 4: {
                u32 *cache = base;

                cache[idx] = val;
                break;
        }
#ifdef CONFIG_64BIT
        case 8: {
                u64 *cache = base;

                cache[idx] = val;
                break;
        }
#endif
        default:
                BUG();
        }
        return false;
}

unsigned int regcache_get_val(struct regmap *map, const void *base,
                              unsigned int idx)
{
        if (!base)
                return -EINVAL;

        /* Use device native format if possible */
        if (map->format.parse_val)
                return map->format.parse_val(regcache_get_val_addr(map, base,
                                                                   idx));

        switch (map->cache_word_size) {
        case 1: {
                const u8 *cache = base;

                return cache[idx];
        }
        case 2: {
                const u16 *cache = base;

                return cache[idx];
        }
        case 4: {
                const u32 *cache = base;

                return cache[idx];
        }
#ifdef CONFIG_64BIT
        case 8: {
                const u64 *cache = base;

                return cache[idx];
        }
#endif
        default:
                BUG();
        }
        /* unreachable */
        return -1;
}

static int regcache_default_cmp(const void *a, const void *b)
{
        const struct reg_default *_a = a;
        const struct reg_default *_b = b;

        return _a->reg - _b->reg;
}

int regcache_lookup_reg(struct regmap *map, unsigned int reg)
{
        struct reg_default key;
        struct reg_default *r;

        key.reg = reg;
        key.def = 0;

        r = bsearch(&key, map->reg_defaults, map->num_reg_defaults,
                    sizeof(struct reg_default), regcache_default_cmp);

        if (r)
                return r - map->reg_defaults;
        else
                return -ENOENT;
}

static bool regcache_reg_present(unsigned long *cache_present, unsigned int idx)
{
        if (!cache_present)
                return true;

        return test_bit(idx, cache_present);
}

static int regcache_sync_block_single(struct regmap *map, void *block,
                                      unsigned long *cache_present,
                                      unsigned int block_base,
                                      unsigned int start, unsigned int end)
{
        unsigned int i, regtmp, val;
        int ret;

        for (i = start; i < end; i++) {
                regtmp = block_base + (i * map->reg_stride);

                if (!regcache_reg_present(cache_present, i) ||
                    !regmap_writeable(map, regtmp))
                        continue;

                val = regcache_get_val(map, block, i);
                if (!regcache_reg_needs_sync(map, regtmp, val))
                        continue;

                map->cache_bypass = true;

                ret = _regmap_write(map, regtmp, val);

                map->cache_bypass = false;
                if (ret != 0) {
                        dev_err(map->dev, "Unable to sync register %#x. %d\n",
                                regtmp, ret);
                        return ret;
                }
                dev_dbg(map->dev, "Synced register %#x, value %#x\n",
                        regtmp, val);
        }

        return 0;
}

static int regcache_sync_block_raw_flush(struct regmap *map, const void **data,
                                         unsigned int base, unsigned int cur)
{
        size_t val_bytes = map->format.val_bytes;
        int ret, count;

        if (*data == NULL)
                return 0;

        count = (cur - base) / map->reg_stride;

        dev_dbg(map->dev, "Writing %zu bytes for %d registers from 0x%x-0x%x\n",
                count * val_bytes, count, base, cur - map->reg_stride);

        map->cache_bypass = true;

        ret = _regmap_raw_write(map, base, *data, count * val_bytes);
        if (ret)
                dev_err(map->dev, "Unable to sync registers %#x-%#x. %d\n",
                        base, cur - map->reg_stride, ret);

        map->cache_bypass = false;

        *data = NULL;

        return ret;
}

static int regcache_sync_block_raw(struct regmap *map, void *block,
                            unsigned long *cache_present,
                            unsigned int block_base, unsigned int start,
                            unsigned int end)
{
        unsigned int i, val;
        unsigned int regtmp = 0;
        unsigned int base = 0;
        const void *data = NULL;
        int ret;

        for (i = start; i < end; i++) {
                regtmp = block_base + (i * map->reg_stride);

                if (!regcache_reg_present(cache_present, i) ||
                    !regmap_writeable(map, regtmp)) {
                        ret = regcache_sync_block_raw_flush(map, &data,
                                                            base, regtmp);
                        if (ret != 0)
                                return ret;
                        continue;
                }

                val = regcache_get_val(map, block, i);
                if (!regcache_reg_needs_sync(map, regtmp, val)) {
                        ret = regcache_sync_block_raw_flush(map, &data,
                                                            base, regtmp);
                        if (ret != 0)
                                return ret;
                        continue;
                }

                if (!data) {
                        data = regcache_get_val_addr(map, block, i);
                        base = regtmp;
                }
        }

        return regcache_sync_block_raw_flush(map, &data, base, regtmp +
                        map->reg_stride);
}

int regcache_sync_block(struct regmap *map, void *block,
                        unsigned long *cache_present,
                        unsigned int block_base, unsigned int start,
                        unsigned int end)
{
        if (regmap_can_raw_write(map) && !map->use_single_write)
                return regcache_sync_block_raw(map, block, cache_present,
                                               block_base, start, end);
        else
                return regcache_sync_block_single(map, block, cache_present,
                                                  block_base, start, end);
}