// SPDX-License-Identifier: GPL-2.0
//
// Register map access API - Memory region with raw access
//
// This is intended for testing only
//
// Copyright (c) 2023, Arm Ltd

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/swab.h>

#include "internal.h"

static unsigned int decode_reg(enum regmap_endian endian, const void *reg)
{
        const u16 *r = reg;

        if (endian == REGMAP_ENDIAN_BIG)
                return be16_to_cpu(*r);
        else
                return le16_to_cpu(*r);
}

static int regmap_raw_ram_gather_write(void *context,
                                       const void *reg, size_t reg_len,
                                       const void *val, size_t val_len)
{
        struct regmap_ram_data *data = context;
        unsigned int r;
        u16 *our_buf = (u16 *)data->vals;
        int i;

        if (reg_len != 2)
                return -EINVAL;
        if (val_len % 2)
                return -EINVAL;

        r = decode_reg(data->reg_endian, reg);
        if (data->noinc_reg && data->noinc_reg(data, r)) {
                memcpy(&our_buf[r], val + val_len - 2, 2);
                data->written[r] = true;
        } else {
                memcpy(&our_buf[r], val, val_len);

                for (i = 0; i < val_len / 2; i++)
                        data->written[r + i] = true;
        }
        
        return 0;
}

static int regmap_raw_ram_write(void *context, const void *data, size_t count)
{
        return regmap_raw_ram_gather_write(context, data, 2,
                                           data + 2, count - 2);
}

static int regmap_raw_ram_read(void *context,
                               const void *reg, size_t reg_len,
                               void *val, size_t val_len)
{
        struct regmap_ram_data *data = context;
        unsigned int r;
        u16 *our_buf = (u16 *)data->vals;
        int i;

        if (reg_len != 2)
                return -EINVAL;
        if (val_len % 2)
                return -EINVAL;

        r = decode_reg(data->reg_endian, reg);
        if (data->noinc_reg && data->noinc_reg(data, r)) {
                for (i = 0; i < val_len; i += 2)
                        memcpy(val + i, &our_buf[r], 2);
                data->read[r] = true;
        } else {
                memcpy(val, &our_buf[r], val_len);

                for (i = 0; i < val_len / 2; i++)
                        data->read[r + i] = true;
        }

        return 0;
}

static void regmap_raw_ram_free_context(void *context)
{
        struct regmap_ram_data *data = context;

        kfree(data->vals);
        kfree(data->read);
        kfree(data->written);
        kfree(data);
}

static const struct regmap_bus regmap_raw_ram = {
        .fast_io = true,
        .write = regmap_raw_ram_write,
        .gather_write = regmap_raw_ram_gather_write,
        .read = regmap_raw_ram_read,
        .free_context = regmap_raw_ram_free_context,
};

struct regmap *__regmap_init_raw_ram(struct device *dev,
                                     const struct regmap_config *config,
                                     struct regmap_ram_data *data,
                                     struct lock_class_key *lock_key,
                                     const char *lock_name)
{
        struct regmap *map;

        if (config->reg_bits != 16)
                return ERR_PTR(-EINVAL);

        if (!config->max_register) {
                pr_crit("No max_register specified for RAM regmap\n");
                return ERR_PTR(-EINVAL);
        }

        data->read = kzalloc_objs(bool, config->max_register + 1);
        if (!data->read)
                return ERR_PTR(-ENOMEM);

        data->written = kzalloc_objs(bool, config->max_register + 1);
        if (!data->written)
                return ERR_PTR(-ENOMEM);

        data->reg_endian = config->reg_format_endian;

        map = __regmap_init(dev, &regmap_raw_ram, data, config,
                            lock_key, lock_name);

        return map;
}
EXPORT_SYMBOL_GPL(__regmap_init_raw_ram);

MODULE_DESCRIPTION("Register map access API - Memory region with raw access");
MODULE_LICENSE("GPL v2");