// SPDX-License-Identifier: GPL-2.0
//
// Register map access API - SPI support
//
// Copyright 2011 Wolfson Microelectronics plc
//
// Author: Mark Brown <broonie@opensource.wolfsonmicro.com>

#include <linux/regmap.h>
#include <linux/spi/spi.h>
#include <linux/module.h>

#include "internal.h"

struct regmap_async_spi {
        struct regmap_async core;
        struct spi_message m;
        struct spi_transfer t[2];
};

static void regmap_spi_complete(void *data)
{
        struct regmap_async_spi *async = data;

        regmap_async_complete_cb(&async->core, async->m.status);
}

static int regmap_spi_write(void *context, const void *data, size_t count)
{
        struct device *dev = context;
        struct spi_device *spi = to_spi_device(dev);

        return spi_write(spi, data, count);
}

static int regmap_spi_gather_write(void *context,
                                   const void *reg, size_t reg_len,
                                   const void *val, size_t val_len)
{
        struct device *dev = context;
        struct spi_device *spi = to_spi_device(dev);
        struct spi_message m;
        struct spi_transfer t[2] = { { .tx_buf = reg, .len = reg_len, },
                                     { .tx_buf = val, .len = val_len, }, };

        spi_message_init(&m);
        spi_message_add_tail(&t[0], &m);
        spi_message_add_tail(&t[1], &m);

        return spi_sync(spi, &m);
}

static int regmap_spi_async_write(void *context,
                                  const void *reg, size_t reg_len,
                                  const void *val, size_t val_len,
                                  struct regmap_async *a)
{
        struct regmap_async_spi *async = container_of(a,
                                                      struct regmap_async_spi,
                                                      core);
        struct device *dev = context;
        struct spi_device *spi = to_spi_device(dev);

        async->t[0].tx_buf = reg;
        async->t[0].len = reg_len;
        async->t[1].tx_buf = val;
        async->t[1].len = val_len;

        spi_message_init(&async->m);
        spi_message_add_tail(&async->t[0], &async->m);
        if (val)
                spi_message_add_tail(&async->t[1], &async->m);

        async->m.complete = regmap_spi_complete;
        async->m.context = async;

        return spi_async(spi, &async->m);
}

static struct regmap_async *regmap_spi_async_alloc(void)
{
        struct regmap_async_spi *async_spi;

        async_spi = kzalloc_obj(*async_spi);
        if (!async_spi)
                return NULL;

        return &async_spi->core;
}

static int regmap_spi_read(void *context,
                           const void *reg, size_t reg_size,
                           void *val, size_t val_size)
{
        struct device *dev = context;
        struct spi_device *spi = to_spi_device(dev);

        return spi_write_then_read(spi, reg, reg_size, val, val_size);
}

static const struct regmap_bus regmap_spi = {
        .write = regmap_spi_write,
        .gather_write = regmap_spi_gather_write,
        .async_write = regmap_spi_async_write,
        .async_alloc = regmap_spi_async_alloc,
        .read = regmap_spi_read,
        .read_flag_mask = 0x80,
        .reg_format_endian_default = REGMAP_ENDIAN_BIG,
        .val_format_endian_default = REGMAP_ENDIAN_BIG,
};

static const struct regmap_bus *regmap_get_spi_bus(struct spi_device *spi,
                                                   const struct regmap_config *config)
{
        size_t max_size = spi_max_transfer_size(spi);
        size_t max_msg_size, reg_reserve_size;
        struct regmap_bus *bus;

        if (max_size != SIZE_MAX) {
                bus = kmemdup(&regmap_spi, sizeof(*bus), GFP_KERNEL);
                if (!bus)
                        return ERR_PTR(-ENOMEM);

                max_msg_size = spi_max_message_size(spi);
                reg_reserve_size = (config->reg_bits + config->pad_bits) / BITS_PER_BYTE;
                if (max_size + reg_reserve_size > max_msg_size)
                        max_size -= reg_reserve_size;

                bus->free_on_exit = true;
                bus->max_raw_read = max_size;
                bus->max_raw_write = max_size;

                return bus;
        }

        return &regmap_spi;
}

struct regmap *__regmap_init_spi(struct spi_device *spi,
                                 const struct regmap_config *config,
                                 struct lock_class_key *lock_key,
                                 const char *lock_name)
{
        const struct regmap_bus *bus = regmap_get_spi_bus(spi, config);

        if (IS_ERR(bus))
                return ERR_CAST(bus);

        return __regmap_init(&spi->dev, bus, &spi->dev, config, lock_key, lock_name);
}
EXPORT_SYMBOL_GPL(__regmap_init_spi);

struct regmap *__devm_regmap_init_spi(struct spi_device *spi,
                                      const struct regmap_config *config,
                                      struct lock_class_key *lock_key,
                                      const char *lock_name)
{
        const struct regmap_bus *bus = regmap_get_spi_bus(spi, config);

        if (IS_ERR(bus))
                return ERR_CAST(bus);

        return __devm_regmap_init(&spi->dev, bus, &spi->dev, config, lock_key, lock_name);
}
EXPORT_SYMBOL_GPL(__devm_regmap_init_spi);

MODULE_DESCRIPTION("regmap SPI Module");
MODULE_LICENSE("GPL");