// SPDX-License-Identifier: GPL-2.0-only
/* MCP23S08 SPI GPIO driver */

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

#include "pinctrl-mcp23s08.h"

#define MCP_MAX_DEV_PER_CS      8

/*
 * A given spi_device can represent up to eight mcp23sxx chips
 * sharing the same chipselect but using different addresses
 * (e.g. chips #0 and #3 might be populated, but not #1 or #2).
 * Driver data holds all the per-chip data.
 */
struct mcp23s08_driver_data {
        unsigned                ngpio;
        struct mcp23s08         *mcp[8];
        struct mcp23s08         chip[];
};

static int mcp23sxx_spi_write(void *context, const void *data, size_t count)
{
        struct mcp23s08 *mcp = context;
        struct spi_device *spi = to_spi_device(mcp->dev);
        struct spi_message m;
        struct spi_transfer t[2] = { { .tx_buf = &mcp->addr, .len = 1, },
                                     { .tx_buf = data, .len = count, }, };

        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 mcp23sxx_spi_gather_write(void *context,
                                const void *reg, size_t reg_size,
                                const void *val, size_t val_size)
{
        struct mcp23s08 *mcp = context;
        struct spi_device *spi = to_spi_device(mcp->dev);
        struct spi_message m;
        struct spi_transfer t[3] = { { .tx_buf = &mcp->addr, .len = 1, },
                                     { .tx_buf = reg, .len = reg_size, },
                                     { .tx_buf = val, .len = val_size, }, };

        spi_message_init(&m);
        spi_message_add_tail(&t[0], &m);
        spi_message_add_tail(&t[1], &m);
        spi_message_add_tail(&t[2], &m);

        return spi_sync(spi, &m);
}

static int mcp23sxx_spi_read(void *context, const void *reg, size_t reg_size,
                                void *val, size_t val_size)
{
        struct mcp23s08 *mcp = context;
        struct spi_device *spi = to_spi_device(mcp->dev);
        u8 tx[2];

        if (reg_size != 1)
                return -EINVAL;

        tx[0] = mcp->addr | 0x01;
        tx[1] = *((u8 *) reg);

        return spi_write_then_read(spi, tx, sizeof(tx), val, val_size);
}

static const struct regmap_bus mcp23sxx_spi_regmap = {
        .write = mcp23sxx_spi_write,
        .gather_write = mcp23sxx_spi_gather_write,
        .read = mcp23sxx_spi_read,
};

static int mcp23s08_spi_regmap_init(struct mcp23s08 *mcp, struct device *dev,
                                    unsigned int addr, unsigned int type)
{
        const struct regmap_config *config;
        struct regmap_config *copy;
        const char *name;

        switch (type) {
        case MCP_TYPE_S08:
                mcp->reg_shift = 0;
                mcp->chip.ngpio = 8;
                mcp->chip.label = devm_kasprintf(dev, GFP_KERNEL, "mcp23s08.%d", addr);

                config = &mcp23x08_regmap;
                name = devm_kasprintf(dev, GFP_KERNEL, "%d", addr);
                break;

        case MCP_TYPE_S17:
                mcp->reg_shift = 1;
                mcp->chip.ngpio = 16;
                mcp->chip.label = devm_kasprintf(dev, GFP_KERNEL, "mcp23s17.%d", addr);

                config = &mcp23x17_regmap;
                name = devm_kasprintf(dev, GFP_KERNEL, "%d", addr);
                break;

        case MCP_TYPE_S18:
                mcp->reg_shift = 1;
                mcp->chip.ngpio = 16;
                mcp->chip.label = "mcp23s18";

                config = &mcp23x17_regmap;
                name = config->name;
                break;

        default:
                dev_err(dev, "invalid device type (%d)\n", type);
                return -EINVAL;
        }

        copy = devm_kmemdup(dev, config, sizeof(*config), GFP_KERNEL);
        if (!copy)
                return -ENOMEM;

        copy->name = name;

        mcp->regmap = devm_regmap_init(dev, &mcp23sxx_spi_regmap, mcp, copy);
        if (IS_ERR(mcp->regmap))
                dev_err(dev, "regmap init failed for %s\n", mcp->chip.label);
        return PTR_ERR_OR_ZERO(mcp->regmap);
}

static int mcp23s08_probe(struct spi_device *spi)
{
        struct device *dev = &spi->dev;
        struct mcp23s08_driver_data *data;
        unsigned long spi_present_mask;
        const void *match;
        unsigned int addr;
        unsigned int ngpio = 0;
        int chips;
        int type;
        int ret;
        u32 v;

        match = device_get_match_data(dev);
        if (match)
                type = (int)(uintptr_t)match;
        else
                type = spi_get_device_id(spi)->driver_data;

        ret = device_property_read_u32(dev, "microchip,spi-present-mask", &v);
        if (ret) {
                ret = device_property_read_u32(dev, "mcp,spi-present-mask", &v);
                if (ret) {
                        dev_err(dev, "missing spi-present-mask");
                        return ret;
                }
        }
        spi_present_mask = v;

        if (!spi_present_mask || spi_present_mask >= BIT(MCP_MAX_DEV_PER_CS)) {
                dev_err(dev, "invalid spi-present-mask");
                return -ENODEV;
        }

        chips = hweight_long(spi_present_mask);

        data = devm_kzalloc(dev, struct_size(data, chip, chips), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        spi_set_drvdata(spi, data);

        for_each_set_bit(addr, &spi_present_mask, MCP_MAX_DEV_PER_CS) {
                data->mcp[addr] = &data->chip[--chips];
                data->mcp[addr]->irq = spi->irq;

                ret = mcp23s08_spi_regmap_init(data->mcp[addr], dev, addr, type);
                if (ret)
                        return ret;

                data->mcp[addr]->pinctrl_desc.name = devm_kasprintf(dev, GFP_KERNEL,
                                                                    "mcp23xxx-pinctrl.%d",
                                                                    addr);
                if (!data->mcp[addr]->pinctrl_desc.name)
                        return -ENOMEM;

                ret = mcp23s08_probe_one(data->mcp[addr], dev, 0x40 | (addr << 1), type, -1);
                if (ret < 0)
                        return ret;

                ngpio += data->mcp[addr]->chip.ngpio;
        }
        data->ngpio = ngpio;

        return 0;
}

static const struct spi_device_id mcp23s08_ids[] = {
        { "mcp23s08", MCP_TYPE_S08 },
        { "mcp23s17", MCP_TYPE_S17 },
        { "mcp23s18", MCP_TYPE_S18 },
        { }
};
MODULE_DEVICE_TABLE(spi, mcp23s08_ids);

static const struct of_device_id mcp23s08_spi_of_match[] = {
        {
                .compatible = "microchip,mcp23s08",
                .data = (void *) MCP_TYPE_S08,
        },
        {
                .compatible = "microchip,mcp23s17",
                .data = (void *) MCP_TYPE_S17,
        },
        {
                .compatible = "microchip,mcp23s18",
                .data = (void *) MCP_TYPE_S18,
        },
/* NOTE: The use of the mcp prefix is deprecated and will be removed. */
        {
                .compatible = "mcp,mcp23s08",
                .data = (void *) MCP_TYPE_S08,
        },
        {
                .compatible = "mcp,mcp23s17",
                .data = (void *) MCP_TYPE_S17,
        },
        { }
};
MODULE_DEVICE_TABLE(of, mcp23s08_spi_of_match);

static struct spi_driver mcp23s08_driver = {
        .probe          = mcp23s08_probe,
        .id_table       = mcp23s08_ids,
        .driver = {
                .name   = "mcp23s08",
                .of_match_table = mcp23s08_spi_of_match,
        },
};

static int __init mcp23s08_spi_init(void)
{
        return spi_register_driver(&mcp23s08_driver);
}

/*
 * Register after SPI postcore initcall and before
 * subsys initcalls that may rely on these GPIOs.
 */
subsys_initcall(mcp23s08_spi_init);

static void mcp23s08_spi_exit(void)
{
        spi_unregister_driver(&mcp23s08_driver);
}
module_exit(mcp23s08_spi_exit);

MODULE_LICENSE("GPL");