// SPDX-License-Identifier: GPL-2.0
/*
 * I2C driver for Bosch BMI323 6-Axis IMU.
 *
 * Copyright (C) 2023, Jagath Jog J <jagathjog1996@gmail.com>
 */

#include <linux/i2c.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/regmap.h>

#include "bmi323.h"

struct bmi323_i2c_priv {
        struct i2c_client *i2c;
        u8 i2c_rx_buffer[BMI323_FIFO_LENGTH_IN_BYTES + BMI323_I2C_DUMMY];
};

/*
 * From BMI323 datasheet section 4: Notes on the Serial Interface Support.
 * Each I2C register read operation requires to read two dummy bytes before
 * the actual payload.
 */
static int bmi323_regmap_i2c_read(void *context, const void *reg_buf,
                                  size_t reg_size, void *val_buf,
                                  size_t val_size)
{
        struct bmi323_i2c_priv *priv = context;
        struct i2c_msg msgs[2];
        int ret;

        msgs[0].addr = priv->i2c->addr;
        msgs[0].flags = priv->i2c->flags;
        msgs[0].len = reg_size;
        msgs[0].buf = (u8 *)reg_buf;

        msgs[1].addr = priv->i2c->addr;
        msgs[1].len = val_size + BMI323_I2C_DUMMY;
        msgs[1].buf = priv->i2c_rx_buffer;
        msgs[1].flags = priv->i2c->flags | I2C_M_RD;

        ret = i2c_transfer(priv->i2c->adapter, msgs, ARRAY_SIZE(msgs));
        if (ret < 0)
                return -EIO;

        memcpy(val_buf, priv->i2c_rx_buffer + BMI323_I2C_DUMMY, val_size);

        return 0;
}

static int bmi323_regmap_i2c_write(void *context, const void *data,
                                   size_t count)
{
        struct bmi323_i2c_priv *priv = context;
        u8 reg;

        reg = *(u8 *)data;
        return i2c_smbus_write_i2c_block_data(priv->i2c, reg,
                                              count - sizeof(u8),
                                              data + sizeof(u8));
}

static const struct regmap_bus bmi323_regmap_bus = {
        .read = bmi323_regmap_i2c_read,
        .write = bmi323_regmap_i2c_write,
};

static const struct regmap_config bmi323_i2c_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .max_register = BMI323_CFG_RES_REG,
        .val_format_endian = REGMAP_ENDIAN_LITTLE,
};

static int bmi323_i2c_probe(struct i2c_client *i2c)
{
        struct device *dev = &i2c->dev;
        struct bmi323_i2c_priv *priv;
        struct regmap *regmap;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->i2c = i2c;
        regmap = devm_regmap_init(dev, &bmi323_regmap_bus, priv,
                                  &bmi323_i2c_regmap_config);
        if (IS_ERR(regmap))
                return dev_err_probe(dev, PTR_ERR(regmap),
                                     "Failed to initialize I2C Regmap\n");

        return bmi323_core_probe(dev);
}

static const struct acpi_device_id bmi323_acpi_match[] = {
        /*
         * The "BOSC0200" identifier used here is not unique to bmi323 devices.
         * The same "BOSC0200" identifier is found in the ACPI tables of devices
         * using the bmc150 chip. This creates a conflict with duplicate ACPI
         * identifiers which multiple drivers want to use. If a non-bmi323
         * device starts to load with this "BOSC0200" ACPI match here, then the
         * chip ID check portion should fail because the chip IDs received (via
         * i2c) are unique between bmc150 and bmi323 and the driver should
         * relinquish the device. If and when a different driver (such as
         * bmc150) starts to load with the "BOSC0200" ACPI match, a short reset
         * should ensure that the device is not in a bad state during that
         * driver initialization. This device reset does occur in both the
         * bmi323 and bmc150 init sequences.
         */
        { "BOSC0200" },
        { }
};
MODULE_DEVICE_TABLE(acpi, bmi323_acpi_match);

static const struct i2c_device_id bmi323_i2c_ids[] = {
        { "bmi323" },
        { }
};
MODULE_DEVICE_TABLE(i2c, bmi323_i2c_ids);

static const struct of_device_id bmi323_of_i2c_match[] = {
        { .compatible = "bosch,bmi323" },
        { }
};
MODULE_DEVICE_TABLE(of, bmi323_of_i2c_match);

static struct i2c_driver bmi323_i2c_driver = {
        .driver = {
                .name = "bmi323",
                .pm = pm_ptr(&bmi323_core_pm_ops),
                .of_match_table = bmi323_of_i2c_match,
                .acpi_match_table = bmi323_acpi_match,
        },
        .probe = bmi323_i2c_probe,
        .id_table = bmi323_i2c_ids,
};
module_i2c_driver(bmi323_i2c_driver);

MODULE_DESCRIPTION("Bosch BMI323 IMU driver");
MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("IIO_BMI323");