// SPDX-License-Identifier: GPL-2.0+
/*
 * I2C driver for Renesas Synchronization Management Unit (SMU) devices.
 *
 * Copyright (C) 2021 Integrated Device Technology, Inc., a Renesas Company.
 */

#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mfd/core.h>
#include <linux/mfd/rsmu.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#include "rsmu.h"

/*
 * 32-bit register address: the lower 8 bits of the register address come
 * from the offset addr byte and the upper 24 bits come from the page register.
 */
#define RSMU_CM_PAGE_ADDR               0xFC
#define RSMU_CM_PAGE_MASK               0xFFFFFF00
#define RSMU_CM_ADDRESS_MASK            0x000000FF

/*
 * 15-bit register address: the lower 7 bits of the register address come
 * from the offset addr byte and the upper 8 bits come from the page register.
 */
#define RSMU_SABRE_PAGE_ADDR            0x7F
#define RSMU_SABRE_PAGE_WINDOW          128

typedef int (*rsmu_rw_device)(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes);

static const struct regmap_range_cfg rsmu_sabre_range_cfg[] = {
        {
                .range_min = 0,
                .range_max = 0x400,
                .selector_reg = RSMU_SABRE_PAGE_ADDR,
                .selector_mask = 0xFF,
                .selector_shift = 0,
                .window_start = 0,
                .window_len = RSMU_SABRE_PAGE_WINDOW,
        }
};

static bool rsmu_sabre_volatile_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case RSMU_SABRE_PAGE_ADDR:
                return false;
        default:
                return true;
        }
}

static int rsmu_smbus_i2c_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
{
        struct i2c_client *client = to_i2c_client(rsmu->dev);

        return i2c_smbus_write_i2c_block_data(client, reg, bytes, buf);
}

static int rsmu_smbus_i2c_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
{
        struct i2c_client *client = to_i2c_client(rsmu->dev);
        int ret;

        ret = i2c_smbus_read_i2c_block_data(client, reg, bytes, buf);
        if (ret == bytes)
                return 0;
        else if (ret < 0)
                return ret;
        else
                return -EIO;
}

static int rsmu_i2c_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
{
        struct i2c_client *client = to_i2c_client(rsmu->dev);
        struct i2c_msg msg[2];
        int cnt;

        msg[0].addr = client->addr;
        msg[0].flags = 0;
        msg[0].len = 1;
        msg[0].buf = &reg;

        msg[1].addr = client->addr;
        msg[1].flags = I2C_M_RD;
        msg[1].len = bytes;
        msg[1].buf = buf;

        cnt = i2c_transfer(client->adapter, msg, 2);

        if (cnt < 0) {
                dev_err(rsmu->dev, "i2c_transfer failed at addr: %04x!", reg);
                return cnt;
        } else if (cnt != 2) {
                dev_err(rsmu->dev,
                        "i2c_transfer sent only %d of 2 messages", cnt);
                return -EIO;
        }

        return 0;
}

static int rsmu_i2c_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
{
        struct i2c_client *client = to_i2c_client(rsmu->dev);
        /* we add 1 byte for device register */
        u8 msg[RSMU_MAX_WRITE_COUNT + 1];
        int cnt;

        if (bytes > RSMU_MAX_WRITE_COUNT)
                return -EINVAL;

        msg[0] = reg;
        memcpy(&msg[1], buf, bytes);

        cnt = i2c_master_send(client, msg, bytes + 1);

        if (cnt < 0) {
                dev_err(&client->dev,
                        "i2c_master_send failed at addr: %04x!", reg);
                return cnt;
        }

        return 0;
}

static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u32 reg,
                                    rsmu_rw_device rsmu_write_device)
{
        u32 page = reg & RSMU_CM_PAGE_MASK;
        u8 buf[4];
        int err;

        /* Do not modify offset register for none-scsr registers */
        if (reg < RSMU_CM_SCSR_BASE)
                return 0;

        /* Simply return if we are on the same page */
        if (rsmu->page == page)
                return 0;

        buf[0] = 0x0;
        buf[1] = (u8)((page >> 8) & 0xFF);
        buf[2] = (u8)((page >> 16) & 0xFF);
        buf[3] = (u8)((page >> 24) & 0xFF);

        err = rsmu_write_device(rsmu, RSMU_CM_PAGE_ADDR, buf, sizeof(buf));
        if (err)
                dev_err(rsmu->dev, "Failed to set page offset 0x%x\n", page);
        else
                /* Remember the last page */
                rsmu->page = page;

        return err;
}

static int rsmu_i2c_reg_read(void *context, unsigned int reg, unsigned int *val)
{
        struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
        u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
        int err;

        err = rsmu_write_page_register(rsmu, reg, rsmu_i2c_write_device);
        if (err)
                return err;

        err = rsmu_i2c_read_device(rsmu, addr, (u8 *)val, 1);
        if (err)
                dev_err(rsmu->dev, "Failed to read offset address 0x%x\n", addr);

        return err;
}

static int rsmu_i2c_reg_write(void *context, unsigned int reg, unsigned int val)
{
        struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
        u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
        u8 data = (u8)val;
        int err;

        err = rsmu_write_page_register(rsmu, reg, rsmu_i2c_write_device);
        if (err)
                return err;

        err = rsmu_i2c_write_device(rsmu, addr, &data, 1);
        if (err)
                dev_err(rsmu->dev,
                        "Failed to write offset address 0x%x\n", addr);

        return err;
}

static int rsmu_smbus_i2c_reg_read(void *context, unsigned int reg, unsigned int *val)
{
        struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
        u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
        int err;

        err = rsmu_write_page_register(rsmu, reg, rsmu_smbus_i2c_write_device);
        if (err)
                return err;

        err = rsmu_smbus_i2c_read_device(rsmu, addr, (u8 *)val, 1);
        if (err)
                dev_err(rsmu->dev, "Failed to read offset address 0x%x\n", addr);

        return err;
}

static int rsmu_smbus_i2c_reg_write(void *context, unsigned int reg, unsigned int val)
{
        struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
        u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
        u8 data = (u8)val;
        int err;

        err = rsmu_write_page_register(rsmu, reg, rsmu_smbus_i2c_write_device);
        if (err)
                return err;

        err = rsmu_smbus_i2c_write_device(rsmu, addr, &data, 1);
        if (err)
                dev_err(rsmu->dev,
                        "Failed to write offset address 0x%x\n", addr);

        return err;
}

static const struct regmap_config rsmu_i2c_cm_regmap_config = {
        .reg_bits = 32,
        .val_bits = 8,
        .max_register = 0x20120000,
        .reg_read = rsmu_i2c_reg_read,
        .reg_write = rsmu_i2c_reg_write,
        .cache_type = REGCACHE_NONE,
};

static const struct regmap_config rsmu_smbus_i2c_cm_regmap_config = {
        .reg_bits = 32,
        .val_bits = 8,
        .max_register = 0x20120000,
        .reg_read = rsmu_smbus_i2c_reg_read,
        .reg_write = rsmu_smbus_i2c_reg_write,
        .cache_type = REGCACHE_NONE,
};

static const struct regmap_config rsmu_sabre_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = 0x400,
        .ranges = rsmu_sabre_range_cfg,
        .num_ranges = ARRAY_SIZE(rsmu_sabre_range_cfg),
        .volatile_reg = rsmu_sabre_volatile_reg,
        .cache_type = REGCACHE_MAPLE,
        .can_multi_write = true,
};

static const struct regmap_config rsmu_sl_regmap_config = {
        .reg_bits = 16,
        .val_bits = 8,
        .reg_format_endian = REGMAP_ENDIAN_BIG,
        .max_register = 0x340,
        .cache_type = REGCACHE_NONE,
        .can_multi_write = true,
};

static int rsmu_i2c_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        const struct regmap_config *cfg;
        struct rsmu_ddata *rsmu;
        int ret;

        rsmu = devm_kzalloc(&client->dev, sizeof(*rsmu), GFP_KERNEL);
        if (!rsmu)
                return -ENOMEM;

        i2c_set_clientdata(client, rsmu);

        rsmu->dev = &client->dev;
        rsmu->type = (enum rsmu_type)id->driver_data;

        switch (rsmu->type) {
        case RSMU_CM:
                if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                        cfg = &rsmu_i2c_cm_regmap_config;
                } else if (i2c_check_functionality(client->adapter,
                                                   I2C_FUNC_SMBUS_I2C_BLOCK)) {
                        cfg = &rsmu_smbus_i2c_cm_regmap_config;
                } else {
                        dev_err(rsmu->dev, "Unsupported i2c adapter\n");
                        return -ENOTSUPP;
                }
                break;
        case RSMU_SABRE:
                cfg = &rsmu_sabre_regmap_config;
                break;
        case RSMU_SL:
                cfg = &rsmu_sl_regmap_config;
                break;
        default:
                dev_err(rsmu->dev, "Unsupported RSMU device type: %d\n", rsmu->type);
                return -ENODEV;
        }

        if (rsmu->type == RSMU_CM)
                rsmu->regmap = devm_regmap_init(&client->dev, NULL, client, cfg);
        else
                rsmu->regmap = devm_regmap_init_i2c(client, cfg);

        if (IS_ERR(rsmu->regmap)) {
                ret = PTR_ERR(rsmu->regmap);
                dev_err(rsmu->dev, "Failed to allocate register map: %d\n", ret);
                return ret;
        }

        return rsmu_core_init(rsmu);
}

static void rsmu_i2c_remove(struct i2c_client *client)
{
        struct rsmu_ddata *rsmu = i2c_get_clientdata(client);

        rsmu_core_exit(rsmu);
}

static const struct i2c_device_id rsmu_i2c_id[] = {
        { "8a34000",  RSMU_CM },
        { "8a34001",  RSMU_CM },
        { "82p33810", RSMU_SABRE },
        { "82p33811", RSMU_SABRE },
        { "8v19n850", RSMU_SL },
        { "8v19n851", RSMU_SL },
        {}
};
MODULE_DEVICE_TABLE(i2c, rsmu_i2c_id);

static const struct of_device_id rsmu_i2c_of_match[] = {
        { .compatible = "idt,8a34000",  .data = (void *)RSMU_CM },
        { .compatible = "idt,8a34001",  .data = (void *)RSMU_CM },
        { .compatible = "idt,82p33810", .data = (void *)RSMU_SABRE },
        { .compatible = "idt,82p33811", .data = (void *)RSMU_SABRE },
        { .compatible = "idt,8v19n850", .data = (void *)RSMU_SL },
        { .compatible = "idt,8v19n851", .data = (void *)RSMU_SL },
        {}
};
MODULE_DEVICE_TABLE(of, rsmu_i2c_of_match);

static struct i2c_driver rsmu_i2c_driver = {
        .driver = {
                .name = "rsmu-i2c",
                .of_match_table = rsmu_i2c_of_match,
        },
        .probe = rsmu_i2c_probe,
        .remove = rsmu_i2c_remove,
        .id_table = rsmu_i2c_id,
};

static int __init rsmu_i2c_init(void)
{
        return i2c_add_driver(&rsmu_i2c_driver);
}
subsys_initcall(rsmu_i2c_init);

static void __exit rsmu_i2c_exit(void)
{
        i2c_del_driver(&rsmu_i2c_driver);
}
module_exit(rsmu_i2c_exit);

MODULE_DESCRIPTION("Renesas SMU I2C driver");
MODULE_LICENSE("GPL");