// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright 2020 Google Inc
// Copyright 2025 Linaro Ltd.
//
// NVMEM driver for Maxim MAX77759

#include <linux/dev_printk.h>
#include <linux/device.h>
#include <linux/device/driver.h>
#include <linux/err.h>
#include <linux/mfd/max77759.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/overflow.h>
#include <linux/platform_device.h>
#include <linux/string.h>

#define MAX77759_NVMEM_OPCODE_HEADER_LEN 3
/*
 * NVMEM commands have a three byte header (which becomes part of the command),
 * so we need to subtract that.
 */
#define MAX77759_NVMEM_SIZE (MAX77759_MAXQ_OPCODE_MAXLENGTH \
                             - MAX77759_NVMEM_OPCODE_HEADER_LEN)

struct max77759_nvmem {
        struct device *dev;
        struct max77759 *max77759;
};

static int max77759_nvmem_reg_read(void *priv, unsigned int offset,
                                   void *val, size_t bytes)
{
        struct max77759_nvmem *nvmem = priv;
        DEFINE_FLEX(struct max77759_maxq_command, cmd, cmd, length,
                    MAX77759_NVMEM_OPCODE_HEADER_LEN);
        DEFINE_FLEX(struct max77759_maxq_response, rsp, rsp, length,
                    MAX77759_MAXQ_OPCODE_MAXLENGTH);
        int ret;

        cmd->cmd[0] = MAX77759_MAXQ_OPCODE_USER_SPACE_READ;
        cmd->cmd[1] = offset;
        cmd->cmd[2] = bytes;
        rsp->length = bytes + MAX77759_NVMEM_OPCODE_HEADER_LEN;

        ret = max77759_maxq_command(nvmem->max77759, cmd, rsp);
        if (ret < 0)
                return ret;

        if (memcmp(cmd->cmd, rsp->rsp, MAX77759_NVMEM_OPCODE_HEADER_LEN)) {
                dev_warn(nvmem->dev, "protocol error (read)\n");
                return -EIO;
        }

        memcpy(val, &rsp->rsp[MAX77759_NVMEM_OPCODE_HEADER_LEN], bytes);

        return 0;
}

static int max77759_nvmem_reg_write(void *priv, unsigned int offset,
                                    void *val, size_t bytes)
{
        struct max77759_nvmem *nvmem = priv;
        DEFINE_FLEX(struct max77759_maxq_command, cmd, cmd, length,
                    MAX77759_MAXQ_OPCODE_MAXLENGTH);
        DEFINE_FLEX(struct max77759_maxq_response, rsp, rsp, length,
                    MAX77759_MAXQ_OPCODE_MAXLENGTH);
        int ret;

        cmd->cmd[0] = MAX77759_MAXQ_OPCODE_USER_SPACE_WRITE;
        cmd->cmd[1] = offset;
        cmd->cmd[2] = bytes;
        memcpy(&cmd->cmd[MAX77759_NVMEM_OPCODE_HEADER_LEN], val, bytes);
        cmd->length = bytes + MAX77759_NVMEM_OPCODE_HEADER_LEN;
        rsp->length = cmd->length;

        ret = max77759_maxq_command(nvmem->max77759, cmd, rsp);
        if (ret < 0)
                return ret;

        if (memcmp(cmd->cmd, rsp->rsp, cmd->length)) {
                dev_warn(nvmem->dev, "protocol error (write)\n");
                return -EIO;
        }

        return 0;
}

static int max77759_nvmem_probe(struct platform_device *pdev)
{
        struct nvmem_config config = {
                .dev = &pdev->dev,
                .name = dev_name(&pdev->dev),
                .id = NVMEM_DEVID_NONE,
                .type = NVMEM_TYPE_EEPROM,
                .ignore_wp = true,
                .size = MAX77759_NVMEM_SIZE,
                .word_size = sizeof(u8),
                .stride = sizeof(u8),
                .reg_read = max77759_nvmem_reg_read,
                .reg_write = max77759_nvmem_reg_write,
        };
        struct max77759_nvmem *nvmem;

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

        nvmem->dev = &pdev->dev;
        nvmem->max77759 = dev_get_drvdata(pdev->dev.parent);

        config.priv = nvmem;

        return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
}

static const struct of_device_id max77759_nvmem_of_id[] = {
        { .compatible = "maxim,max77759-nvmem", },
        { }
};
MODULE_DEVICE_TABLE(of, max77759_nvmem_of_id);

static const struct platform_device_id max77759_nvmem_platform_id[] = {
        { "max77759-nvmem", },
        { }
};
MODULE_DEVICE_TABLE(platform, max77759_nvmem_platform_id);

static struct platform_driver max77759_nvmem_driver = {
        .driver = {
                .name = "max77759-nvmem",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = max77759_nvmem_of_id,
        },
        .probe = max77759_nvmem_probe,
        .id_table = max77759_nvmem_platform_id,
};

module_platform_driver(max77759_nvmem_driver);

MODULE_AUTHOR("André Draszik <andre.draszik@linaro.org>");
MODULE_DESCRIPTION("NVMEM driver for Maxim MAX77759");
MODULE_LICENSE("GPL");