// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
 */

#include <linux/bcm47xx_nvram.h>
#include <linux/etherdevice.h>
#include <linux/hex.h>
#include <linux/if_ether.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define NVRAM_MAGIC                     "FLSH"

/**
 * struct brcm_nvram - driver state internal struct
 *
 * @dev:                NVMEM device pointer
 * @nvmem_size:         Size of the whole space available for NVRAM
 * @data:               NVRAM data copy stored to avoid poking underlying flash controller
 * @data_len:           NVRAM data size
 * @padding_byte:       Padding value used to fill remaining space
 * @cells:              Array of discovered NVMEM cells
 * @ncells:             Number of elements in cells
 */
struct brcm_nvram {
        struct device *dev;
        size_t nvmem_size;
        uint8_t *data;
        size_t data_len;
        uint8_t padding_byte;
        struct nvmem_cell_info *cells;
        int ncells;
};

struct brcm_nvram_header {
        char magic[4];
        __le32 len;
        __le32 crc_ver_init;    /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
        __le32 config_refresh;  /* 0:15 sdram_config, 16:31 sdram_refresh */
        __le32 config_ncdl;     /* ncdl values for memc */
};

static int brcm_nvram_read(void *context, unsigned int offset, void *val,
                           size_t bytes)
{
        struct brcm_nvram *priv = context;
        size_t to_copy;

        if (offset + bytes > priv->data_len)
                to_copy = max_t(ssize_t, (ssize_t)priv->data_len - offset, 0);
        else
                to_copy = bytes;

        memcpy(val, priv->data + offset, to_copy);

        memset((uint8_t *)val + to_copy, priv->padding_byte, bytes - to_copy);

        return 0;
}

static int brcm_nvram_copy_data(struct brcm_nvram *priv, struct platform_device *pdev)
{
        struct resource *res;
        void __iomem *base;

        base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(base))
                return PTR_ERR(base);

        priv->nvmem_size = resource_size(res);

        priv->padding_byte = readb(base + priv->nvmem_size - 1);
        for (priv->data_len = priv->nvmem_size;
             priv->data_len;
             priv->data_len--) {
                if (readb(base + priv->data_len - 1) != priv->padding_byte)
                        break;
        }
        WARN(priv->data_len > SZ_128K, "Unexpected (big) NVRAM size: %zu B\n", priv->data_len);

        priv->data = devm_kzalloc(priv->dev, priv->data_len, GFP_KERNEL);
        if (!priv->data)
                return -ENOMEM;

        memcpy_fromio(priv->data, base, priv->data_len);

        bcm47xx_nvram_init_from_iomem(base, priv->data_len);

        return 0;
}

static int brcm_nvram_read_post_process_macaddr(void *context, const char *id, int index,
                                                unsigned int offset, void *buf, size_t bytes)
{
        u8 mac[ETH_ALEN];

        if (bytes != MAC_ADDR_STR_LEN)
                return -EINVAL;

        if (!mac_pton(buf, mac))
                return -EINVAL;

        if (index)
                eth_addr_add(mac, index);

        ether_addr_copy(buf, mac);

        return 0;
}

static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
                                size_t len)
{
        struct device *dev = priv->dev;
        char *var, *value;
        uint8_t tmp;
        int idx;
        int err = 0;

        tmp = priv->data[len - 1];
        priv->data[len - 1] = '\0';

        priv->ncells = 0;
        for (var = data + sizeof(struct brcm_nvram_header);
             var < (char *)data + len && *var;
             var += strlen(var) + 1) {
                priv->ncells++;
        }

        priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
        if (!priv->cells) {
                err = -ENOMEM;
                goto out;
        }

        for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
             var < (char *)data + len && *var;
             var = value + strlen(value) + 1, idx++) {
                char *eq, *name;

                eq = strchr(var, '=');
                if (!eq)
                        break;
                *eq = '\0';
                name = devm_kstrdup(dev, var, GFP_KERNEL);
                *eq = '=';
                if (!name) {
                        err = -ENOMEM;
                        goto out;
                }
                value = eq + 1;

                priv->cells[idx].name = name;
                priv->cells[idx].offset = value - (char *)data;
                priv->cells[idx].bytes = strlen(value);
                priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
                if (!strcmp(name, "et0macaddr") ||
                    !strcmp(name, "et1macaddr") ||
                    !strcmp(name, "et2macaddr")) {
                        priv->cells[idx].raw_len = strlen(value);
                        priv->cells[idx].bytes = ETH_ALEN;
                        priv->cells[idx].read_post_process = brcm_nvram_read_post_process_macaddr;
                }
        }

out:
        priv->data[len - 1] = tmp;
        return err;
}

static int brcm_nvram_parse(struct brcm_nvram *priv)
{
        struct brcm_nvram_header *header = (struct brcm_nvram_header *)priv->data;
        struct device *dev = priv->dev;
        size_t len;
        int err;

        if (memcmp(header->magic, NVRAM_MAGIC, 4)) {
                dev_err(dev, "Invalid NVRAM magic\n");
                return -EINVAL;
        }

        len = le32_to_cpu(header->len);
        if (len > priv->nvmem_size) {
                dev_err(dev, "NVRAM length (%zd) exceeds mapped size (%zd)\n", len,
                        priv->nvmem_size);
                return -EINVAL;
        }

        err = brcm_nvram_add_cells(priv, priv->data, len);
        if (err)
                dev_err(dev, "Failed to add cells: %d\n", err);

        return 0;
}

static int brcm_nvram_probe(struct platform_device *pdev)
{
        struct nvmem_config config = {
                .name = "brcm-nvram",
                .reg_read = brcm_nvram_read,
        };
        struct device *dev = &pdev->dev;
        struct brcm_nvram *priv;
        int err;

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

        err = brcm_nvram_copy_data(priv, pdev);
        if (err)
                return err;

        err = brcm_nvram_parse(priv);
        if (err)
                return err;

        config.dev = dev;
        config.cells = priv->cells;
        config.ncells = priv->ncells;
        config.priv = priv;
        config.size = priv->nvmem_size;

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

static const struct of_device_id brcm_nvram_of_match_table[] = {
        { .compatible = "brcm,nvram", },
        {},
};

static struct platform_driver brcm_nvram_driver = {
        .probe = brcm_nvram_probe,
        .driver = {
                .name = "brcm_nvram",
                .of_match_table = brcm_nvram_of_match_table,
        },
};

static int __init brcm_nvram_init(void)
{
        return platform_driver_register(&brcm_nvram_driver);
}

subsys_initcall_sync(brcm_nvram_init);

MODULE_AUTHOR("Rafał Miłecki");
MODULE_DESCRIPTION("Broadcom I/O-mapped NVRAM support driver");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);