// SPDX-License-Identifier: GPL-2.0-only
/*
 * Parser for TRX format partitions
 *
 * Copyright (C) 2012 - 2017 Rafał Miłecki <rafal@milecki.pl>
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>

#define TRX_PARSER_MAX_PARTS            4

/* Magics */
#define TRX_MAGIC                       0x30524448
#define UBI_EC_MAGIC                    0x23494255      /* UBI# */

struct trx_header {
        uint32_t magic;
        uint32_t length;
        uint32_t crc32;
        uint16_t flags;
        uint16_t version;
        uint32_t offset[3];
} __packed;

static const char *parser_trx_data_part_name(struct mtd_info *master,
                                             size_t offset)
{
        uint32_t buf;
        size_t bytes_read;
        int err;

        err  = mtd_read(master, offset, sizeof(buf), &bytes_read,
                        (uint8_t *)&buf);
        if (err && !mtd_is_bitflip(err)) {
                pr_err("mtd_read error while parsing (offset: 0x%zX): %d\n",
                        offset, err);
                goto out_default;
        }

        if (buf == UBI_EC_MAGIC)
                return "ubi";

out_default:
        return "rootfs";
}

static int parser_trx_parse(struct mtd_info *mtd,
                            const struct mtd_partition **pparts,
                            struct mtd_part_parser_data *data)
{
        struct device_node *np = mtd_get_of_node(mtd);
        struct mtd_partition *parts;
        struct mtd_partition *part;
        struct trx_header trx;
        size_t bytes_read;
        uint8_t curr_part = 0, i = 0;
        uint32_t trx_magic = TRX_MAGIC;
        int err;

        /* Get different magic from device tree if specified */
        err = of_property_read_u32(np, "brcm,trx-magic", &trx_magic);
        if (err != 0 && err != -EINVAL)
                pr_err("failed to parse \"brcm,trx-magic\" DT attribute, using default: %d\n", err);

        parts = kzalloc_objs(struct mtd_partition, TRX_PARSER_MAX_PARTS);
        if (!parts)
                return -ENOMEM;

        err = mtd_read(mtd, 0, sizeof(trx), &bytes_read, (uint8_t *)&trx);
        if (err) {
                pr_err("MTD reading error: %d\n", err);
                kfree(parts);
                return err;
        }

        if (trx.magic != trx_magic) {
                kfree(parts);
                return -ENOENT;
        }

        /* We have LZMA loader if there is address in offset[2] */
        if (trx.offset[2]) {
                part = &parts[curr_part++];
                part->name = "loader";
                part->offset = trx.offset[i];
                i++;
        }

        if (trx.offset[i]) {
                part = &parts[curr_part++];
                part->name = "linux";
                part->offset = trx.offset[i];
                i++;
        }

        if (trx.offset[i]) {
                part = &parts[curr_part++];
                part->name = parser_trx_data_part_name(mtd, trx.offset[i]);
                part->offset = trx.offset[i];
                i++;
        }

        /*
         * Assume that every partition ends at the beginning of the one it is
         * followed by.
         */
        for (i = 0; i < curr_part; i++) {
                u64 next_part_offset = (i < curr_part - 1) ?
                                       parts[i + 1].offset : mtd->size;

                parts[i].size = next_part_offset - parts[i].offset;
        }

        *pparts = parts;
        return i;
};

static const struct of_device_id mtd_parser_trx_of_match_table[] = {
        { .compatible = "brcm,trx" },
        {},
};
MODULE_DEVICE_TABLE(of, mtd_parser_trx_of_match_table);

static struct mtd_part_parser mtd_parser_trx = {
        .parse_fn = parser_trx_parse,
        .name = "trx",
        .of_match_table = mtd_parser_trx_of_match_table,
};
module_mtd_part_parser(mtd_parser_trx);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Parser for TRX format partitions");