// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2017 Free Electrons
 * Copyright (C) 2017 NextThing Co
 *
 * Author: Boris Brezillon <boris.brezillon@free-electrons.com>
 */

#include "internals.h"

/* Bit for detecting BENAND */
#define TOSHIBA_NAND_ID4_IS_BENAND              BIT(7)

/* Recommended to rewrite for BENAND */
#define TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED BIT(3)

/* ECC Status Read Command for BENAND */
#define TOSHIBA_NAND_CMD_ECC_STATUS_READ        0x7A

/* ECC Status Mask for BENAND */
#define TOSHIBA_NAND_ECC_STATUS_MASK            0x0F

/* Uncorrectable Error for BENAND */
#define TOSHIBA_NAND_ECC_STATUS_UNCORR          0x0F

/* Max ECC Steps for BENAND */
#define TOSHIBA_NAND_MAX_ECC_STEPS              8

static int toshiba_nand_benand_read_eccstatus_op(struct nand_chip *chip,
                                                 u8 *buf)
{
        u8 *ecc_status = buf;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(&chip->data_interface);
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(TOSHIBA_NAND_CMD_ECC_STATUS_READ,
                                    PSEC_TO_NSEC(sdr->tADL_min)),
                        NAND_OP_8BIT_DATA_IN(chip->ecc.steps, ecc_status, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                return nand_exec_op(chip, &op);
        }

        return -ENOTSUPP;
}

static int toshiba_nand_benand_eccstatus(struct nand_chip *chip)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;
        unsigned int max_bitflips = 0;
        u8 status, ecc_status[TOSHIBA_NAND_MAX_ECC_STEPS];

        /* Check Status */
        ret = toshiba_nand_benand_read_eccstatus_op(chip, ecc_status);
        if (!ret) {
                unsigned int i, bitflips = 0;

                for (i = 0; i < chip->ecc.steps; i++) {
                        bitflips = ecc_status[i] & TOSHIBA_NAND_ECC_STATUS_MASK;
                        if (bitflips == TOSHIBA_NAND_ECC_STATUS_UNCORR) {
                                mtd->ecc_stats.failed++;
                        } else {
                                mtd->ecc_stats.corrected += bitflips;
                                max_bitflips = max(max_bitflips, bitflips);
                        }
                }

                return max_bitflips;
        }

        /*
         * Fallback to regular status check if
         * toshiba_nand_benand_read_eccstatus_op() failed.
         */
        ret = nand_status_op(chip, &status);
        if (ret)
                return ret;

        if (status & NAND_STATUS_FAIL) {
                /* uncorrected */
                mtd->ecc_stats.failed++;
        } else if (status & TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED) {
                /* corrected */
                max_bitflips = mtd->bitflip_threshold;
                mtd->ecc_stats.corrected += max_bitflips;
        }

        return max_bitflips;
}

static int
toshiba_nand_read_page_benand(struct nand_chip *chip, uint8_t *buf,
                              int oob_required, int page)
{
        int ret;

        ret = nand_read_page_raw(chip, buf, oob_required, page);
        if (ret)
                return ret;

        return toshiba_nand_benand_eccstatus(chip);
}

static int
toshiba_nand_read_subpage_benand(struct nand_chip *chip, uint32_t data_offs,
                                 uint32_t readlen, uint8_t *bufpoi, int page)
{
        int ret;

        ret = nand_read_page_op(chip, page, data_offs,
                                bufpoi + data_offs, readlen);
        if (ret)
                return ret;

        return toshiba_nand_benand_eccstatus(chip);
}

static void toshiba_nand_benand_init(struct nand_chip *chip)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        /*
         * On BENAND, the entire OOB region can be used by the MTD user.
         * The calculated ECC bytes are stored into other isolated
         * area which is not accessible to users.
         * This is why chip->ecc.bytes = 0.
         */
        chip->ecc.bytes = 0;
        chip->ecc.size = 512;
        chip->ecc.strength = 8;
        chip->ecc.read_page = toshiba_nand_read_page_benand;
        chip->ecc.read_subpage = toshiba_nand_read_subpage_benand;
        chip->ecc.write_page = nand_write_page_raw;
        chip->ecc.read_page_raw = nand_read_page_raw_notsupp;
        chip->ecc.write_page_raw = nand_write_page_raw_notsupp;

        chip->options |= NAND_SUBPAGE_READ;

        mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
}

static void toshiba_nand_decode_id(struct nand_chip *chip)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        struct nand_memory_organization *memorg;

        memorg = nanddev_get_memorg(&chip->base);

        nand_decode_ext_id(chip);

        /*
         * Toshiba 24nm raw SLC (i.e., not BENAND) have 32B OOB per
         * 512B page. For Toshiba SLC, we decode the 5th/6th byte as
         * follows:
         * - ID byte 6, bits[2:0]: 100b -> 43nm, 101b -> 32nm,
         *                         110b -> 24nm
         * - ID byte 5, bit[7]:    1 -> BENAND, 0 -> raw SLC
         */
        if (chip->id.len >= 6 && nand_is_slc(chip) &&
            (chip->id.data[5] & 0x7) == 0x6 /* 24nm */ &&
            !(chip->id.data[4] & TOSHIBA_NAND_ID4_IS_BENAND) /* !BENAND */) {
                memorg->oobsize = 32 * memorg->pagesize >> 9;
                mtd->oobsize = memorg->oobsize;
        }

        /*
         * Extract ECC requirements from 6th id byte.
         * For Toshiba SLC, ecc requrements are as follows:
         *  - 43nm: 1 bit ECC for each 512Byte is required.
         *  - 32nm: 4 bit ECC for each 512Byte is required.
         *  - 24nm: 8 bit ECC for each 512Byte is required.
         */
        if (chip->id.len >= 6 && nand_is_slc(chip)) {
                chip->base.eccreq.step_size = 512;
                switch (chip->id.data[5] & 0x7) {
                case 0x4:
                        chip->base.eccreq.strength = 1;
                        break;
                case 0x5:
                        chip->base.eccreq.strength = 4;
                        break;
                case 0x6:
                        chip->base.eccreq.strength = 8;
                        break;
                default:
                        WARN(1, "Could not get ECC info");
                        chip->base.eccreq.step_size = 0;
                        break;
                }
        }
}

static int tc58teg5dclta00_init(struct nand_chip *chip)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        chip->onfi_timing_mode_default = 5;
        chip->options |= NAND_NEED_SCRAMBLING;
        mtd_set_pairing_scheme(mtd, &dist3_pairing_scheme);

        return 0;
}

static int toshiba_nand_init(struct nand_chip *chip)
{
        if (nand_is_slc(chip))
                chip->options |= NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE;

        /* Check that chip is BENAND and ECC mode is on-die */
        if (nand_is_slc(chip) && chip->ecc.mode == NAND_ECC_ON_DIE &&
            chip->id.data[4] & TOSHIBA_NAND_ID4_IS_BENAND)
                toshiba_nand_benand_init(chip);

        if (!strcmp("TC58TEG5DCLTA00", chip->parameters.model))
                tc58teg5dclta00_init(chip);

        return 0;
}

const struct nand_manufacturer_ops toshiba_nand_manuf_ops = {
        .detect = toshiba_nand_decode_id,
        .init = toshiba_nand_init,
};