drivers/mtd/nand/nand_samsung.c

/*
 * Copyright (C) 2017 Free Electrons
 * Copyright (C) 2017 NextThing Co
 *
 * Author: Boris Brezillon <boris.brezillon@free-electrons.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/mtd/nand.h>

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

	/* New Samsung (6 byte ID): Samsung K9GAG08U0F (p.44) */
	if (chip->id.len == 6 && !nand_is_slc(chip) &&
	    chip->id.data[5] != 0x00) {
		u8 extid = chip->id.data[3];

		/* Get pagesize */
		mtd->writesize = 2048 << (extid & 0x03);

		extid >>= 2;

		/* Get oobsize */
		switch (((extid >> 2) & 0x4) | (extid & 0x3)) {
		case 1:
			mtd->oobsize = 128;
			break;
		case 2:
			mtd->oobsize = 218;
			break;
		case 3:
			mtd->oobsize = 400;
			break;
		case 4:
			mtd->oobsize = 436;
			break;
		case 5:
			mtd->oobsize = 512;
			break;
		case 6:
			mtd->oobsize = 640;
			break;
		default:
			/*
			 * We should never reach this case, but if that
			 * happens, this probably means Samsung decided to use
			 * a different extended ID format, and we should find
			 * a way to support it.
			 */
			WARN(1, "Invalid OOB size value");
			break;
		}

		/* Get blocksize */
		extid >>= 2;
		mtd->erasesize = (128 * 1024) <<
				 (((extid >> 1) & 0x04) | (extid & 0x03));

		/* Extract ECC requirements from 5th id byte*/
		extid = (chip->id.data[4] >> 4) & 0x07;
		if (extid < 5) {
			chip->ecc_step_ds = 512;
			chip->ecc_strength_ds = 1 << extid;
		} else {
			chip->ecc_step_ds = 1024;
			switch (extid) {
			case 5:
				chip->ecc_strength_ds = 24;
				break;
			case 6:
				chip->ecc_strength_ds = 40;
				break;
			case 7:
				chip->ecc_strength_ds = 60;
				break;
			}
		}
	} else {
		nand_decode_ext_id(chip);
	}
}

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

	if (mtd->writesize > 512)
		chip->options |= NAND_SAMSUNG_LP_OPTIONS;

	if (!nand_is_slc(chip))
		chip->bbt_options |= NAND_BBT_SCANLASTPAGE;
	else
		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;

	return 0;
}

const struct nand_manufacturer_ops samsung_nand_manuf_ops = {
	.detect = samsung_nand_decode_id,
	.init = samsung_nand_init,
};