diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 66e94258b6c5..523e44cbba2a 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -290,6 +290,126 @@ static struct spi_nor *mtd_to_spi_nor(struct mtd_info *mtd)
 	return mtd->priv;
 }
 
+static u8 spi_nor_convert_opcode(u8 opcode, const u8 table[][2], size_t size)
+{
+	size_t i;
+
+	for (i = 0; i < size; i++)
+		if (table[i][0] == opcode)
+			return table[i][1];
+
+	/* No conversion found, keep input op code. */
+	return opcode;
+}
+
+static u8 spi_nor_convert_3to4_read(u8 opcode)
+{
+	static const u8 spi_nor_3to4_read[][2] = {
+		{ SPINOR_OP_READ,	SPINOR_OP_READ_4B },
+		{ SPINOR_OP_READ_FAST,	SPINOR_OP_READ_FAST_4B },
+		{ SPINOR_OP_READ_1_1_2,	SPINOR_OP_READ_1_1_2_4B },
+		{ SPINOR_OP_READ_1_2_2,	SPINOR_OP_READ_1_2_2_4B },
+		{ SPINOR_OP_READ_1_1_4,	SPINOR_OP_READ_1_1_4_4B },
+		{ SPINOR_OP_READ_1_4_4,	SPINOR_OP_READ_1_4_4_4B },
+
+		{ SPINOR_OP_READ_1_1_1_DTR,	SPINOR_OP_READ_1_1_1_DTR_4B },
+		{ SPINOR_OP_READ_1_2_2_DTR,	SPINOR_OP_READ_1_2_2_DTR_4B },
+		{ SPINOR_OP_READ_1_4_4_DTR,	SPINOR_OP_READ_1_4_4_DTR_4B },
+	};
+
+	return spi_nor_convert_opcode(opcode, spi_nor_3to4_read,
+				      ARRAY_SIZE(spi_nor_3to4_read));
+}
+
+static u8 spi_nor_convert_3to4_program(u8 opcode)
+{
+	static const u8 spi_nor_3to4_program[][2] = {
+		{ SPINOR_OP_PP,		SPINOR_OP_PP_4B },
+		{ SPINOR_OP_PP_1_1_4,	SPINOR_OP_PP_1_1_4_4B },
+		{ SPINOR_OP_PP_1_4_4,	SPINOR_OP_PP_1_4_4_4B },
+	};
+
+	return spi_nor_convert_opcode(opcode, spi_nor_3to4_program,
+				      ARRAY_SIZE(spi_nor_3to4_program));
+}
+
+static u8 spi_nor_convert_3to4_erase(u8 opcode)
+{
+	static const u8 spi_nor_3to4_erase[][2] = {
+		{ SPINOR_OP_BE_4K,	SPINOR_OP_BE_4K_4B },
+		{ SPINOR_OP_BE_32K,	SPINOR_OP_BE_32K_4B },
+		{ SPINOR_OP_SE,		SPINOR_OP_SE_4B },
+	};
+
+	return spi_nor_convert_opcode(opcode, spi_nor_3to4_erase,
+				      ARRAY_SIZE(spi_nor_3to4_erase));
+}
+
+static void spi_nor_set_4byte_opcodes(struct spi_nor *nor,
+				      const struct flash_info *info)
+{
+	/* Do some manufacturer fixups first */
+	switch (JEDEC_MFR(info)) {
+	case SNOR_MFR_SPANSION:
+		/* No small sector erase for 4-byte command set */
+		nor->erase_opcode = SPINOR_OP_SE;
+		nor->mtd.erasesize = info->sector_size;
+		break;
+
+	default:
+		break;
+	}
+
+	nor->read_opcode = spi_nor_convert_3to4_read(nor->read_opcode);
+	nor->program_opcode = spi_nor_convert_3to4_program(nor->program_opcode);
+	nor->erase_opcode = spi_nor_convert_3to4_erase(nor->erase_opcode);
+}
+
+/* Enable/disable 4-byte addressing mode. */
+static int set_4byte(struct spi_nor *nor, const struct flash_info *info,
+		     int enable)
+{
+	int status;
+	bool need_wren = false;
+	u8 cmd;
+
+	switch (JEDEC_MFR(info)) {
+	case SNOR_MFR_ST:
+	case SNOR_MFR_MICRON:
+		/* Some Micron need WREN command; all will accept it */
+		need_wren = true;
+	case SNOR_MFR_MACRONIX:
+	case SNOR_MFR_WINBOND:
+		if (need_wren)
+			write_enable(nor);
+
+		cmd = enable ? SPINOR_OP_EN4B : SPINOR_OP_EX4B;
+		status = nor->write_reg(nor, cmd, NULL, 0);
+		if (need_wren)
+			write_disable(nor);
+
+		if (!status && !enable &&
+		    JEDEC_MFR(info) == SNOR_MFR_WINBOND) {
+			/*
+			 * On Winbond W25Q256FV, leaving 4byte mode causes
+			 * the Extended Address Register to be set to 1, so all
+			 * 3-byte-address reads come from the second 16M.
+			 * We must clear the register to enable normal behavior.
+			 */
+			write_enable(nor);
+			nor->cmd_buf[0] = 0;
+			nor->write_reg(nor, SPINOR_OP_WREAR, nor->cmd_buf, 1);
+			write_disable(nor);
+		}
+
+		return status;
+	default:
+		/* Spansion style */
+		nor->cmd_buf[0] = enable << 7;
+		return nor->write_reg(nor, SPINOR_OP_BRWR, nor->cmd_buf, 1);
+	}
+}
+
 static int spi_nor_sr_ready(struct spi_nor *nor)
 {
 	int sr = read_sr(nor);
@@ -1663,6 +1783,21 @@ static int spi_nor_init(struct spi_nor *nor)
 		}
 	}
 
+	if (nor->addr_width == 4 &&
+	    (JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) &&
+	    !(nor->info->flags & SPI_NOR_4B_OPCODES)) {
+		/*
+		 * If the RESET# pin isn't hooked up properly, or the system
+		 * otherwise doesn't perform a reset command in the boot
+		 * sequence, it's impossible to 100% protect against unexpected
+		 * reboots (e.g., crashes). Warn the user (or hopefully, system
+		 * designer) that this is bad.
+		 */
+		if (nor->flags & SNOR_F_BROKEN_RESET)
+			printf("enabling reset hack; may not recover from unexpected reboots\n");
+		set_4byte(nor, nor->info, 1);
+	}
+
 	return 0;
 }
 
@@ -1772,6 +1907,12 @@ int spi_nor_scan(struct spi_nor *nor)
 
 	if (info->addr_width) {
 		nor->addr_width = info->addr_width;
+	} else if (mtd->size > 0x1000000) {
+		/* enable 4-byte addressing if the device exceeds 16MiB */
+		nor->addr_width = 4;
+		if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
+		    info->flags & SPI_NOR_4B_OPCODES)
+			spi_nor_set_4byte_opcodes(nor, info);
 	} else {
 		nor->addr_width = 3;
 	}
