Merge tag 'spi-nor/for-5.5' into mtd/next

SPI NOR core changes:
- introduce 'struct spi_nor_controller_ops',
- clean the Register Operations methods,
- use dev_dbg insted of dev_err for low level info,
- fix retlen handling in sst_write(),
- fix silent truncations in spi_nor_read and spi_nor_read_raw(),
- fix the clearing of QE bit on lock()/unlock(),
- rework the disabling of the block write protection,
- rework the Quad Enable methods,
- make sure nor->spimem and nor->controller_ops are mutually exclusive,
- set default Quad Enable method for ISSI flashes,
- add support for few flashes.

SPI NOR controller drivers changes:
- intel-spi:
	- support chips without software sequencer,
	- add support for Intel Cannon Lake and Intel Comet Lake-H flashes.

8 files changed, 991 insertions, 712 deletions

diff --git a/drivers/mtd/spi-nor/aspeed-smc.c b/drivers/mtd/spi-nor/aspeed-smc.c
index 009c1da8574c..2b7cabbb680c 100644
--- a/drivers/mtd/spi-nor/aspeed-smc.c
+++ b/drivers/mtd/spi-nor/aspeed-smc.c
@@ -320,7 +320,8 @@ static void aspeed_smc_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
 	mutex_unlock(&chip->controller->mutex);
 }
 
-static int aspeed_smc_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int aspeed_smc_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
+			       size_t len)
 {
 	struct aspeed_smc_chip *chip = nor->priv;
 
@@ -331,8 +332,8 @@ static int aspeed_smc_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
 	return 0;
 }
 
-static int aspeed_smc_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
-				int len)
+static int aspeed_smc_write_reg(struct spi_nor *nor, u8 opcode, const u8 *buf,
+				size_t len)
 {
 	struct aspeed_smc_chip *chip = nor->priv;
 
@@ -746,6 +747,15 @@ static int aspeed_smc_chip_setup_finish(struct aspeed_smc_chip *chip)
 	return 0;
 }
 
+static const struct spi_nor_controller_ops aspeed_smc_controller_ops = {
+	.prepare = aspeed_smc_prep,
+	.unprepare = aspeed_smc_unprep,
+	.read_reg = aspeed_smc_read_reg,
+	.write_reg = aspeed_smc_write_reg,
+	.read = aspeed_smc_read_user,
+	.write = aspeed_smc_write_user,
+};
+
 static int aspeed_smc_setup_flash(struct aspeed_smc_controller *controller,
 				  struct device_node *np, struct resource *r)
 {
@@ -805,12 +815,7 @@ static int aspeed_smc_setup_flash(struct aspeed_smc_controller *controller,
 		nor->dev = dev;
 		nor->priv = chip;
 		spi_nor_set_flash_node(nor, child);
-		nor->read = aspeed_smc_read_user;
-		nor->write = aspeed_smc_write_user;
-		nor->read_reg = aspeed_smc_read_reg;
-		nor->write_reg = aspeed_smc_write_reg;
-		nor->prepare = aspeed_smc_prep;
-		nor->unprepare = aspeed_smc_unprep;
+		nor->controller_ops = &aspeed_smc_controller_ops;
 
 		ret = aspeed_smc_chip_setup_init(chip, r);
 		if (ret)
diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index 37be80bd511e..06f997247d0f 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -285,7 +285,7 @@ static irqreturn_t cqspi_irq_handler(int this_irq, void *dev)
 	return IRQ_HANDLED;
 }
 
-static unsigned int cqspi_calc_rdreg(struct spi_nor *nor, const u8 opcode)
+static unsigned int cqspi_calc_rdreg(struct spi_nor *nor)
 {
 	struct cqspi_flash_pdata *f_pdata = nor->priv;
 	u32 rdreg = 0;
@@ -354,27 +354,27 @@ static int cqspi_exec_flash_cmd(struct cqspi_st *cqspi, unsigned int reg)
 	return cqspi_wait_idle(cqspi);
 }
 
-static int cqspi_command_read(struct spi_nor *nor,
-			      const u8 *txbuf, const unsigned n_tx,
-			      u8 *rxbuf, const unsigned n_rx)
+static int cqspi_command_read(struct spi_nor *nor, u8 opcode,
+			      u8 *rxbuf, size_t n_rx)
 {
 	struct cqspi_flash_pdata *f_pdata = nor->priv;
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	void __iomem *reg_base = cqspi->iobase;
 	unsigned int rdreg;
 	unsigned int reg;
-	unsigned int read_len;
+	size_t read_len;
 	int status;
 
 	if (!n_rx || n_rx > CQSPI_STIG_DATA_LEN_MAX || !rxbuf) {
-		dev_err(nor->dev, "Invalid input argument, len %d rxbuf 0x%p\n",
+		dev_err(nor->dev,
+			"Invalid input argument, len %zu rxbuf 0x%p\n",
 			n_rx, rxbuf);
 		return -EINVAL;
 	}
 
-	reg = txbuf[0] << CQSPI_REG_CMDCTRL_OPCODE_LSB;
+	reg = opcode << CQSPI_REG_CMDCTRL_OPCODE_LSB;
 
-	rdreg = cqspi_calc_rdreg(nor, txbuf[0]);
+	rdreg = cqspi_calc_rdreg(nor);
 	writel(rdreg, reg_base + CQSPI_REG_RD_INSTR);
 
 	reg |= (0x1 << CQSPI_REG_CMDCTRL_RD_EN_LSB);
@@ -404,19 +404,19 @@ static int cqspi_command_read(struct spi_nor *nor,
 }
 
 static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
-			       const u8 *txbuf, const unsigned n_tx)
+			       const u8 *txbuf, size_t n_tx)
 {
 	struct cqspi_flash_pdata *f_pdata = nor->priv;
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	void __iomem *reg_base = cqspi->iobase;
 	unsigned int reg;
 	unsigned int data;
-	u32 write_len;
+	size_t write_len;
 	int ret;
 
 	if (n_tx > CQSPI_STIG_DATA_LEN_MAX || (n_tx && !txbuf)) {
 		dev_err(nor->dev,
-			"Invalid input argument, cmdlen %d txbuf 0x%p\n",
+			"Invalid input argument, cmdlen %zu txbuf 0x%p\n",
 			n_tx, txbuf);
 		return -EINVAL;
 	}
@@ -470,7 +470,7 @@ static int cqspi_read_setup(struct spi_nor *nor)
 	unsigned int reg;
 
 	reg = nor->read_opcode << CQSPI_REG_RD_INSTR_OPCODE_LSB;
-	reg |= cqspi_calc_rdreg(nor, nor->read_opcode);
+	reg |= cqspi_calc_rdreg(nor);
 
 	/* Setup dummy clock cycles */
 	dummy_clk = nor->read_dummy;
@@ -603,7 +603,7 @@ static int cqspi_write_setup(struct spi_nor *nor)
 	/* Set opcode. */
 	reg = nor->program_opcode << CQSPI_REG_WR_INSTR_OPCODE_LSB;
 	writel(reg, reg_base + CQSPI_REG_WR_INSTR);
-	reg = cqspi_calc_rdreg(nor, nor->program_opcode);
+	reg = cqspi_calc_rdreg(nor);
 	writel(reg, reg_base + CQSPI_REG_RD_INSTR);
 
 	reg = readl(reg_base + CQSPI_REG_SIZE);
@@ -1050,7 +1050,7 @@ static int cqspi_erase(struct spi_nor *nor, loff_t offs)
 		return ret;
 
 	/* Send write enable, then erase commands. */
-	ret = nor->write_reg(nor, SPINOR_OP_WREN, NULL, 0);
+	ret = nor->controller_ops->write_reg(nor, SPINOR_OP_WREN, NULL, 0);
 	if (ret)
 		return ret;
 
@@ -1080,18 +1080,19 @@ static void cqspi_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
 	mutex_unlock(&cqspi->bus_mutex);
 }
 
-static int cqspi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int cqspi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, size_t len)
 {
 	int ret;
 
 	ret = cqspi_set_protocol(nor, 0);
 	if (!ret)
-		ret = cqspi_command_read(nor, &opcode, 1, buf, len);
+		ret = cqspi_command_read(nor, opcode, buf, len);
 
 	return ret;
 }
 
-static int cqspi_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int cqspi_write_reg(struct spi_nor *nor, u8 opcode, const u8 *buf,
+			   size_t len)
 {
 	int ret;
 
@@ -1216,6 +1217,16 @@ static void cqspi_request_mmap_dma(struct cqspi_st *cqspi)
 	init_completion(&cqspi->rx_dma_complete);
 }
 
+static const struct spi_nor_controller_ops cqspi_controller_ops = {
+	.prepare = cqspi_prep,
+	.unprepare = cqspi_unprep,
+	.read_reg = cqspi_read_reg,
+	.write_reg = cqspi_write_reg,
+	.read = cqspi_read,
+	.write = cqspi_write,
+	.erase = cqspi_erase,
+};
+
 static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
 {
 	struct platform_device *pdev = cqspi->pdev;
@@ -1265,14 +1276,7 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
 		nor->dev = dev;
 		spi_nor_set_flash_node(nor, np);
 		nor->priv = f_pdata;
-
-		nor->read_reg = cqspi_read_reg;
-		nor->write_reg = cqspi_write_reg;
-		nor->read = cqspi_read;
-		nor->write = cqspi_write;
-		nor->erase = cqspi_erase;
-		nor->prepare = cqspi_prep;
-		nor->unprepare = cqspi_unprep;
+		nor->controller_ops = &cqspi_controller_ops;
 
 		mtd->name = devm_kasprintf(dev, GFP_KERNEL, "%s.%d",
 					   dev_name(dev), cs);
diff --git a/drivers/mtd/spi-nor/hisi-sfc.c b/drivers/mtd/spi-nor/hisi-sfc.c
index 6dac9dd8bf42..a1258216f89d 100644
--- a/drivers/mtd/spi-nor/hisi-sfc.c
+++ b/drivers/mtd/spi-nor/hisi-sfc.c
@@ -177,7 +177,7 @@ static void hisi_spi_nor_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
 }
 
 static int hisi_spi_nor_op_reg(struct spi_nor *nor,
-				u8 opcode, int len, u8 optype)
+				u8 opcode, size_t len, u8 optype)
 {
 	struct hifmc_priv *priv = nor->priv;
 	struct hifmc_host *host = priv->host;
@@ -200,7 +200,7 @@ static int hisi_spi_nor_op_reg(struct spi_nor *nor,
 }
 
 static int hisi_spi_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
-		int len)
+				 size_t len)
 {
 	struct hifmc_priv *priv = nor->priv;
 	struct hifmc_host *host = priv->host;
@@ -215,7 +215,7 @@ static int hisi_spi_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
 }
 
 static int hisi_spi_nor_write_reg(struct spi_nor *nor, u8 opcode,
-				u8 *buf, int len)
+				  const u8 *buf, size_t len)
 {
 	struct hifmc_priv *priv = nor->priv;
 	struct hifmc_host *host = priv->host;
@@ -311,6 +311,15 @@ static ssize_t hisi_spi_nor_write(struct spi_nor *nor, loff_t to,
 	return len;
 }
 
+static const struct spi_nor_controller_ops hisi_controller_ops = {
+	.prepare = hisi_spi_nor_prep,
+	.unprepare = hisi_spi_nor_unprep,
+	.read_reg = hisi_spi_nor_read_reg,
+	.write_reg = hisi_spi_nor_write_reg,
+	.read = hisi_spi_nor_read,
+	.write = hisi_spi_nor_write,
+};
+
 /**
  * Get spi flash device information and register it as a mtd device.
  */
@@ -357,14 +366,8 @@ static int hisi_spi_nor_register(struct device_node *np,
 	}
 	priv->host = host;
 	nor->priv = priv;
+	nor->controller_ops = &hisi_controller_ops;
 
-	nor->prepare = hisi_spi_nor_prep;
-	nor->unprepare = hisi_spi_nor_unprep;
-	nor->read_reg = hisi_spi_nor_read_reg;
-	nor->write_reg = hisi_spi_nor_write_reg;
-	nor->read = hisi_spi_nor_read;
-	nor->write = hisi_spi_nor_write;
-	nor->erase = NULL;
 	ret = spi_nor_scan(nor, NULL, &hwcaps);
 	if (ret)
 		return ret;
diff --git a/drivers/mtd/spi-nor/intel-spi-pci.c b/drivers/mtd/spi-nor/intel-spi-pci.c
index 3cda8e7a68f8..3d8987baea2a 100644
--- a/drivers/mtd/spi-nor/intel-spi-pci.c
+++ b/drivers/mtd/spi-nor/intel-spi-pci.c
@@ -20,6 +20,10 @@ static const struct intel_spi_boardinfo bxt_info = {
 	.type = INTEL_SPI_BXT,
 };
 
+static const struct intel_spi_boardinfo cnl_info = {
+	.type = INTEL_SPI_CNL,
+};
+
 static int intel_spi_pci_probe(struct pci_dev *pdev,
 			       const struct pci_device_id *id)
 {
@@ -61,6 +65,7 @@ static void intel_spi_pci_remove(struct pci_dev *pdev)
 
 static const struct pci_device_id intel_spi_pci_ids[] = {
 	{ PCI_VDEVICE(INTEL, 0x02a4), (unsigned long)&bxt_info },
+	{ PCI_VDEVICE(INTEL, 0x06a4), (unsigned long)&bxt_info },
 	{ PCI_VDEVICE(INTEL, 0x18e0), (unsigned long)&bxt_info },
 	{ PCI_VDEVICE(INTEL, 0x19e0), (unsigned long)&bxt_info },
 	{ PCI_VDEVICE(INTEL, 0x34a4), (unsigned long)&bxt_info },
@@ -68,6 +73,7 @@ static const struct pci_device_id intel_spi_pci_ids[] = {
 	{ PCI_VDEVICE(INTEL, 0xa0a4), (unsigned long)&bxt_info },
 	{ PCI_VDEVICE(INTEL, 0xa1a4), (unsigned long)&bxt_info },
 	{ PCI_VDEVICE(INTEL, 0xa224), (unsigned long)&bxt_info },
+	{ PCI_VDEVICE(INTEL, 0xa324), (unsigned long)&cnl_info },
 	{ },
 };
 MODULE_DEVICE_TABLE(pci, intel_spi_pci_ids);
diff --git a/drivers/mtd/spi-nor/intel-spi.c b/drivers/mtd/spi-nor/intel-spi.c
index 43e55a2e9b27..61d2a0ad2131 100644
--- a/drivers/mtd/spi-nor/intel-spi.c
+++ b/drivers/mtd/spi-nor/intel-spi.c
@@ -108,6 +108,10 @@
 #define BXT_FREG_NUM			12
 #define BXT_PR_NUM			6
 
+#define CNL_PR				0x84
+#define CNL_FREG_NUM			6
+#define CNL_PR_NUM			5
+
 #define LVSCC				0xc4
 #define UVSCC				0xc8
 #define ERASE_OPCODE_SHIFT		8
@@ -187,12 +191,16 @@ static void intel_spi_dump_regs(struct intel_spi *ispi)
 		dev_dbg(ispi->dev, "PR(%d)=0x%08x\n", i,
 			readl(ispi->pregs + PR(i)));
 
-	value = readl(ispi->sregs + SSFSTS_CTL);
-	dev_dbg(ispi->dev, "SSFSTS_CTL=0x%08x\n", value);
-	dev_dbg(ispi->dev, "PREOP_OPTYPE=0x%08x\n",
-		readl(ispi->sregs + PREOP_OPTYPE));
-	dev_dbg(ispi->dev, "OPMENU0=0x%08x\n", readl(ispi->sregs + OPMENU0));
-	dev_dbg(ispi->dev, "OPMENU1=0x%08x\n", readl(ispi->sregs + OPMENU1));
+	if (ispi->sregs) {
+		value = readl(ispi->sregs + SSFSTS_CTL);
+		dev_dbg(ispi->dev, "SSFSTS_CTL=0x%08x\n", value);
+		dev_dbg(ispi->dev, "PREOP_OPTYPE=0x%08x\n",
+			readl(ispi->sregs + PREOP_OPTYPE));
+		dev_dbg(ispi->dev, "OPMENU0=0x%08x\n",
+			readl(ispi->sregs + OPMENU0));
+		dev_dbg(ispi->dev, "OPMENU1=0x%08x\n",
+			readl(ispi->sregs + OPMENU1));
+	}
 
 	if (ispi->info->type == INTEL_SPI_BYT)
 		dev_dbg(ispi->dev, "BCR=0x%08x\n", readl(ispi->base + BYT_BCR));
@@ -340,6 +348,13 @@ static int intel_spi_init(struct intel_spi *ispi)
 		ispi->erase_64k = true;
 		break;
 
+	case INTEL_SPI_CNL:
+		ispi->sregs = NULL;
+		ispi->pregs = ispi->base + CNL_PR;
+		ispi->nregions = CNL_FREG_NUM;
+		ispi->pr_num = CNL_PR_NUM;
+		break;
+
 	default:
 		return -EINVAL;
 	}
@@ -367,6 +382,11 @@ static int intel_spi_init(struct intel_spi *ispi)
 		    !(uvscc & ERASE_64K_OPCODE_MASK))
 			ispi->erase_64k = false;
 
+	if (ispi->sregs == NULL && (ispi->swseq_reg || ispi->swseq_erase)) {
+		dev_err(ispi->dev, "software sequencer not supported, but required\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Some controllers can only do basic operations using hardware
 	 * sequencer. All other operations are supposed to be carried out
@@ -383,7 +403,7 @@ static int intel_spi_init(struct intel_spi *ispi)
 	val = readl(ispi->base + HSFSTS_CTL);
 	ispi->locked = !!(val & HSFSTS_CTL_FLOCKDN);
 
-	if (ispi->locked) {
+	if (ispi->locked && ispi->sregs) {
 		/*
 		 * BIOS programs allowed opcodes and then locks down the
 		 * register. So read back what opcodes it decided to support.
@@ -426,7 +446,7 @@ static int intel_spi_opcode_index(struct intel_spi *ispi, u8 opcode, int optype)
 	return 0;
 }
 
-static int intel_spi_hw_cycle(struct intel_spi *ispi, u8 opcode, int len)
+static int intel_spi_hw_cycle(struct intel_spi *ispi, u8 opcode, size_t len)
 {
 	u32 val, status;
 	int ret;
@@ -469,7 +489,7 @@ static int intel_spi_hw_cycle(struct intel_spi *ispi, u8 opcode, int len)
 	return 0;
 }
 
-static int intel_spi_sw_cycle(struct intel_spi *ispi, u8 opcode, int len,
+static int intel_spi_sw_cycle(struct intel_spi *ispi, u8 opcode, size_t len,
 			      int optype)
 {
 	u32 val = 0, status;
@@ -535,7 +555,8 @@ static int intel_spi_sw_cycle(struct intel_spi *ispi, u8 opcode, int len,
 	return 0;
 }
 
-static int intel_spi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int intel_spi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
+			      size_t len)
 {
 	struct intel_spi *ispi = nor->priv;
 	int ret;
@@ -555,7 +576,8 @@ static int intel_spi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
 	return intel_spi_read_block(ispi, buf, len);
 }
 
-static int intel_spi_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int intel_spi_write_reg(struct spi_nor *nor, u8 opcode, const u8 *buf,
+			       size_t len)
 {
 	struct intel_spi *ispi = nor->priv;
 	int ret;
@@ -864,6 +886,14 @@ static void intel_spi_fill_partition(struct intel_spi *ispi,
 	}
 }
 
+static const struct spi_nor_controller_ops intel_spi_controller_ops = {
+	.read_reg = intel_spi_read_reg,
+	.write_reg = intel_spi_write_reg,
+	.read = intel_spi_read,
+	.write = intel_spi_write,
+	.erase = intel_spi_erase,
+};
+
 struct intel_spi *intel_spi_probe(struct device *dev,
 	struct resource *mem, const struct intel_spi_boardinfo *info)
 {
@@ -897,11 +927,7 @@ struct intel_spi *intel_spi_probe(struct device *dev,
 
 	ispi->nor.dev = ispi->dev;
 	ispi->nor.priv = ispi;
-	ispi->nor.read_reg = intel_spi_read_reg;
-	ispi->nor.write_reg = intel_spi_write_reg;
-	ispi->nor.read = intel_spi_read;
-	ispi->nor.write = intel_spi_write;
-	ispi->nor.erase = intel_spi_erase;
+	ispi->nor.controller_ops = &intel_spi_controller_ops;
 
 	ret = spi_nor_scan(&ispi->nor, NULL, &hwcaps);
 	if (ret) {
diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c
index 34db01ab6cab..b1691680d174 100644
--- a/drivers/mtd/spi-nor/mtk-quadspi.c
+++ b/drivers/mtd/spi-nor/mtk-quadspi.c
@@ -151,9 +151,9 @@ static int mtk_nor_execute_cmd(struct mtk_nor *mtk_nor, u8 cmdval)
 }
 
 static int mtk_nor_do_tx_rx(struct mtk_nor *mtk_nor, u8 op,
-			    u8 *tx, int txlen, u8 *rx, int rxlen)
+			    const u8 *tx, size_t txlen, u8 *rx, size_t rxlen)
 {
-	int len = 1 + txlen + rxlen;
+	size_t len = 1 + txlen + rxlen;
 	int i, ret, idx;
 
 	if (len > MTK_NOR_MAX_SHIFT)
@@ -193,7 +193,7 @@ static int mtk_nor_do_tx_rx(struct mtk_nor *mtk_nor, u8 op,
 }
 
 /* Do a WRSR (Write Status Register) command */
-static int mtk_nor_wr_sr(struct mtk_nor *mtk_nor, u8 sr)
+static int mtk_nor_wr_sr(struct mtk_nor *mtk_nor, const u8 sr)
 {
 	writeb(sr, mtk_nor->base + MTK_NOR_PRGDATA5_REG);
 	writeb(8, mtk_nor->base + MTK_NOR_CNT_REG);
@@ -354,7 +354,7 @@ static ssize_t mtk_nor_write(struct spi_nor *nor, loff_t to, size_t len,
 	return len;
 }
 
-static int mtk_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int mtk_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, size_t len)
 {
 	int ret;
 	struct mtk_nor *mtk_nor = nor->priv;
@@ -376,8 +376,8 @@ static int mtk_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
 	return ret;
 }
 
-static int mtk_nor_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
-			     int len)
+static int mtk_nor_write_reg(struct spi_nor *nor, u8 opcode, const u8 *buf,
+			     size_t len)
 {
 	int ret;
 	struct mtk_nor *mtk_nor = nor->priv;
@@ -419,6 +419,13 @@ static int mtk_nor_enable_clk(struct mtk_nor *mtk_nor)
 	return 0;
 }
 
+static const struct spi_nor_controller_ops mtk_controller_ops = {
+	.read_reg = mtk_nor_read_reg,
+	.write_reg = mtk_nor_write_reg,
+	.read = mtk_nor_read,
+	.write = mtk_nor_write,
+};
+
 static int mtk_nor_init(struct mtk_nor *mtk_nor,
 			struct device_node *flash_node)
 {
@@ -438,12 +445,8 @@ static int mtk_nor_init(struct mtk_nor *mtk_nor,
 	nor->dev = mtk_nor->dev;
 	nor->priv = mtk_nor;
 	spi_nor_set_flash_node(nor, flash_node);
+	nor->controller_ops = &mtk_controller_ops;
 
-	/* fill the hooks to spi nor */
-	nor->read = mtk_nor_read;
-	nor->read_reg = mtk_nor_read_reg;
-	nor->write = mtk_nor_write;
-	nor->write_reg = mtk_nor_write_reg;
 	nor->mtd.name = "mtk_nor";
 	/* initialized with NULL */
 	ret = spi_nor_scan(nor, NULL, &hwcaps);
diff --git a/drivers/mtd/spi-nor/nxp-spifi.c b/drivers/mtd/spi-nor/nxp-spifi.c
index 4a871587392b..9a5b1a7c636a 100644
--- a/drivers/mtd/spi-nor/nxp-spifi.c
+++ b/drivers/mtd/spi-nor/nxp-spifi.c
@@ -123,7 +123,8 @@ static int nxp_spifi_set_memory_mode_on(struct nxp_spifi *spifi)
 	return ret;
 }
 
-static int nxp_spifi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int nxp_spifi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
+			      size_t len)
 {
 	struct nxp_spifi *spifi = nor->priv;
 	u32 cmd;
@@ -145,7 +146,8 @@ static int nxp_spifi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
 	return nxp_spifi_wait_for_cmd(spifi);
 }
 
-static int nxp_spifi_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+static int nxp_spifi_write_reg(struct spi_nor *nor, u8 opcode, const u8 *buf,
+			       size_t len)
 {
 	struct nxp_spifi *spifi = nor->priv;
 	u32 cmd;
@@ -263,9 +265,18 @@ static int nxp_spifi_setup_memory_cmd(struct nxp_spifi *spifi)
 static void nxp_spifi_dummy_id_read(struct spi_nor *nor)
 {
 	u8 id[SPI_NOR_MAX_ID_LEN];
-	nor->read_reg(nor, SPINOR_OP_RDID, id, SPI_NOR_MAX_ID_LEN);
+	nor->controller_ops->read_reg(nor, SPINOR_OP_RDID, id,
+				      SPI_NOR_MAX_ID_LEN);
 }
 
+static const struct spi_nor_controller_ops nxp_spifi_controller_ops = {
+	.read_reg  = nxp_spifi_read_reg,
+	.write_reg = nxp_spifi_write_reg,
+	.read  = nxp_spifi_read,
+	.write = nxp_spifi_write,
+	.erase = nxp_spifi_erase,
+};
+
 static int nxp_spifi_setup_flash(struct nxp_spifi *spifi,
 				 struct device_node *np)
 {
@@ -332,11 +343,7 @@ static int nxp_spifi_setup_flash(struct nxp_spifi *spifi,
 	spifi->nor.dev   = spifi->dev;
 	spi_nor_set_flash_node(&spifi->nor, np);
 	spifi->nor.priv  = spifi;
-	spifi->nor.read  = nxp_spifi_read;
-	spifi->nor.write = nxp_spifi_write;
-	spifi->nor.erase = nxp_spifi_erase;
-	spifi->nor.read_reg  = nxp_spifi_read_reg;
-	spifi->nor.write_reg = nxp_spifi_write_reg;
+	spifi->nor.controller_ops = &nxp_spifi_controller_ops;
 
 	/*
 	 * The first read on a hard reset isn't reliable so do a
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 1d8621d43160..f4afe123e9dc 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -338,7 +338,7 @@ static ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
 	if (nor->spimem)
 		return spi_nor_spimem_read_data(nor, from, len, buf);
 
-	return nor->read(nor, from, len, buf);
+	return nor->controller_ops->read(nor, from, len, buf);
 }
 
 /**
@@ -385,239 +385,172 @@ static ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
 	if (nor->spimem)
 		return spi_nor_spimem_write_data(nor, to, len, buf);
 
-	return nor->write(nor, to, len, buf);
+	return nor->controller_ops->write(nor, to, len, buf);
 }
 
-/*
- * Read the status register, returning its value in the location
- * Return the status register value.
- * Returns negative if error occurred.
+/**
+ * spi_nor_write_enable() - Set write enable latch with Write Enable command.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
-static int read_sr(struct spi_nor *nor)
+static int spi_nor_write_enable(struct spi_nor *nor)
 {
 	int ret;
 
 	if (nor->spimem) {
 		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDSR, 1),
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WREN, 1),
 				   SPI_MEM_OP_NO_ADDR,
 				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 1));
+				   SPI_MEM_OP_NO_DATA);
 
 		ret = spi_mem_exec_op(nor->spimem, &op);
 	} else {
-		ret = nor->read_reg(nor, SPINOR_OP_RDSR, nor->bouncebuf, 1);
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_WREN,
+						     NULL, 0);
 	}
 
-	if (ret < 0) {
-		pr_err("error %d reading SR\n", (int) ret);
-		return ret;
-	}
+	if (ret)
+		dev_dbg(nor->dev, "error %d on Write Enable\n", ret);
 
-	return nor->bouncebuf[0];
+	return ret;
 }
 
-/*
- * Read the flag status register, returning its value in the location
- * Return the status register value.
- * Returns negative if error occurred.
+/**
+ * spi_nor_write_disable() - Send Write Disable instruction to the chip.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
-static int read_fsr(struct spi_nor *nor)
+static int spi_nor_write_disable(struct spi_nor *nor)
 {
 	int ret;
 
 	if (nor->spimem) {
 		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDFSR, 1),
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRDI, 1),
 				   SPI_MEM_OP_NO_ADDR,
 				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 1));
+				   SPI_MEM_OP_NO_DATA);
 
 		ret = spi_mem_exec_op(nor->spimem, &op);
 	} else {
-		ret = nor->read_reg(nor, SPINOR_OP_RDFSR, nor->bouncebuf, 1);
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_WRDI,
+						     NULL, 0);
 	}
 
-	if (ret < 0) {
-		pr_err("error %d reading FSR\n", ret);
-		return ret;
-	}
+	if (ret)
+		dev_dbg(nor->dev, "error %d on Write Disable\n", ret);
 
-	return nor->bouncebuf[0];
+	return ret;
 }
 
-/*
- * Read configuration register, returning its value in the
- * location. Return the configuration register value.
- * Returns negative if error occurred.
+/**
+ * spi_nor_read_sr() - Read the Status Register.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @sr:		pointer to a DMA-able buffer where the value of the
+ *              Status Register will be written.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
-static int read_cr(struct spi_nor *nor)
+static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
 {
 	int ret;
 
 	if (nor->spimem) {
 		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDCR, 1),
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDSR, 1),
 				   SPI_MEM_OP_NO_ADDR,
 				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 1));
+				   SPI_MEM_OP_DATA_IN(1, sr, 1));
 
 		ret = spi_mem_exec_op(nor->spimem, &op);
 	} else {
-		ret = nor->read_reg(nor, SPINOR_OP_RDCR, nor->bouncebuf, 1);
+		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDSR,
+						    sr, 1);
 	}
 
-	if (ret < 0) {
-		dev_err(nor->dev, "error %d reading CR\n", ret);
-		return ret;
-	}
+	if (ret)
+		dev_dbg(nor->dev, "error %d reading SR\n", ret);
 
-	return nor->bouncebuf[0];
+	return ret;
 }
 
-/*
- * Write status register 1 byte
- * Returns negative if error occurred.
+/**
+ * spi_nor_read_fsr() - Read the Flag Status Register.
+ * @nor:	pointer to 'struct spi_nor'
+ * @fsr:	pointer to a DMA-able buffer where the value of the
+ *              Flag Status Register will be written.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
-static int write_sr(struct spi_nor *nor, u8 val)
+static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr)
 {
-	nor->bouncebuf[0] = val;
-	if (nor->spimem) {
-		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRSR, 1),
-				   SPI_MEM_OP_NO_ADDR,
-				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 1));
-
-		return spi_mem_exec_op(nor->spimem, &op);
-	}
-
-	return nor->write_reg(nor, SPINOR_OP_WRSR, nor->bouncebuf, 1);
-}
+	int ret;
 
-/*
- * Set write enable latch with Write Enable command.
- * Returns negative if error occurred.
- */
-static int write_enable(struct spi_nor *nor)
-{
 	if (nor->spimem) {
 		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WREN, 1),
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDFSR, 1),
 				   SPI_MEM_OP_NO_ADDR,
 				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_NO_DATA);
+				   SPI_MEM_OP_DATA_IN(1, fsr, 1));
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDFSR,
+						    fsr, 1);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_WREN, NULL, 0);
+	if (ret)
+		dev_dbg(nor->dev, "error %d reading FSR\n", ret);
+
+	return ret;
 }
 
-/*
- * Send write disable instruction to the chip.
+/**
+ * spi_nor_read_cr() - Read the Configuration Register using the
+ * SPINOR_OP_RDCR (35h) command.
+ * @nor:	pointer to 'struct spi_nor'
+ * @cr:		pointer to a DMA-able buffer where the value of the
+ *              Configuration Register will be written.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
-static int write_disable(struct spi_nor *nor)
+static int spi_nor_read_cr(struct spi_nor *nor, u8 *cr)
 {
+	int ret;
+
 	if (nor->spimem) {
 		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRDI, 1),
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDCR, 1),
 				   SPI_MEM_OP_NO_ADDR,
 				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_NO_DATA);
+				   SPI_MEM_OP_DATA_IN(1, cr, 1));
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDCR, cr, 1);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_WRDI, NULL, 0);
-}
-
-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_8,	SPINOR_OP_READ_1_1_8_4B },
-		{ SPINOR_OP_READ_1_8_8,	SPINOR_OP_READ_1_8_8_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 },
-		{ SPINOR_OP_PP_1_1_8,	SPINOR_OP_PP_1_1_8_4B },
-		{ SPINOR_OP_PP_1_8_8,	SPINOR_OP_PP_1_8_8_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)
-{
-	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);
-
-	if (!spi_nor_has_uniform_erase(nor)) {
-		struct spi_nor_erase_map *map = &nor->params.erase_map;
-		struct spi_nor_erase_type *erase;
-		int i;
+	if (ret)
+		dev_dbg(nor->dev, "error %d reading CR\n", ret);
 
-		for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++) {
-			erase = &map->erase_type[i];
-			erase->opcode =
-				spi_nor_convert_3to4_erase(erase->opcode);
-		}
-	}
+	return ret;
 }
 
+/**
+ * macronix_set_4byte() - Set 4-byte address mode for Macronix flashes.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @enable:	true to enter the 4-byte address mode, false to exit the 4-byte
+ *		address mode.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int macronix_set_4byte(struct spi_nor *nor, bool enable)
 {
+	int ret;
+
 	if (nor->spimem) {
 		struct spi_mem_op op =
 			SPI_MEM_OP(SPI_MEM_OP_CMD(enable ?
@@ -628,26 +561,55 @@ static int macronix_set_4byte(struct spi_nor *nor, bool enable)
 				  SPI_MEM_OP_NO_DUMMY,
 				  SPI_MEM_OP_NO_DATA);
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor,
+						     enable ? SPINOR_OP_EN4B :
+							      SPINOR_OP_EX4B,
+						     NULL, 0);
 	}
 
-	return nor->write_reg(nor, enable ? SPINOR_OP_EN4B : SPINOR_OP_EX4B,
-			      NULL, 0);
+	if (ret)
+		dev_dbg(nor->dev, "error %d setting 4-byte mode\n", ret);
+
+	return ret;
 }
 
+/**
+ * st_micron_set_4byte() - Set 4-byte address mode for ST and Micron flashes.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @enable:	true to enter the 4-byte address mode, false to exit the 4-byte
+ *		address mode.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int st_micron_set_4byte(struct spi_nor *nor, bool enable)
 {
 	int ret;
 
-	write_enable(nor);
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		return ret;
+
 	ret = macronix_set_4byte(nor, enable);
-	write_disable(nor);
+	if (ret)
+		return ret;
 
-	return ret;
+	return spi_nor_write_disable(nor);
 }
 
+/**
+ * spansion_set_4byte() - Set 4-byte address mode for Spansion flashes.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @enable:	true to enter the 4-byte address mode, false to exit the 4-byte
+ *		address mode.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spansion_set_4byte(struct spi_nor *nor, bool enable)
 {
+	int ret;
+
 	nor->bouncebuf[0] = enable << 7;
 
 	if (nor->spimem) {
@@ -657,14 +619,29 @@ static int spansion_set_4byte(struct spi_nor *nor, bool enable)
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_DATA_OUT(1, nor->bouncebuf, 1));
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_BRWR,
+						     nor->bouncebuf, 1);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_BRWR, nor->bouncebuf, 1);
+	if (ret)
+		dev_dbg(nor->dev, "error %d setting 4-byte mode\n", ret);
+
+	return ret;
 }
 
+/**
+ * spi_nor_write_ear() - Write Extended Address Register.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @ear:	value to write to the Extended Address Register.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spi_nor_write_ear(struct spi_nor *nor, u8 ear)
 {
+	int ret;
+
 	nor->bouncebuf[0] = ear;
 
 	if (nor->spimem) {
@@ -674,12 +651,26 @@ static int spi_nor_write_ear(struct spi_nor *nor, u8 ear)
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_DATA_OUT(1, nor->bouncebuf, 1));
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_WREAR,
+						     nor->bouncebuf, 1);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_WREAR, nor->bouncebuf, 1);
+	if (ret)
+		dev_dbg(nor->dev, "error %d writing EAR\n", ret);
+
+	return ret;
 }
 
+/**
+ * winbond_set_4byte() - Set 4-byte address mode for Winbond flashes.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @enable:	true to enter the 4-byte address mode, false to exit the 4-byte
+ *		address mode.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int winbond_set_4byte(struct spi_nor *nor, bool enable)
 {
 	int ret;
@@ -693,15 +684,29 @@ static int winbond_set_4byte(struct spi_nor *nor, bool enable)
 	 * 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);
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		return ret;
+
 	ret = spi_nor_write_ear(nor, 0);
-	write_disable(nor);
+	if (ret)
+		return ret;
 
-	return ret;
+	return spi_nor_write_disable(nor);
 }
 
+/**
+ * spi_nor_xread_sr() - Read the Status Register on S3AN flashes.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @sr:		pointer to a DMA-able buffer where the value of the
+ *              Status Register will be written.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spi_nor_xread_sr(struct spi_nor *nor, u8 *sr)
 {
+	int ret;
+
 	if (nor->spimem) {
 		struct spi_mem_op op =
 			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_XRDSR, 1),
@@ -709,27 +714,44 @@ static int spi_nor_xread_sr(struct spi_nor *nor, u8 *sr)
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_DATA_IN(1, sr, 1));
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_XRDSR,
+						    sr, 1);
 	}
 
-	return nor->read_reg(nor, SPINOR_OP_XRDSR, sr, 1);
+	if (ret)
+		dev_dbg(nor->dev, "error %d reading XRDSR\n", ret);
+
+	return ret;
 }
 
+/**
+ * s3an_sr_ready() - Query the Status Register of the S3AN flash to see if the
+ * flash is ready for new commands.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int s3an_sr_ready(struct spi_nor *nor)
 {
 	int ret;
 
 	ret = spi_nor_xread_sr(nor, nor->bouncebuf);
-	if (ret < 0) {
-		dev_err(nor->dev, "error %d reading XRDSR\n", (int) ret);
+	if (ret)
 		return ret;
-	}
 
 	return !!(nor->bouncebuf[0] & XSR_RDY);
 }
 
-static int spi_nor_clear_sr(struct spi_nor *nor)
+/**
+ * spi_nor_clear_sr() - Clear the Status Register.
+ * @nor:	pointer to 'struct spi_nor'.
+ */
+static void spi_nor_clear_sr(struct spi_nor *nor)
 {
+	int ret;
+
 	if (nor->spimem) {
 		struct spi_mem_op op =
 			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_CLSR, 1),
@@ -737,20 +759,33 @@ static int spi_nor_clear_sr(struct spi_nor *nor)
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_NO_DATA);
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_CLSR,
+						     NULL, 0);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_CLSR, NULL, 0);
+	if (ret)
+		dev_dbg(nor->dev, "error %d clearing SR\n", ret);
 }
 
+/**
+ * spi_nor_sr_ready() - Query the Status Register to see if the flash is ready
+ * for new commands.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spi_nor_sr_ready(struct spi_nor *nor)
 {
-	int sr = read_sr(nor);
-	if (sr < 0)
-		return sr;
+	int ret = spi_nor_read_sr(nor, nor->bouncebuf);
+
+	if (ret)
+		return ret;
 
-	if (nor->flags & SNOR_F_USE_CLSR && sr & (SR_E_ERR | SR_P_ERR)) {
-		if (sr & SR_E_ERR)
+	if (nor->flags & SNOR_F_USE_CLSR &&
+	    nor->bouncebuf[0] & (SR_E_ERR | SR_P_ERR)) {
+		if (nor->bouncebuf[0] & SR_E_ERR)
 			dev_err(nor->dev, "Erase Error occurred\n");
 		else
 			dev_err(nor->dev, "Programming Error occurred\n");
@@ -759,11 +794,17 @@ static int spi_nor_sr_ready(struct spi_nor *nor)
 		return -EIO;
 	}
 
-	return !(sr & SR_WIP);
+	return !(nor->bouncebuf[0] & SR_WIP);
 }
 
-static int spi_nor_clear_fsr(struct spi_nor *nor)
+/**
+ * spi_nor_clear_fsr() - Clear the Flag Status Register.
+ * @nor:	pointer to 'struct spi_nor'.
+ */
+static void spi_nor_clear_fsr(struct spi_nor *nor)
 {
+	int ret;
+
 	if (nor->spimem) {
 		struct spi_mem_op op =
 			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_CLFSR, 1),
@@ -771,25 +812,37 @@ static int spi_nor_clear_fsr(struct spi_nor *nor)
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_NO_DATA);
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_CLFSR,
+						     NULL, 0);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_CLFSR, NULL, 0);
+	if (ret)
+		dev_dbg(nor->dev, "error %d clearing FSR\n", ret);
 }
 
+/**
+ * spi_nor_fsr_ready() - Query the Flag Status Register to see if the flash is
+ * ready for new commands.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spi_nor_fsr_ready(struct spi_nor *nor)
 {
-	int fsr = read_fsr(nor);
-	if (fsr < 0)
-		return fsr;
+	int ret = spi_nor_read_fsr(nor, nor->bouncebuf);
 
-	if (fsr & (FSR_E_ERR | FSR_P_ERR)) {
-		if (fsr & FSR_E_ERR)
+	if (ret)
+		return ret;
+
+	if (nor->bouncebuf[0] & (FSR_E_ERR | FSR_P_ERR)) {
+		if (nor->bouncebuf[0] & FSR_E_ERR)
 			dev_err(nor->dev, "Erase operation failed.\n");
 		else
 			dev_err(nor->dev, "Program operation failed.\n");
 
-		if (fsr & FSR_PT_ERR)
+		if (nor->bouncebuf[0] & FSR_PT_ERR)
 			dev_err(nor->dev,
 			"Attempted to modify a protected sector.\n");
 
@@ -797,9 +850,15 @@ static int spi_nor_fsr_ready(struct spi_nor *nor)
 		return -EIO;
 	}
 
-	return fsr & FSR_READY;
+	return nor->bouncebuf[0] & FSR_READY;
 }
 
+/**
+ * spi_nor_ready() - Query the flash to see if it is ready for new commands.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spi_nor_ready(struct spi_nor *nor)
 {
 	int sr, fsr;
@@ -816,9 +875,13 @@ static int spi_nor_ready(struct spi_nor *nor)
 	return sr && fsr;
 }
 
-/*
- * Service routine to read status register until ready, or timeout occurs.
- * Returns non-zero if error.
+/**
+ * spi_nor_wait_till_ready_with_timeout() - Service routine to read the
+ * Status Register until ready, or timeout occurs.
+ * @nor:		pointer to "struct spi_nor".
+ * @timeout_jiffies:	jiffies to wait until timeout.
+ *
+ * Return: 0 on success, -errno otherwise.
  */
 static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor,
 						unsigned long timeout_jiffies)
@@ -841,24 +904,305 @@ static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor,
 		cond_resched();
 	}
 
-	dev_err(nor->dev, "flash operation timed out\n");
+	dev_dbg(nor->dev, "flash operation timed out\n");
 
 	return -ETIMEDOUT;
 }
 
+/**
+ * spi_nor_wait_till_ready() - Wait for a predefined amount of time for the
+ * flash to be ready, or timeout occurs.
+ * @nor:	pointer to "struct spi_nor".
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
 static int spi_nor_wait_till_ready(struct spi_nor *nor)
 {
 	return spi_nor_wait_till_ready_with_timeout(nor,
 						    DEFAULT_READY_WAIT_JIFFIES);
 }
 
-/*
- * Erase the whole flash memory
+/**
+ * spi_nor_write_sr() - Write the Status Register.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @sr:		pointer to DMA-able buffer to write to the Status Register.
+ * @len:	number of bytes to write to the Status Register.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_write_sr(struct spi_nor *nor, const u8 *sr, size_t len)
+{
+	int ret;
+
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		return ret;
+
+	if (nor->spimem) {
+		struct spi_mem_op op =
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRSR, 1),
+				   SPI_MEM_OP_NO_ADDR,
+				   SPI_MEM_OP_NO_DUMMY,
+				   SPI_MEM_OP_DATA_OUT(len, sr, 1));
+
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_WRSR,
+						     sr, len);
+	}
+
+	if (ret) {
+		dev_dbg(nor->dev, "error %d writing SR\n", ret);
+		return ret;
+	}
+
+	return spi_nor_wait_till_ready(nor);
+}
+
+/**
+ * spi_nor_write_sr1_and_check() - Write one byte to the Status Register 1 and
+ * ensure that the byte written match the received value.
+ * @nor:	pointer to a 'struct spi_nor'.
+ * @sr1:	byte value to be written to the Status Register.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_write_sr1_and_check(struct spi_nor *nor, u8 sr1)
+{
+	int ret;
+
+	nor->bouncebuf[0] = sr1;
+
+	ret = spi_nor_write_sr(nor, nor->bouncebuf, 1);
+	if (ret)
+		return ret;
+
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	if (nor->bouncebuf[0] != sr1) {
+		dev_dbg(nor->dev, "SR1: read back test failed\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * spi_nor_write_16bit_sr_and_check() - Write the Status Register 1 and the
+ * Status Register 2 in one shot. Ensure that the byte written in the Status
+ * Register 1 match the received value, and that the 16-bit Write did not
+ * affect what was already in the Status Register 2.
+ * @nor:	pointer to a 'struct spi_nor'.
+ * @sr1:	byte value to be written to the Status Register 1.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_write_16bit_sr_and_check(struct spi_nor *nor, u8 sr1)
+{
+	int ret;
+	u8 *sr_cr = nor->bouncebuf;
+	u8 cr_written;
+
+	/* Make sure we don't overwrite the contents of Status Register 2. */
+	if (!(nor->flags & SNOR_F_NO_READ_CR)) {
+		ret = spi_nor_read_cr(nor, &sr_cr[1]);
+		if (ret)
+			return ret;
+	} else if (nor->params.quad_enable) {
+		/*
+		 * If the Status Register 2 Read command (35h) is not
+		 * supported, we should at least be sure we don't
+		 * change the value of the SR2 Quad Enable bit.
+		 *
+		 * We can safely assume that when the Quad Enable method is
+		 * set, the value of the QE bit is one, as a consequence of the
+		 * nor->params.quad_enable() call.
+		 *
+		 * We can safely assume that the Quad Enable bit is present in
+		 * the Status Register 2 at BIT(1). According to the JESD216
+		 * revB standard, BFPT DWORDS[15], bits 22:20, the 16-bit
+		 * Write Status (01h) command is available just for the cases
+		 * in which the QE bit is described in SR2 at BIT(1).
+		 */
+		sr_cr[1] = SR2_QUAD_EN_BIT1;
+	} else {
+		sr_cr[1] = 0;
+	}
+
+	sr_cr[0] = sr1;
+
+	ret = spi_nor_write_sr(nor, sr_cr, 2);
+	if (ret)
+		return ret;
+
+	if (nor->flags & SNOR_F_NO_READ_CR)
+		return 0;
+
+	cr_written = sr_cr[1];
+
+	ret = spi_nor_read_cr(nor, &sr_cr[1]);
+	if (ret)
+		return ret;
+
+	if (cr_written != sr_cr[1]) {
+		dev_dbg(nor->dev, "CR: read back test failed\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * spi_nor_write_16bit_cr_and_check() - Write the Status Register 1 and the
+ * Configuration Register in one shot. Ensure that the byte written in the
+ * Configuration Register match the received value, and that the 16-bit Write
+ * did not affect what was already in the Status Register 1.
+ * @nor:	pointer to a 'struct spi_nor'.
+ * @cr:		byte value to be written to the Configuration Register.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
+{
+	int ret;
+	u8 *sr_cr = nor->bouncebuf;
+	u8 sr_written;
+
+	/* Keep the current value of the Status Register 1. */
+	ret = spi_nor_read_sr(nor, sr_cr);
+	if (ret)
+		return ret;
+
+	sr_cr[1] = cr;
+
+	ret = spi_nor_write_sr(nor, sr_cr, 2);
+	if (ret)
+		return ret;
+
+	sr_written = sr_cr[0];
+
+	ret = spi_nor_read_sr(nor, sr_cr);
+	if (ret)
+		return ret;
+
+	if (sr_written != sr_cr[0]) {
+		dev_dbg(nor->dev, "SR: Read back test failed\n");
+		return -EIO;
+	}
+
+	if (nor->flags & SNOR_F_NO_READ_CR)
+		return 0;
+
+	ret = spi_nor_read_cr(nor, &sr_cr[1]);
+	if (ret)
+		return ret;
+
+	if (cr != sr_cr[1]) {
+		dev_dbg(nor->dev, "CR: read back test failed\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * spi_nor_write_sr_and_check() - Write the Status Register 1 and ensure that
+ * the byte written match the received value without affecting other bits in the
+ * Status Register 1 and 2.
+ * @nor:	pointer to a 'struct spi_nor'.
+ * @sr1:	byte value to be written to the Status Register.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
+{
+	if (nor->flags & SNOR_F_HAS_16BIT_SR)
+		return spi_nor_write_16bit_sr_and_check(nor, sr1);
+
+	return spi_nor_write_sr1_and_check(nor, sr1);
+}
+
+/**
+ * spi_nor_write_sr2() - Write the Status Register 2 using the
+ * SPINOR_OP_WRSR2 (3eh) command.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @sr2:	pointer to DMA-able buffer to write to the Status Register 2.
  *
- * Returns 0 if successful, non-zero otherwise.
+ * Return: 0 on success, -errno otherwise.
  */
-static int erase_chip(struct spi_nor *nor)
+static int spi_nor_write_sr2(struct spi_nor *nor, const u8 *sr2)
 {
+	int ret;
+
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		return ret;
+
+	if (nor->spimem) {
+		struct spi_mem_op op =
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRSR2, 1),
+				   SPI_MEM_OP_NO_ADDR,
+				   SPI_MEM_OP_NO_DUMMY,
+				   SPI_MEM_OP_DATA_OUT(1, sr2, 1));
+
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_WRSR2,
+						     sr2, 1);
+	}
+
+	if (ret) {
+		dev_dbg(nor->dev, "error %d writing SR2\n", ret);
+		return ret;
+	}
+
+	return spi_nor_wait_till_ready(nor);
+}
+
+/**
+ * spi_nor_read_sr2() - Read the Status Register 2 using the
+ * SPINOR_OP_RDSR2 (3fh) command.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @sr2:	pointer to DMA-able buffer where the value of the
+ *		Status Register 2 will be written.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_read_sr2(struct spi_nor *nor, u8 *sr2)
+{
+	int ret;
+
+	if (nor->spimem) {
+		struct spi_mem_op op =
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDSR2, 1),
+				   SPI_MEM_OP_NO_ADDR,
+				   SPI_MEM_OP_NO_DUMMY,
+				   SPI_MEM_OP_DATA_IN(1, sr2, 1));
+
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDSR2,
+						    sr2, 1);
+	}
+
+	if (ret)
+		dev_dbg(nor->dev, "error %d reading SR2\n", ret);
+
+	return ret;
+}
+
+/**
+ * spi_nor_erase_chip() - Erase the entire flash memory.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_erase_chip(struct spi_nor *nor)
+{
+	int ret;
+
 	dev_dbg(nor->dev, " %lldKiB\n", (long long)(nor->mtd.size >> 10));
 
 	if (nor->spimem) {
@@ -868,10 +1212,99 @@ static int erase_chip(struct spi_nor *nor)
 				   SPI_MEM_OP_NO_DUMMY,
 				   SPI_MEM_OP_NO_DATA);
 
-		return spi_mem_exec_op(nor->spimem, &op);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->write_reg(nor, SPINOR_OP_CHIP_ERASE,
+						     NULL, 0);
 	}
 
-	return nor->write_reg(nor, SPINOR_OP_CHIP_ERASE, NULL, 0);
+	if (ret)
+		dev_dbg(nor->dev, "error %d erasing chip\n", ret);
+
+	return ret;
+}
+
+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_8,	SPINOR_OP_READ_1_1_8_4B },
+		{ SPINOR_OP_READ_1_8_8,	SPINOR_OP_READ_1_8_8_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 },
+		{ SPINOR_OP_PP_1_1_8,	SPINOR_OP_PP_1_1_8_4B },
+		{ SPINOR_OP_PP_1_8_8,	SPINOR_OP_PP_1_8_8_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)
+{
+	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);
+
+	if (!spi_nor_has_uniform_erase(nor)) {
+		struct spi_nor_erase_map *map = &nor->params.erase_map;
+		struct spi_nor_erase_type *erase;
+		int i;
+
+		for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++) {
+			erase = &map->erase_type[i];
+			erase->opcode =
+				spi_nor_convert_3to4_erase(erase->opcode);
+		}
+	}
 }
 
 static int spi_nor_lock_and_prep(struct spi_nor *nor, enum spi_nor_ops ops)
@@ -880,10 +1313,9 @@ static int spi_nor_lock_and_prep(struct spi_nor *nor, enum spi_nor_ops ops)
 
 	mutex_lock(&nor->lock);
 
-	if (nor->prepare) {
-		ret = nor->prepare(nor, ops);
+	if (nor->controller_ops &&  nor->controller_ops->prepare) {
+		ret = nor->controller_ops->prepare(nor, ops);
 		if (ret) {
-			dev_err(nor->dev, "failed in the preparation.\n");
 			mutex_unlock(&nor->lock);
 			return ret;
 		}
@@ -893,8 +1325,8 @@ static int spi_nor_lock_and_prep(struct spi_nor *nor, enum spi_nor_ops ops)
 
 static void spi_nor_unlock_and_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
 {
-	if (nor->unprepare)
-		nor->unprepare(nor, ops);
+	if (nor->controller_ops && nor->controller_ops->unprepare)
+		nor->controller_ops->unprepare(nor, ops);
 	mutex_unlock(&nor->lock);
 }
 
@@ -935,9 +1367,6 @@ static int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
 
 	addr = spi_nor_convert_addr(nor, addr);
 
-	if (nor->erase)
-		return nor->erase(nor, addr);
-
 	if (nor->spimem) {
 		struct spi_mem_op op =
 			SPI_MEM_OP(SPI_MEM_OP_CMD(nor->erase_opcode, 1),
@@ -946,6 +1375,8 @@ static int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
 				   SPI_MEM_OP_NO_DATA);
 
 		return spi_mem_exec_op(nor->spimem, &op);
+	} else if (nor->controller_ops->erase) {
+		return nor->controller_ops->erase(nor, addr);
 	}
 
 	/*
@@ -957,8 +1388,8 @@ static int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
 		addr >>= 8;
 	}
 
-	return nor->write_reg(nor, nor->erase_opcode, nor->bouncebuf,
-			      nor->addr_width);
+	return nor->controller_ops->write_reg(nor, nor->erase_opcode,
+					      nor->bouncebuf, nor->addr_width);
 }
 
 /**
@@ -1208,7 +1639,9 @@ static int spi_nor_erase_multi_sectors(struct spi_nor *nor, u64 addr, u32 len)
 	list_for_each_entry_safe(cmd, next, &erase_list, list) {
 		nor->erase_opcode = cmd->opcode;
 		while (cmd->count) {
-			write_enable(nor);
+			ret = spi_nor_write_enable(nor);
+			if (ret)
+				goto destroy_erase_cmd_list;
 
 			ret = spi_nor_erase_sector(nor, addr);
 			if (ret)
@@ -1263,12 +1696,13 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 	if (len == mtd->size && !(nor->flags & SNOR_F_NO_OP_CHIP_ERASE)) {
 		unsigned long timeout;
 
-		write_enable(nor);
+		ret = spi_nor_write_enable(nor);
+		if (ret)
+			goto erase_err;
 
-		if (erase_chip(nor)) {
-			ret = -EIO;
+		ret = spi_nor_erase_chip(nor);
+		if (ret)
 			goto erase_err;
-		}
 
 		/*
 		 * Scale the timeout linearly with the size of the flash, with
@@ -1291,7 +1725,9 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 	/* "sector"-at-a-time erase */
 	} else if (spi_nor_has_uniform_erase(nor)) {
 		while (len) {
-			write_enable(nor);
+			ret = spi_nor_write_enable(nor);
+			if (ret)
+				goto erase_err;
 
 			ret = spi_nor_erase_sector(nor, addr);
 			if (ret)
@@ -1312,7 +1748,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 			goto erase_err;
 	}
 
-	write_disable(nor);
+	ret = spi_nor_write_disable(nor);
 
 erase_err:
 	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_ERASE);
@@ -1320,27 +1756,6 @@ erase_err:
 	return ret;
 }
 
-/* Write status register and ensure bits in mask match written values */
-static int write_sr_and_check(struct spi_nor *nor, u8 status_new, u8 mask)
-{
-	int ret;
-
-	write_enable(nor);
-	ret = write_sr(nor, status_new);
-	if (ret)
-		return ret;
-
-	ret = spi_nor_wait_till_ready(nor);
-	if (ret)
-		return ret;
-
-	ret = read_sr(nor);
-	if (ret < 0)
-		return ret;
-
-	return ((ret & mask) != (status_new & mask)) ? -EIO : 0;
-}
-
 static void stm_get_locked_range(struct spi_nor *nor, u8 sr, loff_t *ofs,
 				 uint64_t *len)
 {
@@ -1433,16 +1848,18 @@ static int stm_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
 static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
 	struct mtd_info *mtd = &nor->mtd;
-	int status_old, status_new;
+	int ret, status_old, status_new;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 shift = ffs(mask) - 1, pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
 
-	status_old = read_sr(nor);
-	if (status_old < 0)
-		return status_old;
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	status_old = nor->bouncebuf[0];
 
 	/* If nothing in our range is unlocked, we don't need to do anything */
 	if (stm_is_locked_sr(nor, ofs, len, status_old))
@@ -1502,7 +1919,7 @@ static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	if ((status_new & mask) < (status_old & mask))
 		return -EINVAL;
 
-	return write_sr_and_check(nor, status_new, mask);
+	return spi_nor_write_sr_and_check(nor, status_new);
 }
 
 /*
@@ -1513,16 +1930,18 @@ static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
 	struct mtd_info *mtd = &nor->mtd;
-	int status_old, status_new;
+	int ret, status_old, status_new;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 shift = ffs(mask) - 1, pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
 
-	status_old = read_sr(nor);
-	if (status_old < 0)
-		return status_old;
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	status_old = nor->bouncebuf[0];
 
 	/* If nothing in our range is locked, we don't need to do anything */
 	if (stm_is_unlocked_sr(nor, ofs, len, status_old))
@@ -1585,7 +2004,7 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	if ((status_new & mask) > (status_old & mask))
 		return -EINVAL;
 
-	return write_sr_and_check(nor, status_new, mask);
+	return spi_nor_write_sr_and_check(nor, status_new);
 }
 
 /*
@@ -1597,13 +2016,13 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
  */
 static int stm_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len)
 {
-	int status;
+	int ret;
 
-	status = read_sr(nor);
-	if (status < 0)
-		return status;
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
 
-	return stm_is_locked_sr(nor, ofs, len, status);
+	return stm_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]);
 }
 
 static const struct spi_nor_locking_ops stm_locking_ops = {
@@ -1657,242 +2076,59 @@ static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 	return ret;
 }
 
-/*
- * Write status Register and configuration register with 2 bytes
- * The first byte will be written to the status register, while the
- * second byte will be written to the configuration register.
- * Return negative if error occurred.
- */
-static int write_sr_cr(struct spi_nor *nor, u8 *sr_cr)
-{
-	int ret;
-
-	write_enable(nor);
-
-	if (nor->spimem) {
-		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRSR, 1),
-				   SPI_MEM_OP_NO_ADDR,
-				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_OUT(2, sr_cr, 1));
-
-		ret = spi_mem_exec_op(nor->spimem, &op);
-	} else {
-		ret = nor->write_reg(nor, SPINOR_OP_WRSR, sr_cr, 2);
-	}
-
-	if (ret < 0) {
-		dev_err(nor->dev,
-			"error while writing configuration register\n");
-		return -EINVAL;
-	}
-
-	ret = spi_nor_wait_till_ready(nor);
-	if (ret) {
-		dev_err(nor->dev,
-			"timeout while writing configuration register\n");
-		return ret;
-	}
-
-	return 0;
-}
-
-/**
- * macronix_quad_enable() - set QE bit in Status Register.
- * @nor:	pointer to a 'struct spi_nor'
- *
- * Set the Quad Enable (QE) bit in the Status Register.
- *
- * bit 6 of the Status Register is the QE bit for Macronix like QSPI memories.
- *
- * Return: 0 on success, -errno otherwise.
- */
-static int macronix_quad_enable(struct spi_nor *nor)
-{
-	int ret, val;
-
-	val = read_sr(nor);
-	if (val < 0)
-		return val;
-	if (val & SR_QUAD_EN_MX)
-		return 0;
-
-	write_enable(nor);
-
-	write_sr(nor, val | SR_QUAD_EN_MX);
-
-	ret = spi_nor_wait_till_ready(nor);
-	if (ret)
-		return ret;
-
-	ret = read_sr(nor);
-	if (!(ret > 0 && (ret & SR_QUAD_EN_MX))) {
-		dev_err(nor->dev, "Macronix Quad bit not set\n");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 /**
- * spansion_quad_enable() - set QE bit in Configuraiton Register.
+ * spi_nor_sr1_bit6_quad_enable() - Set the Quad Enable BIT(6) in the Status
+ * Register 1.
  * @nor:	pointer to a 'struct spi_nor'
  *
- * Set the Quad Enable (QE) bit in the Configuration Register.
- * This function is kept for legacy purpose because it has been used for a
- * long time without anybody complaining but it should be considered as
- * deprecated and maybe buggy.
- * First, this function doesn't care about the previous values of the Status
- * and Configuration Registers when it sets the QE bit (bit 1) in the
- * Configuration Register: all other bits are cleared, which may have unwanted
- * side effects like removing some block protections.
- * Secondly, it uses the Read Configuration Register (35h) instruction though
- * some very old and few memories don't support this instruction. If a pull-up
- * resistor is present on the MISO/IO1 line, we might still be able to pass the
- * "read back" test because the QSPI memory doesn't recognize the command,
- * so leaves the MISO/IO1 line state unchanged, hence read_cr() returns 0xFF.
- *
- * bit 1 of the Configuration Register is the QE bit for Spansion like QSPI
- * memories.
+ * Bit 6 of the Status Register 1 is the QE bit for Macronix like QSPI memories.
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spansion_quad_enable(struct spi_nor *nor)
+static int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor)
 {
-	u8 *sr_cr = nor->bouncebuf;
 	int ret;
 
-	sr_cr[0] = 0;
-	sr_cr[1] = CR_QUAD_EN_SPAN;
-	ret = write_sr_cr(nor, sr_cr);
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
 	if (ret)
 		return ret;
 
-	/* read back and check it */
-	ret = read_cr(nor);
-	if (!(ret > 0 && (ret & CR_QUAD_EN_SPAN))) {
-		dev_err(nor->dev, "Spansion Quad bit not set\n");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-/**
- * spansion_no_read_cr_quad_enable() - set QE bit in Configuration Register.
- * @nor:	pointer to a 'struct spi_nor'
- *
- * Set the Quad Enable (QE) bit in the Configuration Register.
- * This function should be used with QSPI memories not supporting the Read
- * Configuration Register (35h) instruction.
- *
- * bit 1 of the Configuration Register is the QE bit for Spansion like QSPI
- * memories.
- *
- * Return: 0 on success, -errno otherwise.
- */
-static int spansion_no_read_cr_quad_enable(struct spi_nor *nor)
-{
-	u8 *sr_cr = nor->bouncebuf;
-	int ret;
+	if (nor->bouncebuf[0] & SR1_QUAD_EN_BIT6)
+		return 0;
 
-	/* Keep the current value of the Status Register. */
-	ret = read_sr(nor);
-	if (ret < 0) {
-		dev_err(nor->dev, "error while reading status register\n");
-		return -EINVAL;
-	}
-	sr_cr[0] = ret;
-	sr_cr[1] = CR_QUAD_EN_SPAN;
+	nor->bouncebuf[0] |= SR1_QUAD_EN_BIT6;
 
-	return write_sr_cr(nor, sr_cr);
+	return spi_nor_write_sr1_and_check(nor, nor->bouncebuf[0]);
 }
 
 /**
- * spansion_read_cr_quad_enable() - set QE bit in Configuration Register.
- * @nor:	pointer to a 'struct spi_nor'
- *
- * Set the Quad Enable (QE) bit in the Configuration Register.
- * This function should be used with QSPI memories supporting the Read
- * Configuration Register (35h) instruction.
+ * spi_nor_sr2_bit1_quad_enable() - set the Quad Enable BIT(1) in the Status
+ * Register 2.
+ * @nor:       pointer to a 'struct spi_nor'.
  *
- * bit 1 of the Configuration Register is the QE bit for Spansion like QSPI
- * memories.
+ * Bit 1 of the Status Register 2 is the QE bit for Spansion like QSPI memories.
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spansion_read_cr_quad_enable(struct spi_nor *nor)
+static int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor)
 {
-	struct device *dev = nor->dev;
-	u8 *sr_cr = nor->bouncebuf;
 	int ret;
 
-	/* Check current Quad Enable bit value. */
-	ret = read_cr(nor);
-	if (ret < 0) {
-		dev_err(dev, "error while reading configuration register\n");
-		return -EINVAL;
-	}
-
-	if (ret & CR_QUAD_EN_SPAN)
-		return 0;
-
-	sr_cr[1] = ret | CR_QUAD_EN_SPAN;
-
-	/* Keep the current value of the Status Register. */
-	ret = read_sr(nor);
-	if (ret < 0) {
-		dev_err(dev, "error while reading status register\n");
-		return -EINVAL;
-	}
-	sr_cr[0] = ret;
+	if (nor->flags & SNOR_F_NO_READ_CR)
+		return spi_nor_write_16bit_cr_and_check(nor, SR2_QUAD_EN_BIT1);
 
-	ret = write_sr_cr(nor, sr_cr);
+	ret = spi_nor_read_cr(nor, nor->bouncebuf);
 	if (ret)
 		return ret;
 
-	/* Read back and check it. */
-	ret = read_cr(nor);
-	if (!(ret > 0 && (ret & CR_QUAD_EN_SPAN))) {
-		dev_err(nor->dev, "Spansion Quad bit not set\n");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-static int spi_nor_write_sr2(struct spi_nor *nor, u8 *sr2)
-{
-	if (nor->spimem) {
-		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRSR2, 1),
-				   SPI_MEM_OP_NO_ADDR,
-				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_OUT(1, sr2, 1));
-
-		return spi_mem_exec_op(nor->spimem, &op);
-	}
-
-	return nor->write_reg(nor, SPINOR_OP_WRSR2, sr2, 1);
-}
-
-static int spi_nor_read_sr2(struct spi_nor *nor, u8 *sr2)
-{
-	if (nor->spimem) {
-		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDSR2, 1),
-				   SPI_MEM_OP_NO_ADDR,
-				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(1, sr2, 1));
-
-		return spi_mem_exec_op(nor->spimem, &op);
-	}
+	if (nor->bouncebuf[0] & SR2_QUAD_EN_BIT1)
+		return 0;
 
-	return nor->read_reg(nor, SPINOR_OP_RDSR2, sr2, 1);
+	return spi_nor_write_16bit_cr_and_check(nor, nor->bouncebuf[0]);
 }
 
 /**
- * sr2_bit7_quad_enable() - set QE bit in Status Register 2.
+ * spi_nor_sr2_bit7_quad_enable() - set QE bit in Status Register 2.
  * @nor:	pointer to a 'struct spi_nor'
  *
  * Set the Quad Enable (QE) bit in the Status Register 2.
@@ -1903,10 +2139,11 @@ static int spi_nor_read_sr2(struct spi_nor *nor, u8 *sr2)
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int sr2_bit7_quad_enable(struct spi_nor *nor)
+static int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor)
 {
 	u8 *sr2 = nor->bouncebuf;
 	int ret;
+	u8 sr2_written;
 
 	/* Check current Quad Enable bit value. */
 	ret = spi_nor_read_sr2(nor, sr2);
@@ -1918,117 +2155,23 @@ static int sr2_bit7_quad_enable(struct spi_nor *nor)
 	/* Update the Quad Enable bit. */
 	*sr2 |= SR2_QUAD_EN_BIT7;
 
-	write_enable(nor);
-
 	ret = spi_nor_write_sr2(nor, sr2);
-	if (ret < 0) {
-		dev_err(nor->dev, "error while writing status register 2\n");
-		return -EINVAL;
-	}
-
-	ret = spi_nor_wait_till_ready(nor);
-	if (ret < 0) {
-		dev_err(nor->dev, "timeout while writing status register 2\n");
+	if (ret)
 		return ret;
-	}
+
+	sr2_written = *sr2;
 
 	/* Read back and check it. */
 	ret = spi_nor_read_sr2(nor, sr2);
-	if (!(ret > 0 && (*sr2 & SR2_QUAD_EN_BIT7))) {
-		dev_err(nor->dev, "SR2 Quad bit not set\n");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-/**
- * spi_nor_clear_sr_bp() - clear the Status Register Block Protection bits.
- * @nor:        pointer to a 'struct spi_nor'
- *
- * Read-modify-write function that clears the Block Protection bits from the
- * Status Register without affecting other bits.
- *
- * Return: 0 on success, -errno otherwise.
- */
-static int spi_nor_clear_sr_bp(struct spi_nor *nor)
-{
-	int ret;
-	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
-
-	ret = read_sr(nor);
-	if (ret < 0) {
-		dev_err(nor->dev, "error while reading status register\n");
-		return ret;
-	}
-
-	write_enable(nor);
-
-	ret = write_sr(nor, ret & ~mask);
-	if (ret) {
-		dev_err(nor->dev, "write to status register failed\n");
-		return ret;
-	}
-
-	ret = spi_nor_wait_till_ready(nor);
 	if (ret)
-		dev_err(nor->dev, "timeout while writing status register\n");
-	return ret;
-}
-
-/**
- * spi_nor_spansion_clear_sr_bp() - clear the Status Register Block Protection
- * bits on spansion flashes.
- * @nor:        pointer to a 'struct spi_nor'
- *
- * Read-modify-write function that clears the Block Protection bits from the
- * Status Register without affecting other bits. The function is tightly
- * coupled with the spansion_quad_enable() function. Both assume that the Write
- * Register with 16 bits, together with the Read Configuration Register (35h)
- * instructions are supported.
- *
- * Return: 0 on success, -errno otherwise.
- */
-static int spi_nor_spansion_clear_sr_bp(struct spi_nor *nor)
-{
-	int ret;
-	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
-	u8 *sr_cr =  nor->bouncebuf;
-
-	/* Check current Quad Enable bit value. */
-	ret = read_cr(nor);
-	if (ret < 0) {
-		dev_err(nor->dev,
-			"error while reading configuration register\n");
 		return ret;
-	}
-
-	/*
-	 * When the configuration register Quad Enable bit is one, only the
-	 * Write Status (01h) command with two data bytes may be used.
-	 */
-	if (ret & CR_QUAD_EN_SPAN) {
-		sr_cr[1] = ret;
-
-		ret = read_sr(nor);
-		if (ret < 0) {
-			dev_err(nor->dev,
-				"error while reading status register\n");
-			return ret;
-		}
-		sr_cr[0] = ret & ~mask;
 
-		ret = write_sr_cr(nor, sr_cr);
-		if (ret)
-			dev_err(nor->dev, "16-bit write register failed\n");
-		return ret;
+	if (*sr2 != sr2_written) {
+		dev_dbg(nor->dev, "SR2: Read back test failed\n");
+		return -EIO;
 	}
 
-	/*
-	 * If the Quad Enable bit is zero, use the Write Status (01h) command
-	 * with one data byte.
-	 */
-	return spi_nor_clear_sr_bp(nor);
+	return 0;
 }
 
 /* Used when the "_ext_id" is two bytes at most */
@@ -2136,7 +2279,7 @@ static void gd25q256_default_init(struct spi_nor *nor)
 	 * indicate the quad_enable method for this case, we need
 	 * to set it in the default_init fixup hook.
 	 */
-	nor->params.quad_enable = macronix_quad_enable;
+	nor->params.quad_enable = spi_nor_sr1_bit6_quad_enable;
 }
 
 static struct spi_nor_fixups gd25q256_fixups = {
@@ -2179,6 +2322,8 @@ static const struct flash_info spi_nor_ids[] = {
 	{ "en25q64",    INFO(0x1c3017, 0, 64 * 1024,  128, SECT_4K) },
 	{ "en25q80a",   INFO(0x1c3014, 0, 64 * 1024,   16,
 			SECT_4K | SPI_NOR_DUAL_READ) },
+	{ "en25qh16",   INFO(0x1c7015, 0, 64 * 1024,   32,
+			SECT_4K | SPI_NOR_DUAL_READ) },
 	{ "en25qh32",   INFO(0x1c7016, 0, 64 * 1024,   64, 0) },
 	{ "en25qh64",   INFO(0x1c7017, 0, 64 * 1024,  128,
 			SECT_4K | SPI_NOR_DUAL_READ) },
@@ -2267,6 +2412,10 @@ static const struct flash_info spi_nor_ids[] = {
 			SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 	{ "is25wp128",  INFO(0x9d7018, 0, 64 * 1024, 256,
 			SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
+	{ "is25wp256", INFO(0x9d7019, 0, 64 * 1024, 512,
+			    SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
+			    SPI_NOR_4B_OPCODES)
+		       .fixups = &is25lp256_fixups },
 
 	/* Macronix */
 	{ "mx25l512e",   INFO(0xc22010, 0, 64 * 1024,   1, SECT_4K) },
@@ -2482,6 +2631,8 @@ static const struct flash_info spi_nor_ids[] = {
 	{ "w25q256", INFO(0xef4019, 0, 64 * 1024, 512, SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 	{ "w25q256jvm", INFO(0xef7019, 0, 64 * 1024, 512,
 			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
+	{ "w25q256jw", INFO(0xef6019, 0, 64 * 1024, 512,
+			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 	{ "w25m512jv", INFO(0xef7119, 0, 64 * 1024, 1024,
 			SECT_4K | SPI_NOR_QUAD_READ | SPI_NOR_DUAL_READ) },
 
@@ -2520,11 +2671,11 @@ static const struct flash_info *spi_nor_read_id(struct spi_nor *nor)
 
 		tmp = spi_mem_exec_op(nor->spimem, &op);
 	} else {
-		tmp = nor->read_reg(nor, SPINOR_OP_RDID, id,
-				    SPI_NOR_MAX_ID_LEN);
+		tmp = nor->controller_ops->read_reg(nor, SPINOR_OP_RDID, id,
+						    SPI_NOR_MAX_ID_LEN);
 	}
-	if (tmp < 0) {
-		dev_err(nor->dev, "error %d reading JEDEC ID\n", tmp);
+	if (tmp) {
+		dev_dbg(nor->dev, "error %d reading JEDEC ID\n", tmp);
 		return ERR_PTR(tmp);
 	}
 
@@ -2544,7 +2695,7 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 			size_t *retlen, u_char *buf)
 {
 	struct spi_nor *nor = mtd_to_spi_nor(mtd);
-	int ret;
+	ssize_t ret;
 
 	dev_dbg(nor->dev, "from 0x%08x, len %zd\n", (u32)from, len);
 
@@ -2583,7 +2734,7 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
 		size_t *retlen, const u_char *buf)
 {
 	struct spi_nor *nor = mtd_to_spi_nor(mtd);
-	size_t actual;
+	size_t actual = 0;
 	int ret;
 
 	dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);
@@ -2592,26 +2743,28 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
 	if (ret)
 		return ret;
 
-	write_enable(nor);
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		goto out;
 
 	nor->sst_write_second = false;
 
-	actual = to % 2;
 	/* Start write from odd address. */
-	if (actual) {
+	if (to % 2) {
 		nor->program_opcode = SPINOR_OP_BP;
 
 		/* write one byte. */
 		ret = spi_nor_write_data(nor, to, 1, buf);
 		if (ret < 0)
-			goto sst_write_err;
-		WARN(ret != 1, "While writing 1 byte written %i bytes\n",
-		     (int)ret);
+			goto out;
+		WARN(ret != 1, "While writing 1 byte written %i bytes\n", ret);
 		ret = spi_nor_wait_till_ready(nor);
 		if (ret)
-			goto sst_write_err;
+			goto out;
+
+		to++;
+		actual++;
 	}
-	to += actual;
 
 	/* Write out most of the data here. */
 	for (; actual < len - 1; actual += 2) {
@@ -2620,39 +2773,44 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
 		/* write two bytes. */
 		ret = spi_nor_write_data(nor, to, 2, buf + actual);
 		if (ret < 0)
-			goto sst_write_err;
-		WARN(ret != 2, "While writing 2 bytes written %i bytes\n",
-		     (int)ret);
+			goto out;
+		WARN(ret != 2, "While writing 2 bytes written %i bytes\n", ret);
 		ret = spi_nor_wait_till_ready(nor);
 		if (ret)
-			goto sst_write_err;
+			goto out;
 		to += 2;
 		nor->sst_write_second = true;
 	}
 	nor->sst_write_second = false;
 
-	write_disable(nor);
+	ret = spi_nor_write_disable(nor);
+	if (ret)
+		goto out;
+
 	ret = spi_nor_wait_till_ready(nor);
 	if (ret)
-		goto sst_write_err;
+		goto out;
 
 	/* Write out trailing byte if it exists. */
 	if (actual != len) {
-		write_enable(nor);
+		ret = spi_nor_write_enable(nor);
+		if (ret)
+			goto out;
 
 		nor->program_opcode = SPINOR_OP_BP;
 		ret = spi_nor_write_data(nor, to, 1, buf + actual);
 		if (ret < 0)
-			goto sst_write_err;
-		WARN(ret != 1, "While writing 1 byte written %i bytes\n",
-		     (int)ret);
+			goto out;
+		WARN(ret != 1, "While writing 1 byte written %i bytes\n", ret);
 		ret = spi_nor_wait_till_ready(nor);
 		if (ret)
-			goto sst_write_err;
-		write_disable(nor);
+			goto out;
+
 		actual += 1;
+
+		ret = spi_nor_write_disable(nor);
 	}
-sst_write_err:
+out:
 	*retlen += actual;
 	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_WRITE);
 	return ret;
@@ -2701,7 +2859,10 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 
 		addr = spi_nor_convert_addr(nor, addr);
 
-		write_enable(nor);
+		ret = spi_nor_write_enable(nor);
+		if (ret)
+			goto write_err;
+
 		ret = spi_nor_write_data(nor, addr, page_remain, buf + i);
 		if (ret < 0)
 			goto write_err;
@@ -2722,13 +2883,21 @@ write_err:
 static int spi_nor_check(struct spi_nor *nor)
 {
 	if (!nor->dev ||
-	    (!nor->spimem &&
-	    (!nor->read || !nor->write || !nor->read_reg ||
-	      !nor->write_reg))) {
+	    (!nor->spimem && !nor->controller_ops) ||
+	    (!nor->spimem && nor->controller_ops &&
+	    (!nor->controller_ops->read ||
+	     !nor->controller_ops->write ||
+	     !nor->controller_ops->read_reg ||
+	     !nor->controller_ops->write_reg))) {
 		pr_err("spi-nor: please fill all the necessary fields!\n");
 		return -EINVAL;
 	}
 
+	if (nor->spimem && nor->controller_ops) {
+		dev_err(nor->dev, "nor->spimem and nor->controller_ops are mutually exclusive, please set just one of them.\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -2738,10 +2907,8 @@ static int s3an_nor_setup(struct spi_nor *nor,
 	int ret;
 
 	ret = spi_nor_xread_sr(nor, nor->bouncebuf);
-	if (ret < 0) {
-		dev_err(nor->dev, "error %d reading XRDSR\n", (int) ret);
+	if (ret)
 		return ret;
-	}
 
 	nor->erase_opcode = SPINOR_OP_XSE;
 	nor->program_opcode = SPINOR_OP_XPP;
@@ -2865,7 +3032,7 @@ static int spi_nor_hwcaps_pp2cmd(u32 hwcaps)
  */
 static int spi_nor_read_raw(struct spi_nor *nor, u32 addr, size_t len, u8 *buf)
 {
-	int ret;
+	ssize_t ret;
 
 	while (len) {
 		ret = spi_nor_read_data(nor, addr, len, buf);
@@ -3489,20 +3656,39 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 		break;
 
 	case BFPT_DWORD15_QER_SR2_BIT1_BUGGY:
+		/*
+		 * Writing only one byte to the Status Register has the
+		 * side-effect of clearing Status Register 2.
+		 */
 	case BFPT_DWORD15_QER_SR2_BIT1_NO_RD:
-		params->quad_enable = spansion_no_read_cr_quad_enable;
+		/*
+		 * Read Configuration Register (35h) instruction is not
+		 * supported.
+		 */
+		nor->flags |= SNOR_F_HAS_16BIT_SR | SNOR_F_NO_READ_CR;
+		params->quad_enable = spi_nor_sr2_bit1_quad_enable;
 		break;
 
 	case BFPT_DWORD15_QER_SR1_BIT6:
-		params->quad_enable = macronix_quad_enable;
+		nor->flags &= ~SNOR_F_HAS_16BIT_SR;
+		params->quad_enable = spi_nor_sr1_bit6_quad_enable;
 		break;
 
 	case BFPT_DWORD15_QER_SR2_BIT7:
-		params->quad_enable = sr2_bit7_quad_enable;
+		nor->flags &= ~SNOR_F_HAS_16BIT_SR;
+		params->quad_enable = spi_nor_sr2_bit7_quad_enable;
 		break;
 
 	case BFPT_DWORD15_QER_SR2_BIT1:
-		params->quad_enable = spansion_read_cr_quad_enable;
+		/*
+		 * JESD216 rev B or later does not specify if writing only one
+		 * byte to the Status Register clears or not the Status
+		 * Register 2, so let's be cautious and keep the default
+		 * assumption of a 16-bit Write Status (01h) command.
+		 */
+		nor->flags |= SNOR_F_HAS_16BIT_SR;
+
+		params->quad_enable = spi_nor_sr2_bit1_quad_enable;
 		break;
 
 	default:
@@ -4101,7 +4287,7 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
 		err = spi_nor_read_sfdp(nor, sizeof(header),
 					psize, param_headers);
 		if (err < 0) {
-			dev_err(dev, "failed to read SFDP parameter headers\n");
+			dev_dbg(dev, "failed to read SFDP parameter headers\n");
 			goto exit;
 		}
 	}
@@ -4348,7 +4534,7 @@ static int spi_nor_default_setup(struct spi_nor *nor,
 	/* Select the (Fast) Read command. */
 	err = spi_nor_select_read(nor, shared_mask);
 	if (err) {
-		dev_err(nor->dev,
+		dev_dbg(nor->dev,
 			"can't select read settings supported by both the SPI controller and memory.\n");
 		return err;
 	}
@@ -4356,7 +4542,7 @@ static int spi_nor_default_setup(struct spi_nor *nor,
 	/* Select the Page Program command. */
 	err = spi_nor_select_pp(nor, shared_mask);
 	if (err) {
-		dev_err(nor->dev,
+		dev_dbg(nor->dev,
 			"can't select write settings supported by both the SPI controller and memory.\n");
 		return err;
 	}
@@ -4364,7 +4550,7 @@ static int spi_nor_default_setup(struct spi_nor *nor,
 	/* Select the Sector Erase command. */
 	err = spi_nor_select_erase(nor);
 	if (err) {
-		dev_err(nor->dev,
+		dev_dbg(nor->dev,
 			"can't select erase settings supported by both the SPI controller and memory.\n");
 		return err;
 	}
@@ -4381,12 +4567,32 @@ static int spi_nor_setup(struct spi_nor *nor,
 	return nor->params.setup(nor, hwcaps);
 }
 
+static void atmel_set_default_init(struct spi_nor *nor)
+{
+	nor->flags |= SNOR_F_HAS_LOCK;
+}
+
+static void intel_set_default_init(struct spi_nor *nor)
+{
+	nor->flags |= SNOR_F_HAS_LOCK;
+}
+
+static void issi_set_default_init(struct spi_nor *nor)
+{
+	nor->params.quad_enable = spi_nor_sr1_bit6_quad_enable;
+}
+
 static void macronix_set_default_init(struct spi_nor *nor)
 {
-	nor->params.quad_enable = macronix_quad_enable;
+	nor->params.quad_enable = spi_nor_sr1_bit6_quad_enable;
 	nor->params.set_4byte = macronix_set_4byte;
 }
 
+static void sst_set_default_init(struct spi_nor *nor)
+{
+	nor->flags |= SNOR_F_HAS_LOCK;
+}
+
 static void st_micron_set_default_init(struct spi_nor *nor)
 {
 	nor->flags |= SNOR_F_HAS_LOCK;
@@ -4408,6 +4614,18 @@ static void spi_nor_manufacturer_init_params(struct spi_nor *nor)
 {
 	/* Init flash parameters based on MFR */
 	switch (JEDEC_MFR(nor->info)) {
+	case SNOR_MFR_ATMEL:
+		atmel_set_default_init(nor);
+		break;
+
+	case SNOR_MFR_INTEL:
+		intel_set_default_init(nor);
+		break;
+
+	case SNOR_MFR_ISSI:
+		issi_set_default_init(nor);
+		break;
+
 	case SNOR_MFR_MACRONIX:
 		macronix_set_default_init(nor);
 		break;
@@ -4417,6 +4635,10 @@ static void spi_nor_manufacturer_init_params(struct spi_nor *nor)
 		st_micron_set_default_init(nor);
 		break;
 
+	case SNOR_MFR_SST:
+		sst_set_default_init(nor);
+		break;
+
 	case SNOR_MFR_WINBOND:
 		winbond_set_default_init(nor);
 		break;
@@ -4465,9 +4687,11 @@ static void spi_nor_info_init_params(struct spi_nor *nor)
 	u8 i, erase_mask;
 
 	/* Initialize legacy flash parameters and settings. */
-	params->quad_enable = spansion_quad_enable;
+	params->quad_enable = spi_nor_sr2_bit1_quad_enable;
 	params->set_4byte = spansion_set_4byte;
 	params->setup = spi_nor_default_setup;
+	/* Default to 16-bit Write Status (01h) Command */
+	nor->flags |= SNOR_F_HAS_16BIT_SR;
 
 	/* Set SPI NOR sizes. */
 	params->size = (u64)info->sector_size * info->n_sectors;
@@ -4675,25 +4899,36 @@ static int spi_nor_quad_enable(struct spi_nor *nor)
 	return nor->params.quad_enable(nor);
 }
 
+/**
+ * spi_nor_unlock_all() - Unlocks the entire flash memory array.
+ * @nor:	pointer to a 'struct spi_nor'.
+ *
+ * Some SPI NOR flashes are write protected by default after a power-on reset
+ * cycle, in order to avoid inadvertent writes during power-up. Backward
+ * compatibility imposes to unlock the entire flash memory array at power-up
+ * by default.
+ */
+static int spi_nor_unlock_all(struct spi_nor *nor)
+{
+	if (nor->flags & SNOR_F_HAS_LOCK)
+		return spi_nor_unlock(&nor->mtd, 0, nor->params.size);
+
+	return 0;
+}
+
 static int spi_nor_init(struct spi_nor *nor)
 {
 	int err;
 
-	if (nor->clear_sr_bp) {
-		if (nor->params.quad_enable == spansion_quad_enable)
-			nor->clear_sr_bp = spi_nor_spansion_clear_sr_bp;
-
-		err = nor->clear_sr_bp(nor);
-		if (err) {
-			dev_err(nor->dev,
-				"fail to clear block protection bits\n");
-			return err;
-		}
+	err = spi_nor_quad_enable(nor);
+	if (err) {
+		dev_dbg(nor->dev, "quad mode not supported\n");
+		return err;
 	}
 
-	err = spi_nor_quad_enable(nor);
+	err = spi_nor_unlock_all(nor);
 	if (err) {
-		dev_err(nor->dev, "quad mode not supported\n");
+		dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n");
 		return err;
 	}
 
@@ -4761,7 +4996,7 @@ static int spi_nor_set_addr_width(struct spi_nor *nor)
 	}
 
 	if (nor->addr_width > SPI_NOR_MAX_ADDR_WIDTH) {
-		dev_err(nor->dev, "address width is too large: %u\n",
+		dev_dbg(nor->dev, "address width is too large: %u\n",
 			nor->addr_width);
 		return -EINVAL;
 	}
@@ -4879,16 +5114,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (info->flags & SPI_NOR_HAS_LOCK)
 		nor->flags |= SNOR_F_HAS_LOCK;
 
-	/*
-	 * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
-	 * with the software protection bits set.
-	 */
-	if (JEDEC_MFR(nor->info) == SNOR_MFR_ATMEL ||
-	    JEDEC_MFR(nor->info) == SNOR_MFR_INTEL ||
-	    JEDEC_MFR(nor->info) == SNOR_MFR_SST ||
-	    nor->info->flags & SPI_NOR_HAS_LOCK)
-		nor->clear_sr_bp = spi_nor_clear_sr_bp;
-
 	/* Init flash parameters based on flash_info struct and SFDP */
 	spi_nor_init_params(nor);