mtd: nand: Qualcomm NAND controller driver

The Qualcomm NAND controller is found in SoCs like IPQ806x, MSM7xx,
MDM9x15 series.

It exists as a sub block inside the IPs EBI2 (External Bus Interface 2)
and QPIC (Qualcomm Parallel Interface Controller). These IPs provide a
broader interface for external slow peripheral devices such as LCD and
NAND/NOR flash memory or SRAM like interfaces.

We add support for the NAND controller found within EBI2. For the SoCs
of our interest, we only use the NAND controller within EBI2. Therefore,
it's safe for us to assume that the NAND controller is a standalone block
within the SoC.

The controller supports 512B, 2kB, 4kB and 8kB page 8-bit and 16-bit NAND
flash devices. It contains a HW ECC block that supports BCH ECC (4, 8 and
16 bit correction/step) and RS ECC(4 bit correction/step) that covers main
and spare data. The controller contains an internal 512 byte page buffer
to which we read/write via DMA. The EBI2 type NAND controller uses ADM DMA
for register read/write and data transfers. The controller performs page
reads and writes at a codeword/step level of 512 bytes. It can support up
to 2 external chips of different configurations.

The driver prepares register read and write configuration descriptors for
each codeword, followed by data descriptors to read or write data from the
controller's internal buffer. It uses a single ADM DMA channel that we get
via dmaengine API. The controller requires 2 ADM CRCIs for command and
data flow control. These are passed via DT.

The ecc layout used by the controller is syndrome like, but we can't use
the standard syndrome ecc ops because of several reasons. First, the amount
of data bytes covered by ecc isn't same in each step. Second, writing to
free oob space requires us writing to the entire step in which the oob
lies. This forces us to create our own ecc ops.

One more difference is how the controller accesses the bad block marker.
The controller ignores reading the marker when ECC is enabled. ECC needs
to be explicity disabled to read or write to the bad block marker. The
nand_bbt helpers library hence can't access BBMs for the controller.
For now, we skip the creation of BBT and populate chip->block_bad and
chip->block_markbad helpers instead.

Reviewed-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 2223 insertions, 0 deletions

diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
new file mode 100644
index 000000000000..f550a57e6eea
--- /dev/null
+++ b/drivers/mtd/nand/qcom_nandc.c
@@ -0,0 +1,2223 @@
+/*
+ * Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/clk.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/module.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/partitions.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_mtd.h>
+#include <linux/delay.h>
+
+/* NANDc reg offsets */
+#define	NAND_FLASH_CMD			0x00
+#define	NAND_ADDR0			0x04
+#define	NAND_ADDR1			0x08
+#define	NAND_FLASH_CHIP_SELECT		0x0c
+#define	NAND_EXEC_CMD			0x10
+#define	NAND_FLASH_STATUS		0x14
+#define	NAND_BUFFER_STATUS		0x18
+#define	NAND_DEV0_CFG0			0x20
+#define	NAND_DEV0_CFG1			0x24
+#define	NAND_DEV0_ECC_CFG		0x28
+#define	NAND_DEV1_ECC_CFG		0x2c
+#define	NAND_DEV1_CFG0			0x30
+#define	NAND_DEV1_CFG1			0x34
+#define	NAND_READ_ID			0x40
+#define	NAND_READ_STATUS		0x44
+#define	NAND_DEV_CMD0			0xa0
+#define	NAND_DEV_CMD1			0xa4
+#define	NAND_DEV_CMD2			0xa8
+#define	NAND_DEV_CMD_VLD		0xac
+#define	SFLASHC_BURST_CFG		0xe0
+#define	NAND_ERASED_CW_DETECT_CFG	0xe8
+#define	NAND_ERASED_CW_DETECT_STATUS	0xec
+#define	NAND_EBI2_ECC_BUF_CFG		0xf0
+#define	FLASH_BUF_ACC			0x100
+
+#define	NAND_CTRL			0xf00
+#define	NAND_VERSION			0xf08
+#define	NAND_READ_LOCATION_0		0xf20
+#define	NAND_READ_LOCATION_1		0xf24
+
+/* dummy register offsets, used by write_reg_dma */
+#define	NAND_DEV_CMD1_RESTORE		0xdead
+#define	NAND_DEV_CMD_VLD_RESTORE	0xbeef
+
+/* NAND_FLASH_CMD bits */
+#define	PAGE_ACC			BIT(4)
+#define	LAST_PAGE			BIT(5)
+
+/* NAND_FLASH_CHIP_SELECT bits */
+#define	NAND_DEV_SEL			0
+#define	DM_EN				BIT(2)
+
+/* NAND_FLASH_STATUS bits */
+#define	FS_OP_ERR			BIT(4)
+#define	FS_READY_BSY_N			BIT(5)
+#define	FS_MPU_ERR			BIT(8)
+#define	FS_DEVICE_STS_ERR		BIT(16)
+#define	FS_DEVICE_WP			BIT(23)
+
+/* NAND_BUFFER_STATUS bits */
+#define	BS_UNCORRECTABLE_BIT		BIT(8)
+#define	BS_CORRECTABLE_ERR_MSK		0x1f
+
+/* NAND_DEVn_CFG0 bits */
+#define	DISABLE_STATUS_AFTER_WRITE	4
+#define	CW_PER_PAGE			6
+#define	UD_SIZE_BYTES			9
+#define	ECC_PARITY_SIZE_BYTES_RS	19
+#define	SPARE_SIZE_BYTES		23
+#define	NUM_ADDR_CYCLES			27
+#define	STATUS_BFR_READ			30
+#define	SET_RD_MODE_AFTER_STATUS	31
+
+/* NAND_DEVn_CFG0 bits */
+#define	DEV0_CFG1_ECC_DISABLE		0
+#define	WIDE_FLASH			1
+#define	NAND_RECOVERY_CYCLES		2
+#define	CS_ACTIVE_BSY			5
+#define	BAD_BLOCK_BYTE_NUM		6
+#define	BAD_BLOCK_IN_SPARE_AREA		16
+#define	WR_RD_BSY_GAP			17
+#define	ENABLE_BCH_ECC			27
+
+/* NAND_DEV0_ECC_CFG bits */
+#define	ECC_CFG_ECC_DISABLE		0
+#define	ECC_SW_RESET			1
+#define	ECC_MODE			4
+#define	ECC_PARITY_SIZE_BYTES_BCH	8
+#define	ECC_NUM_DATA_BYTES		16
+#define	ECC_FORCE_CLK_OPEN		30
+
+/* NAND_DEV_CMD1 bits */
+#define	READ_ADDR			0
+
+/* NAND_DEV_CMD_VLD bits */
+#define	READ_START_VLD			0
+
+/* NAND_EBI2_ECC_BUF_CFG bits */
+#define	NUM_STEPS			0
+
+/* NAND_ERASED_CW_DETECT_CFG bits */
+#define	ERASED_CW_ECC_MASK		1
+#define	AUTO_DETECT_RES			0
+#define	MASK_ECC			(1 << ERASED_CW_ECC_MASK)
+#define	RESET_ERASED_DET		(1 << AUTO_DETECT_RES)
+#define	ACTIVE_ERASED_DET		(0 << AUTO_DETECT_RES)
+#define	CLR_ERASED_PAGE_DET		(RESET_ERASED_DET | MASK_ECC)
+#define	SET_ERASED_PAGE_DET		(ACTIVE_ERASED_DET | MASK_ECC)
+
+/* NAND_ERASED_CW_DETECT_STATUS bits */
+#define	PAGE_ALL_ERASED			BIT(7)
+#define	CODEWORD_ALL_ERASED		BIT(6)
+#define	PAGE_ERASED			BIT(5)
+#define	CODEWORD_ERASED			BIT(4)
+#define	ERASED_PAGE			(PAGE_ALL_ERASED | PAGE_ERASED)
+#define	ERASED_CW			(CODEWORD_ALL_ERASED | CODEWORD_ERASED)
+
+/* Version Mask */
+#define	NAND_VERSION_MAJOR_MASK		0xf0000000
+#define	NAND_VERSION_MAJOR_SHIFT	28
+#define	NAND_VERSION_MINOR_MASK		0x0fff0000
+#define	NAND_VERSION_MINOR_SHIFT	16
+
+/* NAND OP_CMDs */
+#define	PAGE_READ			0x2
+#define	PAGE_READ_WITH_ECC		0x3
+#define	PAGE_READ_WITH_ECC_SPARE	0x4
+#define	PROGRAM_PAGE			0x6
+#define	PAGE_PROGRAM_WITH_ECC		0x7
+#define	PROGRAM_PAGE_SPARE		0x9
+#define	BLOCK_ERASE			0xa
+#define	FETCH_ID			0xb
+#define	RESET_DEVICE			0xd
+
+/*
+ * the NAND controller performs reads/writes with ECC in 516 byte chunks.
+ * the driver calls the chunks 'step' or 'codeword' interchangeably
+ */
+#define	NANDC_STEP_SIZE			512
+
+/*
+ * the largest page size we support is 8K, this will have 16 steps/codewords
+ * of 512 bytes each
+ */
+#define	MAX_NUM_STEPS			(SZ_8K / NANDC_STEP_SIZE)
+
+/* we read at most 3 registers per codeword scan */
+#define	MAX_REG_RD			(3 * MAX_NUM_STEPS)
+
+/* ECC modes supported by the controller */
+#define	ECC_NONE	BIT(0)
+#define	ECC_RS_4BIT	BIT(1)
+#define	ECC_BCH_4BIT	BIT(2)
+#define	ECC_BCH_8BIT	BIT(3)
+
+struct desc_info {
+	struct list_head node;
+
+	enum dma_data_direction dir;
+	struct scatterlist sgl;
+	struct dma_async_tx_descriptor *dma_desc;
+};
+
+/*
+ * holds the current register values that we want to write. acts as a contiguous
+ * chunk of memory which we use to write the controller registers through DMA.
+ */
+struct nandc_regs {
+	__le32 cmd;
+	__le32 addr0;
+	__le32 addr1;
+	__le32 chip_sel;
+	__le32 exec;
+
+	__le32 cfg0;
+	__le32 cfg1;
+	__le32 ecc_bch_cfg;
+
+	__le32 clrflashstatus;
+	__le32 clrreadstatus;
+
+	__le32 cmd1;
+	__le32 vld;
+
+	__le32 orig_cmd1;
+	__le32 orig_vld;
+
+	__le32 ecc_buf_cfg;
+};
+
+/*
+ * NAND controller data struct
+ *
+ * @controller:			base controller structure
+ * @host_list:			list containing all the chips attached to the
+ *				controller
+ * @dev:			parent device
+ * @base:			MMIO base
+ * @base_dma:			physical base address of controller registers
+ * @core_clk:			controller clock
+ * @aon_clk:			another controller clock
+ *
+ * @chan:			dma channel
+ * @cmd_crci:			ADM DMA CRCI for command flow control
+ * @data_crci:			ADM DMA CRCI for data flow control
+ * @desc_list:			DMA descriptor list (list of desc_infos)
+ *
+ * @data_buffer:		our local DMA buffer for page read/writes,
+ *				used when we can't use the buffer provided
+ *				by upper layers directly
+ * @buf_size/count/start:	markers for chip->read_buf/write_buf functions
+ * @reg_read_buf:		local buffer for reading back registers via DMA
+ * @reg_read_pos:		marker for data read in reg_read_buf
+ *
+ * @regs:			a contiguous chunk of memory for DMA register
+ *				writes. contains the register values to be
+ *				written to controller
+ * @cmd1/vld:			some fixed controller register values
+ * @ecc_modes:			supported ECC modes by the current controller,
+ *				initialized via DT match data
+ */
+struct qcom_nand_controller {
+	struct nand_hw_control controller;
+	struct list_head host_list;
+
+	struct device *dev;
+
+	void __iomem *base;
+	dma_addr_t base_dma;
+
+	struct clk *core_clk;
+	struct clk *aon_clk;
+
+	struct dma_chan *chan;
+	unsigned int cmd_crci;
+	unsigned int data_crci;
+	struct list_head desc_list;
+
+	u8		*data_buffer;
+	int		buf_size;
+	int		buf_count;
+	int		buf_start;
+
+	__le32 *reg_read_buf;
+	int reg_read_pos;
+
+	struct nandc_regs *regs;
+
+	u32 cmd1, vld;
+	u32 ecc_modes;
+};
+
+/*
+ * NAND chip structure
+ *
+ * @chip:			base NAND chip structure
+ * @node:			list node to add itself to host_list in
+ *				qcom_nand_controller
+ *
+ * @cs:				chip select value for this chip
+ * @cw_size:			the number of bytes in a single step/codeword
+ *				of a page, consisting of all data, ecc, spare
+ *				and reserved bytes
+ * @cw_data:			the number of bytes within a codeword protected
+ *				by ECC
+ * @use_ecc:			request the controller to use ECC for the
+ *				upcoming read/write
+ * @bch_enabled:		flag to tell whether BCH ECC mode is used
+ * @ecc_bytes_hw:		ECC bytes used by controller hardware for this
+ *				chip
+ * @status:			value to be returned if NAND_CMD_STATUS command
+ *				is executed
+ * @last_command:		keeps track of last command on this chip. used
+ *				for reading correct status
+ *
+ * @cfg0, cfg1, cfg0_raw..:	NANDc register configurations needed for
+ *				ecc/non-ecc mode for the current nand flash
+ *				device
+ */
+struct qcom_nand_host {
+	struct nand_chip chip;
+	struct list_head node;
+
+	int cs;
+	int cw_size;
+	int cw_data;
+	bool use_ecc;
+	bool bch_enabled;
+	int ecc_bytes_hw;
+	int spare_bytes;
+	int bbm_size;
+	u8 status;
+	int last_command;
+
+	u32 cfg0, cfg1;
+	u32 cfg0_raw, cfg1_raw;
+	u32 ecc_buf_cfg;
+	u32 ecc_bch_cfg;
+	u32 clrflashstatus;
+	u32 clrreadstatus;
+};
+
+static inline struct qcom_nand_host *to_qcom_nand_host(struct nand_chip *chip)
+{
+	return container_of(chip, struct qcom_nand_host, chip);
+}
+
+static inline struct qcom_nand_controller *
+get_qcom_nand_controller(struct nand_chip *chip)
+{
+	return container_of(chip->controller, struct qcom_nand_controller,
+			    controller);
+}
+
+static inline u32 nandc_read(struct qcom_nand_controller *nandc, int offset)
+{
+	return ioread32(nandc->base + offset);
+}
+
+static inline void nandc_write(struct qcom_nand_controller *nandc, int offset,
+			       u32 val)
+{
+	iowrite32(val, nandc->base + offset);
+}
+
+static __le32 *offset_to_nandc_reg(struct nandc_regs *regs, int offset)
+{
+	switch (offset) {
+	case NAND_FLASH_CMD:
+		return &regs->cmd;
+	case NAND_ADDR0:
+		return &regs->addr0;
+	case NAND_ADDR1:
+		return &regs->addr1;
+	case NAND_FLASH_CHIP_SELECT:
+		return &regs->chip_sel;
+	case NAND_EXEC_CMD:
+		return &regs->exec;
+	case NAND_FLASH_STATUS:
+		return &regs->clrflashstatus;
+	case NAND_DEV0_CFG0:
+		return &regs->cfg0;
+	case NAND_DEV0_CFG1:
+		return &regs->cfg1;
+	case NAND_DEV0_ECC_CFG:
+		return &regs->ecc_bch_cfg;
+	case NAND_READ_STATUS:
+		return &regs->clrreadstatus;
+	case NAND_DEV_CMD1:
+		return &regs->cmd1;
+	case NAND_DEV_CMD1_RESTORE:
+		return &regs->orig_cmd1;
+	case NAND_DEV_CMD_VLD:
+		return &regs->vld;
+	case NAND_DEV_CMD_VLD_RESTORE:
+		return &regs->orig_vld;
+	case NAND_EBI2_ECC_BUF_CFG:
+		return &regs->ecc_buf_cfg;
+	default:
+		return NULL;
+	}
+}
+
+static void nandc_set_reg(struct qcom_nand_controller *nandc, int offset,
+			  u32 val)
+{
+	struct nandc_regs *regs = nandc->regs;
+	__le32 *reg;
+
+	reg = offset_to_nandc_reg(regs, offset);
+
+	if (reg)
+		*reg = cpu_to_le32(val);
+}
+
+/* helper to configure address register values */
+static void set_address(struct qcom_nand_host *host, u16 column, int page)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	if (chip->options & NAND_BUSWIDTH_16)
+		column >>= 1;
+
+	nandc_set_reg(nandc, NAND_ADDR0, page << 16 | column);
+	nandc_set_reg(nandc, NAND_ADDR1, page >> 16 & 0xff);
+}
+
+/*
+ * update_rw_regs:	set up read/write register values, these will be
+ *			written to the NAND controller registers via DMA
+ *
+ * @num_cw:		number of steps for the read/write operation
+ * @read:		read or write operation
+ */
+static void update_rw_regs(struct qcom_nand_host *host, int num_cw, bool read)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	u32 cmd, cfg0, cfg1, ecc_bch_cfg;
+
+	if (read) {
+		if (host->use_ecc)
+			cmd = PAGE_READ_WITH_ECC | PAGE_ACC | LAST_PAGE;
+		else
+			cmd = PAGE_READ | PAGE_ACC | LAST_PAGE;
+	} else {
+			cmd = PROGRAM_PAGE | PAGE_ACC | LAST_PAGE;
+	}
+
+	if (host->use_ecc) {
+		cfg0 = (host->cfg0 & ~(7U << CW_PER_PAGE)) |
+				(num_cw - 1) << CW_PER_PAGE;
+
+		cfg1 = host->cfg1;
+		ecc_bch_cfg = host->ecc_bch_cfg;
+	} else {
+		cfg0 = (host->cfg0_raw & ~(7U << CW_PER_PAGE)) |
+				(num_cw - 1) << CW_PER_PAGE;
+
+		cfg1 = host->cfg1_raw;
+		ecc_bch_cfg = 1 << ECC_CFG_ECC_DISABLE;
+	}
+
+	nandc_set_reg(nandc, NAND_FLASH_CMD, cmd);
+	nandc_set_reg(nandc, NAND_DEV0_CFG0, cfg0);
+	nandc_set_reg(nandc, NAND_DEV0_CFG1, cfg1);
+	nandc_set_reg(nandc, NAND_DEV0_ECC_CFG, ecc_bch_cfg);
+	nandc_set_reg(nandc, NAND_EBI2_ECC_BUF_CFG, host->ecc_buf_cfg);
+	nandc_set_reg(nandc, NAND_FLASH_STATUS, host->clrflashstatus);
+	nandc_set_reg(nandc, NAND_READ_STATUS, host->clrreadstatus);
+	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
+}
+
+static int prep_dma_desc(struct qcom_nand_controller *nandc, bool read,
+			 int reg_off, const void *vaddr, int size,
+			 bool flow_control)
+{
+	struct desc_info *desc;
+	struct dma_async_tx_descriptor *dma_desc;
+	struct scatterlist *sgl;
+	struct dma_slave_config slave_conf;
+	enum dma_transfer_direction dir_eng;
+	int ret;
+
+	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+
+	sgl = &desc->sgl;
+
+	sg_init_one(sgl, vaddr, size);
+
+	if (read) {
+		dir_eng = DMA_DEV_TO_MEM;
+		desc->dir = DMA_FROM_DEVICE;
+	} else {
+		dir_eng = DMA_MEM_TO_DEV;
+		desc->dir = DMA_TO_DEVICE;
+	}
+
+	ret = dma_map_sg(nandc->dev, sgl, 1, desc->dir);
+	if (ret == 0) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	memset(&slave_conf, 0x00, sizeof(slave_conf));
+
+	slave_conf.device_fc = flow_control;
+	if (read) {
+		slave_conf.src_maxburst = 16;
+		slave_conf.src_addr = nandc->base_dma + reg_off;
+		slave_conf.slave_id = nandc->data_crci;
+	} else {
+		slave_conf.dst_maxburst = 16;
+		slave_conf.dst_addr = nandc->base_dma + reg_off;
+		slave_conf.slave_id = nandc->cmd_crci;
+	}
+
+	ret = dmaengine_slave_config(nandc->chan, &slave_conf);
+	if (ret) {
+		dev_err(nandc->dev, "failed to configure dma channel\n");
+		goto err;
+	}
+
+	dma_desc = dmaengine_prep_slave_sg(nandc->chan, sgl, 1, dir_eng, 0);
+	if (!dma_desc) {
+		dev_err(nandc->dev, "failed to prepare desc\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	desc->dma_desc = dma_desc;
+
+	list_add_tail(&desc->node, &nandc->desc_list);
+
+	return 0;
+err:
+	kfree(desc);
+
+	return ret;
+}
+
+/*
+ * read_reg_dma:	prepares a descriptor to read a given number of
+ *			contiguous registers to the reg_read_buf pointer
+ *
+ * @first:		offset of the first register in the contiguous block
+ * @num_regs:		number of registers to read
+ */
+static int read_reg_dma(struct qcom_nand_controller *nandc, int first,
+			int num_regs)
+{
+	bool flow_control = false;
+	void *vaddr;
+	int size;
+
+	if (first == NAND_READ_ID || first == NAND_FLASH_STATUS)
+		flow_control = true;
+
+	size = num_regs * sizeof(u32);
+	vaddr = nandc->reg_read_buf + nandc->reg_read_pos;
+	nandc->reg_read_pos += num_regs;
+
+	return prep_dma_desc(nandc, true, first, vaddr, size, flow_control);
+}
+
+/*
+ * write_reg_dma:	prepares a descriptor to write a given number of
+ *			contiguous registers
+ *
+ * @first:		offset of the first register in the contiguous block
+ * @num_regs:		number of registers to write
+ */
+static int write_reg_dma(struct qcom_nand_controller *nandc, int first,
+			 int num_regs)
+{
+	bool flow_control = false;
+	struct nandc_regs *regs = nandc->regs;
+	void *vaddr;
+	int size;
+
+	vaddr = offset_to_nandc_reg(regs, first);
+
+	if (first == NAND_FLASH_CMD)
+		flow_control = true;
+
+	if (first == NAND_DEV_CMD1_RESTORE)
+		first = NAND_DEV_CMD1;
+
+	if (first == NAND_DEV_CMD_VLD_RESTORE)
+		first = NAND_DEV_CMD_VLD;
+
+	size = num_regs * sizeof(u32);
+
+	return prep_dma_desc(nandc, false, first, vaddr, size, flow_control);
+}
+
+/*
+ * read_data_dma:	prepares a DMA descriptor to transfer data from the
+ *			controller's internal buffer to the buffer 'vaddr'
+ *
+ * @reg_off:		offset within the controller's data buffer
+ * @vaddr:		virtual address of the buffer we want to write to
+ * @size:		DMA transaction size in bytes
+ */
+static int read_data_dma(struct qcom_nand_controller *nandc, int reg_off,
+			 const u8 *vaddr, int size)
+{
+	return prep_dma_desc(nandc, true, reg_off, vaddr, size, false);
+}
+
+/*
+ * write_data_dma:	prepares a DMA descriptor to transfer data from
+ *			'vaddr' to the controller's internal buffer
+ *
+ * @reg_off:		offset within the controller's data buffer
+ * @vaddr:		virtual address of the buffer we want to read from
+ * @size:		DMA transaction size in bytes
+ */
+static int write_data_dma(struct qcom_nand_controller *nandc, int reg_off,
+			  const u8 *vaddr, int size)
+{
+	return prep_dma_desc(nandc, false, reg_off, vaddr, size, false);
+}
+
+/*
+ * helper to prepare dma descriptors to configure registers needed for reading a
+ * codeword/step in a page
+ */
+static void config_cw_read(struct qcom_nand_controller *nandc)
+{
+	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
+	write_reg_dma(nandc, NAND_DEV0_CFG0, 3);
+	write_reg_dma(nandc, NAND_EBI2_ECC_BUF_CFG, 1);
+
+	write_reg_dma(nandc, NAND_EXEC_CMD, 1);
+
+	read_reg_dma(nandc, NAND_FLASH_STATUS, 2);
+	read_reg_dma(nandc, NAND_ERASED_CW_DETECT_STATUS, 1);
+}
+
+/*
+ * helpers to prepare dma descriptors used to configure registers needed for
+ * writing a codeword/step in a page
+ */
+static void config_cw_write_pre(struct qcom_nand_controller *nandc)
+{
+	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
+	write_reg_dma(nandc, NAND_DEV0_CFG0, 3);
+	write_reg_dma(nandc, NAND_EBI2_ECC_BUF_CFG, 1);
+}
+
+static void config_cw_write_post(struct qcom_nand_controller *nandc)
+{
+	write_reg_dma(nandc, NAND_EXEC_CMD, 1);
+
+	read_reg_dma(nandc, NAND_FLASH_STATUS, 1);
+
+	write_reg_dma(nandc, NAND_FLASH_STATUS, 1);
+	write_reg_dma(nandc, NAND_READ_STATUS, 1);
+}
+
+/*
+ * the following functions are used within chip->cmdfunc() to perform different
+ * NAND_CMD_* commands
+ */
+
+/* sets up descriptors for NAND_CMD_PARAM */
+static int nandc_param(struct qcom_nand_host *host)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	/*
+	 * NAND_CMD_PARAM is called before we know much about the FLASH chip
+	 * in use. we configure the controller to perform a raw read of 512
+	 * bytes to read onfi params
+	 */
+	nandc_set_reg(nandc, NAND_FLASH_CMD, PAGE_READ | PAGE_ACC | LAST_PAGE);
+	nandc_set_reg(nandc, NAND_ADDR0, 0);
+	nandc_set_reg(nandc, NAND_ADDR1, 0);
+	nandc_set_reg(nandc, NAND_DEV0_CFG0, 0 << CW_PER_PAGE
+					| 512 << UD_SIZE_BYTES
+					| 5 << NUM_ADDR_CYCLES
+					| 0 << SPARE_SIZE_BYTES);
+	nandc_set_reg(nandc, NAND_DEV0_CFG1, 7 << NAND_RECOVERY_CYCLES
+					| 0 << CS_ACTIVE_BSY
+					| 17 << BAD_BLOCK_BYTE_NUM
+					| 1 << BAD_BLOCK_IN_SPARE_AREA
+					| 2 << WR_RD_BSY_GAP
+					| 0 << WIDE_FLASH
+					| 1 << DEV0_CFG1_ECC_DISABLE);
+	nandc_set_reg(nandc, NAND_EBI2_ECC_BUF_CFG, 1 << ECC_CFG_ECC_DISABLE);
+
+	/* configure CMD1 and VLD for ONFI param probing */
+	nandc_set_reg(nandc, NAND_DEV_CMD_VLD,
+		      (nandc->vld & ~(1 << READ_START_VLD))
+		      | 0 << READ_START_VLD);
+	nandc_set_reg(nandc, NAND_DEV_CMD1,
+		      (nandc->cmd1 & ~(0xFF << READ_ADDR))
+		      | NAND_CMD_PARAM << READ_ADDR);
+
+	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
+
+	nandc_set_reg(nandc, NAND_DEV_CMD1_RESTORE, nandc->cmd1);
+	nandc_set_reg(nandc, NAND_DEV_CMD_VLD_RESTORE, nandc->vld);
+
+	write_reg_dma(nandc, NAND_DEV_CMD_VLD, 1);
+	write_reg_dma(nandc, NAND_DEV_CMD1, 1);
+
+	nandc->buf_count = 512;
+	memset(nandc->data_buffer, 0xff, nandc->buf_count);
+
+	config_cw_read(nandc);
+
+	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer,
+		      nandc->buf_count);
+
+	/* restore CMD1 and VLD regs */
+	write_reg_dma(nandc, NAND_DEV_CMD1_RESTORE, 1);
+	write_reg_dma(nandc, NAND_DEV_CMD_VLD_RESTORE, 1);
+
+	return 0;
+}
+
+/* sets up descriptors for NAND_CMD_ERASE1 */
+static int erase_block(struct qcom_nand_host *host, int page_addr)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	nandc_set_reg(nandc, NAND_FLASH_CMD,
+		      BLOCK_ERASE | PAGE_ACC | LAST_PAGE);
+	nandc_set_reg(nandc, NAND_ADDR0, page_addr);
+	nandc_set_reg(nandc, NAND_ADDR1, 0);
+	nandc_set_reg(nandc, NAND_DEV0_CFG0,
+		      host->cfg0_raw & ~(7 << CW_PER_PAGE));
+	nandc_set_reg(nandc, NAND_DEV0_CFG1, host->cfg1_raw);
+	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
+	nandc_set_reg(nandc, NAND_FLASH_STATUS, host->clrflashstatus);
+	nandc_set_reg(nandc, NAND_READ_STATUS, host->clrreadstatus);
+
+	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
+	write_reg_dma(nandc, NAND_DEV0_CFG0, 2);
+	write_reg_dma(nandc, NAND_EXEC_CMD, 1);
+
+	read_reg_dma(nandc, NAND_FLASH_STATUS, 1);
+
+	write_reg_dma(nandc, NAND_FLASH_STATUS, 1);
+	write_reg_dma(nandc, NAND_READ_STATUS, 1);
+
+	return 0;
+}
+
+/* sets up descriptors for NAND_CMD_READID */
+static int read_id(struct qcom_nand_host *host, int column)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	if (column == -1)
+		return 0;
+
+	nandc_set_reg(nandc, NAND_FLASH_CMD, FETCH_ID);
+	nandc_set_reg(nandc, NAND_ADDR0, column);
+	nandc_set_reg(nandc, NAND_ADDR1, 0);
+	nandc_set_reg(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
+	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
+
+	write_reg_dma(nandc, NAND_FLASH_CMD, 4);
+	write_reg_dma(nandc, NAND_EXEC_CMD, 1);
+
+	read_reg_dma(nandc, NAND_READ_ID, 1);
+
+	return 0;
+}
+
+/* sets up descriptors for NAND_CMD_RESET */
+static int reset(struct qcom_nand_host *host)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	nandc_set_reg(nandc, NAND_FLASH_CMD, RESET_DEVICE);
+	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
+
+	write_reg_dma(nandc, NAND_FLASH_CMD, 1);
+	write_reg_dma(nandc, NAND_EXEC_CMD, 1);
+
+	read_reg_dma(nandc, NAND_FLASH_STATUS, 1);
+
+	return 0;
+}
+
+/* helpers to submit/free our list of dma descriptors */
+static int submit_descs(struct qcom_nand_controller *nandc)
+{
+	struct desc_info *desc;
+	dma_cookie_t cookie = 0;
+
+	list_for_each_entry(desc, &nandc->desc_list, node)
+		cookie = dmaengine_submit(desc->dma_desc);
+
+	if (dma_sync_wait(nandc->chan, cookie) != DMA_COMPLETE)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static void free_descs(struct qcom_nand_controller *nandc)
+{
+	struct desc_info *desc, *n;
+
+	list_for_each_entry_safe(desc, n, &nandc->desc_list, node) {
+		list_del(&desc->node);
+		dma_unmap_sg(nandc->dev, &desc->sgl, 1, desc->dir);
+		kfree(desc);
+	}
+}
+
+/* reset the register read buffer for next NAND operation */
+static void clear_read_regs(struct qcom_nand_controller *nandc)
+{
+	nandc->reg_read_pos = 0;
+	memset(nandc->reg_read_buf, 0,
+	       MAX_REG_RD * sizeof(*nandc->reg_read_buf));
+}
+
+static void pre_command(struct qcom_nand_host *host, int command)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	nandc->buf_count = 0;
+	nandc->buf_start = 0;
+	host->use_ecc = false;
+	host->last_command = command;
+
+	clear_read_regs(nandc);
+}
+
+/*
+ * this is called after NAND_CMD_PAGEPROG and NAND_CMD_ERASE1 to set our
+ * privately maintained status byte, this status byte can be read after
+ * NAND_CMD_STATUS is called
+ */
+static void parse_erase_write_errors(struct qcom_nand_host *host, int command)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int num_cw;
+	int i;
+
+	num_cw = command == NAND_CMD_PAGEPROG ? ecc->steps : 1;
+
+	for (i = 0; i < num_cw; i++) {
+		u32 flash_status = le32_to_cpu(nandc->reg_read_buf[i]);
+
+		if (flash_status & FS_MPU_ERR)
+			host->status &= ~NAND_STATUS_WP;
+
+		if (flash_status & FS_OP_ERR || (i == (num_cw - 1) &&
+						 (flash_status &
+						  FS_DEVICE_STS_ERR)))
+			host->status |= NAND_STATUS_FAIL;
+	}
+}
+
+static void post_command(struct qcom_nand_host *host, int command)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	switch (command) {
+	case NAND_CMD_READID:
+		memcpy(nandc->data_buffer, nandc->reg_read_buf,
+		       nandc->buf_count);
+		break;
+	case NAND_CMD_PAGEPROG:
+	case NAND_CMD_ERASE1:
+		parse_erase_write_errors(host, command);
+		break;
+	default:
+		break;
+	}
+}
+
+/*
+ * Implements chip->cmdfunc. It's  only used for a limited set of commands.
+ * The rest of the commands wouldn't be called by upper layers. For example,
+ * NAND_CMD_READOOB would never be called because we have our own versions
+ * of read_oob ops for nand_ecc_ctrl.
+ */
+static void qcom_nandc_command(struct mtd_info *mtd, unsigned int command,
+			       int column, int page_addr)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	bool wait = false;
+	int ret = 0;
+
+	pre_command(host, command);
+
+	switch (command) {
+	case NAND_CMD_RESET:
+		ret = reset(host);
+		wait = true;
+		break;
+
+	case NAND_CMD_READID:
+		nandc->buf_count = 4;
+		ret = read_id(host, column);
+		wait = true;
+		break;
+
+	case NAND_CMD_PARAM:
+		ret = nandc_param(host);
+		wait = true;
+		break;
+
+	case NAND_CMD_ERASE1:
+		ret = erase_block(host, page_addr);
+		wait = true;
+		break;
+
+	case NAND_CMD_READ0:
+		/* we read the entire page for now */
+		WARN_ON(column != 0);
+
+		host->use_ecc = true;
+		set_address(host, 0, page_addr);
+		update_rw_regs(host, ecc->steps, true);
+		break;
+
+	case NAND_CMD_SEQIN:
+		WARN_ON(column != 0);
+		set_address(host, 0, page_addr);
+		break;
+
+	case NAND_CMD_PAGEPROG:
+	case NAND_CMD_STATUS:
+	case NAND_CMD_NONE:
+	default:
+		break;
+	}
+
+	if (ret) {
+		dev_err(nandc->dev, "failure executing command %d\n",
+			command);
+		free_descs(nandc);
+		return;
+	}
+
+	if (wait) {
+		ret = submit_descs(nandc);
+		if (ret)
+			dev_err(nandc->dev,
+				"failure submitting descs for command %d\n",
+				command);
+	}
+
+	free_descs(nandc);
+
+	post_command(host, command);
+}
+
+/*
+ * when using BCH ECC, the HW flags an error in NAND_FLASH_STATUS if it read
+ * an erased CW, and reports an erased CW in NAND_ERASED_CW_DETECT_STATUS.
+ *
+ * when using RS ECC, the HW reports the same erros when reading an erased CW,
+ * but it notifies that it is an erased CW by placing special characters at
+ * certain offsets in the buffer.
+ *
+ * verify if the page is erased or not, and fix up the page for RS ECC by
+ * replacing the special characters with 0xff.
+ */
+static bool erased_chunk_check_and_fixup(u8 *data_buf, int data_len)
+{
+	u8 empty1, empty2;
+
+	/*
+	 * an erased page flags an error in NAND_FLASH_STATUS, check if the page
+	 * is erased by looking for 0x54s at offsets 3 and 175 from the
+	 * beginning of each codeword
+	 */
+
+	empty1 = data_buf[3];
+	empty2 = data_buf[175];
+
+	/*
+	 * if the erased codework markers, if they exist override them with
+	 * 0xffs
+	 */
+	if ((empty1 == 0x54 && empty2 == 0xff) ||
+	    (empty1 == 0xff && empty2 == 0x54)) {
+		data_buf[3] = 0xff;
+		data_buf[175] = 0xff;
+	}
+
+	/*
+	 * check if the entire chunk contains 0xffs or not. if it doesn't, then
+	 * restore the original values at the special offsets
+	 */
+	if (memchr_inv(data_buf, 0xff, data_len)) {
+		data_buf[3] = empty1;
+		data_buf[175] = empty2;
+
+		return false;
+	}
+
+	return true;
+}
+
+struct read_stats {
+	__le32 flash;
+	__le32 buffer;
+	__le32 erased_cw;
+};
+
+/*
+ * reads back status registers set by the controller to notify page read
+ * errors. this is equivalent to what 'ecc->correct()' would do.
+ */
+static int parse_read_errors(struct qcom_nand_host *host, u8 *data_buf,
+			     u8 *oob_buf)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	unsigned int max_bitflips = 0;
+	struct read_stats *buf;
+	int i;
+
+	buf = (struct read_stats *)nandc->reg_read_buf;
+
+	for (i = 0; i < ecc->steps; i++, buf++) {
+		u32 flash, buffer, erased_cw;
+		int data_len, oob_len;
+
+		if (i == (ecc->steps - 1)) {
+			data_len = ecc->size - ((ecc->steps - 1) << 2);
+			oob_len = ecc->steps << 2;
+		} else {
+			data_len = host->cw_data;
+			oob_len = 0;
+		}
+
+		flash = le32_to_cpu(buf->flash);
+		buffer = le32_to_cpu(buf->buffer);
+		erased_cw = le32_to_cpu(buf->erased_cw);
+
+		if (flash & (FS_OP_ERR | FS_MPU_ERR)) {
+			bool erased;
+
+			/* ignore erased codeword errors */
+			if (host->bch_enabled) {
+				erased = (erased_cw & ERASED_CW) == ERASED_CW ?
+					 true : false;
+			} else {
+				erased = erased_chunk_check_and_fixup(data_buf,
+								      data_len);
+			}
+
+			if (erased) {
+				data_buf += data_len;
+				if (oob_buf)
+					oob_buf += oob_len + ecc->bytes;
+				continue;
+			}
+
+			if (buffer & BS_UNCORRECTABLE_BIT) {
+				int ret, ecclen, extraooblen;
+				void *eccbuf;
+
+				eccbuf = oob_buf ? oob_buf + oob_len : NULL;
+				ecclen = oob_buf ? host->ecc_bytes_hw : 0;
+				extraooblen = oob_buf ? oob_len : 0;
+
+				/*
+				 * make sure it isn't an erased page reported
+				 * as not-erased by HW because of a few bitflips
+				 */
+				ret = nand_check_erased_ecc_chunk(data_buf,
+					data_len, eccbuf, ecclen, oob_buf,
+					extraooblen, ecc->strength);
+				if (ret < 0) {
+					mtd->ecc_stats.failed++;
+				} else {
+					mtd->ecc_stats.corrected += ret;
+					max_bitflips =
+						max_t(unsigned int, max_bitflips, ret);
+				}
+			}
+		} else {
+			unsigned int stat;
+
+			stat = buffer & BS_CORRECTABLE_ERR_MSK;
+			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max(max_bitflips, stat);
+		}
+
+		data_buf += data_len;
+		if (oob_buf)
+			oob_buf += oob_len + ecc->bytes;
+	}
+
+	return max_bitflips;
+}
+
+/*
+ * helper to perform the actual page read operation, used by ecc->read_page(),
+ * ecc->read_oob()
+ */
+static int read_page_ecc(struct qcom_nand_host *host, u8 *data_buf,
+			 u8 *oob_buf)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int i, ret;
+
+	/* queue cmd descs for each codeword */
+	for (i = 0; i < ecc->steps; i++) {
+		int data_size, oob_size;
+
+		if (i == (ecc->steps - 1)) {
+			data_size = ecc->size - ((ecc->steps - 1) << 2);
+			oob_size = (ecc->steps << 2) + host->ecc_bytes_hw +
+				   host->spare_bytes;
+		} else {
+			data_size = host->cw_data;
+			oob_size = host->ecc_bytes_hw + host->spare_bytes;
+		}
+
+		config_cw_read(nandc);
+
+		if (data_buf)
+			read_data_dma(nandc, FLASH_BUF_ACC, data_buf,
+				      data_size);
+
+		/*
+		 * when ecc is enabled, the controller doesn't read the real
+		 * or dummy bad block markers in each chunk. To maintain a
+		 * consistent layout across RAW and ECC reads, we just
+		 * leave the real/dummy BBM offsets empty (i.e, filled with
+		 * 0xffs)
+		 */
+		if (oob_buf) {
+			int j;
+
+			for (j = 0; j < host->bbm_size; j++)
+				*oob_buf++ = 0xff;
+
+			read_data_dma(nandc, FLASH_BUF_ACC + data_size,
+				      oob_buf, oob_size);
+		}
+
+		if (data_buf)
+			data_buf += data_size;
+		if (oob_buf)
+			oob_buf += oob_size;
+	}
+
+	ret = submit_descs(nandc);
+	if (ret)
+		dev_err(nandc->dev, "failure to read page/oob\n");
+
+	free_descs(nandc);
+
+	return ret;
+}
+
+/*
+ * a helper that copies the last step/codeword of a page (containing free oob)
+ * into our local buffer
+ */
+static int copy_last_cw(struct qcom_nand_host *host, int page)
+{
+	struct nand_chip *chip = &host->chip;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int size;
+	int ret;
+
+	clear_read_regs(nandc);
+
+	size = host->use_ecc ? host->cw_data : host->cw_size;
+
+	/* prepare a clean read buffer */
+	memset(nandc->data_buffer, 0xff, size);
+
+	set_address(host, host->cw_size * (ecc->steps - 1), page);
+	update_rw_regs(host, 1, true);
+
+	config_cw_read(nandc);
+
+	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, size);
+
+	ret = submit_descs(nandc);
+	if (ret)
+		dev_err(nandc->dev, "failed to copy last codeword\n");
+
+	free_descs(nandc);
+
+	return ret;
+}
+
+/* implements ecc->read_page() */
+static int qcom_nandc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
+				uint8_t *buf, int oob_required, int page)
+{
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	u8 *data_buf, *oob_buf = NULL;
+	int ret;
+
+	data_buf = buf;
+	oob_buf = oob_required ? chip->oob_poi : NULL;
+
+	ret = read_page_ecc(host, data_buf, oob_buf);
+	if (ret) {
+		dev_err(nandc->dev, "failure to read page\n");
+		return ret;
+	}
+
+	return parse_read_errors(host, data_buf, oob_buf);
+}
+
+/* implements ecc->read_page_raw() */
+static int qcom_nandc_read_page_raw(struct mtd_info *mtd,
+				    struct nand_chip *chip, uint8_t *buf,
+				    int oob_required, int page)
+{
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	u8 *data_buf, *oob_buf;
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int i, ret;
+
+	data_buf = buf;
+	oob_buf = chip->oob_poi;
+
+	host->use_ecc = false;
+	update_rw_regs(host, ecc->steps, true);
+
+	for (i = 0; i < ecc->steps; i++) {
+		int data_size1, data_size2, oob_size1, oob_size2;
+		int reg_off = FLASH_BUF_ACC;
+
+		data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1);
+		oob_size1 = host->bbm_size;
+
+		if (i == (ecc->steps - 1)) {
+			data_size2 = ecc->size - data_size1 -
+				     ((ecc->steps - 1) << 2);
+			oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw +
+				    host->spare_bytes;
+		} else {
+			data_size2 = host->cw_data - data_size1;
+			oob_size2 = host->ecc_bytes_hw + host->spare_bytes;
+		}
+
+		config_cw_read(nandc);
+
+		read_data_dma(nandc, reg_off, data_buf, data_size1);
+		reg_off += data_size1;
+		data_buf += data_size1;
+
+		read_data_dma(nandc, reg_off, oob_buf, oob_size1);
+		reg_off += oob_size1;
+		oob_buf += oob_size1;
+
+		read_data_dma(nandc, reg_off, data_buf, data_size2);
+		reg_off += data_size2;
+		data_buf += data_size2;
+
+		read_data_dma(nandc, reg_off, oob_buf, oob_size2);
+		oob_buf += oob_size2;
+	}
+
+	ret = submit_descs(nandc);
+	if (ret)
+		dev_err(nandc->dev, "failure to read raw page\n");
+
+	free_descs(nandc);
+
+	return 0;
+}
+
+/* implements ecc->read_oob() */
+static int qcom_nandc_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
+			       int page)
+{
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int ret;
+
+	clear_read_regs(nandc);
+
+	host->use_ecc = true;
+	set_address(host, 0, page);
+	update_rw_regs(host, ecc->steps, true);
+
+	ret = read_page_ecc(host, NULL, chip->oob_poi);
+	if (ret)
+		dev_err(nandc->dev, "failure to read oob\n");
+
+	return ret;
+}
+
+/* implements ecc->write_page() */
+static int qcom_nandc_write_page(struct mtd_info *mtd, struct nand_chip *chip,
+				 const uint8_t *buf, int oob_required, int page)
+{
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	u8 *data_buf, *oob_buf;
+	int i, ret;
+
+	clear_read_regs(nandc);
+
+	data_buf = (u8 *)buf;
+	oob_buf = chip->oob_poi;
+
+	host->use_ecc = true;
+	update_rw_regs(host, ecc->steps, false);
+
+	for (i = 0; i < ecc->steps; i++) {
+		int data_size, oob_size;
+
+		if (i == (ecc->steps - 1)) {
+			data_size = ecc->size - ((ecc->steps - 1) << 2);
+			oob_size = (ecc->steps << 2) + host->ecc_bytes_hw +
+				   host->spare_bytes;
+		} else {
+			data_size = host->cw_data;
+			oob_size = ecc->bytes;
+		}
+
+		config_cw_write_pre(nandc);
+
+		write_data_dma(nandc, FLASH_BUF_ACC, data_buf, data_size);
+
+		/*
+		 * when ECC is enabled, we don't really need to write anything
+		 * to oob for the first n - 1 codewords since these oob regions
+		 * just contain ECC bytes that's written by the controller
+		 * itself. For the last codeword, we skip the bbm positions and
+		 * write to the free oob area.
+		 */
+		if (i == (ecc->steps - 1)) {
+			oob_buf += host->bbm_size;
+
+			write_data_dma(nandc, FLASH_BUF_ACC + data_size,
+				       oob_buf, oob_size);
+		}
+
+		config_cw_write_post(nandc);
+
+		data_buf += data_size;
+		oob_buf += oob_size;
+	}
+
+	ret = submit_descs(nandc);
+	if (ret)
+		dev_err(nandc->dev, "failure to write page\n");
+
+	free_descs(nandc);
+
+	return ret;
+}
+
+/* implements ecc->write_page_raw() */
+static int qcom_nandc_write_page_raw(struct mtd_info *mtd,
+				     struct nand_chip *chip, const uint8_t *buf,
+				     int oob_required, int page)
+{
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	u8 *data_buf, *oob_buf;
+	int i, ret;
+
+	clear_read_regs(nandc);
+
+	data_buf = (u8 *)buf;
+	oob_buf = chip->oob_poi;
+
+	host->use_ecc = false;
+	update_rw_regs(host, ecc->steps, false);
+
+	for (i = 0; i < ecc->steps; i++) {
+		int data_size1, data_size2, oob_size1, oob_size2;
+		int reg_off = FLASH_BUF_ACC;
+
+		data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1);
+		oob_size1 = host->bbm_size;
+
+		if (i == (ecc->steps - 1)) {
+			data_size2 = ecc->size - data_size1 -
+				     ((ecc->steps - 1) << 2);
+			oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw +
+				    host->spare_bytes;
+		} else {
+			data_size2 = host->cw_data - data_size1;
+			oob_size2 = host->ecc_bytes_hw + host->spare_bytes;
+		}
+
+		config_cw_write_pre(nandc);
+
+		write_data_dma(nandc, reg_off, data_buf, data_size1);
+		reg_off += data_size1;
+		data_buf += data_size1;
+
+		write_data_dma(nandc, reg_off, oob_buf, oob_size1);
+		reg_off += oob_size1;
+		oob_buf += oob_size1;
+
+		write_data_dma(nandc, reg_off, data_buf, data_size2);
+		reg_off += data_size2;
+		data_buf += data_size2;
+
+		write_data_dma(nandc, reg_off, oob_buf, oob_size2);
+		oob_buf += oob_size2;
+
+		config_cw_write_post(nandc);
+	}
+
+	ret = submit_descs(nandc);
+	if (ret)
+		dev_err(nandc->dev, "failure to write raw page\n");
+
+	free_descs(nandc);
+
+	return ret;
+}
+
+/*
+ * implements ecc->write_oob()
+ *
+ * the NAND controller cannot write only data or only oob within a codeword,
+ * since ecc is calculated for the combined codeword. we first copy the
+ * entire contents for the last codeword(data + oob), replace the old oob
+ * with the new one in chip->oob_poi, and then write the entire codeword.
+ * this read-copy-write operation results in a slight performance loss.
+ */
+static int qcom_nandc_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
+				int page)
+{
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	u8 *oob = chip->oob_poi;
+	int free_boff;
+	int data_size, oob_size;
+	int ret, status = 0;
+
+	host->use_ecc = true;
+
+	ret = copy_last_cw(host, page);
+	if (ret)
+		return ret;
+
+	clear_read_regs(nandc);
+
+	/* calculate the data and oob size for the last codeword/step */
+	data_size = ecc->size - ((ecc->steps - 1) << 2);
+	oob_size = ecc->steps << 2;
+
+	free_boff = ecc->layout->oobfree[0].offset;
+
+	/* override new oob content to last codeword */
+	memcpy(nandc->data_buffer + data_size, oob + free_boff, oob_size);
+
+	set_address(host, host->cw_size * (ecc->steps - 1), page);
+	update_rw_regs(host, 1, false);
+
+	config_cw_write_pre(nandc);
+	write_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer,
+		       data_size + oob_size);
+	config_cw_write_post(nandc);
+
+	ret = submit_descs(nandc);
+
+	free_descs(nandc);
+
+	if (ret) {
+		dev_err(nandc->dev, "failure to write oob\n");
+		return -EIO;
+	}
+
+	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+
+	status = chip->waitfunc(mtd, chip);
+
+	return status & NAND_STATUS_FAIL ? -EIO : 0;
+}
+
+static int qcom_nandc_block_bad(struct mtd_info *mtd, loff_t ofs)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int page, ret, bbpos, bad = 0;
+	u32 flash_status;
+
+	page = (int)(ofs >> chip->page_shift) & chip->pagemask;
+
+	/*
+	 * configure registers for a raw sub page read, the address is set to
+	 * the beginning of the last codeword, we don't care about reading ecc
+	 * portion of oob. we just want the first few bytes from this codeword
+	 * that contains the BBM
+	 */
+	host->use_ecc = false;
+
+	ret = copy_last_cw(host, page);
+	if (ret)
+		goto err;
+
+	flash_status = le32_to_cpu(nandc->reg_read_buf[0]);
+
+	if (flash_status & (FS_OP_ERR | FS_MPU_ERR)) {
+		dev_warn(nandc->dev, "error when trying to read BBM\n");
+		goto err;
+	}
+
+	bbpos = mtd->writesize - host->cw_size * (ecc->steps - 1);
+
+	bad = nandc->data_buffer[bbpos] != 0xff;
+
+	if (chip->options & NAND_BUSWIDTH_16)
+		bad = bad || (nandc->data_buffer[bbpos + 1] != 0xff);
+err:
+	return bad;
+}
+
+static int qcom_nandc_block_markbad(struct mtd_info *mtd, loff_t ofs)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int page, ret, status = 0;
+
+	clear_read_regs(nandc);
+
+	/*
+	 * to mark the BBM as bad, we flash the entire last codeword with 0s.
+	 * we don't care about the rest of the content in the codeword since
+	 * we aren't going to use this block again
+	 */
+	memset(nandc->data_buffer, 0x00, host->cw_size);
+
+	page = (int)(ofs >> chip->page_shift) & chip->pagemask;
+
+	/* prepare write */
+	host->use_ecc = false;
+	set_address(host, host->cw_size * (ecc->steps - 1), page);
+	update_rw_regs(host, 1, false);
+
+	config_cw_write_pre(nandc);
+	write_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, host->cw_size);
+	config_cw_write_post(nandc);
+
+	ret = submit_descs(nandc);
+
+	free_descs(nandc);
+
+	if (ret) {
+		dev_err(nandc->dev, "failure to update BBM\n");
+		return -EIO;
+	}
+
+	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+
+	status = chip->waitfunc(mtd, chip);
+
+	return status & NAND_STATUS_FAIL ? -EIO : 0;
+}
+
+/*
+ * the three functions below implement chip->read_byte(), chip->read_buf()
+ * and chip->write_buf() respectively. these aren't used for
+ * reading/writing page data, they are used for smaller data like reading
+ * id, status etc
+ */
+static uint8_t qcom_nandc_read_byte(struct mtd_info *mtd)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_host *host = to_qcom_nand_host(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	u8 *buf = nandc->data_buffer;
+	u8 ret = 0x0;
+
+	if (host->last_command == NAND_CMD_STATUS) {
+		ret = host->status;
+
+		host->status = NAND_STATUS_READY | NAND_STATUS_WP;
+
+		return ret;
+	}
+
+	if (nandc->buf_start < nandc->buf_count)
+		ret = buf[nandc->buf_start++];
+
+	return ret;
+}
+
+static void qcom_nandc_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	int real_len = min_t(size_t, len, nandc->buf_count - nandc->buf_start);
+
+	memcpy(buf, nandc->data_buffer + nandc->buf_start, real_len);
+	nandc->buf_start += real_len;
+}
+
+static void qcom_nandc_write_buf(struct mtd_info *mtd, const uint8_t *buf,
+				 int len)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	int real_len = min_t(size_t, len, nandc->buf_count - nandc->buf_start);
+
+	memcpy(nandc->data_buffer + nandc->buf_start, buf, real_len);
+
+	nandc->buf_start += real_len;
+}
+
+/* we support only one external chip for now */
+static void qcom_nandc_select_chip(struct mtd_info *mtd, int chipnr)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+
+	if (chipnr <= 0)
+		return;
+
+	dev_warn(nandc->dev, "invalid chip select\n");
+}
+
+/*
+ * NAND controller page layout info
+ *
+ * Layout with ECC enabled:
+ *
+ * |----------------------|  |---------------------------------|
+ * |           xx.......yy|  |             *********xx.......yy|
+ * |    DATA   xx..ECC..yy|  |    DATA     **SPARE**xx..ECC..yy|
+ * |   (516)   xx.......yy|  |  (516-n*4)  **(n*4)**xx.......yy|
+ * |           xx.......yy|  |             *********xx.......yy|
+ * |----------------------|  |---------------------------------|
+ *     codeword 1,2..n-1                  codeword n
+ *  <---(528/532 Bytes)-->    <-------(528/532 Bytes)--------->
+ *
+ * n = Number of codewords in the page
+ * . = ECC bytes
+ * * = Spare/free bytes
+ * x = Unused byte(s)
+ * y = Reserved byte(s)
+ *
+ * 2K page: n = 4, spare = 16 bytes
+ * 4K page: n = 8, spare = 32 bytes
+ * 8K page: n = 16, spare = 64 bytes
+ *
+ * the qcom nand controller operates at a sub page/codeword level. each
+ * codeword is 528 and 532 bytes for 4 bit and 8 bit ECC modes respectively.
+ * the number of ECC bytes vary based on the ECC strength and the bus width.
+ *
+ * the first n - 1 codewords contains 516 bytes of user data, the remaining
+ * 12/16 bytes consist of ECC and reserved data. The nth codeword contains
+ * both user data and spare(oobavail) bytes that sum up to 516 bytes.
+ *
+ * When we access a page with ECC enabled, the reserved bytes(s) are not
+ * accessible at all. When reading, we fill up these unreadable positions
+ * with 0xffs. When writing, the controller skips writing the inaccessible
+ * bytes.
+ *
+ * Layout with ECC disabled:
+ *
+ * |------------------------------|  |---------------------------------------|
+ * |         yy          xx.......|  |         bb          *********xx.......|
+ * |  DATA1  yy  DATA2   xx..ECC..|  |  DATA1  bb  DATA2   **SPARE**xx..ECC..|
+ * | (size1) yy (size2)  xx.......|  | (size1) bb (size2)  **(n*4)**xx.......|
+ * |         yy          xx.......|  |         bb          *********xx.......|
+ * |------------------------------|  |---------------------------------------|
+ *         codeword 1,2..n-1                        codeword n
+ *  <-------(528/532 Bytes)------>    <-----------(528/532 Bytes)----------->
+ *
+ * n = Number of codewords in the page
+ * . = ECC bytes
+ * * = Spare/free bytes
+ * x = Unused byte(s)
+ * y = Dummy Bad Bock byte(s)
+ * b = Real Bad Block byte(s)
+ * size1/size2 = function of codeword size and 'n'
+ *
+ * when the ECC block is disabled, one reserved byte (or two for 16 bit bus
+ * width) is now accessible. For the first n - 1 codewords, these are dummy Bad
+ * Block Markers. In the last codeword, this position contains the real BBM
+ *
+ * In order to have a consistent layout between RAW and ECC modes, we assume
+ * the following OOB layout arrangement:
+ *
+ * |-----------|  |--------------------|
+ * |yyxx.......|  |bb*********xx.......|
+ * |yyxx..ECC..|  |bb*FREEOOB*xx..ECC..|
+ * |yyxx.......|  |bb*********xx.......|
+ * |yyxx.......|  |bb*********xx.......|
+ * |-----------|  |--------------------|
+ *  first n - 1       nth OOB region
+ *  OOB regions
+ *
+ * n = Number of codewords in the page
+ * . = ECC bytes
+ * * = FREE OOB bytes
+ * y = Dummy bad block byte(s) (inaccessible when ECC enabled)
+ * x = Unused byte(s)
+ * b = Real bad block byte(s) (inaccessible when ECC enabled)
+ *
+ * This layout is read as is when ECC is disabled. When ECC is enabled, the
+ * inaccessible Bad Block byte(s) are ignored when we write to a page/oob,
+ * and assumed as 0xffs when we read a page/oob. The ECC, unused and
+ * dummy/real bad block bytes are grouped as ecc bytes in nand_ecclayout (i.e,
+ * ecc->bytes is the sum of the three).
+ */
+
+static struct nand_ecclayout *
+qcom_nand_create_layout(struct qcom_nand_host *host)
+{
+	struct nand_chip *chip = &host->chip;
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	struct nand_ecclayout *layout;
+	int i, j, steps, pos = 0, shift = 0;
+
+	layout = devm_kzalloc(nandc->dev, sizeof(*layout), GFP_KERNEL);
+	if (!layout)
+		return NULL;
+
+	steps = mtd->writesize / ecc->size;
+	layout->eccbytes = steps * ecc->bytes;
+
+	layout->oobfree[0].offset = (steps - 1) * ecc->bytes + host->bbm_size;
+	layout->oobfree[0].length = steps << 2;
+
+	/*
+	 * the oob bytes in the first n - 1 codewords are all grouped together
+	 * in the format:
+	 * DUMMY_BBM + UNUSED + ECC
+	 */
+	for (i = 0; i < steps - 1; i++) {
+		for (j = 0; j < ecc->bytes; j++)
+			layout->eccpos[pos++] = i * ecc->bytes + j;
+	}
+
+	/*
+	 * the oob bytes in the last codeword are grouped in the format:
+	 * BBM + FREE OOB + UNUSED + ECC
+	 */
+
+	/* fill up the bbm positions */
+	for (j = 0; j < host->bbm_size; j++)
+		layout->eccpos[pos++] = i * ecc->bytes + j;
+
+	/*
+	 * fill up the ecc and reserved positions, their indices are offseted
+	 * by the free oob region
+	 */
+	shift = layout->oobfree[0].length + host->bbm_size;
+
+	for (j = 0; j < (host->ecc_bytes_hw + host->spare_bytes); j++)
+		layout->eccpos[pos++] = i * ecc->bytes + shift + j;
+
+	return layout;
+}
+
+static int qcom_nand_host_setup(struct qcom_nand_host *host)
+{
+	struct nand_chip *chip = &host->chip;
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+	int cwperpage, bad_block_byte;
+	bool wide_bus;
+	int ecc_mode = 1;
+
+	/*
+	 * the controller requires each step consists of 512 bytes of data.
+	 * bail out if DT has populated a wrong step size.
+	 */
+	if (ecc->size != NANDC_STEP_SIZE) {
+		dev_err(nandc->dev, "invalid ecc size\n");
+		return -EINVAL;
+	}
+
+	wide_bus = chip->options & NAND_BUSWIDTH_16 ? true : false;
+
+	if (ecc->strength >= 8) {
+		/* 8 bit ECC defaults to BCH ECC on all platforms */
+		host->bch_enabled = true;
+		ecc_mode = 1;
+
+		if (wide_bus) {
+			host->ecc_bytes_hw = 14;
+			host->spare_bytes = 0;
+			host->bbm_size = 2;
+		} else {
+			host->ecc_bytes_hw = 13;
+			host->spare_bytes = 2;
+			host->bbm_size = 1;
+		}
+	} else {
+		/*
+		 * if the controller supports BCH for 4 bit ECC, the controller
+		 * uses lesser bytes for ECC. If RS is used, the ECC bytes is
+		 * always 10 bytes
+		 */
+		if (nandc->ecc_modes & ECC_BCH_4BIT) {
+			/* BCH */
+			host->bch_enabled = true;
+			ecc_mode = 0;
+
+			if (wide_bus) {
+				host->ecc_bytes_hw = 8;
+				host->spare_bytes = 2;
+				host->bbm_size = 2;
+			} else {
+				host->ecc_bytes_hw = 7;
+				host->spare_bytes = 4;
+				host->bbm_size = 1;
+			}
+		} else {
+			/* RS */
+			host->ecc_bytes_hw = 10;
+
+			if (wide_bus) {
+				host->spare_bytes = 0;
+				host->bbm_size = 2;
+			} else {
+				host->spare_bytes = 1;
+				host->bbm_size = 1;
+			}
+		}
+	}
+
+	/*
+	 * we consider ecc->bytes as the sum of all the non-data content in a
+	 * step. It gives us a clean representation of the oob area (even if
+	 * all the bytes aren't used for ECC).It is always 16 bytes for 8 bit
+	 * ECC and 12 bytes for 4 bit ECC
+	 */
+	ecc->bytes = host->ecc_bytes_hw + host->spare_bytes + host->bbm_size;
+
+	ecc->read_page		= qcom_nandc_read_page;
+	ecc->read_page_raw	= qcom_nandc_read_page_raw;
+	ecc->read_oob		= qcom_nandc_read_oob;
+	ecc->write_page		= qcom_nandc_write_page;
+	ecc->write_page_raw	= qcom_nandc_write_page_raw;
+	ecc->write_oob		= qcom_nandc_write_oob;
+
+	ecc->mode = NAND_ECC_HW;
+
+	ecc->layout = qcom_nand_create_layout(host);
+	if (!ecc->layout)
+		return -ENOMEM;
+
+	cwperpage = mtd->writesize / ecc->size;
+
+	/*
+	 * DATA_UD_BYTES varies based on whether the read/write command protects
+	 * spare data with ECC too. We protect spare data by default, so we set
+	 * it to main + spare data, which are 512 and 4 bytes respectively.
+	 */
+	host->cw_data = 516;
+
+	/*
+	 * total bytes in a step, either 528 bytes for 4 bit ECC, or 532 bytes
+	 * for 8 bit ECC
+	 */
+	host->cw_size = host->cw_data + ecc->bytes;
+
+	if (ecc->bytes * (mtd->writesize / ecc->size) > mtd->oobsize) {
+		dev_err(nandc->dev, "ecc data doesn't fit in OOB area\n");
+		return -EINVAL;
+	}
+
+	bad_block_byte = mtd->writesize - host->cw_size * (cwperpage - 1) + 1;
+
+	host->cfg0 = (cwperpage - 1) << CW_PER_PAGE
+				| host->cw_data << UD_SIZE_BYTES
+				| 0 << DISABLE_STATUS_AFTER_WRITE
+				| 5 << NUM_ADDR_CYCLES
+				| host->ecc_bytes_hw << ECC_PARITY_SIZE_BYTES_RS
+				| 0 << STATUS_BFR_READ
+				| 1 << SET_RD_MODE_AFTER_STATUS
+				| host->spare_bytes << SPARE_SIZE_BYTES;
+
+	host->cfg1 = 7 << NAND_RECOVERY_CYCLES
+				| 0 <<  CS_ACTIVE_BSY
+				| bad_block_byte << BAD_BLOCK_BYTE_NUM
+				| 0 << BAD_BLOCK_IN_SPARE_AREA
+				| 2 << WR_RD_BSY_GAP
+				| wide_bus << WIDE_FLASH
+				| host->bch_enabled << ENABLE_BCH_ECC;
+
+	host->cfg0_raw = (cwperpage - 1) << CW_PER_PAGE
+				| host->cw_size << UD_SIZE_BYTES
+				| 5 << NUM_ADDR_CYCLES
+				| 0 << SPARE_SIZE_BYTES;
+
+	host->cfg1_raw = 7 << NAND_RECOVERY_CYCLES
+				| 0 << CS_ACTIVE_BSY
+				| 17 << BAD_BLOCK_BYTE_NUM
+				| 1 << BAD_BLOCK_IN_SPARE_AREA
+				| 2 << WR_RD_BSY_GAP
+				| wide_bus << WIDE_FLASH
+				| 1 << DEV0_CFG1_ECC_DISABLE;
+
+	host->ecc_bch_cfg = host->bch_enabled << ECC_CFG_ECC_DISABLE
+				| 0 << ECC_SW_RESET
+				| host->cw_data << ECC_NUM_DATA_BYTES
+				| 1 << ECC_FORCE_CLK_OPEN
+				| ecc_mode << ECC_MODE
+				| host->ecc_bytes_hw << ECC_PARITY_SIZE_BYTES_BCH;
+
+	host->ecc_buf_cfg = 0x203 << NUM_STEPS;
+
+	host->clrflashstatus = FS_READY_BSY_N;
+	host->clrreadstatus = 0xc0;
+
+	dev_dbg(nandc->dev,
+		"cfg0 %x cfg1 %x ecc_buf_cfg %x ecc_bch cfg %x cw_size %d cw_data %d strength %d parity_bytes %d steps %d\n",
+		host->cfg0, host->cfg1, host->ecc_buf_cfg, host->ecc_bch_cfg,
+		host->cw_size, host->cw_data, ecc->strength, ecc->bytes,
+		cwperpage);
+
+	return 0;
+}
+
+static int qcom_nandc_alloc(struct qcom_nand_controller *nandc)
+{
+	int ret;
+
+	ret = dma_set_coherent_mask(nandc->dev, DMA_BIT_MASK(32));
+	if (ret) {
+		dev_err(nandc->dev, "failed to set DMA mask\n");
+		return ret;
+	}
+
+	/*
+	 * we use the internal buffer for reading ONFI params, reading small
+	 * data like ID and status, and preforming read-copy-write operations
+	 * when writing to a codeword partially. 532 is the maximum possible
+	 * size of a codeword for our nand controller
+	 */
+	nandc->buf_size = 532;
+
+	nandc->data_buffer = devm_kzalloc(nandc->dev, nandc->buf_size,
+					GFP_KERNEL);
+	if (!nandc->data_buffer)
+		return -ENOMEM;
+
+	nandc->regs = devm_kzalloc(nandc->dev, sizeof(*nandc->regs),
+					GFP_KERNEL);
+	if (!nandc->regs)
+		return -ENOMEM;
+
+	nandc->reg_read_buf = devm_kzalloc(nandc->dev,
+				MAX_REG_RD * sizeof(*nandc->reg_read_buf),
+				GFP_KERNEL);
+	if (!nandc->reg_read_buf)
+		return -ENOMEM;
+
+	nandc->chan = dma_request_slave_channel(nandc->dev, "rxtx");
+	if (!nandc->chan) {
+		dev_err(nandc->dev, "failed to request slave channel\n");
+		return -ENODEV;
+	}
+
+	INIT_LIST_HEAD(&nandc->desc_list);
+	INIT_LIST_HEAD(&nandc->host_list);
+
+	spin_lock_init(&nandc->controller.lock);
+	init_waitqueue_head(&nandc->controller.wq);
+
+	return 0;
+}
+
+static void qcom_nandc_unalloc(struct qcom_nand_controller *nandc)
+{
+	dma_release_channel(nandc->chan);
+}
+
+/* one time setup of a few nand controller registers */
+static int qcom_nandc_setup(struct qcom_nand_controller *nandc)
+{
+	/* kill onenand */
+	nandc_write(nandc, SFLASHC_BURST_CFG, 0);
+
+	/* enable ADM DMA */
+	nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
+
+	/* save the original values of these registers */
+	nandc->cmd1 = nandc_read(nandc, NAND_DEV_CMD1);
+	nandc->vld = nandc_read(nandc, NAND_DEV_CMD_VLD);
+
+	return 0;
+}
+
+static int qcom_nand_host_init(struct qcom_nand_controller *nandc,
+			       struct qcom_nand_host *host,
+			       struct device_node *dn)
+{
+	struct nand_chip *chip = &host->chip;
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct device *dev = nandc->dev;
+	int ret;
+
+	ret = of_property_read_u32(dn, "reg", &host->cs);
+	if (ret) {
+		dev_err(dev, "can't get chip-select\n");
+		return -ENXIO;
+	}
+
+	nand_set_flash_node(chip, dn);
+	mtd->name = devm_kasprintf(dev, GFP_KERNEL, "qcom_nand.%d", host->cs);
+	mtd->owner = THIS_MODULE;
+	mtd->dev.parent = dev;
+
+	chip->cmdfunc		= qcom_nandc_command;
+	chip->select_chip	= qcom_nandc_select_chip;
+	chip->read_byte		= qcom_nandc_read_byte;
+	chip->read_buf		= qcom_nandc_read_buf;
+	chip->write_buf		= qcom_nandc_write_buf;
+
+	/*
+	 * the bad block marker is readable only when we read the last codeword
+	 * of a page with ECC disabled. currently, the nand_base and nand_bbt
+	 * helpers don't allow us to read BB from a nand chip with ECC
+	 * disabled (MTD_OPS_PLACE_OOB is set by default). use the block_bad
+	 * and block_markbad helpers until we permanently switch to using
+	 * MTD_OPS_RAW for all drivers (with the help of badblockbits)
+	 */
+	chip->block_bad		= qcom_nandc_block_bad;
+	chip->block_markbad	= qcom_nandc_block_markbad;
+
+	chip->controller = &nandc->controller;
+	chip->options |= NAND_NO_SUBPAGE_WRITE | NAND_USE_BOUNCE_BUFFER |
+			 NAND_SKIP_BBTSCAN;
+
+	/* set up initial status value */
+	host->status = NAND_STATUS_READY | NAND_STATUS_WP;
+
+	ret = nand_scan_ident(mtd, 1, NULL);
+	if (ret)
+		return ret;
+
+	ret = qcom_nand_host_setup(host);
+	if (ret)
+		return ret;
+
+	ret = nand_scan_tail(mtd);
+	if (ret)
+		return ret;
+
+	return mtd_device_register(mtd, NULL, 0);
+}
+
+/* parse custom DT properties here */
+static int qcom_nandc_parse_dt(struct platform_device *pdev)
+{
+	struct qcom_nand_controller *nandc = platform_get_drvdata(pdev);
+	struct device_node *np = nandc->dev->of_node;
+	int ret;
+
+	ret = of_property_read_u32(np, "qcom,cmd-crci", &nandc->cmd_crci);
+	if (ret) {
+		dev_err(nandc->dev, "command CRCI unspecified\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(np, "qcom,data-crci", &nandc->data_crci);
+	if (ret) {
+		dev_err(nandc->dev, "data CRCI unspecified\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int qcom_nandc_probe(struct platform_device *pdev)
+{
+	struct qcom_nand_controller *nandc;
+	struct qcom_nand_host *host;
+	const void *dev_data;
+	struct device *dev = &pdev->dev;
+	struct device_node *dn = dev->of_node, *child;
+	struct resource *res;
+	int ret;
+
+	nandc = devm_kzalloc(&pdev->dev, sizeof(*nandc), GFP_KERNEL);
+	if (!nandc)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, nandc);
+	nandc->dev = dev;
+
+	dev_data = of_device_get_match_data(dev);
+	if (!dev_data) {
+		dev_err(&pdev->dev, "failed to get device data\n");
+		return -ENODEV;
+	}
+
+	nandc->ecc_modes = (unsigned long)dev_data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	nandc->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(nandc->base))
+		return PTR_ERR(nandc->base);
+
+	nandc->base_dma = phys_to_dma(dev, (phys_addr_t)res->start);
+
+	nandc->core_clk = devm_clk_get(dev, "core");
+	if (IS_ERR(nandc->core_clk))
+		return PTR_ERR(nandc->core_clk);
+
+	nandc->aon_clk = devm_clk_get(dev, "aon");
+	if (IS_ERR(nandc->aon_clk))
+		return PTR_ERR(nandc->aon_clk);
+
+	ret = qcom_nandc_parse_dt(pdev);
+	if (ret)
+		return ret;
+
+	ret = qcom_nandc_alloc(nandc);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(nandc->core_clk);
+	if (ret)
+		goto err_core_clk;
+
+	ret = clk_prepare_enable(nandc->aon_clk);
+	if (ret)
+		goto err_aon_clk;
+
+	ret = qcom_nandc_setup(nandc);
+	if (ret)
+		goto err_setup;
+
+	for_each_available_child_of_node(dn, child) {
+		if (of_device_is_compatible(child, "qcom,nandcs")) {
+			host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL);
+			if (!host) {
+				of_node_put(child);
+				ret = -ENOMEM;
+				goto err_cs_init;
+			}
+
+			ret = qcom_nand_host_init(nandc, host, child);
+			if (ret) {
+				devm_kfree(dev, host);
+				continue;
+			}
+
+			list_add_tail(&host->node, &nandc->host_list);
+		}
+	}
+
+	if (list_empty(&nandc->host_list)) {
+		ret = -ENODEV;
+		goto err_cs_init;
+	}
+
+	return 0;
+
+err_cs_init:
+	list_for_each_entry(host, &nandc->host_list, node)
+		nand_release(nand_to_mtd(&host->chip));
+err_setup:
+	clk_disable_unprepare(nandc->aon_clk);
+err_aon_clk:
+	clk_disable_unprepare(nandc->core_clk);
+err_core_clk:
+	qcom_nandc_unalloc(nandc);
+
+	return ret;
+}
+
+static int qcom_nandc_remove(struct platform_device *pdev)
+{
+	struct qcom_nand_controller *nandc = platform_get_drvdata(pdev);
+	struct qcom_nand_host *host;
+
+	list_for_each_entry(host, &nandc->host_list, node)
+		nand_release(nand_to_mtd(&host->chip));
+
+	qcom_nandc_unalloc(nandc);
+
+	clk_disable_unprepare(nandc->aon_clk);
+	clk_disable_unprepare(nandc->core_clk);
+
+	return 0;
+}
+
+#define EBI2_NANDC_ECC_MODES	(ECC_RS_4BIT | ECC_BCH_8BIT)
+
+/*
+ * data will hold a struct pointer containing more differences once we support
+ * more controller variants
+ */
+static const struct of_device_id qcom_nandc_of_match[] = {
+	{	.compatible = "qcom,ipq806x-nand",
+		.data = (void *)EBI2_NANDC_ECC_MODES,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_nandc_of_match);
+
+static struct platform_driver qcom_nandc_driver = {
+	.driver = {
+		.name = "qcom-nandc",
+		.of_match_table = qcom_nandc_of_match,
+	},
+	.probe   = qcom_nandc_probe,
+	.remove  = qcom_nandc_remove,
+};
+module_platform_driver(qcom_nandc_driver);
+
+MODULE_AUTHOR("Archit Taneja <architt@codeaurora.org>");
+MODULE_DESCRIPTION("Qualcomm NAND Controller driver");
+MODULE_LICENSE("GPL v2");