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/*
 * Copyright (C) 2018 Stefan Agner <stefan@agner.ch>
 * Copyright (C) 2014-2015 Lucas Stach <dev@lynxeye.de>
 * Copyright (C) 2012 Avionic Design GmbH
 */

#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/rawnand.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reset.h>

#define COMMAND					0x00
#define   COMMAND_GO				BIT(31)
#define   COMMAND_CLE				BIT(30)
#define   COMMAND_ALE				BIT(29)
#define   COMMAND_PIO				BIT(28)
#define   COMMAND_TX				BIT(27)
#define   COMMAND_RX				BIT(26)
#define   COMMAND_SEC_CMD			BIT(25)
#define   COMMAND_AFT_DAT			BIT(24)
#define   COMMAND_TRANS_SIZE(size)		((((size) - 1) & 0xf) << 20)
#define   COMMAND_A_VALID			BIT(19)
#define   COMMAND_B_VALID			BIT(18)
#define   COMMAND_RD_STATUS_CHK			BIT(17)
#define   COMMAND_RBSY_CHK			BIT(16)
#define   COMMAND_CE(x)				BIT(8 + ((x) & 0x7))
#define   COMMAND_CLE_SIZE(size)		((((size) - 1) & 0x3) << 4)
#define   COMMAND_ALE_SIZE(size)		((((size) - 1) & 0xf) << 0)

#define STATUS					0x04

#define ISR					0x08
#define   ISR_CORRFAIL_ERR			BIT(24)
#define   ISR_UND				BIT(7)
#define   ISR_OVR				BIT(6)
#define   ISR_CMD_DONE				BIT(5)
#define   ISR_ECC_ERR				BIT(4)

#define IER					0x0c
#define   IER_ERR_TRIG_VAL(x)			(((x) & 0xf) << 16)
#define   IER_UND				BIT(7)
#define   IER_OVR				BIT(6)
#define   IER_CMD_DONE				BIT(5)
#define   IER_ECC_ERR				BIT(4)
#define   IER_GIE				BIT(0)

#define CONFIG					0x10
#define   CONFIG_HW_ECC				BIT(31)
#define   CONFIG_ECC_SEL			BIT(30)
#define   CONFIG_ERR_COR			BIT(29)
#define   CONFIG_PIPE_EN			BIT(28)
#define   CONFIG_TVAL_4				(0 << 24)
#define   CONFIG_TVAL_6				(1 << 24)
#define   CONFIG_TVAL_8				(2 << 24)
#define   CONFIG_SKIP_SPARE			BIT(23)
#define   CONFIG_BUS_WIDTH_16			BIT(21)
#define   CONFIG_COM_BSY			BIT(20)
#define   CONFIG_PS_256				(0 << 16)
#define   CONFIG_PS_512				(1 << 16)
#define   CONFIG_PS_1024			(2 << 16)
#define   CONFIG_PS_2048			(3 << 16)
#define   CONFIG_PS_4096			(4 << 16)
#define   CONFIG_SKIP_SPARE_SIZE_4		(0 << 14)
#define   CONFIG_SKIP_SPARE_SIZE_8		(1 << 14)
#define   CONFIG_SKIP_SPARE_SIZE_12		(2 << 14)
#define   CONFIG_SKIP_SPARE_SIZE_16		(3 << 14)
#define   CONFIG_TAG_BYTE_SIZE(x)			((x) & 0xff)

#define TIMING_1				0x14
#define   TIMING_TRP_RESP(x)			(((x) & 0xf) << 28)
#define   TIMING_TWB(x)				(((x) & 0xf) << 24)
#define   TIMING_TCR_TAR_TRR(x)			(((x) & 0xf) << 20)
#define   TIMING_TWHR(x)			(((x) & 0xf) << 16)
#define   TIMING_TCS(x)				(((x) & 0x3) << 14)
#define   TIMING_TWH(x)				(((x) & 0x3) << 12)
#define   TIMING_TWP(x)				(((x) & 0xf) <<  8)
#define   TIMING_TRH(x)				(((x) & 0x3) <<  4)
#define   TIMING_TRP(x)				(((x) & 0xf) <<  0)

#define RESP					0x18

#define TIMING_2				0x1c
#define   TIMING_TADL(x)			((x) & 0xf)

#define CMD_REG1				0x20
#define CMD_REG2				0x24
#define ADDR_REG1				0x28
#define ADDR_REG2				0x2c

#define DMA_MST_CTRL				0x30
#define   DMA_MST_CTRL_GO			BIT(31)
#define   DMA_MST_CTRL_IN			(0 << 30)
#define   DMA_MST_CTRL_OUT			BIT(30)
#define   DMA_MST_CTRL_PERF_EN			BIT(29)
#define   DMA_MST_CTRL_IE_DONE			BIT(28)
#define   DMA_MST_CTRL_REUSE			BIT(27)
#define   DMA_MST_CTRL_BURST_1			(2 << 24)
#define   DMA_MST_CTRL_BURST_4			(3 << 24)
#define   DMA_MST_CTRL_BURST_8			(4 << 24)
#define   DMA_MST_CTRL_BURST_16			(5 << 24)
#define   DMA_MST_CTRL_IS_DONE			BIT(20)
#define   DMA_MST_CTRL_EN_A			BIT(2)
#define   DMA_MST_CTRL_EN_B			BIT(1)

#define DMA_CFG_A				0x34
#define DMA_CFG_B				0x38

#define FIFO_CTRL				0x3c
#define   FIFO_CTRL_CLR_ALL			BIT(3)

#define DATA_PTR				0x40
#define TAG_PTR					0x44
#define ECC_PTR					0x48

#define DEC_STATUS				0x4c
#define   DEC_STATUS_A_ECC_FAIL			BIT(1)
#define   DEC_STATUS_ERR_COUNT_MASK		0x00ff0000
#define   DEC_STATUS_ERR_COUNT_SHIFT		16

#define HWSTATUS_CMD				0x50
#define HWSTATUS_MASK				0x54
#define   HWSTATUS_RDSTATUS_MASK(x)		(((x) & 0xff) << 24)
#define   HWSTATUS_RDSTATUS_VALUE(x)		(((x) & 0xff) << 16)
#define   HWSTATUS_RBSY_MASK(x)			(((x) & 0xff) << 8)
#define   HWSTATUS_RBSY_VALUE(x)		(((x) & 0xff) << 0)

#define BCH_CONFIG				0xcc
#define   BCH_ENABLE				BIT(0)
#define   BCH_TVAL_4				(0 << 4)
#define   BCH_TVAL_8				(1 << 4)
#define   BCH_TVAL_14				(2 << 4)
#define   BCH_TVAL_16				(3 << 4)

#define DEC_STAT_RESULT				0xd0
#define DEC_STAT_BUF				0xd4
#define   DEC_STAT_BUF_FAIL_SEC_FLAG_MASK	0xff000000
#define   DEC_STAT_BUF_FAIL_SEC_FLAG_SHIFT	24
#define   DEC_STAT_BUF_CORR_SEC_FLAG_MASK	0x00ff0000
#define   DEC_STAT_BUF_CORR_SEC_FLAG_SHIFT	16
#define   DEC_STAT_BUF_MAX_CORR_CNT_MASK	0x00001f00
#define   DEC_STAT_BUF_MAX_CORR_CNT_SHIFT	8

#define OFFSET(val, off)	((val) < (off) ? 0 : (val) - (off))

#define SKIP_SPARE_BYTES	4
#define BITS_PER_STEP_RS	18
#define BITS_PER_STEP_BCH	13

#define INT_MASK		(IER_UND | IER_OVR | IER_CMD_DONE | IER_GIE)
#define HWSTATUS_CMD_DEFAULT	NAND_STATUS_READY
#define HWSTATUS_MASK_DEFAULT	(HWSTATUS_RDSTATUS_MASK(1) | \
				HWSTATUS_RDSTATUS_VALUE(0) | \
				HWSTATUS_RBSY_MASK(NAND_STATUS_READY) | \
				HWSTATUS_RBSY_VALUE(NAND_STATUS_READY))

struct tegra_nand_controller {
	struct nand_controller controller;
	struct device *dev;
	void __iomem *regs;
	int irq;
	struct clk *clk;
	struct completion command_complete;
	struct completion dma_complete;
	bool last_read_error;
	int cur_cs;
	struct nand_chip *chip;
};

struct tegra_nand_chip {
	struct nand_chip chip;
	struct gpio_desc *wp_gpio;
	struct mtd_oob_region ecc;
	u32 config;
	u32 config_ecc;
	u32 bch_config;
	int cs[1];
};

static inline struct tegra_nand_controller *
			to_tegra_ctrl(struct nand_controller *hw_ctrl)
{
	return container_of(hw_ctrl, struct tegra_nand_controller, controller);
}

static inline struct tegra_nand_chip *to_tegra_chip(struct nand_chip *chip)
{
	return container_of(chip, struct tegra_nand_chip, chip);
}

static int tegra_nand_ooblayout_rs_ecc(struct mtd_info *mtd, int section,
				       struct mtd_oob_region *oobregion)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	int bytes_per_step = DIV_ROUND_UP(BITS_PER_STEP_RS * chip->ecc.strength,
					  BITS_PER_BYTE);

	if (section > 0)
		return -ERANGE;

	oobregion->offset = SKIP_SPARE_BYTES;
	oobregion->length = round_up(bytes_per_step * chip->ecc.steps, 4);

	return 0;
}

static int tegra_nand_ooblayout_no_free(struct mtd_info *mtd, int section,
					struct mtd_oob_region *oobregion)
{
	return -ERANGE;
}

static const struct mtd_ooblayout_ops tegra_nand_oob_rs_ops = {
	.ecc = tegra_nand_ooblayout_rs_ecc,
	.free = tegra_nand_ooblayout_no_free,
};

static int tegra_nand_ooblayout_bch_ecc(struct mtd_info *mtd, int section,
					struct mtd_oob_region *oobregion)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	int bytes_per_step = DIV_ROUND_UP(BITS_PER_STEP_BCH * chip->ecc.strength,
					  BITS_PER_BYTE);

	if (section > 0)
		return -ERANGE;

	oobregion->offset = SKIP_SPARE_BYTES;
	oobregion->length = round_up(bytes_per_step * chip->ecc.steps, 4);

	return 0;
}

static const struct mtd_ooblayout_ops tegra_nand_oob_bch_ops = {
	.ecc = tegra_nand_ooblayout_bch_ecc,
	.free = tegra_nand_ooblayout_no_free,
};

static irqreturn_t tegra_nand_irq(int irq, void *data)
{
	struct tegra_nand_controller *ctrl = data;
	u32 isr, dma;

	isr = readl_relaxed(ctrl->regs + ISR);
	dma = readl_relaxed(ctrl->regs + DMA_MST_CTRL);
	dev_dbg(ctrl->dev, "isr %08x\n", isr);

	if (!isr && !(dma & DMA_MST_CTRL_IS_DONE))
		return IRQ_NONE;

	/*
	 * The bit name is somewhat missleading: This is also set when
	 * HW ECC was successful. The data sheet states:
	 * Correctable OR Un-correctable errors occurred in the DMA transfer...
	 */
	if (isr & ISR_CORRFAIL_ERR)
		ctrl->last_read_error = true;

	if (isr & ISR_CMD_DONE)
		complete(&ctrl->command_complete);

	if (isr & ISR_UND)
		dev_err(ctrl->dev, "FIFO underrun\n");

	if (isr & ISR_OVR)
		dev_err(ctrl->dev, "FIFO overrun\n");

	/* handle DMA interrupts */
	if (dma & DMA_MST_CTRL_IS_DONE) {
		writel_relaxed(dma, ctrl->regs + DMA_MST_CTRL);
		complete(&ctrl->dma_complete);
	}

	/* clear interrupts */
	writel_relaxed(isr, ctrl->regs + ISR);

	return IRQ_HANDLED;
}

static const char * const tegra_nand_reg_names[] = {
	"COMMAND",
	"STATUS",
	"ISR",
	"IER",
	"CONFIG",
	"TIMING",
	NULL,
	"TIMING2",
	"CMD_REG1",
	"CMD_REG2",
	"ADDR_REG1",
	"ADDR_REG2",
	"DMA_MST_CTRL",
	"DMA_CFG_A",
	"DMA_CFG_B",
	"FIFO_CTRL",
};

static void tegra_nand_dump_reg(struct tegra_nand_controller *ctrl)
{
	u32 reg;
	int i;

	dev_err(ctrl->dev, "Tegra NAND controller register dump\n");
	for (i = 0; i < ARRAY_SIZE(tegra_nand_reg_names); i++) {
		const char *reg_name = tegra_nand_reg_names[i];

		if (!reg_name)
			continue;

		reg = readl_relaxed(ctrl->regs + (i * 4));
		dev_err(ctrl->dev, "%s: 0x%08x\n", reg_name, reg);
	}
}

static void tegra_nand_controller_abort(struct tegra_nand_controller *ctrl)
{
	u32 isr, dma;

	disable_irq(ctrl->irq);

	/* Abort current command/DMA operation */
	writel_relaxed(0, ctrl->regs + DMA_MST_CTRL);
	writel_relaxed(0, ctrl->regs + COMMAND);

	/* clear interrupts */
	isr = readl_relaxed(ctrl->regs + ISR);
	writel_relaxed(isr, ctrl->regs + ISR);
	dma = readl_relaxed(ctrl->regs + DMA_MST_CTRL);
	writel_relaxed(dma, ctrl->regs + DMA_MST_CTRL);

	reinit_completion(&ctrl->command_complete);
	reinit_completion(&ctrl->dma_complete);

	enable_irq(ctrl->irq);
}

static int tegra_nand_cmd(struct nand_chip *chip,
			  const struct nand_subop *subop)
{
	const struct nand_op_instr *instr;
	const struct nand_op_instr *instr_data_in = NULL;
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
	unsigned int op_id, size = 0, offset = 0;
	bool first_cmd = true;
	u32 reg, cmd = 0;
	int ret;

	for (op_id = 0; op_id < subop->ninstrs; op_id++) {
		unsigned int naddrs, i;
		const u8 *addrs;
		u32 addr1 = 0, addr2 = 0;

		instr = &subop->instrs[op_id];

		switch (instr->type) {
		case NAND_OP_CMD_INSTR:
			if (first_cmd) {
				cmd |= COMMAND_CLE;
				writel_relaxed(instr->ctx.cmd.opcode,
					       ctrl->regs + CMD_REG1);
			} else {
				cmd |= COMMAND_SEC_CMD;
				writel_relaxed(instr->ctx.cmd.opcode,
					       ctrl->regs + CMD_REG2);
			}
			first_cmd = false;
			break;

		case NAND_OP_ADDR_INSTR:
			offset = nand_subop_get_addr_start_off(subop, op_id);
			naddrs = nand_subop_get_num_addr_cyc(subop, op_id);
			addrs = &instr->ctx.addr.addrs[offset];

			cmd |= COMMAND_ALE | COMMAND_ALE_SIZE(naddrs);
			for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
				addr1 |= *addrs++ << (BITS_PER_BYTE * i);
			naddrs -= i;
			for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
				addr2 |= *addrs++ << (BITS_PER_BYTE * i);

			writel_relaxed(addr1, ctrl->regs + ADDR_REG1);
			writel_relaxed(addr2, ctrl->regs + ADDR_REG2);
			break;

		case NAND_OP_DATA_IN_INSTR:
			size = nand_subop_get_data_len(subop, op_id);
			offset = nand_subop_get_data_start_off(subop, op_id);

			cmd |= COMMAND_TRANS_SIZE(size) | COMMAND_PIO |
				COMMAND_RX | COMMAND_A_VALID;

			instr_data_in = instr;
			break;

		case NAND_OP_DATA_OUT_INSTR:
			size = nand_subop_get_data_len(subop, op_id);
			offset = nand_subop_get_data_start_off(subop, op_id);

			cmd |= COMMAND_TRANS_SIZE(size) | COMMAND_PIO |
				COMMAND_TX | COMMAND_A_VALID;
			memcpy(&reg, instr->ctx.data.buf.out + offset, size);

			writel_relaxed(reg, ctrl->regs + RESP);
			break;

		case NAND_OP_WAITRDY_INSTR:
			cmd |= COMMAND_RBSY_CHK;
			break;
		}
	}

	cmd |= COMMAND_GO | COMMAND_CE(ctrl->cur_cs);
	writel_relaxed(cmd, ctrl->regs + COMMAND);
	ret = wait_for_completion_timeout(&ctrl->command_complete,
					  msecs_to_jiffies(500));
	if (!ret) {
		dev_err(ctrl->dev, "COMMAND timeout\n");
		tegra_nand_dump_reg(ctrl);
		tegra_nand_controller_abort(ctrl);
		return -ETIMEDOUT;
	}

	if (instr_data_in) {
		reg = readl_relaxed(ctrl->regs + RESP);
		memcpy(instr_data_in->ctx.data.buf.in + offset, &reg, size);
	}

	return 0;
}

static const struct nand_op_parser tegra_nand_op_parser = NAND_OP_PARSER(
	NAND_OP_PARSER_PATTERN(tegra_nand_cmd,
		NAND_OP_PARSER_PAT_CMD_ELEM(true),
		NAND_OP_PARSER_PAT_ADDR_ELEM(true, 8),
		NAND_OP_PARSER_PAT_CMD_ELEM(true),
		NAND_OP_PARSER_PAT_WAITRDY_ELEM(true)),
	NAND_OP_PARSER_PATTERN(tegra_nand_cmd,
		NAND_OP_PARSER_PAT_DATA_OUT_ELEM(false, 4)),
	NAND_OP_PARSER_PATTERN(tegra_nand_cmd,
		NAND_OP_PARSER_PAT_CMD_ELEM(true),
		NAND_OP_PARSER_PAT_ADDR_ELEM(true, 8),
		NAND_OP_PARSER_PAT_CMD_ELEM(true),
		NAND_OP_PARSER_PAT_WAITRDY_ELEM(true),
		NAND_OP_PARSER_PAT_DATA_IN_ELEM(true, 4)),
	);

static int tegra_nand_exec_op(struct nand_chip *chip,
			      const struct nand_operation *op,
			      bool check_only)
{
	return nand_op_parser_exec_op(chip, &tegra_nand_op_parser, op,
				      check_only);
}

static void tegra_nand_select_chip(struct mtd_info *mtd, int die_nr)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct tegra_nand_chip *nand = to_tegra_chip(chip);
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);

	WARN_ON(die_nr >= (int)ARRAY_SIZE(nand->cs));

	if (die_nr < 0 || die_nr > 0) {
		ctrl->cur_cs = -1;
		return;
	}

	ctrl->cur_cs = nand->cs[die_nr];
}

static void tegra_nand_hw_ecc(struct tegra_nand_controller *ctrl,
			      struct nand_chip *chip, bool enable)
{
	struct tegra_nand_chip *nand = to_tegra_chip(chip);

	if (chip->ecc.algo == NAND_ECC_BCH && enable)
		writel_relaxed(nand->bch_config, ctrl->regs + BCH_CONFIG);
	else
		writel_relaxed(0, ctrl->regs + BCH_CONFIG);

	if (enable)
		writel_relaxed(nand->config_ecc, ctrl->regs + CONFIG);
	else
		writel_relaxed(nand->config, ctrl->regs + CONFIG);
}

static int tegra_nand_page_xfer(struct mtd_info *mtd, struct nand_chip *chip,
				void *buf, void *oob_buf, int oob_len, int page,
				bool read)
{
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
	enum dma_data_direction dir = read ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
	dma_addr_t dma_addr = 0, dma_addr_oob = 0;
	u32 addr1, cmd, dma_ctrl;
	int ret;

	if (read) {
		writel_relaxed(NAND_CMD_READ0, ctrl->regs + CMD_REG1);
		writel_relaxed(NAND_CMD_READSTART, ctrl->regs + CMD_REG2);
	} else {
		writel_relaxed(NAND_CMD_SEQIN, ctrl->regs + CMD_REG1);
		writel_relaxed(NAND_CMD_PAGEPROG, ctrl->regs + CMD_REG2);
	}
	cmd = COMMAND_CLE | COMMAND_SEC_CMD;

	/* Lower 16-bits are column, by default 0 */
	addr1 = page << 16;

	if (!buf)
		addr1 |= mtd->writesize;
	writel_relaxed(addr1, ctrl->regs + ADDR_REG1);

	if (chip->options & NAND_ROW_ADDR_3) {
		writel_relaxed(page >> 16, ctrl->regs + ADDR_REG2);
		cmd |= COMMAND_ALE | COMMAND_ALE_SIZE(5);
	} else {
		cmd |= COMMAND_ALE | COMMAND_ALE_SIZE(4);
	}

	if (buf) {
		dma_addr = dma_map_single(ctrl->dev, buf, mtd->writesize, dir);
		ret = dma_mapping_error(ctrl->dev, dma_addr);
		if (ret) {
			dev_err(ctrl->dev, "dma mapping error\n");
			return -EINVAL;
		}

		writel_relaxed(mtd->writesize - 1, ctrl->regs + DMA_CFG_A);
		writel_relaxed(dma_addr, ctrl->regs + DATA_PTR);
	}

	if (oob_buf) {
		dma_addr_oob = dma_map_single(ctrl->dev, oob_buf, mtd->oobsize,
					      dir);
		ret = dma_mapping_error(ctrl->dev, dma_addr_oob);
		if (ret) {
			dev_err(ctrl->dev, "dma mapping error\n");
			ret = -EINVAL;
			goto err_unmap_dma_page;
		}

		writel_relaxed(oob_len - 1, ctrl->regs + DMA_CFG_B);
		writel_relaxed(dma_addr_oob, ctrl->regs + TAG_PTR);
	}

	dma_ctrl = DMA_MST_CTRL_GO | DMA_MST_CTRL_PERF_EN |
		   DMA_MST_CTRL_IE_DONE | DMA_MST_CTRL_IS_DONE |
		   DMA_MST_CTRL_BURST_16;

	if (buf)
		dma_ctrl |= DMA_MST_CTRL_EN_A;
	if (oob_buf)
		dma_ctrl |= DMA_MST_CTRL_EN_B;

	if (read)
		dma_ctrl |= DMA_MST_CTRL_IN | DMA_MST_CTRL_REUSE;
	else
		dma_ctrl |= DMA_MST_CTRL_OUT;

	writel_relaxed(dma_ctrl, ctrl->regs + DMA_MST_CTRL);

	cmd |= COMMAND_GO | COMMAND_RBSY_CHK | COMMAND_TRANS_SIZE(9) |
	       COMMAND_CE(ctrl->cur_cs);

	if (buf)
		cmd |= COMMAND_A_VALID;
	if (oob_buf)
		cmd |= COMMAND_B_VALID;

	if (read)
		cmd |= COMMAND_RX;
	else
		cmd |= COMMAND_TX | COMMAND_AFT_DAT;

	writel_relaxed(cmd, ctrl->regs + COMMAND);

	ret = wait_for_completion_timeout(&ctrl->command_complete,
					  msecs_to_jiffies(500));
	if (!ret) {
		dev_err(ctrl->dev, "COMMAND timeout\n");
		tegra_nand_dump_reg(ctrl);
		tegra_nand_controller_abort(ctrl);
		ret = -ETIMEDOUT;
		goto err_unmap_dma;
	}

	ret = wait_for_completion_timeout(&ctrl->dma_complete,
					  msecs_to_jiffies(500));
	if (!ret) {
		dev_err(ctrl->dev, "DMA timeout\n");
		tegra_nand_dump_reg(ctrl);
		tegra_nand_controller_abort(ctrl);
		ret = -ETIMEDOUT;
		goto err_unmap_dma;
	}
	ret = 0;

err_unmap_dma:
	if (oob_buf)
		dma_unmap_single(ctrl->dev, dma_addr_oob, mtd->oobsize, dir);
err_unmap_dma_page:
	if (buf)
		dma_unmap_single(ctrl->dev, dma_addr, mtd->writesize, dir);

	return ret;
}

static int tegra_nand_read_page_raw(struct mtd_info *mtd,
				    struct nand_chip *chip, u8 *buf,
				    int oob_required, int page)
{
	void *oob_buf = oob_required ? chip->oob_poi : NULL;

	return tegra_nand_page_xfer(mtd, chip, buf, oob_buf,
				    mtd->oobsize, page, true);
}

static int tegra_nand_write_page_raw(struct mtd_info *mtd,
				     struct nand_chip *chip, const u8 *buf,
				     int oob_required, int page)
{
	void *oob_buf = oob_required ? chip->oob_poi : NULL;

	return tegra_nand_page_xfer(mtd, chip, (void *)buf, oob_buf,
				     mtd->oobsize, page, false);
}

static int tegra_nand_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
			       int page)
{
	return tegra_nand_page_xfer(mtd, chip, NULL, chip->oob_poi,
				    mtd->oobsize, page, true);
}

static int tegra_nand_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
				int page)
{
	return tegra_nand_page_xfer(mtd, chip, NULL, chip->oob_poi,
				    mtd->oobsize, page, false);
}

static int tegra_nand_read_page_hwecc(struct mtd_info *mtd,
				      struct nand_chip *chip, u8 *buf,
				      int oob_required, int page)
{
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
	struct tegra_nand_chip *nand = to_tegra_chip(chip);
	void *oob_buf = oob_required ? chip->oob_poi : NULL;
	u32 dec_stat, max_corr_cnt;
	unsigned long fail_sec_flag;
	int ret;

	tegra_nand_hw_ecc(ctrl, chip, true);
	ret = tegra_nand_page_xfer(mtd, chip, buf, oob_buf, 0, page, true);
	tegra_nand_hw_ecc(ctrl, chip, false);
	if (ret)
		return ret;

	/* No correctable or un-correctable errors, page must have 0 bitflips */
	if (!ctrl->last_read_error)
		return 0;

	/*
	 * Correctable or un-correctable errors occurred. Use DEC_STAT_BUF
	 * which contains information for all ECC selections.
	 *
	 * Note that since we do not use Command Queues DEC_RESULT does not
	 * state the number of pages we can read from the DEC_STAT_BUF. But
	 * since CORRFAIL_ERR did occur during page read we do have a valid
	 * result in DEC_STAT_BUF.
	 */
	ctrl->last_read_error = false;
	dec_stat = readl_relaxed(ctrl->regs + DEC_STAT_BUF);

	fail_sec_flag = (dec_stat & DEC_STAT_BUF_FAIL_SEC_FLAG_MASK) >>
			DEC_STAT_BUF_FAIL_SEC_FLAG_SHIFT;

	max_corr_cnt = (dec_stat & DEC_STAT_BUF_MAX_CORR_CNT_MASK) >>
		       DEC_STAT_BUF_MAX_CORR_CNT_SHIFT;

	if (fail_sec_flag) {
		int bit, max_bitflips = 0;

		/*
		 * Since we do not support subpage writes, a complete page
		 * is either written or not. We can take a shortcut here by
		 * checking wheather any of the sector has been successful
		 * read. If at least one sectors has been read successfully,
		 * the page must have been a written previously. It cannot
		 * be an erased page.
		 *
		 * E.g. controller might return fail_sec_flag with 0x4, which
		 * would mean only the third sector failed to correct. The
		 * page must have been written and the third sector is really
		 * not correctable anymore.
		 */
		if (fail_sec_flag ^ GENMASK(chip->ecc.steps - 1, 0)) {
			mtd->ecc_stats.failed += hweight8(fail_sec_flag);
			return max_corr_cnt;
		}

		/*
		 * All sectors failed to correct, but the ECC isn't smart
		 * enough to figure out if a page is really just erased.
		 * Read OOB data and check whether data/OOB is completely
		 * erased or if error correction just failed for all sub-
		 * pages.
		 */
		ret = tegra_nand_read_oob(mtd, chip, page);
		if (ret < 0)
			return ret;

		for_each_set_bit(bit, &fail_sec_flag, chip->ecc.steps) {
			u8 *data = buf + (chip->ecc.size * bit);
			u8 *oob = chip->oob_poi + nand->ecc.offset +
				  (chip->ecc.bytes * bit);

			ret = nand_check_erased_ecc_chunk(data, chip->ecc.size,
							  oob, chip->ecc.bytes,
							  NULL, 0,
							  chip->ecc.strength);
			if (ret < 0) {
				mtd->ecc_stats.failed++;
			} else {
				mtd->ecc_stats.corrected += ret;
				max_bitflips = max(ret, max_bitflips);
			}
		}

		return max_t(unsigned int, max_corr_cnt, max_bitflips);
	} else {
		int corr_sec_flag;

		corr_sec_flag = (dec_stat & DEC_STAT_BUF_CORR_SEC_FLAG_MASK) >>
				DEC_STAT_BUF_CORR_SEC_FLAG_SHIFT;

		/*
		 * The value returned in the register is the maximum of
		 * bitflips encountered in any of the ECC regions. As there is
		 * no way to get the number of bitflips in a specific regions
		 * we are not able to deliver correct stats but instead
		 * overestimate the number of corrected bitflips by assuming
		 * that all regions where errors have been corrected
		 * encountered the maximum number of bitflips.
		 */
		mtd->ecc_stats.corrected += max_corr_cnt * hweight8(corr_sec_flag);

		return max_corr_cnt;
	}
}

static int tegra_nand_write_page_hwecc(struct mtd_info *mtd,
				       struct nand_chip *chip, const u8 *buf,
				       int oob_required, int page)
{
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
	void *oob_buf = oob_required ? chip->oob_poi : NULL;
	int ret;

	tegra_nand_hw_ecc(ctrl, chip, true);
	ret = tegra_nand_page_xfer(mtd, chip, (void *)buf, oob_buf,
				   0, page, false);
	tegra_nand_hw_ecc(ctrl, chip, false);

	return ret;
}

static void tegra_nand_setup_timing(struct tegra_nand_controller *ctrl,
				    const struct nand_sdr_timings *timings)
{
	/*
	 * The period (and all other timings in this function) is in ps,
	 * so need to take care here to avoid integer overflows.
	 */
	unsigned int rate = clk_get_rate(ctrl->clk) / 1000000;
	unsigned int period = DIV_ROUND_UP(1000000, rate);
	u32 val, reg = 0;

	val = DIV_ROUND_UP(max3(timings->tAR_min, timings->tRR_min,
				timings->tRC_min), period);
	reg |= TIMING_TCR_TAR_TRR(OFFSET(val, 3));

	val = DIV_ROUND_UP(max(max(timings->tCS_min, timings->tCH_min),
			       max(timings->tALS_min, timings->tALH_min)),
			   period);
	reg |= TIMING_TCS(OFFSET(val, 2));

	val = DIV_ROUND_UP(max(timings->tRP_min, timings->tREA_max) + 6000,
			   period);
	reg |= TIMING_TRP(OFFSET(val, 1)) | TIMING_TRP_RESP(OFFSET(val, 1));

	reg |= TIMING_TWB(OFFSET(DIV_ROUND_UP(timings->tWB_max, period), 1));
	reg |= TIMING_TWHR(OFFSET(DIV_ROUND_UP(timings->tWHR_min, period), 1));
	reg |= TIMING_TWH(OFFSET(DIV_ROUND_UP(timings->tWH_min, period), 1));
	reg |= TIMING_TWP(OFFSET(DIV_ROUND_UP(timings->tWP_min, period), 1));
	reg |= TIMING_TRH(OFFSET(DIV_ROUND_UP(timings->tREH_min, period), 1));

	writel_relaxed(reg, ctrl->regs + TIMING_1);

	val = DIV_ROUND_UP(timings->tADL_min, period);
	reg = TIMING_TADL(OFFSET(val, 3));

	writel_relaxed(reg, ctrl->regs + TIMING_2);
}

static int tegra_nand_setup_data_interface(struct mtd_info *mtd, int csline,
					const struct nand_data_interface *conf)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
	const struct nand_sdr_timings *timings;

	timings = nand_get_sdr_timings(conf);
	if (IS_ERR(timings))
		return PTR_ERR(timings);

	if (csline == NAND_DATA_IFACE_CHECK_ONLY)
		return 0;

	tegra_nand_setup_timing(ctrl, timings);

	return 0;
}

static const int rs_strength_bootable[] = { 4 };
static const int rs_strength[] = { 4, 6, 8 };
static const int bch_strength_bootable[] = { 8, 16 };
static const int bch_strength[] = { 4, 8, 14, 16 };

static int tegra_nand_get_strength(struct nand_chip *chip, const int *strength,
				   int strength_len, int bits_per_step,
				   int oobsize)
{
	bool maximize = chip->ecc.options & NAND_ECC_MAXIMIZE;
	int i;

	/*
	 * Loop through available strengths. Backwards in case we try to
	 * maximize the BCH strength.
	 */
	for (i = 0; i < strength_len; i++) {
		int strength_sel, bytes_per_step, bytes_per_page;

		if (maximize) {
			strength_sel = strength[strength_len - i - 1];
		} else {
			strength_sel = strength[i];

			if (strength_sel < chip->ecc_strength_ds)
				continue;
		}

		bytes_per_step = DIV_ROUND_UP(bits_per_step * strength_sel,
					      BITS_PER_BYTE);
		bytes_per_page = round_up(bytes_per_step * chip->ecc.steps, 4);

		/* Check whether strength fits OOB */
		if (bytes_per_page < (oobsize - SKIP_SPARE_BYTES))
			return strength_sel;
	}

	return -EINVAL;
}

static int tegra_nand_select_strength(struct nand_chip *chip, int oobsize)
{
	const int *strength;
	int strength_len, bits_per_step;

	switch (chip->ecc.algo) {
	case NAND_ECC_RS:
		bits_per_step = BITS_PER_STEP_RS;
		if (chip->options & NAND_IS_BOOT_MEDIUM) {
			strength = rs_strength_bootable;
			strength_len = ARRAY_SIZE(rs_strength_bootable);
		} else {
			strength = rs_strength;
			strength_len = ARRAY_SIZE(rs_strength);
		}
		break;
	case NAND_ECC_BCH:
		bits_per_step = BITS_PER_STEP_BCH;
		if (chip->options & NAND_IS_BOOT_MEDIUM) {
			strength = bch_strength_bootable;
			strength_len = ARRAY_SIZE(bch_strength_bootable);
		} else {
			strength = bch_strength;
			strength_len = ARRAY_SIZE(bch_strength);
		}
		break;
	default:
		return -EINVAL;
	}

	return tegra_nand_get_strength(chip, strength, strength_len,
				       bits_per_step, oobsize);
}

static int tegra_nand_attach_chip(struct nand_chip *chip)
{
	struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
	struct tegra_nand_chip *nand = to_tegra_chip(chip);
	struct mtd_info *mtd = nand_to_mtd(chip);
	int bits_per_step;
	int ret;

	if (chip->bbt_options & NAND_BBT_USE_FLASH)
		chip->bbt_options |= NAND_BBT_NO_OOB;

	chip->ecc.mode = NAND_ECC_HW;
	chip->ecc.size = 512;
	chip->ecc.steps = mtd->writesize / chip->ecc.size;
	if (chip->ecc_step_ds != 512) {
		dev_err(ctrl->dev, "Unsupported step size %d\n",
			chip->ecc_step_ds);
		return -EINVAL;
	}

	chip->ecc.read_page = tegra_nand_read_page_hwecc;
	chip->ecc.write_page = tegra_nand_write_page_hwecc;
	chip->ecc.read_page_raw = tegra_nand_read_page_raw;
	chip->ecc.write_page_raw = tegra_nand_write_page_raw;
	chip->ecc.read_oob = tegra_nand_read_oob;
	chip->ecc.write_oob = tegra_nand_write_oob;

	if (chip->options & NAND_BUSWIDTH_16)
		nand->config |= CONFIG_BUS_WIDTH_16;

	if (chip->ecc.algo == NAND_ECC_UNKNOWN) {
		if (mtd->writesize < 2048)
			chip->ecc.algo = NAND_ECC_RS;
		else
			chip->ecc.algo = NAND_ECC_BCH;
	}

	if (chip->ecc.algo == NAND_ECC_BCH && mtd->writesize < 2048) {
		dev_err(ctrl->dev, "BCH supports 2K or 4K page size only\n");
		return -EINVAL;
	}

	if (!chip->ecc.strength) {
		ret = tegra_nand_select_strength(chip, mtd->oobsize);
		if (ret < 0) {
			dev_err(ctrl->dev,
				"No valid strength found, minimum %d\n",
				chip->ecc_strength_ds);
			return ret;
		}

		chip->ecc.strength = ret;
	}

	nand->config_ecc = CONFIG_PIPE_EN | CONFIG_SKIP_SPARE |
			   CONFIG_SKIP_SPARE_SIZE_4;

	switch (chip->ecc.algo) {
	case NAND_ECC_RS:
		bits_per_step = BITS_PER_STEP_RS * chip->ecc.strength;
		mtd_set_ooblayout(mtd, &tegra_nand_oob_rs_ops);
		nand->config_ecc |= CONFIG_HW_ECC | CONFIG_ECC_SEL |
				    CONFIG_ERR_COR;
		switch (chip->ecc.strength) {
		case 4:
			nand->config_ecc |= CONFIG_TVAL_4;
			break;
		case 6:
			nand->config_ecc |= CONFIG_TVAL_6;
			break;
		case 8:
			nand->config_ecc |= CONFIG_TVAL_8;
			break;
		default:
			dev_err(ctrl->dev, "ECC strength %d not supported\n",
				chip->ecc.strength);
			return -EINVAL;
		}
		break;
	case NAND_ECC_BCH:
		bits_per_step = BITS_PER_STEP_BCH * chip->ecc.strength;
		mtd_set_ooblayout(mtd, &tegra_nand_oob_bch_ops);
		nand->bch_config = BCH_ENABLE;
		switch (chip->ecc.strength) {
		case 4:
			nand->bch_config |= BCH_TVAL_4;
			break;
		case 8:
			nand->bch_config |= BCH_TVAL_8;
			break;
		case 14:
			nand->bch_config |= BCH_TVAL_14;
			break;
		case 16:
			nand->bch_config |= BCH_TVAL_16;
			break;
		default:
			dev_err(ctrl->dev, "ECC strength %d not supported\n",
				chip->ecc.strength);
			return -EINVAL;
		}
		break;
	default:
		dev_err(ctrl->dev, "ECC algorithm not supported\n");
		return -EINVAL;
	}

	dev_info(ctrl->dev, "Using %s with strength %d per 512 byte step\n",
		 chip->ecc.algo == NAND_ECC_BCH ? "BCH" : "RS",
		 chip->ecc.strength);

	chip->ecc.bytes = DIV_ROUND_UP(bits_per_step, BITS_PER_BYTE);

	switch (mtd->writesize) {
	case 256:
		nand->config |= CONFIG_PS_256;
		break;
	case 512:
		nand->config |= CONFIG_PS_512;
		break;
	case 1024:
		nand->config |= CONFIG_PS_1024;
		break;
	case 2048:
		nand->config |= CONFIG_PS_2048;
		break;
	case 4096:
		nand->config |= CONFIG_PS_4096;
		break;
	default:
		dev_err(ctrl->dev, "Unsupported writesize %d\n",
			mtd->writesize);
		return -ENODEV;
	}

	/* Store complete configuration for HW ECC in config_ecc */
	nand->config_ecc |= nand->config;

	/* Non-HW ECC read/writes complete OOB */
	nand->config |= CONFIG_TAG_BYTE_SIZE(mtd->oobsize - 1);
	writel_relaxed(nand->config, ctrl->regs + CONFIG);

	return 0;
}

static const struct nand_controller_ops tegra_nand_controller_ops = {
	.attach_chip = &tegra_nand_attach_chip,
};

static int tegra_nand_chips_init(struct device *dev,
				 struct tegra_nand_controller *ctrl)
{
	struct device_node *np = dev->of_node;
	struct device_node *np_nand;
	int nsels, nchips = of_get_child_count(np);
	struct tegra_nand_chip *nand;
	struct mtd_info *mtd;
	struct nand_chip *chip;
	int ret;
	u32 cs;

	if (nchips != 1) {
		dev_err(dev, "Currently only one NAND chip supported\n");
		return -EINVAL;
	}

	np_nand = of_get_next_child(np, NULL);

	nsels = of_property_count_elems_of_size(np_nand, "reg", sizeof(u32));
	if (nsels != 1) {
		dev_err(dev, "Missing/invalid reg property\n");
		return -EINVAL;
	}

	/* Retrieve CS id, currently only single die NAND supported */
	ret = of_property_read_u32(np_nand, "reg", &cs);
	if (ret) {
		dev_err(dev, "could not retrieve reg property: %d\n", ret);
		return ret;
	}

	nand = devm_kzalloc(dev, sizeof(*nand), GFP_KERNEL);
	if (!nand)
		return -ENOMEM;

	nand->cs[0] = cs;

	nand->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_LOW);

	if (IS_ERR(nand->wp_gpio)) {
		ret = PTR_ERR(nand->wp_gpio);
		dev_err(dev, "Failed to request WP GPIO: %d\n", ret);
		return ret;
	}

	chip = &nand->chip;
	chip->controller = &ctrl->controller;

	mtd = nand_to_mtd(chip);

	mtd->dev.parent = dev;
	mtd->owner = THIS_MODULE;

	nand_set_flash_node(chip, np_nand);

	if (!mtd->name)
		mtd->name = "tegra_nand";

	chip->options = NAND_NO_SUBPAGE_WRITE | NAND_USE_BOUNCE_BUFFER;
	chip->exec_op = tegra_nand_exec_op;
	chip->select_chip = tegra_nand_select_chip;
	chip->setup_data_interface = tegra_nand_setup_data_interface;

	ret = nand_scan(mtd, 1);
	if (ret)
		return ret;

	mtd_ooblayout_ecc(mtd, 0, &nand->ecc);

	ret = mtd_device_register(mtd, NULL, 0);
	if (ret) {
		dev_err(dev, "Failed to register mtd device: %d\n", ret);
		nand_cleanup(chip);
		return ret;
	}

	ctrl->chip = chip;

	return 0;
}

static int tegra_nand_probe(struct platform_device *pdev)
{
	struct reset_control *rst;
	struct tegra_nand_controller *ctrl;
	struct resource *res;
	int err = 0;

	ctrl = devm_kzalloc(&pdev->dev, sizeof(*ctrl), GFP_KERNEL);
	if (!ctrl)
		return -ENOMEM;

	ctrl->dev = &pdev->dev;
	nand_controller_init(&ctrl->controller);
	ctrl->controller.ops = &tegra_nand_controller_ops;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	ctrl->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(ctrl->regs))
		return PTR_ERR(ctrl->regs);

	rst = devm_reset_control_get(&pdev->dev, "nand");
	if (IS_ERR(rst))
		return PTR_ERR(rst);

	ctrl->clk = devm_clk_get(&pdev->dev, "nand");
	if (IS_ERR(ctrl->clk))
		return PTR_ERR(ctrl->clk);

	err = clk_prepare_enable(ctrl->clk);
	if (err)
		return err;

	err = reset_control_reset(rst);
	if (err) {
		dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
		goto err_disable_clk;
	}

	writel_relaxed(HWSTATUS_CMD_DEFAULT, ctrl->regs + HWSTATUS_CMD);
	writel_relaxed(HWSTATUS_MASK_DEFAULT, ctrl->regs + HWSTATUS_MASK);
	writel_relaxed(INT_MASK, ctrl->regs + IER);

	init_completion(&ctrl->command_complete);
	init_completion(&ctrl->dma_complete);

	ctrl->irq = platform_get_irq(pdev, 0);
	err = devm_request_irq(&pdev->dev, ctrl->irq, tegra_nand_irq, 0,
			       dev_name(&pdev->dev), ctrl);
	if (err) {
		dev_err(ctrl->dev, "Failed to get IRQ: %d\n", err);
		goto err_disable_clk;
	}

	writel_relaxed(DMA_MST_CTRL_IS_DONE, ctrl->regs + DMA_MST_CTRL);

	err = tegra_nand_chips_init(ctrl->dev, ctrl);
	if (err)
		goto err_disable_clk;

	platform_set_drvdata(pdev, ctrl);

	return 0;

err_disable_clk:
	clk_disable_unprepare(ctrl->clk);
	return err;
}

static int tegra_nand_remove(struct platform_device *pdev)
{
	struct tegra_nand_controller *ctrl = platform_get_drvdata(pdev);
	struct nand_chip *chip = ctrl->chip;
	struct mtd_info *mtd = nand_to_mtd(chip);
	int ret;

	ret = mtd_device_unregister(mtd);
	if (ret)
		return ret;

	nand_cleanup(chip);

	clk_disable_unprepare(ctrl->clk);

	return 0;
}

static const struct of_device_id tegra_nand_of_match[] = {
	{ .compatible = "nvidia,tegra20-nand" },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, tegra_nand_of_match);

static struct platform_driver tegra_nand_driver = {
	.driver = {
		.name = "tegra-nand",
		.of_match_table = tegra_nand_of_match,
	},
	.probe = tegra_nand_probe,
	.remove = tegra_nand_remove,
};
module_platform_driver(tegra_nand_driver);

MODULE_DESCRIPTION("NVIDIA Tegra NAND driver");
MODULE_AUTHOR("Thierry Reding <thierry.reding@nvidia.com>");
MODULE_AUTHOR("Lucas Stach <dev@lynxeye.de>");
MODULE_AUTHOR("Stefan Agner <stefan@agner.ch>");
MODULE_LICENSE("GPL v2"