Re: [PATCH v3 4/6] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver

[Dmitry Osipenko <digetx@gmail.com>]

On Saturday, 9 June 2018 00:51:01 MSK Stefan Agner wrote:
> On 01.06.2018 11:20, Dmitry Osipenko wrote:
> > On 01.06.2018 01:16, Stefan Agner wrote:
> >> Add support for the NAND flash controller found on NVIDIA
> >> Tegra 2 SoCs. This implementation does not make use of the
> >> command queue feature. Regular operations/data transfers are
> >> done in PIO mode. Page read/writes with hardware ECC make
> >> use of the DMA for data transfer.
> >> 
> >> Signed-off-by: Lucas Stach <dev@lynxeye.de>
> >> Signed-off-by: Stefan Agner <stefan@agner.ch>
> >> ---
> >> 
> >>  MAINTAINERS                       |    7 +
> >>  drivers/mtd/nand/raw/Kconfig      |    6 +
> >>  drivers/mtd/nand/raw/Makefile     |    1 +
> >>  drivers/mtd/nand/raw/tegra_nand.c | 1143 +++++++++++++++++++++++++++++
> >>  4 files changed, 1157 insertions(+)
> >>  create mode 100644 drivers/mtd/nand/raw/tegra_nand.c
> >> 
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index 58b9861ccf99..c2e5571c85d4 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -13844,6 +13844,13 @@ M:	Laxman Dewangan <ldewangan@nvidia.com>
> >> 
> >>  S:	Supported
> >>  F:	drivers/input/keyboard/tegra-kbc.c
> >> 
> >> +TEGRA NAND DRIVER
> >> +M:	Stefan Agner <stefan@agner.ch>
> >> +M:	Lucas Stach <dev@lynxeye.de>
> >> +S:	Maintained
> >> +F:	Documentation/devicetree/bindings/mtd/nvidia-tegra20-nand.txt
> >> +F:	drivers/mtd/nand/raw/tegra_nand.c
> >> +
> >> 
> >>  TEGRA PWM DRIVER
> >>  M:	Thierry Reding <thierry.reding@gmail.com>
> >>  S:	Supported
> >> 
> >> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> >> index 19a2b283fbbe..e9093f52371e 100644
> >> --- a/drivers/mtd/nand/raw/Kconfig
> >> +++ b/drivers/mtd/nand/raw/Kconfig
> >> @@ -534,4 +534,10 @@ config MTD_NAND_MTK
> >> 
> >>  	  Enables support for NAND controller on MTK SoCs.
> >>  	  This controller is found on mt27xx, mt81xx, mt65xx SoCs.
> >> 
> >> +config MTD_NAND_TEGRA
> >> +	tristate "Support for NAND controller on NVIDIA Tegra"
> >> +	depends on ARCH_TEGRA || COMPILE_TEST
> >> +	help
> >> +	  Enables support for NAND flash controller on NVIDIA Tegra SoC.
> >> +
> >> 
> >>  endif # MTD_NAND
> >> 
> >> diff --git a/drivers/mtd/nand/raw/Makefile
> >> b/drivers/mtd/nand/raw/Makefile
> >> index 165b7ef9e9a1..d5a5f9832b88 100644
> >> --- a/drivers/mtd/nand/raw/Makefile
> >> +++ b/drivers/mtd/nand/raw/Makefile
> >> @@ -56,6 +56,7 @@ obj-$(CONFIG_MTD_NAND_HISI504)	        +=
> >> hisi504_nand.o
> >> 
> >>  obj-$(CONFIG_MTD_NAND_BRCMNAND)		+= brcmnand/
> >>  obj-$(CONFIG_MTD_NAND_QCOM)		+= qcom_nandc.o
> >>  obj-$(CONFIG_MTD_NAND_MTK)		+= mtk_ecc.o mtk_nand.o
> >> 
> >> +obj-$(CONFIG_MTD_NAND_TEGRA)		+= tegra_nand.o
> >> 
> >>  nand-objs := nand_base.o nand_bbt.o nand_timings.o nand_ids.o
> >>  nand-objs += nand_amd.o
> >> 
> >> diff --git a/drivers/mtd/nand/raw/tegra_nand.c
> >> b/drivers/mtd/nand/raw/tegra_nand.c new file mode 100644
> >> index 000000000000..e9664f2938a3
> >> --- /dev/null
> >> +++ b/drivers/mtd/nand/raw/tegra_nand.c
> >> @@ -0,0 +1,1143 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * 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/delay.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 CMD					0x00
> >> +#define   CMD_GO				BIT(31)
> >> +#define   CMD_CLE				BIT(30)
> >> +#define   CMD_ALE				BIT(29)
> >> +#define   CMD_PIO				BIT(28)
> >> +#define   CMD_TX				BIT(27)
> >> +#define   CMD_RX				BIT(26)
> >> +#define   CMD_SEC_CMD				BIT(25)
> >> +#define   CMD_AFT_DAT				BIT(24)
> >> +#define   CMD_TRANS_SIZE(x)			(((x - 1) & 0xf) << 20)
> >> +#define   CMD_A_VALID				BIT(19)
> >> +#define   CMD_B_VALID				BIT(18)
> >> +#define   CMD_RD_STATUS_CHK			BIT(17)
> >> +#define   CMD_RBSY_CHK				BIT(16)
> >> +#define   CMD_CE(x)				BIT((8 + ((x) & 0x7)))
> >> +#define   CMD_CLE_SIZE(x)			(((x - 1) & 0x3) << 4)
> >> +#define   CMD_ALE_SIZE(x)			(((x - 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 CFG					0x10
> >> +#define   CFG_HW_ECC				BIT(31)
> >> +#define   CFG_ECC_SEL				BIT(30)
> >> +#define   CFG_ERR_COR				BIT(29)
> >> +#define   CFG_PIPE_EN				BIT(28)
> >> +#define   CFG_TVAL_4				(0 << 24)
> >> +#define   CFG_TVAL_6				(1 << 24)
> >> +#define   CFG_TVAL_8				(2 << 24)
> >> +#define   CFG_SKIP_SPARE			BIT(23)
> >> +#define   CFG_BUS_WIDTH_16			BIT(21)
> >> +#define   CFG_COM_BSY				BIT(20)
> >> +#define   CFG_PS_256				(0 << 16)
> >> +#define   CFG_PS_512				(1 << 16)
> >> +#define   CFG_PS_1024				(2 << 16)
> >> +#define   CFG_PS_2048				(3 << 16)
> >> +#define   CFG_PS_4096				(4 << 16)
> >> +#define   CFG_SKIP_SPARE_SIZE_4			(0 << 14)
> >> +#define   CFG_SKIP_SPARE_SIZE_8			(1 << 14)
> >> +#define   CFG_SKIP_SPARE_SIZE_12		(2 << 14)
> >> +#define   CFG_SKIP_SPARE_SIZE_16		(3 << 14)
> >> +#define   CFG_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_1					0x20
> >> +#define CMD_2					0x24
> >> +#define ADDR_1					0x28
> >> +#define ADDR_2					0x2c
> >> +
> >> +#define DMA_CTRL				0x30
> >> +#define   DMA_CTRL_GO				BIT(31)
> >> +#define   DMA_CTRL_IN				(0 << 30)
> >> +#define   DMA_CTRL_OUT				BIT(30)
> >> +#define   DMA_CTRL_PERF_EN			BIT(29)
> >> +#define   DMA_CTRL_IE_DONE			BIT(28)
> >> +#define   DMA_CTRL_REUSE			BIT(27)
> >> +#define   DMA_CTRL_BURST_1			(2 << 24)
> >> +#define   DMA_CTRL_BURST_4			(3 << 24)
> >> +#define   DMA_CTRL_BURST_8			(4 << 24)
> >> +#define   DMA_CTRL_BURST_16			(5 << 24)
> >> +#define   DMA_CTRL_IS_DONE			BIT(20)
> >> +#define   DMA_CTRL_EN_A				BIT(2)
> >> +#define   DMA_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
> >> +
> >> +struct tegra_nand_controller {
> >> +	struct nand_hw_control controller;
> >> +	void __iomem *regs;
> >> +	struct clk *clk;
> >> +	struct device *dev;
> >> +	struct completion command_complete;
> >> +	struct completion dma_complete;
> >> +	bool last_read_error;
> >> +	int cur_chip;
> >> +	struct nand_chip *chip;
> >> +};
> >> +
> >> +struct tegra_nand_chip {
> >> +	struct nand_chip chip;
> >> +	struct gpio_desc *wp_gpio;
> >> +	struct mtd_oob_region tag;
> >> +};
> >> +
> >> +static inline struct tegra_nand_controller *to_tegra_ctrl(
> >> +						struct nand_hw_control *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_rs_free(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 +
> >> +			    round_up(bytes_per_step * chip->ecc.steps, 4);
> >> +	oobregion->length = mtd->oobsize - oobregion->offset;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static const struct mtd_ooblayout_ops tegra_nand_oob_rs_ops = {
> >> +	.ecc = tegra_nand_ooblayout_rs_ecc,
> >> +	.free = tegra_nand_ooblayout_rs_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 int tegra_nand_ooblayout_bch_free(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 +
> >> +			    round_up(bytes_per_step * chip->ecc.steps, 4);
> >> +	oobregion->length = mtd->oobsize - oobregion->offset;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +/*
> >> + * Layout with tag bytes is
> >> + *
> >> + *
> >> ------------------------------------------------------------------------
> >> -- + * | main area                       | skip bytes | tag bytes |
> >> parity | .. | + *
> >> ------------------------------------------------------------------------
> >> -- + *
> >> + * If not tag bytes are written, parity moves right after skip bytes!
> >> + */
> >> +static const struct mtd_ooblayout_ops tegra_nand_oob_bch_ops = {
> >> +	.ecc = tegra_nand_ooblayout_bch_ecc,
> >> +	.free = tegra_nand_ooblayout_bch_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_CTRL);
> >> +	dev_dbg(ctrl->dev, "isr %08x\n", isr);
> >> +
> >> +	if (!isr && !(dma & DMA_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_CTRL_IS_DONE) {
> >> +		writel_relaxed(dma, ctrl->regs + DMA_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 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 |= CMD_CLE;
> >> +				writel_relaxed(instr->ctx.cmd.opcode,
> >> +					       ctrl->regs + CMD_1);
> >> +			} else {
> >> +				cmd |= CMD_SEC_CMD;
> >> +				writel_relaxed(instr->ctx.cmd.opcode,
> >> +					       ctrl->regs + CMD_2);
> >> +			}
> >> +			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 |= CMD_ALE | CMD_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_1);
> >> +			writel_relaxed(addr2, ctrl->regs + ADDR_2);
> >> +			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 |= CMD_TRANS_SIZE(size) | CMD_PIO | CMD_RX |
> >> +				CMD_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 |= CMD_TRANS_SIZE(size) | CMD_PIO | CMD_TX |
> >> +				CMD_A_VALID;
> >> +
> >> +			memcpy(&reg, instr->ctx.data.buf.out + offset, size);
> >> +			writel_relaxed(reg, ctrl->regs + RESP);
> >> +
> >> +			break;
> >> +		case NAND_OP_WAITRDY_INSTR:
> >> +			cmd |= CMD_RBSY_CHK;
> >> +			break;
> >> +
> >> +		}
> >> +	}
> >> +
> >> +	cmd |= CMD_GO | CMD_CE(ctrl->cur_chip);
> >> +	writel_relaxed(cmd, ctrl->regs + CMD);
> >> +	ret = wait_for_completion_timeout(&ctrl->command_complete,
> >> +					  msecs_to_jiffies(500));
> >> +	if (!ret) {
> >> +		dev_err(ctrl->dev, "CMD timeout\n");
> >> +		tegra_nand_dump_reg(ctrl);
> >> +		return -ETIMEDOUT;
> >> +	}
> > 
> > - wait_for_completion_timeout() could fail
> 
> Not according to:
> https://elixir.bootlin.com/linux/latest/source/kernel/sched/completion.c#L14
> 0 https://www.kernel.org/doc/Documentation/scheduler/completion.txt
> 
> Afaik, only the _interruptible variant can fail.

Okay.

> Btw, maybe we should use the _io variant?

Looks like the _io variant is something specific to block/FS subsys and 
shouldn't be used by the drivers.

> > - HW shall be reset
> > - completion shall be re-inited because IRQ could fire just after the
> > completion timeout
> > 
> > I'd write it something like this:
> > 
> > #define INT_MASK	(IER_UND | IER_OVR | IER_CMD_DONE | IER_GIE)
> > 
> > #define HWSTATUS_MASK	(HWSTATUS_RDSTATUS_MASK(1) |		 \
> > 
> > 			 HWSTATUS_RDSTATUS_VALUE(0) |		 \
> > 			 HWSTATUS_RBSY_MASK(NAND_STATUS_READY) | \
> > 			 HWSTATUS_RBSY_VALUE(NAND_STATUS_READY))
> > 
> > #define HW_TIMEOUT	500
> > 
> > void tegra_nand_controller_reset(struct tegra_nand_controller *ctrl)
> > {
> > 
> > 	int err;
> > 	
> > 	disable_irq(ctrl->irq);
> > 	
> > 	err = reset_control_reset(ctrl->rst);
> > 	if (err) {
> > 	
> > 		dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
> > 		msleep(HW_TIMEOUT);
> > 	
> > 	}
> > 	
> > 	writel_relaxed(NAND_CMD_STATUS, ctrl->regs + HWSTATUS_CMD);
> > 	writel_relaxed(HWSTATUS_MASK, ctrl->regs + HWSTATUS_MASK);
> > 	writel_relaxed(INT_MASK, ctrl->regs + ISR);
> 
> If we do a controller reset, there is much more state than that which
> needs to be restored. A lot of it is not readily available currently
> (timing, ECC settings...)
> 
> That seems a lot of work for a code path I do not intend to ever use :-)

Are you sure that resetting HW resets the timing and other registers 
configuration? Reset implementation is HW-specific, like for example in a case 
of a video decoder the registers state is re-intialized on HW reset, but 
registers configuration is untouched in a case of resetting GPU. I'd suggest 
to check whether NAND controller resetting affects the HW configuration.