Re: [RESEND PATCH 2/5] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver

[Stefan Agner <stefan@agner.ch>]

[review sent to my first patch sent off-ml, moving to ml thread]

On 21.05.2018 16:05, Dmitry Osipenko wrote:
> Hello Stefan,
> 
> I don't have expertise to review the actual NAND-related driver logic, so I only
> reviewed the basics. The driver code looks good to me, though I've couple minor
> comments.
> 
> On 21.05.2018 03:16, 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 | 915 ++++++++++++++++++++++++++++++
>>  4 files changed, 929 insertions(+)
>>  create mode 100644 drivers/mtd/nand/raw/tegra_nand.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 58b9861ccf99..a65739681279 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/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..bd56264233ca 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 on NVIDIA Tegra"
>> +	depends on ARCH_TEGRA
>> +	help
>> +	  Enables support for NAND flash on NVIDIA Tegra SoC based boards.
>> +
>>  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..fa236e683fb8
>> --- /dev/null
>> +++ b/drivers/mtd/nand/raw/tegra_nand.c
>> @@ -0,0 +1,915 @@
>> +/*
>> + * Copyright (C) 2018 Stefan Agner <stefan@agner.ch>
>> + * Copyright (C) 2014-2015 Lucas Stach <dev@lynxeye.de>
>> + * Copyright (C) 2012 Avionic Design GmbH
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#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				(1 << 31)
>> +#define   CMD_CLE				(1 << 30)
>> +#define   CMD_ALE				(1 << 29)
>> +#define   CMD_PIO				(1 << 28)
>> +#define   CMD_TX				(1 << 27)
>> +#define   CMD_RX				(1 << 26)
>> +#define   CMD_SEC_CMD				(1 << 25)
>> +#define   CMD_AFT_DAT				(1 << 24)
>> +#define   CMD_TRANS_SIZE(x)			(((x - 1) & 0xf) << 20)
>> +#define   CMD_A_VALID				(1 << 19)
>> +#define   CMD_B_VALID				(1 << 18)
>> +#define   CMD_RD_STATUS_CHK			(1 << 17)
>> +#define   CMD_RBSY_CHK				(1 << 16)
>> +#define   CMD_CE(x)				(1 << (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			(1 << 24)
>> +#define   ISR_UND				(1 << 7)
>> +#define   ISR_OVR				(1 << 6)
>> +#define   ISR_CMD_DONE				(1 << 5)
>> +#define   ISR_ECC_ERR				(1 << 4)
>> +
>> +#define IER					0x0c
>> +#define   IER_ERR_TRIG_VAL(x)			(((x) & 0xf) << 16)
>> +#define   IER_UND				(1 << 7)
>> +#define   IER_OVR				(1 << 6)
>> +#define   IER_CMD_DONE				(1 << 5)
>> +#define   IER_ECC_ERR				(1 << 4)
>> +#define   IER_GIE				(1 << 0)
>> +
>> +#define CFG					0x10
>> +#define   CFG_HW_ECC				(1 << 31)
>> +#define   CFG_ECC_SEL				(1 << 30)
>> +#define   CFG_ERR_COR				(1 << 29)
>> +#define   CFG_PIPE_EN				(1 << 28)
>> +#define   CFG_TVAL_4				(0 << 24)
>> +#define   CFG_TVAL_6				(1 << 24)
>> +#define   CFG_TVAL_8				(2 << 24)
>> +#define   CFG_SKIP_SPARE			(1 << 23)
>> +#define   CFG_BUS_WIDTH_8			(0 << 21)
>> +#define   CFG_BUS_WIDTH_16			(1 << 21)
>> +#define   CFG_COM_BSY				(1 << 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) & 0xf) <<  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				(1 << 31)
>> +#define   DMA_CTRL_IN				(0 << 30)
>> +#define   DMA_CTRL_OUT				(1 << 30)
>> +#define   DMA_CTRL_PERF_EN			(1 << 29)
>> +#define   DMA_CTRL_IE_DONE			(1 << 28)
>> +#define   DMA_CTRL_REUSE			(1 << 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			(1 << 20)
>> +#define   DMA_CTRL_EN_A				(1 <<  2)
>> +#define   DMA_CTRL_EN_B				(1 <<  1)
>> +
>> +#define DMA_CFG_A				0x34
>> +#define DMA_CFG_B				0x38
>> +
>> +#define FIFO_CTRL				0x3c
>> +#define   FIFO_CTRL_CLR_ALL			(1 << 3)
>> +
>> +#define DATA_PTR				0x40
>> +#define TAG_PTR					0x44
>> +#define ECC_PTR					0x48
>> +
>> +#define DEC_STATUS				0x4c
>> +#define   DEC_STATUS_A_ECC_FAIL			(1 << 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 DEC_STAT_RESULT				0xd0
>> +#define DEC_STAT_BUF				0xd4
>> +#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
>> +
>> +struct tegra_nand {
>> +	void __iomem *regs;
>> +	struct clk *clk;
>> +	struct gpio_desc *wp_gpio;
>> +
>> +	struct nand_chip chip;
>> +	struct device *dev;
>> +
>> +	struct completion command_complete;
>> +	struct completion dma_complete;
>> +	bool last_read_error;
>> +
>> +	dma_addr_t data_dma;
>> +	void *data_buf;
>> +	dma_addr_t oob_dma;
>> +	void *oob_buf;
>> +
>> +	int cur_chip;
>> +};
>> +
>> +static inline struct tegra_nand *to_tegra_nand(struct mtd_info *mtd)
>> +{
>> +	struct nand_chip *chip = mtd_to_nand(mtd);
>> +
>> +	return nand_get_controller_data(chip);
>> +}
>> +
>> +static int tegra_nand_ooblayout_16_ecc(struct mtd_info *mtd, int section,
>> +				       struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 4;
>> +	oobregion->length = 4;
>> +
>> +	return 0;
>> +}
>> +
>> +static int tegra_nand_ooblayout_16_free(struct mtd_info *mtd, int section,
>> +					struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 8;
>> +	oobregion->length = 8;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct mtd_ooblayout_ops tegra_nand_oob_16_ops = {
>> +	.ecc = tegra_nand_ooblayout_16_ecc,
>> +	.free = tegra_nand_ooblayout_16_free,
>> +};
>> +
>> +static int tegra_nand_ooblayout_64_ecc(struct mtd_info *mtd, int section,
>> +				       struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 4;
>> +	oobregion->length = 36;
>> +
>> +	return 0;
>> +}
>> +
>> +static int tegra_nand_ooblayout_64_free(struct mtd_info *mtd, int section,
>> +					struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 40;
>> +	oobregion->length = 24;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct mtd_ooblayout_ops tegra_nand_oob_64_ops = {
>> +	.ecc = tegra_nand_ooblayout_64_ecc,
>> +	.free = tegra_nand_ooblayout_64_free,
>> +};
>> +
>> +static int tegra_nand_ooblayout_128_ecc(struct mtd_info *mtd, int section,
>> +				       struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 4;
>> +	oobregion->length = 72;
>> +
>> +	return 0;
>> +}
>> +
>> +static int tegra_nand_ooblayout_128_free(struct mtd_info *mtd, int section,
>> +					struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 76;
>> +	oobregion->length = 52;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct mtd_ooblayout_ops tegra_nand_oob_128_ops = {
>> +	.ecc = tegra_nand_ooblayout_128_ecc,
>> +	.free = tegra_nand_ooblayout_128_free,
>> +};
>> +
>> +static int tegra_nand_ooblayout_224_ecc(struct mtd_info *mtd, int section,
>> +				       struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 4;
>> +	oobregion->length = 144;
>> +
>> +	return 0;
>> +}
>> +
>> +static int tegra_nand_ooblayout_224_free(struct mtd_info *mtd, int section,
>> +					struct mtd_oob_region *oobregion)
>> +{
>> +	if (section > 0)
>> +		return -ERANGE;
>> +
>> +	oobregion->offset = 148;
>> +	oobregion->length = 76;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct mtd_ooblayout_ops tegra_nand_oob_224_ops = {
>> +	.ecc = tegra_nand_ooblayout_224_ecc,
>> +	.free = tegra_nand_ooblayout_224_free,
>> +};
>> +
>> +static irqreturn_t tegra_nand_irq(int irq, void *data)
>> +{
>> +	struct tegra_nand *nand = data;
>> +	u32 isr, dma;
>> +
>> +	isr = readl(nand->regs + ISR);
>> +	dma = readl(nand->regs + DMA_CTRL);
> 
> You could use readl_relaxed() here.
> 
>> +	dev_dbg(nand->dev, "isr %08x\n", isr);
>> +
>> +	if (!isr && !(dma & DMA_CTRL_IS_DONE))
>> +		return IRQ_NONE;
>> +
>> +	if (isr & ISR_CORRFAIL_ERR)
>> +		nand->last_read_error = true;
>> +
>> +	if (isr & ISR_CMD_DONE)
>> +		complete(&nand->command_complete);
>> +
>> +	if (isr & ISR_UND)
>> +		dev_dbg(nand->dev, "FIFO underrun\n");
>> +
>> +	if (isr & ISR_OVR)
>> +		dev_dbg(nand->dev, "FIFO overrun\n");
>> +
>> +	/* handle DMA interrupts */
>> +	if (dma & DMA_CTRL_IS_DONE) {
>> +		writel(dma, nand->regs + DMA_CTRL);
>> +		complete(&nand->dma_complete);
>> +	}
>> +
>> +	/* clear interrupts */
>> +	writel(isr, nand->regs + ISR);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +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 mtd_info *mtd = nand_to_mtd(chip);
>> +	struct tegra_nand *nand = to_tegra_nand(mtd);
>> +	unsigned int op_id = -1, trfr_in_sz = 0, trfr_out_sz = 0, offset = 0;
>> +	bool first_cmd = true;
>> +	bool force8bit;
> 
> The force8bit variable isn't used anywhere in the code, so compiler should warn
> you about the "unused variable", is it the case?
> 
>> +	u32 cmd = 0;
>> +	u32 value;
>> +
> 
> The op_id=-1 above is probably because the loop below was:
> 
> 	while (++op_id < subop->ninstrs) {}
> 
> Both variants are fine, but the for-loop is a bit more explicit. You could omit
> the above op_id variable initialization for consistency.
> 

Agreed, will do the for loop variant.

>> +	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(instr->ctx.cmd.opcode, nand->regs + CMD_1);
>> +			} else {
>> +				cmd |= CMD_SEC_CMD;
>> +				writel(instr->ctx.cmd.opcode, nand->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++ << (8 * i);
>> +			naddrs -= i;
>> +			for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
>> +				addr2 |= *addrs++ << (8 * i);
>> +			writel(addr1, nand->regs + ADDR_1);
>> +			writel(addr2, nand->regs + ADDR_2);
>> +			break;
>> +
>> +		case NAND_OP_DATA_IN_INSTR:
>> +			trfr_in_sz = nand_subop_get_data_len(subop, op_id);
>> +			offset = nand_subop_get_data_start_off(subop, op_id);
>> +
>> +			cmd |= CMD_TRANS_SIZE(trfr_in_sz) | CMD_PIO | CMD_RX | CMD_A_VALID;
>> +
>> +			instr_data_in = instr;
>> +			break;
>> +
>> +		case NAND_OP_DATA_OUT_INSTR:
>> +			trfr_out_sz = nand_subop_get_data_len(subop, op_id);
>> +			offset = nand_subop_get_data_start_off(subop, op_id);
>> +			trfr_out_sz = min_t(size_t, trfr_out_sz, 4);
>> +
>> +			cmd |= CMD_TRANS_SIZE(trfr_out_sz) | CMD_PIO | CMD_TX | CMD_A_VALID;
>> +
>> +			memcpy(&value, instr->ctx.data.buf.out + offset, trfr_out_sz)> +			writel(value, nand->regs + RESP);
> 
> Note:
> 
> The memcpy + readl / writel won't work with a big-endian kernel,
> cpu_to_[bl]e32() should be applied in a such cases.
> 
> Tegra's I2C driver had a similar memcpy-case issue, it was corrected during the
> attempt to get BE kernel support for Tegra. But that attempt was quite long time
> ago and Tegra maintainers were not very excited to have to do more testing work
> for each kernel release and hence Tegra is LE-only as of today.
> 
>> +
>> +			break;
>> +		case NAND_OP_WAITRDY_INSTR:
>> +			cmd |= CMD_RBSY_CHK;
>> +			break;
>> +
>> +		}
>> +	}
>> +
>> +
>> +	cmd |= CMD_GO | CMD_CE(nand->cur_chip);
>> +	writel(cmd, nand->regs + CMD);
>> +	wait_for_completion(&nand->command_complete);
>> +
>> +	if (instr_data_in) {
>> +		u32 value;
>> +		size_t n = min_t(size_t, trfr_in_sz, 4);
>> +
>> +		value = readl(nand->regs + RESP);
>> +		memcpy(instr_data_in->ctx.data.buf.in + offset, &value, n);
>> +	}
>> +
>> +	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 chip)
>> +{
>> +	struct tegra_nand *nand = to_tegra_nand(mtd);
>> +
>> +	nand->cur_chip = chip;
>> +}
>> +
>> +static u32 tegra_nand_fill_address(struct mtd_info *mtd, struct nand_chip *chip,
>> +				   int page)
>> +{
>> +	struct tegra_nand *nand = to_tegra_nand(mtd);
>> +
>> +	/* Lower 16-bits are column, always 0 */
>> +	writel(page << 16, nand->regs + ADDR_1);
>> +
>> +	if (chip->options & NAND_ROW_ADDR_3) {
>> +		writel(page >> 16, nand->regs + ADDR_2);
>> +		return 5;
>> +	}
>> +
>> +	return 4;
>> +}
>> +
>> +static int tegra_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
>> +				uint8_t *buf, int oob_required, int page)
>> +{
>> +	struct tegra_nand *nand = to_tegra_nand(mtd);
>> +	u32 value, addrs;
>> +
>> +	writel(NAND_CMD_READ0, nand->regs + CMD_1);
>> +	writel(NAND_CMD_READSTART, nand->regs + CMD_2);
>> +
>> +	addrs = tegra_nand_fill_address(mtd, chip, page);
>> +
>> +	value = readl(nand->regs + CFG);
>> +	value |= CFG_HW_ECC | CFG_ERR_COR;
>> +	writel(value, nand->regs + CFG);
>> +
>> +	writel(mtd->writesize - 1, nand->regs + DMA_CFG_A);
>> +	writel(nand->data_dma, nand->regs + DATA_PTR);
>> +
>> +	if (oob_required) {
>> +		writel(mtd_ooblayout_count_freebytes(mtd) - 1,
>> +		       nand->regs + DMA_CFG_B);
>> +		writel(nand->oob_dma, nand->regs + TAG_PTR);
>> +	} else {
>> +		writel(0, nand->regs + DMA_CFG_B);
>> +		writel(0, nand->regs + TAG_PTR);
>> +	}
>> +
>> +	value = DMA_CTRL_GO | DMA_CTRL_IN | DMA_CTRL_PERF_EN |
>> +		DMA_CTRL_REUSE | DMA_CTRL_IE_DONE | DMA_CTRL_IS_DONE |
>> +		DMA_CTRL_BURST_8 | DMA_CTRL_EN_A;
> 
> Wouldn't be more efficient to set DMA burst to 16 words? The writesize seems
> always aligned to at least 64 words.
> 

Hm, haven't tested 16 words, 8 was the setting Lucas used.

Are you sure this is only about write size? Not sure, but isn't the ECC
area also DMA'd? On Colibri we use RS with t=8, hence 144 bytes parity,
so this would be properly aligned non the less...

>> +	if (oob_required)
>> +		value |= DMA_CTRL_EN_B;
>> +	writel(value, nand->regs + DMA_CTRL);
>> +
>> +	value = CMD_CLE | CMD_ALE | CMD_ALE_SIZE(addrs) | CMD_SEC_CMD |
>> +		CMD_RBSY_CHK | CMD_GO | CMD_RX | CMD_TRANS_SIZE(9) |
>> +		CMD_A_VALID | CMD_CE(nand->cur_chip);
>> +	if (oob_required)
>> +		value |= CMD_B_VALID;
>> +	writel(value, nand->regs + CMD);
>> +
>> +	wait_for_completion(&nand->command_complete);
>> +	wait_for_completion(&nand->dma_complete);
>> +
>> +	if (oob_required) {
>> +		struct mtd_oob_region oobregion;
>> +
>> +		mtd_ooblayout_free(mtd, 0, &oobregion);
>> +		memcpy(chip->oob_poi, nand->oob_buf + oobregion.offset,
>> +		       mtd_ooblayout_count_freebytes(mtd));
>> +	}
>> +	memcpy(buf, nand->data_buf, mtd->writesize);
>> +
>> +	value = readl(nand->regs + CFG);
>> +	value &= ~(CFG_HW_ECC | CFG_ERR_COR);
>> +	writel(value, nand->regs + CFG);
>> +
>> +	value = readl(nand->regs + DEC_STATUS);
>> +	if (value & DEC_STATUS_A_ECC_FAIL) {
>> +		/*
>> +		 * The ECC isn't smart enough to figure out if a page is
>> +		 * completely erased and flags an error in this case. So we
>> +		 * check the read data here to figure out if it's a legitimate
>> +		 * error or a false positive.
>> +		 */
>> +		int i, err;
>> +		int flips_threshold = chip->ecc.strength / 2;
>> +		int max_bitflips = 0;
>> +
>> +		for (i = 0; i < chip->ecc.steps; i++) {
>> +			u8 *data = buf + (chip->ecc.size * i);
>> +			err = nand_check_erased_ecc_chunk(data, chip->ecc.size,
>> +							  NULL, 0,
>> +							  NULL, 0,
>> +							  flips_threshold);
>> +			if (err < 0)
>> +				return err;
>> +
>> +			max_bitflips += max_bitflips;
>> +		}
>> +
>> +		return max_bitflips;
>> +	}
>> +
>> +	if (nand->last_read_error) {
>> +		int max_corr_cnt, corr_sec_flag;
>> +
>> +		value = readl(nand->regs + DEC_STAT_BUF);
>> +		corr_sec_flag = (value & DEC_STAT_BUF_CORR_SEC_FLAG_MASK) >>
>> +				DEC_STAT_BUF_CORR_SEC_FLAG_SHIFT;
>> +		max_corr_cnt = (value & DEC_STAT_BUF_MAX_CORR_CNT_MASK) >>
>> +			       DEC_STAT_BUF_MAX_CORR_CNT_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);
>> +		nand->last_read_error = false;
>> +		return value;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int tegra_nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
>> +				 const uint8_t *buf, int oob_required, int page)
>> +{
>> +	struct tegra_nand *nand = to_tegra_nand(mtd);
>> +	u32 value, addrs;
>> +
>> +	writel(NAND_CMD_SEQIN, nand->regs + CMD_1);
>> +	writel(NAND_CMD_PAGEPROG, nand->regs + CMD_2);
>> +
>> +	addrs = tegra_nand_fill_address(mtd, chip, page);
>> +
>> +	value = readl(nand->regs + CFG);
>> +	value |= CFG_HW_ECC | CFG_ERR_COR;
>> +	writel(value, nand->regs + CFG);
>> +
>> +	memcpy(nand->data_buf, buf, mtd->writesize);
>> +
>> +	writel(mtd->writesize - 1, nand->regs + DMA_CFG_A);
>> +	writel(nand->data_dma, nand->regs + DATA_PTR);
>> +
>> +	if (oob_required) {
>> +		struct mtd_oob_region oobregion;
>> +
>> +		mtd_ooblayout_free(mtd, 0, &oobregion);
>> +		memcpy(nand->oob_buf, chip->oob_poi + oobregion.offset,
>> +		       mtd_ooblayout_count_freebytes(mtd));
>> +		writel(mtd_ooblayout_count_freebytes(mtd) - 1,
>> +		       nand->regs + DMA_CFG_B);
>> +		writel(nand->oob_dma, nand->regs + TAG_PTR);
>> +	} else {
>> +		writel(0, nand->regs + DMA_CFG_B);
>> +		writel(0, nand->regs + TAG_PTR);
>> +	}
>> +
>> +	value = DMA_CTRL_GO | DMA_CTRL_OUT | DMA_CTRL_PERF_EN |
>> +		DMA_CTRL_IE_DONE | DMA_CTRL_IS_DONE |
>> +		DMA_CTRL_BURST_8 | DMA_CTRL_EN_A;
>> +	if (oob_required)
>> +		value |= DMA_CTRL_EN_B;
>> +	writel(value, nand->regs + DMA_CTRL);
>> +
>> +	value = CMD_CLE | CMD_ALE | CMD_ALE_SIZE(addrs) | CMD_SEC_CMD |
>> +		CMD_AFT_DAT | CMD_RBSY_CHK | CMD_GO | CMD_TX | CMD_A_VALID |
>> +		CMD_TRANS_SIZE(9) | CMD_CE(nand->cur_chip);
>> +	if (oob_required)
>> +		value |= CMD_B_VALID;
>> +	writel(value, nand->regs + CMD);
>> +
>> +	wait_for_completion(&nand->command_complete);
>> +	wait_for_completion(&nand->dma_complete);
>> +
>> +	value = readl(nand->regs + CFG);
>> +	value &= ~(CFG_HW_ECC | CFG_ERR_COR);
>> +	writel(value, nand->regs + CFG);
>> +
>> +	return 0;
>> +}
>> +
>> +static void tegra_nand_setup_timing(struct tegra_nand *nand, int mode)
>> +{
>> +	/*
>> +	 * 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(nand->clk) / 1000000;
>> +	unsigned int period = DIV_ROUND_UP(1000000, rate);
>> +	const struct nand_sdr_timings *timings;
>> +	u32 val, reg = 0;
>> +
>> +	timings = onfi_async_timing_mode_to_sdr_timings(mode);
>> +
>> +	val = DIV_ROUND_UP(max3(timings->tAR_min, timings->tRR_min,
>> +				timings->tRC_min), period);
>> +	if (val > 2)
>> +		val -= 3;
>> +	reg |= TIMING_TCR_TAR_TRR(val);
>> +
>> +	val = DIV_ROUND_UP(max(max(timings->tCS_min, timings->tCH_min),
>> +				   max(timings->tALS_min, timings->tALH_min)),
>> +			   period);
>> +	if (val > 1)
>> +		val -= 2;
>> +	reg |= TIMING_TCS(val);
>> +
>> +	val = DIV_ROUND_UP(max(timings->tRP_min, timings->tREA_max) + 6000,
>> +			   period);
>> +	reg |= TIMING_TRP(val) | TIMING_TRP_RESP(val);
>> +
>> +	reg |= TIMING_TWB(DIV_ROUND_UP(timings->tWB_max, period));
>> +	reg |= TIMING_TWHR(DIV_ROUND_UP(timings->tWHR_min, period));
>> +	reg |= TIMING_TWH(DIV_ROUND_UP(timings->tWH_min, period));
>> +	reg |= TIMING_TWP(DIV_ROUND_UP(timings->tWP_min, period));
>> +	reg |= TIMING_TRH(DIV_ROUND_UP(timings->tRHW_min, period));
>> +
>> +	writel(reg, nand->regs + TIMING_1);
>> +
>> +	val = DIV_ROUND_UP(timings->tADL_min, period);
>> +	if (val > 2)
>> +		val -= 3;
>> +	reg = TIMING_TADL(val);
>> +
>> +	writel(reg, nand->regs + TIMING_2);
>> +}
>> +
>> +static void tegra_nand_setup_chiptiming(struct tegra_nand *nand)
>> +{
>> +	struct nand_chip *chip = &nand->chip;
>> +	int mode;
>> +
>> +	mode = onfi_get_async_timing_mode(chip);
>> +	if (mode == ONFI_TIMING_MODE_UNKNOWN)
>> +		mode = chip->onfi_timing_mode_default;
>> +	else
>> +		mode = fls(mode);
>> +
>> +	tegra_nand_setup_timing(nand, mode);
>> +}
>> +
>> +static int tegra_nand_probe(struct platform_device *pdev)
>> +{
>> +	struct reset_control *rst;
>> +	struct tegra_nand *nand;
>> +	struct nand_chip *chip;
>> +	struct mtd_info *mtd;
>> +	struct resource *res;
>> +	unsigned long value;
>> +	int irq, err = 0;
>> +
>> +	nand = devm_kzalloc(&pdev->dev, sizeof(*nand), GFP_KERNEL);
>> +	if (!nand)
>> +		return -ENOMEM;
>> +
>> +	nand->dev = &pdev->dev;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	nand->regs = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(nand->regs))
>> +		return PTR_ERR(nand->regs);
>> +
>> +	irq = platform_get_irq(pdev, 0);
>> +	err = devm_request_irq(&pdev->dev, irq, tegra_nand_irq, 0,
>> +			       dev_name(&pdev->dev), nand);
>> +	if (err)
>> +		return err;
>> +
>> +	rst = devm_reset_control_get(&pdev->dev, "nand");
>> +	if (IS_ERR(rst))
>> +		return PTR_ERR(rst);
>> +
>> +	nand->clk = devm_clk_get(&pdev->dev, "nand");
>> +	if (IS_ERR(nand->clk))
>> +		return PTR_ERR(nand->clk);
>> +
>> +	nand->wp_gpio = gpiod_get_optional(&pdev->dev, "wp-gpios",
>> +					   GPIOD_OUT_HIGH);
>> +	if (IS_ERR(nand->wp_gpio))
>> +		return PTR_ERR(nand->wp_gpio);
>> +
>> +	err = clk_prepare_enable(nand->clk);
>> +	if (err)
>> +		return err;
>> +
>> +	reset_control_assert(rst);
>> +	udelay(2);
>> +	reset_control_deassert(rst);
> 
> You could use the reset_control_reset() here, though it uses the 1 usec delay
> instead of 2, but I think it shouldn't really matter.
> 
>> +
>> +	value = HWSTATUS_RDSTATUS_MASK(1) | HWSTATUS_RDSTATUS_VALUE(0) |
>> +		HWSTATUS_RBSY_MASK(NAND_STATUS_READY) |
>> +		HWSTATUS_RBSY_VALUE(NAND_STATUS_READY);
>> +	writel(NAND_CMD_STATUS, nand->regs + HWSTATUS_CMD);
>> +	writel(value, nand->regs + HWSTATUS_MASK);
>> +
>> +	init_completion(&nand->command_complete);
>> +	init_completion(&nand->dma_complete);
>> +
>> +	/* clear interrupts */
>> +	value = readl(nand->regs + ISR);
>> +	writel(value, nand->regs + ISR);
> 
> Isn't a set ISR bit means that NAND HW asserts interrupt line? If yes, then you
> may want to move devm_request_irq() after resetting the HW state, to be on a
> safe side.
> 

Agreed.

>> +
>> +	writel(DMA_CTRL_IS_DONE, nand->regs + DMA_CTRL);
>> +
>> +	/* enable interrupts */
>> +	value = IER_UND | IER_OVR | IER_CMD_DONE | IER_ECC_ERR | IER_GIE;
>> +	writel(value, nand->regs + IER);
>> +
>> +	/* reset config */
>> +	writel(0, nand->regs + CFG);
> 
> Is this "reset config" really needed? It is overwritten below in the code.
> 

We already use the NAND peripheral in nand_scan_ident, and then properly
set it up later. I think it is better to have a known config state
during this phase...

> 
> Also, maybe you could factor out the HW reset/init stuff into a respective
> tegra_nand_hw_reset() / tegra_nand_hw_init(), just for consistency.
> 

I will consider that.

Thanks for your review!

--
Stefan

>> +
>> +	chip = &nand->chip;
>> +	mtd = nand_to_mtd(chip);
>> +
>> +	mtd->dev.parent = &pdev->dev;
>> +	mtd->name = "tegra_nand";
>> +	mtd->owner = THIS_MODULE;
>> +
>> +	nand_set_flash_node(chip, pdev->dev.of_node);
>> +	nand_set_controller_data(chip, nand);
>> +
>> +	chip->options = NAND_NO_SUBPAGE_WRITE;
>> +	chip->exec_op = tegra_nand_exec_op;
>> +	chip->select_chip = tegra_nand_select_chip;
>> +	tegra_nand_setup_timing(nand, 0);
>> +
>> +	err = nand_scan_ident(mtd, 1, NULL);
>> +	if (err)
>> +		goto err_disable_clk;
>> +
>> +	if (chip->bbt_options & NAND_BBT_USE_FLASH)
>> +		chip->bbt_options |= NAND_BBT_NO_OOB;
>> +
>> +	nand->data_buf = dmam_alloc_coherent(&pdev->dev, mtd->writesize,
>> +					    &nand->data_dma, GFP_KERNEL);
>> +	if (!nand->data_buf) {
>> +		err = -ENOMEM;
>> +		goto err_disable_clk;
>> +	}
>> +
>> +	nand->oob_buf = dmam_alloc_coherent(&pdev->dev, mtd->oobsize,
>> +					    &nand->oob_dma, GFP_KERNEL);
>> +	if (!nand->oob_buf) {
>> +		err = -ENOMEM;
>> +		goto err_disable_clk;
>> +	}
>> +
>> +	chip->ecc.mode = NAND_ECC_HW;
>> +	chip->ecc.size = 512;
>> +	chip->ecc.read_page = tegra_nand_read_page;
>> +	chip->ecc.write_page = tegra_nand_write_page;
>> +
>> +	value = readl(nand->regs + CFG);
>> +	value |= CFG_PIPE_EN | CFG_SKIP_SPARE | CFG_SKIP_SPARE_SIZE_4 |
>> +		 CFG_TAG_BYTE_SIZE(mtd_ooblayout_count_freebytes(mtd) - 1);
>> +
>> +	if (chip->options & NAND_BUSWIDTH_16)
>> +		value |= CFG_BUS_WIDTH_16;
>> +
>> +	switch (mtd->oobsize) {
>> +	case 16:
>> +		mtd_set_ooblayout(mtd, &tegra_nand_oob_16_ops);
>> +		chip->ecc.strength = 1;
>> +		chip->ecc.bytes = 4;
>> +		break;
>> +	case 64:
>> +		mtd_set_ooblayout(mtd, &tegra_nand_oob_64_ops);
>> +		chip->ecc.strength = 8;
>> +		chip->ecc.bytes = 18;
>> +		value |= CFG_ECC_SEL | CFG_TVAL_8;
>> +		break;
>> +	case 128:
>> +		mtd_set_ooblayout(mtd, &tegra_nand_oob_128_ops);
>> +		chip->ecc.strength = 8;
>> +		chip->ecc.bytes = 18;
>> +		value |= CFG_ECC_SEL | CFG_TVAL_8;
>> +		break;
>> +	case 224:
>> +		mtd_set_ooblayout(mtd, &tegra_nand_oob_224_ops);
>> +		chip->ecc.strength = 8;
>> +		chip->ecc.bytes = 18;
>> +		value |= CFG_ECC_SEL | CFG_TVAL_8;
>> +		break;
>> +	default:
>> +		dev_err(&pdev->dev, "unhandled OOB size %d\n", mtd->oobsize);
>> +		err = -ENODEV;
>> +		goto err_disable_clk;
>> +	}
>> +
>> +	switch (mtd->writesize) {
>> +	case 256:
>> +		value |= CFG_PS_256;
>> +		break;
>> +	case 512:
>> +		value |= CFG_PS_512;
>> +		break;
>> +	case 1024:
>> +		value |= CFG_PS_1024;
>> +		break;
>> +	case 2048:
>> +		value |= CFG_PS_2048;
>> +		break;
>> +	case 4096:
>> +		value |= CFG_PS_4096;
>> +		break;
>> +	default:
>> +		dev_err(&pdev->dev, "unhandled writesize %d\n", mtd->writesize);
>> +		err = -ENODEV;
>> +		goto err_disable_clk;
>> +	}
>> +
>> +	writel(value, nand->regs + CFG);
>> +
>> +	tegra_nand_setup_chiptiming(nand);
>> +
>> +	err = nand_scan_tail(mtd);
>> +	if (err)
>> +		goto err_disable_clk;
>> +
>> +	err = mtd_device_register(mtd, NULL, 0);
>> +	if (err)
>> +		goto err_cleanup_nand;
>> +
>> +	platform_set_drvdata(pdev, nand);
>> +
>> +	return 0;
>> +
>> +err_cleanup_nand:
>> +	nand_cleanup(chip);
>> +err_disable_clk:
>> +	clk_disable_unprepare(nand->clk);
>> +	return err;
>> +}
>> +
>> +static int tegra_nand_remove(struct platform_device *pdev)
>> +{
>> +	struct tegra_nand *nand = platform_get_drvdata(pdev);
>> +
>> +	nand_release(nand_to_mtd(&nand->chip));
>> +
>> +	clk_disable_unprepare(nand->clk);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id tegra_nand_of_match[] = {
>> +	{ .compatible = "nvidia,tegra20-nand" },
>> +	{ /* sentinel */ }
>> +};
>> +
>> +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");
>> +MODULE_DEVICE_TABLE(of, tegra_nand_of_match);
>>