Subject: Re: [PATCH v12 2/8] mtd: rawnand: rockchip: NFC drivers for RK3308, RK2928 and others

From: Johan Jonker <[email-masked]>
Date: Tue, 20 Oct 2020 18:05:31 +0200

Hi Yifeng, Miquèl and others,

I've copied some comments from Miquèl from version 8 to this one here
and added some more. ;)

On 10/20/20 5:17 AM, Yifeng Zhao wrote:
> This driver supports Rockchip NFC (NAND Flash Controller) found on RK3308,
> RK2928, RKPX30, RV1108 and other SOCs. The driver has been tested using
> 8-bit NAND interface on the ARM based RK3308 platform.
>
> Support Rockchip SoCs and NFC versions:
> - PX30 and RK3326(NFCv900).
> 	ECC: 16/40/60/70 bits/1KB.
> 	CLOCK: ahb and nfc.
> - RK3308 and RV1108(NFCv800).
> 	ECC: 16 bits/1KB.
> 	CLOCK: ahb and nfc.
> - RK3036 and RK3128(NFCv622).
> 	ECC: 16/24/40/60 bits/1KB.
> 	CLOCK: ahb and nfc.
> - RK3066, RK3188 and RK2928(NFCv600).
> 	ECC: 16/24/40/60 bits/1KB.
> 	CLOCK: ahb.
>
> Supported features:
> - Read full page data by DMA.
> - Support HW ECC(one step is 1KB).
> - Support 2 - 32K page size.
> - Support 8 CS(depend on SoCs)
>
> Limitations:
> - No support for the ecc step size is 512.
> - Untested on some SoCs.
> - No support for subpages.
> - No support for the builtin randomizer.
> - The original bad block mask is not supported. It is recommended to use
>   the BBT(bad block table).
>
> Signed-off-by: Yifeng Zhao <[email-masked]>
> ---
>
> (no changes since v11)
>
> Changes in v11:
> - Fix compile error.
>
> Changes in v10:
> - Fix compile error on master v5.9-rc7.
>
> Changes in v9:
> - The nfc->buffer will realloc while the page size of the second mtd
>   is large than the first one
> - Fix coding style.
> - Remove struct rk_nfc_clk.
> - Prepend some function with rk_nfc_.
> - Replace function readl_poll_timeout_atomic with
readl_relaxed_poll_timeout.
> - Remove function rk_nfc_read_byte and rk_nfc_write_byte.
> - Don't select the die if 'check_only == true' in function rk_nfc_exec_op.
> - Modify function rk_nfc_write_page and rk_nfc_write_page_raw.
>
> Changes in v7:
> - Rebase to linux-next.
> - Fix coding style.
> - Reserved 4 bytes at the beginning of the oob area.
> - Page raw read and write included ecc data.
>
> Changes in v6:
> - The mtd->name set by NAND label property.
> - Add some comments.
> - Fix compile error.
>
> Changes in v5:
> - Add boot blocks support  with different ECC for bootROM.
> - Rename rockchip-nand.c to rockchip-nand-controller.c.
> - Unification of other variable names.
> - Remove some compatible define.
>
> Changes in v4:
> - Define platform data structure for the register offsets.
> - The compatible define with rkxx_nfc.
> - Use SET_SYSTEM_SLEEP_PM_OPS to define PM_OPS.
> - Use exec_op instead of legacy hooks.
>
> Changes in v2:
> - Fix compile error.
> - Include header files sorted by file name.
>
>  drivers/mtd/nand/raw/Kconfig                  |   12 +
>  drivers/mtd/nand/raw/Makefile                 |    1 +
>  .../mtd/nand/raw/rockchip-nand-controller.c   | 1439 +++++++++++++++++
>  3 files changed, 1452 insertions(+)
>  create mode 100644 drivers/mtd/nand/raw/rockchip-nand-controller.c
>
> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> index 6c46f25b57e2..2cc533e4e239 100644
> --- a/drivers/mtd/nand/raw/Kconfig
> +++ b/drivers/mtd/nand/raw/Kconfig
> @@ -462,6 +462,18 @@ config MTD_NAND_ARASAN
>  	  Enables the driver for the Arasan NAND flash controller on
>  	  Zynq Ultrascale+ MPSoC.
>
> +config MTD_NAND_ROCKCHIP
> +	tristate "Rockchip NAND controller"
> +	depends on ARCH_ROCKCHIP && HAS_IOMEM
> +	help
> +	  Enables support for NAND controller on Rockchip SoCs.
> +	  There are four different versions of NAND FLASH Controllers,
> +	  including:
> +	    NFC v600: RK2928, RK3066, RK3188
> +	    NFC v622: RK3036, RK3128
> +	    NFC v800: RK3308, RV1108
> +	    NFC v900: PX30, RK3326
> +
>  comment "Misc"
>
>  config MTD_SM_COMMON
> diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
> index 2930f5b9015d..960c9be25204 100644
> --- a/drivers/mtd/nand/raw/Makefile
> +++ b/drivers/mtd/nand/raw/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_MTD_NAND_STM32_FMC2)	+= stm32_fmc2_nand.o
>  obj-$(CONFIG_MTD_NAND_MESON)		+= meson_nand.o
>  obj-$(CONFIG_MTD_NAND_CADENCE)		+= cadence-nand-controller.o
>  obj-$(CONFIG_MTD_NAND_ARASAN)		+= arasan-nand-controller.o
> +obj-$(CONFIG_MTD_NAND_ROCKCHIP)		+= rockchip-nand-controller.o
>
>  nand-objs := nand_base.o nand_legacy.o nand_bbt.o nand_timings.o
nand_ids.o
>  nand-objs += nand_onfi.o
> diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c
b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> new file mode 100644
> index 000000000000..cf28c5936209
> --- /dev/null
> +++ b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> @@ -0,0 +1,1439 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +/*
> + * Rockchip NAND Flash controller driver.
> + * Copyright (C) 2020 Rockchip Inc.
> + * Author: Yifeng Zhao <[email-masked]>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
> +#include <linux/interrupt.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/rawnand.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +/*
> + * NFC Page Data Layout:
> + *	1024 Bytes Data + 4Bytes sys data + 28Bytes~124Bytes ecc +
> + *	1024 Bytes Data + 4Bytes sys data + 28Bytes~124Bytes ecc +
> + *	......
> + * NAND Page Data Layout:
> + *	1024 * n Data + m Bytes oob
> + * Original Bad Block Mask Location:
> + *	First byte of oob(spare).
> + * nand_chip->oob_poi data layout:
> + *	4Bytes sys data + .... + 4Bytes sys data + ecc data.
> + */
> +
> +/* NAND controller register definition */
> +#define NFC_READ			(0)
> +#define NFC_WRITE			(1)
> +
> +#define NFC_FMCTL			(0x00)
> +#define   FMCTL_CE_SEL_M		0xFF
> +#define   FMCTL_CE_SEL(x)		(1 << (x))
> +#define   FMCTL_WP			BIT(8)
> +#define   FMCTL_RDY			BIT(9)
> +
> +#define NFC_FMWAIT			(0x04)
> +#define   FLCTL_RST			BIT(0)
> +#define   FLCTL_WR			(1)	/* 0: read, 1: write */
> +#define   FLCTL_XFER_ST			BIT(2)
> +#define   FLCTL_XFER_EN			BIT(3)
> +#define   FLCTL_ACORRECT		BIT(10) /* Auto correct error bits. */
> +#define   FLCTL_XFER_READY		BIT(20)
> +#define   FLCTL_XFER_SECTOR		(22)
> +#define   FLCTL_TOG_FIX			BIT(29)
> +
> +#define   BCHCTL_BANK_M			(7 << 5)
> +#define   BCHCTL_BANK			(5)
> +
> +#define   DMA_ST			BIT(0)
> +#define   DMA_WR			(1)	/* 0: write, 1: read */
> +#define   DMA_EN			BIT(2)
> +#define   DMA_AHB_SIZE			(3)	/* 0: 1, 1: 2, 2: 4 */
> +#define   DMA_BURST_SIZE		(6)	/* 0: 1, 3: 4, 5: 8, 7: 16 */
> +#define   DMA_INC_NUM			(9)	/* 1 - 16 */
> +
> +#define ECC_ERR_CNT(x, e) ((((x) >> (e).low) & (e).low_mask) |\
> +	  (((x) >> (e).high) & (e).high_mask) << (e).low_bn)
> +#define   INT_DMA			BIT(0)
> +#define NFC_BANK			(0x800)
> +#define NFC_BANK_STEP			(0x100)
> +#define   BANK_DATA			(0x00)
> +#define   BANK_ADDR			(0x04)
> +#define   BANK_CMD			(0x08)
> +#define NFC_SRAM0			(0x1000)
> +#define NFC_SRAM1			(0x1400)
> +#define NFC_SRAM_SIZE			(0x400)
> +#define NFC_TIMEOUT			(500000)
> +#define NFC_MAX_OOB_PER_STEP		128
> +#define NFC_MIN_OOB_PER_STEP		64
> +#define MAX_DATA_SIZE			0xFFFC
> +#define MAX_ADDRESS_CYC			6
> +#define NFC_ECC_MAX_MODES		4
> +#define NFC_MAX_NSELS			(8) /* Some Socs only have 1 or 2 CSs. */
> +#define NFC_SYS_DATA_SIZE		(4) /* 4 bytes sys data in oob pre 1024
data.*/
> +#define RK_DEFAULT_CLOCK_RATE		(150 * 1000 * 1000) /* 150 Mhz */
> +#define ACCTIMING(csrw, rwpw, rwcs)	((csrw) << 12 | (rwpw) << 5 | (rwcs))
> +
> +enum nfc_type {
> +	NFC_V6,
> +	NFC_V8,
> +	NFC_V9,
> +};
> +
> +/**
> + * struct rk_ecc_cnt_status: represent a ecc status data.
> + * @err_flag_bit: error flag bit index at register.
> + * @low: ecc count low bit index at register.
> + * @low_mask: mask bit.
> + * @low_bn: ecc count low bit number.
> + * @high: ecc count high bit index at register.
> + * @high_mask: mask bit
> + */
> +struct ecc_cnt_status {
> +	u8 err_flag_bit;
> +	u8 low;
> +	u8 low_mask;
> +	u8 low_bn;
> +	u8 high;
> +	u8 high_mask;
> +};
> +
> +/*
> + * @type: nfc version
> + * @ecc_strengths: ecc strengths
> + * @ecc_cfgs: ecc config values
> + * @flctl_off: FLCTL register offset
> + * @bchctl_off: BCHCTL register offset
> + * @dma_data_buf_off: DMA_DATA_BUF register offset
> + * @dma_oob_buf_off: DMA_OOB_BUF register offset
> + * @dma_cfg_off: DMA_CFG register offset
> + * @dma_st_off: DMA_ST register offset
> + * @bch_st_off: BCG_ST register offset
> + * @randmz_off: RANDMZ register offset
> + * @int_en_off: interrupt enable register offset
> + * @int_clr_off: interrupt clean register offset
> + * @int_st_off: interrupt status register offset
> + * @oob0_off: oob0 register offset
> + * @oob1_off: oob1 register offset
> + * @ecc0: represent ECC0 status data
> + * @ecc1: represent ECC1 status data
> + */
> +struct nfc_cfg {
> +	enum nfc_type type;
> +	u8 ecc_strengths[NFC_ECC_MAX_MODES];
> +	u32 ecc_cfgs[NFC_ECC_MAX_MODES];
> +	u32 flctl_off;
> +	u32 bchctl_off;
> +	u32 dma_cfg_off;
> +	u32 dma_data_buf_off;
> +	u32 dma_oob_buf_off;
> +	u32 dma_st_off;
> +	u32 bch_st_off;
> +	u32 randmz_off;
> +	u32 int_en_off;
> +	u32 int_clr_off;
> +	u32 int_st_off;
> +	u32 oob0_off;
> +	u32 oob1_off;
> +	struct ecc_cnt_status ecc0;
> +	struct ecc_cnt_status ecc1;
> +};
> +
> +struct rk_nfc_nand_chip {
> +	struct list_head node;
> +	struct nand_chip chip;
> +
> +	u16 spare_per_sector;
> +	u16 oob_buf_per_sector;
> +	u16 boot_blks;
> +	u16 boot_ecc;
> +	u16 metadata_size;
> +
> +	u8 nsels;
> +	u8 sels[0];
> +	/* Nothing after this field. */
> +};
> +
> +struct rk_nfc {
> +	struct nand_controller controller;
> +	const struct nfc_cfg *cfg;
> +	struct device *dev;
> +
> +	struct clk *nfc_clk;
> +	struct clk *ahb_clk;
> +	void __iomem *regs;
> +
> +	u32 selected_bank;
> +	u32 band_offset;
> +	u32 cur_clk;
> +
> +	struct completion done;
> +	struct list_head chips;
> +
> +	u8 *buffer;
> +	u8 *page_buf;
> +	u32 *oob_buf;
> +	u32 buffer_size;
> +
> +	unsigned long assigned_cs;
> +};
> +
> +static inline struct rk_nfc_nand_chip *to_rknand(struct nand_chip *chip)
> +{
> +	return container_of(chip, struct rk_nfc_nand_chip, chip);
> +}
> +
> +static inline u8 *nand_data_ptr(struct nand_chip *chip, const u8 *p,
int i)

rk_nfc_buf_to_data_ptr ?

Comment by Miquèl:
Please prepend all your functions with rk_nfc_

For the ftrace filters it is needed to have all functions start with
the same prefix in a module.

> +{
> +	return (u8 *)p + i * chip->ecc.size;
> +}
> +
> +static inline u8 *nand_oob_ptr(struct nand_chip *chip, int i)

same here

> +{
> +	u8 *poi;
> +
> +	poi = chip->oob_poi + i * NFC_SYS_DATA_SIZE;
> +
> +	return poi;
> +}
> +
> +static inline u8 *nand_oob_ecc_ptr(struct nand_chip *chip, int i)

same here

> +{
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +	u8 *poi;
> +
> +	poi = chip->oob_poi + rknand->metadata_size +
> +	      chip->ecc.bytes * i;
> +
> +	return poi;
> +}
> +
> +static inline int rk_nfc_data_len(struct nand_chip *chip)
> +{
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +
> +	return chip->ecc.size + rknand->spare_per_sector;
> +}
> +
> +static inline u8 *rk_nfc_data_ptr(struct nand_chip *chip,  int i)
> +{
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +
> +	return nfc->buffer + i * rk_nfc_data_len(chip);
> +}
> +
> +static inline u8 *rk_nfc_oob_ptr(struct nand_chip *chip, int i)
> +{
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +
> +	return nfc->buffer + i * rk_nfc_data_len(chip) + chip->ecc.size;
> +}
> +
> +static void rk_nfc_select_chip(struct nand_chip *chip, int cs)
> +{
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +	u32 val;
> +
> +	if (cs < 0) {
> +		nfc->selected_bank = -1;
> +		/* Deselect the currently selected target. */
> +		val = readl_relaxed(nfc->regs + NFC_FMCTL);
> +		val &= ~FMCTL_CE_SEL_M;
> +		writel(val, nfc->regs + NFC_FMCTL);
> +		return;
> +	}
> +
> +	nfc->selected_bank = rknand->sels[cs];
> +	nfc->band_offset = NFC_BANK + nfc->selected_bank * NFC_BANK_STEP;
> +
> +	val = readl_relaxed(nfc->regs + NFC_FMCTL);
> +	val &= ~FMCTL_CE_SEL_M;
> +	val |= FMCTL_CE_SEL(nfc->selected_bank);
> +
> +	writel(val, nfc->regs + NFC_FMCTL);
> +}
> +
> +static inline int rk_nfc_wait_ioready(struct rk_nfc *nfc)
> +{
> +	int rc;
> +	u32 val;
> +
> +	rc = readl_relaxed_poll_timeout(nfc->regs + NFC_FMCTL, val,
> +					val & FMCTL_RDY, 10, NFC_TIMEOUT);
> +
> +	return rc;
> +}
> +
> +static void rk_nfc_read_buf(struct rk_nfc *nfc, u8 *buf, int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		buf[i] = readb_relaxed(nfc->regs + nfc->band_offset +
> +				       BANK_DATA);
> +}
> +
> +static void rk_nfc_write_buf(struct rk_nfc *nfc, const u8 *buf, int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		writeb(buf[i], nfc->regs + nfc->band_offset + BANK_DATA);
> +}
> +
> +static int rk_nfc_cmd(struct nand_chip *chip,
> +		      const struct nand_subop *subop)
> +{
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	unsigned int i, j, remaining, start;
> +	int reg_offset = nfc->band_offset;
> +	u8 *inbuf = NULL;
> +	const u8 *outbuf;
> +	u32 cnt = 0;
> +	int ret = 0;
> +
> +	for (i = 0; i < subop->ninstrs; i++) {
> +		const struct nand_op_instr *instr = &subop->instrs[i];
> +
> +		switch (instr->type) {
> +		case NAND_OP_CMD_INSTR:
> +			writeb(instr->ctx.cmd.opcode,
> +			       nfc->regs + reg_offset + BANK_CMD);
> +			break;
> +
> +		case NAND_OP_ADDR_INSTR:
> +			remaining = nand_subop_get_num_addr_cyc(subop, i);
> +			start = nand_subop_get_addr_start_off(subop, i);
> +
> +			for (j = 0; j < 8 && j + start < remaining; j++)
> +				writeb(instr->ctx.addr.addrs[j + start],
> +				       nfc->regs + reg_offset + BANK_ADDR);
> +			break;
> +
> +		case NAND_OP_DATA_IN_INSTR:
> +		case NAND_OP_DATA_OUT_INSTR:
> +			start = nand_subop_get_data_start_off(subop, i);
> +			cnt = nand_subop_get_data_len(subop, i);
> +
> +			if (instr->type == NAND_OP_DATA_OUT_INSTR) {
> +				outbuf = instr->ctx.data.buf.out + start;
> +				rk_nfc_write_buf(nfc, outbuf, cnt);
> +			} else {
> +				inbuf = instr->ctx.data.buf.in + start;
> +				rk_nfc_read_buf(nfc, inbuf, cnt);
> +			}
> +			break;
> +
> +		case NAND_OP_WAITRDY_INSTR:
> +			if (rk_nfc_wait_ioready(nfc) < 0) {
> +				ret = -ETIMEDOUT;
> +				dev_err(nfc->dev, "IO not ready\n");
> +			}
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct nand_op_parser rk_nfc_op_parser = NAND_OP_PARSER(
> +	NAND_OP_PARSER_PATTERN(
> +		rk_nfc_cmd,
> +		NAND_OP_PARSER_PAT_CMD_ELEM(true),
> +		NAND_OP_PARSER_PAT_ADDR_ELEM(true, MAX_ADDRESS_CYC),
> +		NAND_OP_PARSER_PAT_CMD_ELEM(true),
> +		NAND_OP_PARSER_PAT_WAITRDY_ELEM(true),
> +		NAND_OP_PARSER_PAT_DATA_IN_ELEM(true, MAX_DATA_SIZE)),
> +	NAND_OP_PARSER_PATTERN(
> +		rk_nfc_cmd,
> +		NAND_OP_PARSER_PAT_CMD_ELEM(true),
> +		NAND_OP_PARSER_PAT_ADDR_ELEM(true, MAX_ADDRESS_CYC),
> +		NAND_OP_PARSER_PAT_DATA_OUT_ELEM(true, MAX_DATA_SIZE),
> +		NAND_OP_PARSER_PAT_CMD_ELEM(true),
> +		NAND_OP_PARSER_PAT_WAITRDY_ELEM(true)),
> +);
> +
> +static int rk_nfc_exec_op(struct nand_chip *chip,
> +			  const struct nand_operation *op,
> +			  bool check_only)
> +{
> +	if (!check_only)
> +		rk_nfc_select_chip(chip, op->cs);
> +
> +	return nand_op_parser_exec_op(chip, &rk_nfc_op_parser, op,
> +				      check_only);
> +}
> +
> +static int rk_nfc_setup_data_interface(struct nand_chip *chip, int
csline,
> +				       const struct nand_interface_config *conf)
> +{
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	const struct nand_sdr_timings *timings;
> +	u32 rate, tc2rw, trwpw, trw2c;
> +	u32 temp;
> +
> +	if (csline == NAND_DATA_IFACE_CHECK_ONLY)
> +		return 0;
> +
> +	timings = nand_get_sdr_timings(conf);
> +	if (IS_ERR(timings))
> +		return -EOPNOTSUPP;
> +
> +	if (IS_ERR(nfc->nfc_clk))
> +		rate = clk_get_rate(nfc->ahb_clk);
> +	else
> +		rate = clk_get_rate(nfc->nfc_clk);
> +
> +	/* Turn clock rate into kHz. */
> +	rate /= 1000;
> +
> +	tc2rw = 1;
> +	trw2c = 1;
> +
> +	trwpw = max(timings->tWC_min, timings->tRC_min) / 1000;
> +	trwpw = DIV_ROUND_UP(trwpw * rate, 1000000);
> +
> +	temp = timings->tREA_max / 1000;
> +	temp = DIV_ROUND_UP(temp * rate, 1000000);
> +
> +	if (trwpw < temp)
> +		trwpw = temp;
> +
> +	/*
> +	 * ACCON: access timing control register
> +	 * -------------------------------------
> +	 * 31:18: reserved
> +	 * 17:12: csrw, clock cycles from the falling edge of CSn to the
> +	 *   falling edge of RDn or WRn
> +	 * 11:11: reserved
> +	 * 10:05: rwpw, the width of RDn or WRn in processor clock cycles
> +	 * 04:00: rwcs, clock cycles from the rising edge of RDn or WRn to the
> +	 *   rising edge of CSn
> +	 */
> +	temp = ACCTIMING(tc2rw, trwpw, trw2c);
> +	writel(temp, nfc->regs + NFC_FMWAIT);
> +
> +	return 0;
> +}
> +
> +static int rk_nfc_hw_ecc_setup(struct nand_chip *chip,
> +			       struct nand_ecc_ctrl *ecc,
> +			       uint32_t strength)
> +{
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	u32 reg, i;
> +
> +	for (i = 0; i < NFC_ECC_MAX_MODES; i++) {
> +		if (ecc->strength == nfc->cfg->ecc_strengths[i]) {
> +			reg = nfc->cfg->ecc_cfgs[i];
> +			break;
> +		}
> +	}
> +
> +	if (i >= NFC_ECC_MAX_MODES)
> +		return -EINVAL;
> +
> +	writel(reg, nfc->regs + nfc->cfg->bchctl_off);
> +
> +	return 0;
> +}
> +
> +static void rk_nfc_xfer_start(struct rk_nfc *nfc, u8 rw, u8 n_KB,
> +			      dma_addr_t dma_data, dma_addr_t dma_oob)
> +{
> +	u32 dma_reg, fl_reg, bch_reg;
> +
> +	dma_reg = DMA_ST | ((!rw) << DMA_WR) | DMA_EN | (2 << DMA_AHB_SIZE) |
> +	      (7 << DMA_BURST_SIZE) | (16 << DMA_INC_NUM);
> +
> +	fl_reg = (rw << FLCTL_WR) | FLCTL_XFER_EN | FLCTL_ACORRECT |
> +		 (n_KB << FLCTL_XFER_SECTOR) | FLCTL_TOG_FIX;
> +
> +	if (nfc->cfg->type == NFC_V6 || nfc->cfg->type == NFC_V8) {
> +		bch_reg = readl_relaxed(nfc->regs + nfc->cfg->bchctl_off);
> +		bch_reg = (bch_reg & (~BCHCTL_BANK_M)) |
> +			  (nfc->selected_bank << BCHCTL_BANK);
> +		writel(bch_reg, nfc->regs + nfc->cfg->bchctl_off);
> +	}
> +
> +	writel(dma_reg, nfc->regs + nfc->cfg->dma_cfg_off);
> +	writel((u32)dma_data, nfc->regs + nfc->cfg->dma_data_buf_off);
> +	writel((u32)dma_oob, nfc->regs + nfc->cfg->dma_oob_buf_off);
> +	writel(fl_reg, nfc->regs + nfc->cfg->flctl_off);
> +	fl_reg |= FLCTL_XFER_ST;
> +	writel(fl_reg, nfc->regs + nfc->cfg->flctl_off);
> +}
> +
> +static int rk_nfc_wait_for_xfer_done(struct rk_nfc *nfc)
> +{
> +	void __iomem *ptr;
> +	int ret = 0;
> +	u32 reg;
> +
> +	ptr = nfc->regs + nfc->cfg->flctl_off;
> +
> +	ret = readl_relaxed_poll_timeout(ptr, reg,
> +					 reg & FLCTL_XFER_READY,
> +					 10, NFC_TIMEOUT);
> +
> +	return ret;
> +}
> +
> +static int rk_nfc_write_page_raw(struct nand_chip *chip, const u8 *buf,
> +				 int oob_on, int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	int ret = 0;
> +	u32 i;
> +
> +	if (!buf)
> +		memset(nfc->buffer, 0xff, mtd->writesize + mtd->oobsize);
> +
> +	for (i = 0; i < chip->ecc.steps; i++) {
> +		/* Copy data to nfc buffer. */
> +		if (buf)
> +			memcpy(rk_nfc_data_ptr(chip, i),
> +			       nand_data_ptr(chip, buf, i),
> +			       chip->ecc.size);

> +		/*
> +		 * The first four bytes of OOB are reserved for the
> +		 * boot ROM. In some debugging cases, sush as dump

such as

> +		 * data and write back, the last four bytes stored
> +		 * in OOB need to be write back.

such as with a read, erase and write back test
these 4 bytes stored in OOB also need to be written back.

> +		 */
> +		if (!i)
> +			memcpy(rk_nfc_oob_ptr(chip, i),
> +			       nand_oob_ptr(chip, chip->ecc.steps - 1),
> +			       NFC_SYS_DATA_SIZE);
> +		else
> +			memcpy(rk_nfc_oob_ptr(chip, i),
> +			       nand_oob_ptr(chip, i - 1),
> +			       NFC_SYS_DATA_SIZE);
> +		/* Copy ecc data to nfc buffer. */

Copy ECC data to the NFC buffer.

> +		memcpy(rk_nfc_oob_ptr(chip, i) + NFC_SYS_DATA_SIZE,
> +		       nand_oob_ecc_ptr(chip, i),
> +		       chip->ecc.bytes);
> +	}
> +
> +	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
> +	rk_nfc_write_buf(nfc, buf, mtd->writesize + mtd->oobsize);
> +	ret = nand_prog_page_end_op(chip);
> +
> +	/*
> +	 * Deselect the currently selected target after ops done,
> +	 * otherwise the NAND flash will has extra power consumption.

will have

or use for example:

Deselect the currently selected target after the ops is done
to reduce the power consumption.

> +	 */
> +	rk_nfc_select_chip(chip, -1);
> +
> +	return ret;
> +}
> +
> +static int rk_nfc_write_oob(struct nand_chip *chip, int page)
> +{
> +	return rk_nfc_write_page_raw(chip, NULL, 1, page);
> +}
> +
> +static int rk_nfc_write_page_hwecc(struct nand_chip *chip, const u8 *buf,
> +				   int oob_on, int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> +	int oob_step = (ecc->bytes > 60) ? NFC_MAX_OOB_PER_STEP :
> +			NFC_MIN_OOB_PER_STEP;
> +	int pages_per_blk = mtd->erasesize / mtd->writesize;
> +	int ret = 0, i, boot_rom_mode = 0;
> +	dma_addr_t dma_data, dma_oob;
> +	u32 reg;
> +	u8 *oob;
> +
> +	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
> +
> +	memcpy(nfc->page_buf, buf, mtd->writesize);
> +
> +	/*
> +	 * The first blocks (4, 8 or 16 depending on the device) are used
> +	 * by the boot ROM and the first 32 bits of oob need to link to

OOB

> +	 * the next page address in the same block.

Add more explanation why:

We can't copy OOB directly,
because this page address conflicts with the bad block marker (BBM),
so we shift all OOB including the BBM with 4 byte positions.
As consequence the OOB size then is also reduced with 4 bytes.

PA0  PA1  PA2  PA3  | BBM OOB1 OOB2 OOB3 | ...

If a NAND is not a boot medium the first 4 bytes are left untouched
by writing 0xFF to them.

0xFF 0xFF 0xFF 0xFF | BBM OOB1 OOB2 OOB3 | ...

Could you include the above layout to make things more clear?

> +	 * Config the ECC algorithm supported by the boot ROM.

comment by Miquèl:

s/Config/Configure/

> +	 */
> +	if ((page < pages_per_blk * rknand->boot_blks) &&
> +	    (chip->options & NAND_IS_BOOT_MEDIUM)) {
> +		boot_rom_mode = 1;
> +		if (rknand->boot_ecc != ecc->strength)
> +			rk_nfc_hw_ecc_setup(chip, ecc,
> +					    rknand->boot_ecc);
> +	}
> +
> +	for (i = 0; i < ecc->steps; i++) {
> +		if (!i) {
> +			reg = 0xFFFFFFFF;
> +		} else {
> +			oob = chip->oob_poi + (i - 1) * NFC_SYS_DATA_SIZE;
> +			reg = oob[0] | oob[1] << 8 | oob[2] << 16 |
> +			      oob[3] << 24;
> +		}
> +		if (!i && boot_rom_mode)
> +			reg = (page & (pages_per_blk - 1)) * 4;
> +
> +		if (nfc->cfg->type == NFC_V9)
> +			nfc->oob_buf[i] = reg;
> +		else
> +			nfc->oob_buf[i * oob_step / 4] = reg;

Please use brackets.

> +	}
> +
> +	dma_data = dma_map_single(nfc->dev, (void *)nfc->page_buf,

Do you need this cast?

> +				  mtd->writesize, DMA_TO_DEVICE);
> +	dma_oob = dma_map_single(nfc->dev, nfc->oob_buf,
> +				 ecc->steps * oob_step,
> +				 DMA_TO_DEVICE);
> +
> +	reinit_completion(&nfc->done);
> +	writel(INT_DMA, nfc->regs + nfc->cfg->int_en_off);
> +
> +	rk_nfc_xfer_start(nfc, NFC_WRITE, ecc->steps, dma_data,
> +			  dma_oob);
> +	ret = wait_for_completion_timeout(&nfc->done,
> +					  msecs_to_jiffies(100));
> +	if (!ret)
> +		dev_warn(nfc->dev, "write: wait dma done timeout.\n");
> +	/*
> +	 * Whether the DMA transfer is completed or not. The driver
> +	 * needs to check the NFC`s status register to see if the data
> +	 * transfer was completed.
> +	 */
> +	ret = rk_nfc_wait_for_xfer_done(nfc);
> +
> +	dma_unmap_single(nfc->dev, dma_data, mtd->writesize,
> +			 DMA_TO_DEVICE);
> +	dma_unmap_single(nfc->dev, dma_oob, ecc->steps * oob_step,
> +			 DMA_TO_DEVICE);
> +
> +	if (boot_rom_mode && rknand->boot_ecc != ecc->strength)
> +		rk_nfc_hw_ecc_setup(chip, ecc, ecc->strength);
> +
> +	if (ret) {
> +		ret = -EIO;
> +		dev_err(nfc->dev,
> +			"write: wait transfer done timeout.\n");
> +	}
> +
> +	if (ret)
> +		return ret;
> +
> +	ret = nand_prog_page_end_op(chip);
> +
> +	/*
> +	 * Deselect the currently selected target after ops done,

> +	 * otherwise the NAND flash will has extra power consumption.

will have

or use for example:

Deselect the currently selected target after the ops is done
to reduce the power consumption.

> +	 */
> +	rk_nfc_select_chip(chip, -1);
> +
> +	return ret;
> +}
> +
> +static int rk_nfc_read_page_raw(struct nand_chip *chip, u8 *buf, int
oob_on,
> +				int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	int i;
> +
> +	nand_read_page_op(chip, page, 0, NULL, 0);
> +	rk_nfc_read_buf(nfc, nfc->buffer, mtd->writesize + mtd->oobsize);
> +
> +	/*
> +	 * Deselect the currently selected target after ops done,

> +	 * otherwise the NAND flash will has extra power consumption.

will have

or use for example:

Deselect the currently selected target after the ops is done
to reduce the power consumption.

> +	 */
> +	rk_nfc_select_chip(chip, -1);
> +
> +	for (i = 0; i < chip->ecc.steps; i++) {

> +		/*
> +		 * The first four bytes of OOB are reserved for the
> +		 * boot ROM. In some debugging cases, sush as dump data

such as

> +		 * and write back, it`s need to read out this four bytes,

such as with a read, erase and write back test
these 4 bytes also must be saved somewhere,

> +		 * otherwise this information will be lost during write back.

otherwise this information will be lost during a write back.

> +		 */
> +		if (!i)
> +			memcpy(nand_oob_ptr(chip, chip->ecc.steps - 1),
> +			       rk_nfc_oob_ptr(chip, i),
> +			       NFC_SYS_DATA_SIZE);
> +		else
> +			memcpy(nand_oob_ptr(chip, i - 1),
> +			       rk_nfc_oob_ptr(chip, i),
> +			       NFC_SYS_DATA_SIZE);

> +		/* Copy ecc data form nfc buffer. */

Copy ECC data from the NFC buffer.

> +		memcpy(nand_oob_ecc_ptr(chip, i),
> +		       rk_nfc_oob_ptr(chip, i) + NFC_SYS_DATA_SIZE,
> +		       chip->ecc.bytes);

> +		/* Copy data form nfc buffer. */

Copy data from the NFC buffer.

> +		if (buf)
> +			memcpy(nand_data_ptr(chip, buf, i),
> +			       rk_nfc_data_ptr(chip, i),
> +			       chip->ecc.size);
> +	}
> +
> +	return 0;
> +}
> +
> +static int rk_nfc_read_oob(struct nand_chip *chip, int page)
> +{
> +	return rk_nfc_read_page_raw(chip, NULL, 1, page);
> +}
> +
> +static int rk_nfc_read_page_hwecc(struct nand_chip *chip, u8 *buf,
int oob_on,
> +				  int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> +	int oob_step = (ecc->bytes > 60) ? NFC_MAX_OOB_PER_STEP :
> +			NFC_MIN_OOB_PER_STEP;
> +	int pages_per_blk = mtd->erasesize / mtd->writesize;
> +	dma_addr_t dma_data, dma_oob;
> +	int ret = 0, i, boot_rom_mode = 0;
> +	int bitflips = 0, bch_st;
> +	u8 *oob;
> +	u32 tmp;
> +
> +	nand_read_page_op(chip, page, 0, NULL, 0);
> +
> +	dma_data = dma_map_single(nfc->dev, nfc->page_buf,
> +				  mtd->writesize,
> +				  DMA_FROM_DEVICE);
> +	dma_oob = dma_map_single(nfc->dev, nfc->oob_buf,
> +				 ecc->steps * oob_step,
> +				 DMA_FROM_DEVICE);
> +
> +	/*
> +	 * The first blocks (4, 8 or 16 depending on the device)
> +	 * are used by the boot ROM.
> +	 * Config the ECC algorithm supported by the boot ROM.
> +	 */
> +	if ((page < pages_per_blk * rknand->boot_blks) &&
> +	    (chip->options & NAND_IS_BOOT_MEDIUM)) {
> +		boot_rom_mode = 1;
> +		if (rknand->boot_ecc != ecc->strength)
> +			rk_nfc_hw_ecc_setup(chip, ecc,
> +					    rknand->boot_ecc);
> +	}
> +
> +	reinit_completion(&nfc->done);
> +	writel(INT_DMA, nfc->regs + nfc->cfg->int_en_off);
> +	rk_nfc_xfer_start(nfc, NFC_READ, ecc->steps, dma_data,
> +			  dma_oob);
> +	ret = wait_for_completion_timeout(&nfc->done,
> +					  msecs_to_jiffies(100));
> +	if (!ret)
> +		dev_warn(nfc->dev, "read: wait dma done timeout.\n");
> +	/*
> +	 * Whether the DMA transfer is completed or not. The driver
> +	 * needs to check the NFC`s status register to see if the data
> +	 * transfer was completed.
> +	 */
> +	ret = rk_nfc_wait_for_xfer_done(nfc);
> +	dma_unmap_single(nfc->dev, dma_data, mtd->writesize,
> +			 DMA_FROM_DEVICE);
> +	dma_unmap_single(nfc->dev, dma_oob, ecc->steps * oob_step,
> +			 DMA_FROM_DEVICE);
> +
> +	if (ret) {
> +		bitflips = -EIO;
> +		dev_err(nfc->dev,
> +			"read: wait transfer done timeout.\n");
> +		goto out;
> +	}
> +
> +	for (i = 1; i < ecc->steps; i++) {
> +		oob = chip->oob_poi + (i - 1) * NFC_SYS_DATA_SIZE;
> +		if (nfc->cfg->type == NFC_V9)
> +			tmp = nfc->oob_buf[i];
> +		else
> +			tmp = nfc->oob_buf[i * oob_step / 4];
> +		*oob++ = (u8)tmp;
> +		*oob++ = (u8)(tmp >> 8);
> +		*oob++ = (u8)(tmp >> 16);
> +		*oob++ = (u8)(tmp >> 24);
> +	}
> +
> +	for (i = 0; i < ecc->steps / 2; i++) {

Brackets here as well please

> +		bch_st = readl_relaxed(nfc->regs +
> +				       nfc->cfg->bch_st_off + i * 4);
> +		if (bch_st & BIT(nfc->cfg->ecc0.err_flag_bit) ||
> +		    bch_st & BIT(nfc->cfg->ecc1.err_flag_bit)) {
> +			mtd->ecc_stats.failed++;
> +			/* ECC failed, return the minimum number of error bits */
> +			bitflips = ecc->strength + 1;

Could you explain why:

bitflips = -1;

changed to:

bitflips = ecc->strength + 1;

Comment by Miquèl:

I think you should return 0.

Then the upper layer will check for failures.

> +		} else {
> +			ret = ECC_ERR_CNT(bch_st, nfc->cfg->ecc0);
> +			mtd->ecc_stats.corrected += ret;
> +			bitflips = max_t(u32, bitflips, ret);
> +
> +			ret = ECC_ERR_CNT(bch_st, nfc->cfg->ecc1);
> +			mtd->ecc_stats.corrected += ret;
> +			bitflips = max_t(u32, bitflips, ret);
> +		}
> +	}
> +out:
> +	memcpy(buf, nfc->page_buf, mtd->writesize);
> +
> +	if (boot_rom_mode && rknand->boot_ecc != ecc->strength)
> +		rk_nfc_hw_ecc_setup(chip, ecc, ecc->strength);
> +
> +	if (bitflips > ecc->strength)
> +		dev_err(nfc->dev, "read page: %x ecc error!\n", page);
> +
> +	/*
> +	 * Deselect the currently selected target after ops done,

> +	 * otherwise the NAND flash will has extra power consumption.

will have

or use for example:

Deselect the currently selected target after the ops is done
to reduce the power consumption.

> +	 */
> +	rk_nfc_select_chip(chip, -1);
> +
> +	return bitflips;
> +}
> +
> +static inline void rk_nfc_hw_init(struct rk_nfc *nfc)
> +{
> +	/* Disable flash wp. */
> +	writel(FMCTL_WP, nfc->regs + NFC_FMCTL);
> +	/* Config default timing 40ns at 150 Mhz nfc clock. */
> +	writel(0x1081, nfc->regs + NFC_FMWAIT);
> +	/* Disable randomizer and DMA. */
> +	writel(0, nfc->regs + nfc->cfg->randmz_off);
> +	writel(0, nfc->regs + nfc->cfg->dma_cfg_off);
> +	writel(FLCTL_RST, nfc->regs + nfc->cfg->flctl_off);
> +}
> +
> +static irqreturn_t rk_nfc_irq(int irq, void *id)
> +{
> +	struct rk_nfc *nfc = id;
> +	u32 sta, ien;
> +
> +	sta = readl_relaxed(nfc->regs + nfc->cfg->int_st_off);
> +	ien = readl_relaxed(nfc->regs + nfc->cfg->int_en_off);
> +
> +	if (!(sta & ien))
> +		return IRQ_NONE;
> +
> +	writel(sta, nfc->regs + nfc->cfg->int_clr_off);
> +	writel(~sta & ien, nfc->regs + nfc->cfg->int_en_off);
> +
> +	complete(&nfc->done);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int rk_nfc_enable_clk(struct device *dev, struct rk_nfc *nfc)

Change function name, because there are 2 clocks.

_clks with an s to inform that there are several of them.

_clk ==>> _clks

> +{
> +	int ret;
> +
> +	if (!IS_ERR(nfc->nfc_clk)) {
> +		ret = clk_prepare_enable(nfc->nfc_clk);
> +		if (ret) {
> +			dev_err(dev, "failed to enable nfc clk\n");
> +			return ret;
> +		}
> +	}
> +
> +	ret = clk_prepare_enable(nfc->ahb_clk);
> +	if (ret) {
> +		dev_err(dev, "failed to enable ahb clk\n");
> +		if (!IS_ERR(nfc->nfc_clk))
> +			clk_disable_unprepare(nfc->nfc_clk);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void rk_nfc_disable_clk(struct rk_nfc *nfc)

Change function name, because there are 2 clocks.

ditto

_clk ==>> _clks

> +{
> +	if (!IS_ERR(nfc->nfc_clk))
> +		clk_disable_unprepare(nfc->nfc_clk);
> +	clk_disable_unprepare(nfc->ahb_clk);
> +}
> +
> +static int rk_nfc_ooblayout_free(struct mtd_info *mtd, int section,
> +				 struct mtd_oob_region *oob_region)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	/*
> +	 * The beginning of the oob area stores the reserved data for the NFC,

OOB area

> +	 * the size of the reserved data is NFC_SYS_DATA_SIZE bytes.
> +	 */
> +	oob_region->length = rknand->metadata_size - NFC_SYS_DATA_SIZE - 2;
> +	oob_region->offset = NFC_SYS_DATA_SIZE + 2;
> +
> +	return 0;
> +}
> +
> +static int rk_nfc_ooblayout_ecc(struct mtd_info *mtd, int section,
> +				struct mtd_oob_region *oob_region)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +
> +	if (section)
> +		return -ERANGE;
> +

> +	oob_region->offset = rknand->metadata_size;
> +	oob_region->length = mtd->oobsize - oob_region->offset;

	oob_region->length = mtd->oobsize - oob_region->offset;
	oob_region->offset = rknand->metadata_size;

Keep length and offset in the same sort order as in rk_nfc_ooblayout_free().

> +
> +	return 0;
> +}
> +
> +static const struct mtd_ooblayout_ops rk_nfc_ooblayout_ops = {
> +	.free = rk_nfc_ooblayout_free,
> +	.ecc = rk_nfc_ooblayout_ecc,
> +};
> +
> +static int rk_nfc_ecc_init(struct device *dev, struct mtd_info *mtd)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> +	const u8 *strengths = nfc->cfg->ecc_strengths;
> +	u8 max_strength, nfc_max_strength;
> +	int i;
> +
> +	nfc_max_strength = nfc->cfg->ecc_strengths[0];
> +	/* If optional dt settings not present. */
> +	if (!ecc->size || !ecc->strength ||
> +	    ecc->strength > nfc_max_strength) {
> +		chip->ecc.size = 1024;
> +		ecc->steps = mtd->writesize / ecc->size;
> +
> +		/*
> +		 * HW ECC always requests the number of ECC bytes per 1024 byte

> +		 * blocks. 4 Bytes is oob for sys data.

The first 4 OOB bytes are reserved for sys data.

> +		 */
> +		max_strength = ((mtd->oobsize / ecc->steps) - 4) * 8 /
> +				 fls(8 * 1024);
> +		if (max_strength > nfc_max_strength)
> +			max_strength = nfc_max_strength;
> +
> +		for (i = 0; i < 4; i++) {
> +			if (max_strength >= strengths[i])
> +				break;
> +		}
> +
> +		if (i >= 4) {
> +			dev_err(nfc->dev, "Unsupported ECC strength\n");
> +			return -EOPNOTSUPP;
> +		}
> +
> +		ecc->strength = strengths[i];
> +	}
> +	ecc->steps = mtd->writesize / ecc->size;
> +	ecc->bytes = DIV_ROUND_UP(ecc->strength * fls(8 * 1024), 8);
> +	/* HW ECC always work with even numbers of ECC bytes. */
> +	ecc->bytes = ALIGN(ecc->bytes, 2);
> +
> +	rk_nfc_hw_ecc_setup(chip, ecc, ecc->strength);
> +
> +	return 0;
> +}
> +
> +static int rk_nfc_attach_chip(struct nand_chip *chip)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct device *dev = mtd->dev.parent;
> +	struct rk_nfc *nfc = nand_get_controller_data(chip);
> +	struct rk_nfc_nand_chip *rknand = to_rknand(chip);
> +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> +	u8 *temp_buf;
> +	int len, oob_len;
> +	int ret;
> +
> +	if (chip->options & NAND_BUSWIDTH_16) {
> +		dev_err(dev, "16 bits bus width not supported");
> +		return -EINVAL;
> +	}
> +
> +	if (ecc->engine_type != NAND_ECC_ENGINE_TYPE_ON_HOST)
> +		return 0;
> +
> +	ret = rk_nfc_ecc_init(dev, mtd);
> +	if (ret)
> +		return ret;
> +	rknand->spare_per_sector = ecc->bytes + NFC_SYS_DATA_SIZE;
> +	rknand->metadata_size = NFC_SYS_DATA_SIZE * ecc->steps;
> +
> +	if (rknand->metadata_size < NFC_SYS_DATA_SIZE + 2) {
> +		dev_err(dev,
> +			"Driver needs at least %d bytes of meta data\n",
> +			NFC_SYS_DATA_SIZE + 2);
> +		return -EIO;
> +	}

> +	len = mtd->writesize + mtd->oobsize;

> +
> +	/* Check buffer first, avoid duplicate alloc buffer. */
> +	if (nfc->buffer) {
> +		if (len > nfc->buffer_size) {

Check only for buffer_size.
Maybe split in 2. One size variable per buffer.
Reorder flow, see example?

> +			temp_buf = kzalloc(len, GFP_KERNEL | GFP_DMA);
> +			if (!temp_buf)
> +				return -ENOMEM;
> +			kfree(nfc->buffer);

Is there a realloc for kernels or use helper?

> +			nfc->buffer = temp_buf;
> +			nfc->buffer_size = len;
> +
> +			oob_len = ecc->steps * NFC_MAX_OOB_PER_STEP;
> +			temp_buf = kzalloc(oob_len, GFP_KERNEL | GFP_DMA);
> +			if (!temp_buf)
> +				return -ENOMEM;
> +			kfree(nfc->oob_buf);
> +			nfc->oob_buf = (u32 *)temp_buf;
> +		}
> +		return 0;
> +	}
> +

Example:

// Check and resize existing buffer sizes.

new_len = mtd->writesize + mtd->oobsize;

if (nfc->buffer && new_len > nfc->buffer_size) {
  ret = resize(...);
  if (!ret)
    return -ENOMEM;
  nfc->buffer_size = new_len;
}

new_oob_len = ecc->steps * NFC_MAX_OOB_PER_STEP;

if (nfc->oob_buf && new_oob_len > nfc->oob_buffer_size) {
  ret = resize(...);
  if (!ret) {
    free(nfc->buffer);
    return -ENOMEM;
  }
  nfc->oob_buffer_size = new_oob_len;
}

// If no buffers exists then create new buffers.

if (!nfc->buffer) {
  ret = kzalloc(...);
  if (!ret)
    return -ENOMEM;
  nfc->buffer_size = new_len;
}

if (!nfc->oob_buf) {
  ret = kzalloc(...);
  if (!ret) {
    free(nfc->buffer);
    return -ENOMEM;
  }
  nfc->oob_buffer_size = new_oob_len;
}

> +	nfc->buffer = kzalloc(len, GFP_KERNEL | GFP_DMA);
> +	if (!nfc->buffer)
> +		return -ENOMEM;

> +
> +	oob_len = ecc->steps * NFC_MAX_OOB_PER_STEP;
> +	nfc->oob_buf = kzalloc(oob_len, GFP_KERNEL | GFP_DMA);
> +	if (!nfc->oob_buf) {
> +		kfree(nfc->buffer);
> +		nfc->buffer = NULL;

> +		nfc->oob_buf = NULL;

!nfc->oob_buf == (nfc->oob_buf = NULL)

Comment from Miquèl:
I don't think this is needed

If something is NULL then there's no need to set it to NULL again.

> +		return -ENOMEM;
> +	}
> +
> +	nfc->buffer_size = len;
> +	nfc->page_buf = nfc->buffer;
> +
> +	chip->ecc.write_page_raw = rk_nfc_write_page_raw;
> +	chip->ecc.write_page = rk_nfc_write_page_hwecc;
> +	chip->ecc.write_oob_raw = rk_nfc_write_oob;
> +	chip->ecc.write_oob = rk_nfc_write_oob;
> +
> +	chip->ecc.read_page_raw = rk_nfc_read_page_raw;
> +	chip->ecc.read_page = rk_nfc_read_page_hwecc;
> +	chip->ecc.read_oob_raw = rk_nfc_read_oob;
> +	chip->ecc.read_oob = rk_nfc_read_oob;
> +
> +	return 0;
> +}
> +
> +static const struct nand_controller_ops rk_nfc_controller_ops = {
> +	.attach_chip = rk_nfc_attach_chip,
> +	.exec_op = rk_nfc_exec_op,
> +	.setup_interface = rk_nfc_setup_data_interface,
> +};
> +
> +static int rk_nfc_nand_chip_init(struct device *dev, struct rk_nfc *nfc,
> +				 struct device_node *np)
> +{
> +	struct rk_nfc_nand_chip *rknand;
> +	struct nand_chip *chip;
> +	struct mtd_info *mtd;
> +	int nsels;
> +	u32 tmp;
> +	int ret;
> +	int i;
> +
> +	if (!of_get_property(np, "reg", &nsels))
> +		return -ENODEV;
> +	nsels /= sizeof(u32);
> +	if (!nsels || nsels > NFC_MAX_NSELS) {
> +		dev_err(dev, "invalid reg property size %d\n", nsels);
> +		return -EINVAL;
> +	}
> +
> +	rknand = devm_kzalloc(dev, sizeof(*rknand) + nsels * sizeof(u8),
> +			      GFP_KERNEL);
> +	if (!rknand)
> +		return -ENOMEM;
> +
> +	rknand->nsels = nsels;
> +	for (i = 0; i < nsels; i++) {
> +		ret = of_property_read_u32_index(np, "reg", i, &tmp);
> +		if (ret) {
> +			dev_err(dev, "reg property failure : %d\n", ret);
> +			return ret;
> +		}
> +
> +		if (tmp >= NFC_MAX_NSELS) {
> +			dev_err(dev, "invalid CS: %u\n", tmp);
> +			return -EINVAL;
> +		}
> +
> +		if (test_and_set_bit(tmp, &nfc->assigned_cs)) {
> +			dev_err(dev, "CS %u already assigned\n", tmp);
> +			return -EINVAL;
> +		}
> +
> +		rknand->sels[i] = tmp;
> +	}
> +
> +	chip = &rknand->chip;
> +	chip->controller = &nfc->controller;
> +
> +	nand_set_flash_node(chip, np);
> +
> +	nand_set_controller_data(chip, nfc);
> +
> +	chip->options |= NAND_USES_DMA | NAND_NO_SUBPAGE_WRITE;
> +	chip->bbt_options = NAND_BBT_USE_FLASH | NAND_BBT_NO_OOB;
> +
> +	/* Set default mode in case dt entry is missing. */
> +	chip->ecc.engine_type = NAND_ECC_ENGINE_TYPE_ON_HOST;
> +
> +	mtd = nand_to_mtd(chip);
> +	mtd->owner = THIS_MODULE;
> +	mtd->dev.parent = dev;
> +
> +	if (!mtd->name) {
> +		dev_err(nfc->dev, "NAND label property is mandatory\n");
> +		return -EINVAL;
> +	}
> +
> +	mtd_set_ooblayout(mtd, &rk_nfc_ooblayout_ops);
> +	rk_nfc_hw_init(nfc);
> +	ret = nand_scan(chip, nsels);
> +	if (ret)
> +		return ret;
> +
> +	if (chip->options & NAND_IS_BOOT_MEDIUM) {
> +		ret = of_property_read_u32(np, "rockchip,boot-blks", &tmp);
> +		rknand->boot_blks = ret ? 0 : tmp;

Comment by Miquèl:
Can't you guess this entry knowing the IP version/SoC version?

No, "rockchip,boot-blks" depends on the size of multiple partitions
and is user layout dependent.

> +
> +		ret = of_property_read_u32(np, "rockchip,boot-ecc-strength",
> +					   &tmp);
> +		rknand->boot_ecc = ret ? chip->ecc.strength : tmp;
> +	}
> +
> +	ret = mtd_device_register(mtd, NULL, 0);
> +	if (ret) {
> +		dev_err(dev, "mtd parse partition error\n");
> +		nand_cleanup(chip);
> +		return ret;
> +	}
> +
> +	list_add_tail(&rknand->node, &nfc->chips);
> +
> +	return 0;
> +}
> +
> +static void rk_nfc_chips_cleanup(struct rk_nfc *nfc)
> +{
> +	struct rk_nfc_nand_chip *rknand, *tmp;
> +	struct nand_chip *chip;
> +	int ret;
> +
> +	list_for_each_entry_safe(rknand, tmp, &nfc->chips, node) {
> +		chip = &rknand->chip;
> +		ret = mtd_device_unregister(nand_to_mtd(chip));
> +		WARN_ON(ret);
> +		nand_cleanup(chip);
> +		list_del(&rknand->node);
> +	}
> +}
> +
> +static int rk_nfc_nand_chips_init(struct device *dev, struct rk_nfc *nfc)
> +{
> +	struct device_node *np = dev->of_node, *nand_np;
> +	int nchips = of_get_child_count(np);
> +	int ret;
> +
> +	if (!nchips || nchips > NFC_MAX_NSELS) {
> +		dev_err(nfc->dev, "Incorrect number of NAND chips (%d)\n",
> +			nchips);
> +		return -EINVAL;
> +	}
> +
> +	for_each_child_of_node(np, nand_np) {
> +		ret = rk_nfc_nand_chip_init(dev, nfc, nand_np);
> +		if (ret) {
> +			of_node_put(nand_np);
> +			rk_nfc_chips_cleanup(nfc);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct nfc_cfg nfc_v6_cfg = {
> +		.type			= NFC_V6,
> +		.ecc_strengths		= {60, 40, 24, 16},
> +		.ecc_cfgs		= {
> +			0x00040011, 0x00040001, 0x00000011, 0x00000001,
> +		},
> +		.flctl_off		= 0x08,
> +		.bchctl_off		= 0x0C,
> +		.dma_cfg_off		= 0x10,
> +		.dma_data_buf_off	= 0x14,
> +		.dma_oob_buf_off	= 0x18,
> +		.dma_st_off		= 0x1C,
> +		.bch_st_off		= 0x20,
> +		.randmz_off		= 0x150,
> +		.int_en_off		= 0x16C,
> +		.int_clr_off		= 0x170,
> +		.int_st_off		= 0x174,
> +		.oob0_off		= 0x200,
> +		.oob1_off		= 0x230,
> +		.ecc0			= {
> +			.err_flag_bit	= 2,
> +			.low		= 3,
> +			.low_mask	= 0x1F,
> +			.low_bn		= 5,
> +			.high		= 27,
> +			.high_mask	= 0x1,
> +		},
> +		.ecc1			= {
> +			.err_flag_bit	= 15,
> +			.low		= 16,
> +			.low_mask	= 0x1F,
> +			.low_bn		= 5,
> +			.high		= 29,
> +			.high_mask	= 0x1,
> +		},
> +};
> +
> +static struct nfc_cfg nfc_v8_cfg = {
> +		.type			= NFC_V8,
> +		.ecc_strengths		= {16, 16, 16, 16},
> +		.ecc_cfgs		= {
> +			0x00000001, 0x00000001, 0x00000001, 0x00000001,
> +		},
> +		.flctl_off		= 0x08,
> +		.bchctl_off		= 0x0C,
> +		.dma_cfg_off		= 0x10,
> +		.dma_data_buf_off	= 0x14,
> +		.dma_oob_buf_off	= 0x18,
> +		.dma_st_off		= 0x1C,
> +		.bch_st_off		= 0x20,
> +		.randmz_off		= 0x150,
> +		.int_en_off		= 0x16C,
> +		.int_clr_off		= 0x170,
> +		.int_st_off		= 0x174,
> +		.oob0_off		= 0x200,
> +		.oob1_off		= 0x230,
> +		.ecc0			= {
> +			.err_flag_bit	= 2,
> +			.low		= 3,
> +			.low_mask	= 0x1F,
> +			.low_bn		= 5,
> +			.high		= 27,
> +			.high_mask	= 0x1,
> +		},
> +		.ecc1			= {
> +			.err_flag_bit	= 15,
> +			.low		= 16,
> +			.low_mask	= 0x1F,
> +			.low_bn		= 5,
> +			.high		= 29,
> +			.high_mask	= 0x1,
> +		},
> +};
> +
> +static struct nfc_cfg nfc_v9_cfg = {
> +		.type			= NFC_V9,
> +		.ecc_strengths		= {70, 60, 40, 16},
> +		.ecc_cfgs		= {
> +			0x00000001, 0x06000001, 0x04000001, 0x02000001,
> +		},
> +		.flctl_off		= 0x10,
> +		.bchctl_off		= 0x20,
> +		.dma_cfg_off		= 0x30,
> +		.dma_data_buf_off	= 0x34,
> +		.dma_oob_buf_off	= 0x38,
> +		.dma_st_off		= 0x3C,
> +		.bch_st_off		= 0x150,
> +		.randmz_off		= 0x208,
> +		.int_en_off		= 0x120,
> +		.int_clr_off		= 0x124,
> +		.int_st_off		= 0x128,
> +		.oob0_off		= 0x200,
> +		.oob1_off		= 0x204,
> +		.ecc0			= {
> +			.err_flag_bit	= 2,
> +			.low		= 3,
> +			.low_mask	= 0x7F,
> +			.low_bn		= 7,
> +			.high		= 0,
> +			.high_mask	= 0x0,
> +		},
> +		.ecc1			= {
> +			.err_flag_bit	= 18,
> +			.low		= 19,
> +			.low_mask	= 0x7F,
> +			.low_bn		= 7,
> +			.high		= 0,
> +			.high_mask	= 0x0,
> +		},
> +};
> +
> +static const struct of_device_id rk_nfc_id_table[] = {
> +	{
> +		.compatible = "rockchip,px30-nfc",
> +		.data = &nfc_v9_cfg
> +	},
> +	{
> +		.compatible = "rockchip,rk2928-nfc",
> +		.data = &nfc_v6_cfg
> +	},
> +	{
> +		.compatible = "rockchip,rv1108-nfc",
> +		.data = &nfc_v8_cfg
> +	},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, rk_nfc_id_table);
> +
> +static int rk_nfc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct rk_nfc *nfc;
> +	int ret, irq;
> +
> +	nfc = devm_kzalloc(dev, sizeof(*nfc), GFP_KERNEL);
> +	if (!nfc)
> +		return -ENOMEM;
> +
> +	nand_controller_init(&nfc->controller);
> +	INIT_LIST_HEAD(&nfc->chips);
> +	nfc->controller.ops = &rk_nfc_controller_ops;
> +
> +	nfc->cfg = of_device_get_match_data(dev);
> +	nfc->dev = dev;
> +
> +	init_completion(&nfc->done);
> +
> +	nfc->regs = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(nfc->regs)) {
> +		ret = PTR_ERR(nfc->regs);
> +		goto release_nfc;
> +	}
> +
> +	nfc->nfc_clk = devm_clk_get(dev, "nfc");
> +	if (IS_ERR(nfc->nfc_clk)) {
> +		dev_dbg(dev, "no nfc clk\n");
> +		/* Some earlier models, such as rk3066, have no nfc clk. */
> +	}
> +
> +	nfc->ahb_clk = devm_clk_get(dev, "ahb");
> +	if (IS_ERR(nfc->ahb_clk)) {
> +		dev_err(dev, "no ahb clk\n");
> +		ret = PTR_ERR(nfc->ahb_clk);
> +		goto release_nfc;
> +	}
> +
> +	ret = rk_nfc_enable_clk(dev, nfc);
> +	if (ret)
> +		goto release_nfc;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(dev, "no nfc irq resource\n");
> +		ret = -EINVAL;
> +		goto clk_disable;
> +	}
> +
> +	writel(0, nfc->regs + nfc->cfg->int_en_off);
> +	ret = devm_request_irq(dev, irq, rk_nfc_irq, 0x0, "rk-nand", nfc);
> +	if (ret) {
> +		dev_err(dev, "failed to request nfc irq\n");
> +		goto clk_disable;
> +	}
> +
> +	platform_set_drvdata(pdev, nfc);
> +
> +	ret = rk_nfc_nand_chips_init(dev, nfc);
> +	if (ret) {
> +		dev_err(dev, "failed to init NAND chips\n");
> +		goto clk_disable;
> +	}
> +	return 0;
> +
> +clk_disable:
> +	rk_nfc_disable_clk(nfc);
> +release_nfc:
> +	return ret;
> +}
> +
> +static int rk_nfc_remove(struct platform_device *pdev)
> +{
> +	struct rk_nfc *nfc = platform_get_drvdata(pdev);
> +
> +	kfree(nfc->buffer);
> +	kfree(nfc->oob_buf);
> +	rk_nfc_chips_cleanup(nfc);
> +	rk_nfc_disable_clk(nfc);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused rk_nfc_suspend(struct device *dev)
> +{
> +	struct rk_nfc *nfc = dev_get_drvdata(dev);
> +
> +	rk_nfc_disable_clk(nfc);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused rk_nfc_resume(struct device *dev)
> +{
> +	struct rk_nfc *nfc = dev_get_drvdata(dev);
> +	struct rk_nfc_nand_chip *rknand;
> +	struct nand_chip *chip;
> +	int ret;
> +	u32 i;
> +
> +	ret = rk_nfc_enable_clk(dev, nfc);
> +	if (ret)
> +		return ret;
> +
> +	/* Reset NAND chip if VCC was powered off. */
> +	list_for_each_entry(rknand, &nfc->chips, node) {
> +		chip = &rknand->chip;
> +		for (i = 0; i < rknand->nsels; i++)
> +			nand_reset(chip, i);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops rk_nfc_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(rk_nfc_suspend, rk_nfc_resume)
> +};
> +
> +static struct platform_driver rk_nfc_driver = {
> +	.probe = rk_nfc_probe,
> +	.remove = rk_nfc_remove,
> +	.driver = {
> +		.name = "rockchip-nfc",
> +		.of_match_table = rk_nfc_id_table,
> +		.pm = &rk_nfc_pm_ops,
> +	},
> +};
> +
> +module_platform_driver(rk_nfc_driver);
> +
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_AUTHOR("Yifeng Zhao <[email-masked]>");
> +MODULE_DESCRIPTION("Rockchip Nand Flash Controller Driver");
> +MODULE_ALIAS("platform:rockchip-nand-controller");
>

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