Date:   Thu, 18 Oct 2018 21:33:08 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Jianxin Pan <jianxin.pan@...ogic.com>
Cc:     <linux-mtd@...ts.infradead.org>, Rob Herring <robh@...nel.org>,
        Hanjie Lin <hanjie.lin@...ogic.com>,
        Victor Wan <victor.wan@...ogic.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Richard Weinberger <richard@....at>,
        Yixun Lan <yixun.lan@...ogic.com>,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        Liang Yang <liang.yang@...ogic.com>,
        Jian Hu <jian.hu@...ogic.com>,
        Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        linux-amlogic@...ts.infradead.org,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        linux-arm-kernel@...ts.infradead.org,
        Jerome Brunet <jbrunet@...libre.com>
Subject: Re: [PATCH v5 2/2] mtd: rawnand: meson: add support for Amlogic
 NAND flash controller

On Thu, 18 Oct 2018 13:09:05 +0800
Jianxin Pan <jianxin.pan@...ogic.com> wrote:

> From: Liang Yang <liang.yang@...ogic.com>
> 
> Add initial support for the Amlogic NAND flash controller which found
> in the Meson-GXBB/GXL/AXG SoCs.
> 
> Signed-off-by: Liang Yang <liang.yang@...ogic.com>
> Signed-off-by: Yixun Lan <yixun.lan@...ogic.com>
> Signed-off-by: Jianxin Pan <jianxin.pan@...ogic.com>
> ---
>  drivers/mtd/nand/raw/Kconfig      |   10 +
>  drivers/mtd/nand/raw/Makefile     |    1 +
>  drivers/mtd/nand/raw/meson_nand.c | 1370 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 1381 insertions(+)
>  create mode 100644 drivers/mtd/nand/raw/meson_nand.c
> 
> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> index c7efc31..223b041 100644
> --- a/drivers/mtd/nand/raw/Kconfig
> +++ b/drivers/mtd/nand/raw/Kconfig
> @@ -541,4 +541,14 @@ config MTD_NAND_TEGRA
>  	  is supported. Extra OOB bytes when using HW ECC are currently
>  	  not supported.
>  
> +config MTD_NAND_MESON
> +	tristate "Support for NAND controller on Amlogic's Meson SoCs"
> +	depends on ARCH_MESON || COMPILE_TEST
> +	depends on COMMON_CLK_AMLOGIC
> +	select COMMON_CLK_REGMAP_MESON
> +	select MFD_SYSCON
> +	help
> +	  Enables support for NAND controller on Amlogic's Meson SoCs.
> +	  This controller is found on Meson GXBB, GXL, AXG SoCs.
> +
>  endif # MTD_NAND
> diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
> index 57159b3..a2cc2fe 100644
> --- a/drivers/mtd/nand/raw/Makefile
> +++ b/drivers/mtd/nand/raw/Makefile
> @@ -56,6 +56,7 @@ 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
> +obj-$(CONFIG_MTD_NAND_MESON)		+= meson_nand.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/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> new file mode 100644
> index 0000000..bcaac53
> --- /dev/null
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -0,0 +1,1370 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Amlogic Meson Nand Flash Controller Driver
> + *
> + * Copyright (c) 2018 Amlogic, inc.
> + * Author: Liang Yang <liang.yang@...ogic.com>
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/interrupt.h>
> +#include <linux/clk.h>
> +#include <linux/mtd/rawnand.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/iopoll.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +
> +#define NFC_REG_CMD		0x00
> +#define NFC_CMD_DRD		(0x8 << 14)
> +#define NFC_CMD_IDLE		(0xc << 14)
> +#define NFC_CMD_DWR		(0x4 << 14)
> +#define NFC_CMD_CLE		(0x5 << 14)
> +#define NFC_CMD_ALE		(0x6 << 14)
> +#define NFC_CMD_ADL		((0 << 16) | (3 << 20))
> +#define NFC_CMD_ADH		((1 << 16) | (3 << 20))
> +#define NFC_CMD_AIL		((2 << 16) | (3 << 20))
> +#define NFC_CMD_AIH		((3 << 16) | (3 << 20))
> +#define NFC_CMD_SEED		((8 << 16) | (3 << 20))
> +#define NFC_CMD_M2N		((0 << 17) | (2 << 20))
> +#define NFC_CMD_N2M		((1 << 17) | (2 << 20))
> +#define NFC_CMD_RB		BIT(20)
> +#define NFC_CMD_IO6		((0xb << 10) | (1 << 18))
> +
> +#define NFC_REG_CFG		0x04
> +#define NFC_REG_DADR		0x08
> +#define NFC_REG_IADR		0x0c
> +#define NFC_REG_BUF		0x10
> +#define NFC_REG_INFO		0x14
> +#define NFC_REG_DC		0x18
> +#define NFC_REG_ADR		0x1c
> +#define NFC_REG_DL		0x20
> +#define NFC_REG_DH		0x24
> +#define NFC_REG_CADR		0x28
> +#define NFC_REG_SADR		0x2c
> +#define NFC_REG_PINS		0x30
> +#define NFC_REG_VER		0x38
> +
> +#define NFC_RB_IRQ_EN		BIT(21)
> +#define NFC_INT_MASK		(3 << 20)
> +
> +#define CMDRWGEN(cmd_dir, ran, bch, short_mode, page_size, pages)	\
> +	(								\
> +		(cmd_dir)			|			\
> +		((ran) << 19)			|			\
> +		((bch) << 14)			|			\
> +		((short_mode) << 13)		|			\
> +		(((page_size) & 0x7f) << 6)	|			\
> +		((pages) & 0x3f)					\
> +	)
> +
> +#define GENCMDDADDRL(adl, addr)		((adl) | ((addr) & 0xffff))
> +#define GENCMDDADDRH(adh, addr)		((adh) | (((addr) >> 16) & 0xffff))
> +#define GENCMDIADDRL(ail, addr)		((ail) | ((addr) & 0xffff))
> +#define GENCMDIADDRH(aih, addr)		((aih) | (((addr) >> 16) & 0xffff))
> +
> +#define RB_STA(x)		(1 << (26 + (x)))
> +#define DMA_DIR(dir)		((dir) ? NFC_CMD_N2M : NFC_CMD_M2N)
> +
> +#define ECC_CHECK_RETURN_FF	(-1)
> +
> +#define NAND_CE0		(0xe << 10)
> +#define NAND_CE1		(0xd << 10)
> +
> +#define DMA_BUSY_TIMEOUT	0x100000
> +#define CMD_FIFO_EMPTY_TIMEOUT	1000
> +
> +#define MAX_CE_NUM		2
> +
> +/* eMMC clock register, misc control */
> +#define SD_EMMC_CLOCK		0x00
> +#define CLK_ALWAYS_ON		BIT(28)
> +#define CLK_SELECT_NAND		BIT(31)
> +#define CLK_DIV_MASK		GENMASK(5, 0)
> +
> +#define NFC_CLK_CYCLE		6
> +
> +/* nand flash controller delay 3 ns */
> +#define NFC_DEFAULT_DELAY	3000
> +
> +#define MAX_ECC_INDEX		10
> +
> +#define MUX_CLK_NUM_PARENTS	2
> +
> +#define ROW_ADDER(page, index)	(((page) >> (8 * (index))) & 0xff)
> +#define MAX_CYCLE_ROW_ADDRS	3
> +#define MAX_CYCLE_COLUMN_ADDRS	2
> +#define DIRREAD			1
> +#define DIRWRITE		0
> +
> +#define ECC_PARITY_BCH8_512B	14
> +
> +struct meson_nfc_info_format {
> +	u16 info_bytes;
> +
> +	/* bit[5:0] are valid */
> +	u8 zero_cnt;
> +	struct ecc_sta {
> +		u8 eccerr_cnt : 6;
> +		u8 notused : 1;
> +		u8 completed : 1;
> +	} ecc;

It's usually a bad idea to use bitfields for things like HW
regs/descriptors fields because it's hard to tell where the bits are
actually placed (not even sure the C standard defines how this should be
done).

> +	u32 reserved;
> +};

How about defining that the HW returns an array of __le64 instead and then
define the following macros which you can use after converting in the
CPU endianness 

#define ECC_GET_PROTECTED_OOB_BYTE(x, y)	(((x) >> (8 * (1 + y)) & GENMASK(7, 0))
#define ECC_COMPLETE			BIT(31)
#define ECC_ERR_CNT(x)			(((x) >> 24) & GENMASK(5, 0))

(I'm not entirely sure the field positions are correct, but I'll let you
check that).

> +
> +#define PER_INFO_BYTE	(sizeof(struct meson_nfc_info_format))
> +
> +struct meson_nfc_nand_chip {
> +	struct list_head node;
> +	struct nand_chip nand;
> +	bool is_scramble;

I think I already mentioned the NAND_NEED_SCRAMBLING flag []. Please
drop this field and test (chip->flags & NAND_NEED_SCRAMBLING) instead.

> +	int bch_mode;
> +	int nsels;
> +	u8 sels[0];
> +};
> +
> +struct meson_nand_ecc {
> +	int bch;
> +	int strength;
> +};
> +
> +struct meson_nfc_data {
> +	const struct nand_ecc_caps *ecc_caps;
> +};
> +
> +struct meson_nfc_param {
> +	int chip_select;
> +	int rb_select;
> +};
> +
> +struct nand_rw_cmd {
> +	int cmd0;
> +	int col[MAX_CYCLE_COLUMN_ADDRS];
> +	int row[MAX_CYCLE_ROW_ADDRS];
> +	int cmd1;
> +};
> +
> +struct nand_timing {
> +	int twb;
> +	int tadl;
> +	int twhr;
> +};
> +
> +struct meson_nfc {
> +	struct nand_controller controller;
> +	struct clk *core_clk;
> +	struct clk *device_clk;
> +	struct clk *phase_tx;
> +	struct clk *phase_rx;
> +
> +	struct device *dev;
> +	void __iomem *reg_base;
> +	struct regmap *reg_clk;
> +	struct completion completion;
> +	struct list_head chips;
> +	const struct meson_nfc_data *data;
> +	struct meson_nfc_param param;
> +	struct nand_timing timing;
> +	union {
> +		int cmd[32];
> +		struct nand_rw_cmd rw;
> +	} cmdfifo;
> +
> +	dma_addr_t data_dma;
> +	dma_addr_t info_dma;
> +
> +	unsigned long assigned_cs;
> +
> +	u8 *data_buf;
> +	u8 *info_buf;
> +};
> +
> +enum {
> +	NFC_ECC_BCH8_1K		= 2,
> +	NFC_ECC_BCH24_1K,
> +	NFC_ECC_BCH30_1K,
> +	NFC_ECC_BCH40_1K,
> +	NFC_ECC_BCH50_1K,
> +	NFC_ECC_BCH60_1K,
> +};
> +
> +#define MESON_ECC_DATA(b, s)	{ .bch = (b),	.strength = (s)}
> +
> +static int meson_nand_calc_ecc_bytes(int step_size, int strength)
> +{
> +	int ecc_bytes;
> +
> +	if (step_size == 512 && strength == 8)
> +		return ECC_PARITY_BCH8_512B;
> +
> +	ecc_bytes = DIV_ROUND_UP(strength * fls(step_size * 8), 8);
> +	if (ecc_bytes % 2)
> +		ecc_bytes++;

Just a tiny detail, but this can be replaced by ALIGN(ecc_bytes, 2).

> +
> +	return ecc_bytes;
> +}
> +
> +NAND_ECC_CAPS_SINGLE(meson_gxl_ecc_caps,
> +		     meson_nand_calc_ecc_bytes, 1024, 8, 24, 30, 40, 50, 60);
> +NAND_ECC_CAPS_SINGLE(meson_axg_ecc_caps,
> +		     meson_nand_calc_ecc_bytes, 1024, 8);
> +
> +static inline
> +struct meson_nfc_nand_chip *to_meson_nand(struct nand_chip *nand)
> +{
> +	return container_of(nand, struct meson_nfc_nand_chip, nand);
> +}
> +
> +static void meson_nfc_select_chip(struct nand_chip *nand, int chip)
> +{
> +	struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
> +	struct meson_nfc *nfc = nand_get_controller_data(nand);
> +
> +	if (chip < 0 || chip > MAX_CE_NUM)

You can add a WARN_ON_ONCE() around chip > MAX_CE_NUM, because this should
never happen.

> +		return;
> +
> +	nfc->param.chip_select = meson_chip->sels[chip] ? NAND_CE1 : NAND_CE0;
> +	nfc->param.rb_select = nfc->param.chip_select;
> +}
> +
> +static inline void meson_nfc_cmd_idle(struct meson_nfc *nfc, u32 time)
> +{
> +	writel(nfc->param.chip_select | NFC_CMD_IDLE | (time & 0x3ff),
> +	       nfc->reg_base + NFC_REG_CMD);
> +}
> +
> +static inline void meson_nfc_cmd_seed(struct meson_nfc *nfc, u32 seed)
> +{
> +	writel(NFC_CMD_SEED | (0xc2 + (seed & 0x7fff)),
> +	       nfc->reg_base + NFC_REG_CMD);
> +}
> +
> +static void meson_nfc_cmd_access(struct meson_nfc *nfc,
> +				 struct mtd_info *mtd, int raw, bool dir)

Just pass a nand_chip or a meson_nfc_nand_chip object here, nfc and mtd
can be extracted from there.

> +{
> +	struct nand_chip *nand = mtd_to_nand(mtd);
> +	struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
> +	u32 cmd, pagesize, pages;
> +	int bch = meson_chip->bch_mode;
> +	int len = mtd->writesize;
> +	int scramble = meson_chip->is_scramble ? 1 : 0;
> +
> +	pagesize = nand->ecc.size;
> +
> +	if (raw) {
> +		bch = NAND_ECC_NONE;

You set bch to NAND_ECC_NONE but never use the variable afterwards, is
that normal?

> +		len = mtd->writesize + mtd->oobsize;
> +		cmd = (len & 0x3fff) | (scramble << 19) | DMA_DIR(dir);

Please use a macro to describe bit 19:

#define NFC_CMD_SCRAMBLER_ENABLE	BIT(19)

> +		writel(cmd, nfc->reg_base + NFC_REG_CMD);
> +		return;
> +	}
> +
> +	pages = len / nand->ecc.size;
> +
> +	cmd = CMDRWGEN(DMA_DIR(dir), scramble, bch, 0, pagesize, pages);
> +
> +	writel(cmd, nfc->reg_base + NFC_REG_CMD);
> +}
> +
> +static inline void meson_nfc_drain_cmd(struct meson_nfc *nfc)
> +{
> +	/*
> +	 * Insert two commands to make sure all valid commands are finished.
> +	 *
> +	 * The Nand flash controller is designed as two stages pipleline -
> +	 *  a) fetch and b) excute.
> +	 * There might be cases when the driver see command queue is empty,
> +	 * but the Nand flash controller still has two commands buffered,
> +	 * one is fetched into NFC request queue (ready to run), and another
> +	 * is actively executing. So pushing 2 "IDLE" commands guarantees that
> +	 * the pipeline is emptied.
> +	 */
> +	meson_nfc_cmd_idle(nfc, 0);
> +	meson_nfc_cmd_idle(nfc, 0);
> +}
> +
> +static int meson_nfc_wait_cmd_finish(struct meson_nfc *nfc,
> +				     unsigned int timeout_ms)
> +{
> +	u32 cmd_size = 0;
> +	int ret;
> +
> +	/* wait cmd fifo is empty */
> +	ret = readl_poll_timeout(nfc->reg_base + NFC_REG_CMD, cmd_size,
> +				 !((cmd_size >> 22) & 0x1f),

Define a macro to extract the cmd_size:

#define NFC_CMD_GET_SIZE(x)	(((x) >> 22) & GENMASK(4, 0))

> +				 10, timeout_ms * 1000);
> +	if (ret)
> +		dev_err(nfc->dev, "wait for empty cmd FIFO time out\n");
> +
> +	return ret;
> +}
> +
> +static int meson_nfc_wait_dma_finish(struct meson_nfc *nfc)
> +{
> +	meson_nfc_drain_cmd(nfc);
> +
> +	return meson_nfc_wait_cmd_finish(nfc, DMA_BUSY_TIMEOUT);
> +}
> +
> +static inline
> +struct meson_nfc_info_format *nfc_info_ptr(struct meson_nfc *nfc,
> +					   int index)
> +{
> +	return (struct meson_nfc_info_format *)&nfc->info_buf[index * 8];

As said previously, I think ->info_buf should be an array of __le64, and
all you should do here is

	return le64_to_cpu(nfc->info_buf[index]);

Then you can use the macros defined above to extract the results you
need.

> +}
> +
> +static u8 *meson_nfc_oob_ptr(struct meson_nfc *nfc,
> +			     struct mtd_info *mtd, int i)
> +{
> +	struct nand_chip *nand = mtd_to_nand(mtd);
> +	int len;
> +
> +	len = nand->ecc.size * (i + 1) + (nand->ecc.bytes + 2) * i;
> +
> +	return nfc->data_buf + len;
> +}
> +
> +static u8 *meson_nfc_data_ptr(struct meson_nfc *nfc,
> +			      struct mtd_info *mtd, int i)
> +{
> +	struct nand_chip *nand = mtd_to_nand(mtd);
> +	int len;
> +	int temp;
> +
> +	temp = nand->ecc.size + nand->ecc.bytes;
> +	len = (temp + 2) * i;
> +
> +	return nfc->data_buf + len;
> +}
> +
> +static void meson_nfc_prase_data_oob(struct meson_nfc *nfc,

What does prase mean? Maybe _set_ and _get_ would be better that _prase_
and _format_. 

> +				     struct mtd_info *mtd, u8 *buf, u8 *oobbuf)

As said previously, please stop passing mtd objects around. Same goes
for nfc if you already have to pass a nand_chip object.

> +{
> +	struct nand_chip *nand = mtd_to_nand(mtd);
> +	int i, oob_len = 0;
> +	u8 *dsrc, *osrc;
> +
> +	for (i = 0; i < mtd->writesize / nand->ecc.size; i++) {

You have ecc->steps for that, no need to do the division everytime.

> +		if (buf) {
> +			dsrc = meson_nfc_data_ptr(nfc, mtd, i);
> +			memcpy(buf, dsrc, nand->ecc.size);
> +			buf += nand->ecc.size;
> +		}
> +		oob_len = nand->ecc.bytes + 2;

Looks like oob_len does not change, so you can move the oob_len
assignment outside of this loop.

> +		osrc = meson_nfc_oob_ptr(nfc, mtd, i);
> +		memcpy(oobbuf, osrc, oob_len);
> +		oobbuf += oob_len;
> +	}
> +}
> +
> +static void meson_nfc_format_data_oob(struct meson_nfc *nfc,
> +				      struct mtd_info *mtd,
> +				      const u8 *buf, u8 *oobbuf)
> +{
> +	struct nand_chip *nand = mtd_to_nand(mtd);
> +	int i, oob_len = 0;
> +	u8 *dsrc, *osrc;
> +
> +	for (i = 0; i < mtd->writesize / nand->ecc.size; i++) {
> +		if (buf) {
> +			dsrc = meson_nfc_data_ptr(nfc, mtd, i);
> +			memcpy(dsrc, buf, nand->ecc.size);
> +			buf += nand->ecc.size;
> +		}
> +		oob_len = nand->ecc.bytes + 2;
> +		osrc = meson_nfc_oob_ptr(nfc, mtd, i);
> +		memcpy(osrc, oobbuf, oob_len);
> +		oobbuf += oob_len;
> +	}
> +}
> +
> +static int meson_nfc_queue_rb(struct meson_nfc *nfc, int timeout_ms)
> +{
> +	u32 cmd, cfg;
> +	int ret = 0;
> +
> +	meson_nfc_cmd_idle(nfc, nfc->timing.twb);
> +	meson_nfc_drain_cmd(nfc);
> +	meson_nfc_wait_cmd_finish(nfc, CMD_FIFO_EMPTY_TIMEOUT);
> +
> +	cfg = readl(nfc->reg_base + NFC_REG_CFG);
> +	cfg |= (1 << 21);
> +	writel(cfg, nfc->reg_base + NFC_REG_CFG);
> +
> +	init_completion(&nfc->completion);
> +
> +	cmd = NFC_CMD_RB | (0x1 << 14) | nfc->param.chip_select | 0x18;

Please define macros for all those magic values (0x18 and 1 << 14)

> +	writel(cmd, nfc->reg_base + NFC_REG_CMD);
> +
> +	ret = wait_for_completion_timeout(&nfc->completion,
> +					  msecs_to_jiffies(timeout_ms));
> +	if (ret == 0) {
> +		dev_err(nfc->dev, "wait nand irq timeout\n");
> +		ret = -1;

		      -ETIMEDOUT;

> +	}
> +	return ret;
> +}
> +
> +static void meson_nfc_set_user_byte(struct mtd_info *mtd,
> +				    struct nand_chip *chip, u8 *oob_buf)
> +{
> +	struct meson_nfc *nfc = nand_get_controller_data(chip);
> +	struct meson_nfc_info_format *info;
> +	int i, count;
> +
> +	for (i = 0, count = 0; i < chip->ecc.steps; i++, count += 2) {
> +		info = nfc_info_ptr(nfc, i);
> +		info->info_bytes =
> +			oob_buf[count] | (oob_buf[count + 1] << 8);

Use a macro to set/get protected OOB bytes.

> +	}
> +}
> +

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