Date:   Tue, 5 Feb 2019 15:12:56 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Harvey Hunt <harveyhuntnexus@...il.com>,
        Mathieu Malaterre <malat@...ian.org>,
        linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 8/9] mtd: rawnand: ingenic: Add support for the
 JZ4725B

Hi Paul,

Paul Cercueil <paul@...pouillou.net> wrote on Mon,  4 Feb 2019 16:04:25
-0300:

> The boot ROM of the JZ4725B SoC expects a specific OOB layout on the
> NAND, so we use it unconditionally in the ingenic-nand driver.
> 
> Also add the jz4725b-bch driver to support the JZ4725B-specific BCH
> hardware.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
> 
> Changes:
> 
> v2: Instead of forcing the OOB layout, leave it to the board code or
>     devicetree to decide if the jz4725b-specific layout should be used
>     or not.
> 
> v3: - Revert the change in v2, as the previous behaviour was correct.
>     - Also add support for the hardware BCH of the JZ4725B in this
>       patch.
> 
>  drivers/mtd/nand/raw/ingenic/Kconfig        |  10 ++
>  drivers/mtd/nand/raw/ingenic/Makefile       |   1 +
>  drivers/mtd/nand/raw/ingenic/ingenic_nand.c |  48 +++++-
>  drivers/mtd/nand/raw/ingenic/jz4725b_bch.c  | 251 ++++++++++++++++++++++++++++
>  4 files changed, 309 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/mtd/nand/raw/ingenic/jz4725b_bch.c
> 
> diff --git a/drivers/mtd/nand/raw/ingenic/Kconfig b/drivers/mtd/nand/raw/ingenic/Kconfig
> index cc663cc15119..497b46b144f2 100644
> --- a/drivers/mtd/nand/raw/ingenic/Kconfig
> +++ b/drivers/mtd/nand/raw/ingenic/Kconfig
> @@ -27,6 +27,16 @@ config MTD_NAND_JZ4740_ECC
>  	  This driver can also be built as a module. If so, the module
>  	  will be called jz4740-ecc.
>  
> +config MTD_NAND_JZ4725B_BCH
> +	tristate "Hardware BCH support for JZ4725B SoC"
> +	select MTD_NAND_INGENIC_ECC
> +	help
> +	  Enable this driver to support the BCH error-correction hardware
> +	  present on the JZ4725B SoC from Ingenic.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called jz4725b-bch.
> +
>  config MTD_NAND_JZ4780_BCH
>  	tristate "Hardware BCH support for JZ4780 SoC"
>  	select MTD_NAND_INGENIC_ECC
> diff --git a/drivers/mtd/nand/raw/ingenic/Makefile b/drivers/mtd/nand/raw/ingenic/Makefile
> index 563b7effcf59..ab2c5f47e5b7 100644
> --- a/drivers/mtd/nand/raw/ingenic/Makefile
> +++ b/drivers/mtd/nand/raw/ingenic/Makefile
> @@ -3,4 +3,5 @@ obj-$(CONFIG_MTD_NAND_JZ4780) += ingenic_nand.o
>  
>  obj-$(CONFIG_MTD_NAND_INGENIC_ECC) += ingenic_ecc.o
>  obj-$(CONFIG_MTD_NAND_JZ4740_ECC) += jz4740_ecc.o
> +obj-$(CONFIG_MTD_NAND_JZ4725B_BCH) += jz4725b_bch.o
>  obj-$(CONFIG_MTD_NAND_JZ4780_BCH) += jz4780_bch.o
> diff --git a/drivers/mtd/nand/raw/ingenic/ingenic_nand.c b/drivers/mtd/nand/raw/ingenic/ingenic_nand.c
> index 3fd078920b17..0e6d79993ff3 100644
> --- a/drivers/mtd/nand/raw/ingenic/ingenic_nand.c
> +++ b/drivers/mtd/nand/raw/ingenic/ingenic_nand.c
> @@ -34,6 +34,7 @@ struct jz_soc_info {
>  	unsigned long data_offset;
>  	unsigned long addr_offset;
>  	unsigned long cmd_offset;
> +	const struct mtd_ooblayout_ops *oob_layout;
>  };
>  
>  struct ingenic_nand_cs {
> @@ -71,6 +72,41 @@ static inline struct ingenic_nfc *to_ingenic_nfc(struct nand_controller *ctrl)
>  	return container_of(ctrl, struct ingenic_nfc, controller);
>  }
>  
> +static int jz4725b_ooblayout_ecc(struct mtd_info *mtd, int section,
> +				 struct mtd_oob_region *oobregion)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> +
> +	if (section || !ecc->total)
> +		return -ERANGE;
> +
> +	oobregion->length = ecc->total;
> +	oobregion->offset = 3;
> +
> +	return 0;
> +}
> +
> +static int jz4725b_ooblayout_free(struct mtd_info *mtd, int section,
> +				  struct mtd_oob_region *oobregion)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	oobregion->length = mtd->oobsize - ecc->total - 3;
> +	oobregion->offset = 3 + ecc->total;
> +
> +	return 0;
> +}
> +
> +const struct mtd_ooblayout_ops jz4725b_ooblayout_ops = {
> +	.ecc = jz4725b_ooblayout_ecc,
> +	.free = jz4725b_ooblayout_free,
> +};
> +
>  static void ingenic_nand_select_chip(struct nand_chip *chip, int chipnr)
>  {
>  	struct ingenic_nand *nand = to_ingenic_nand(nand_to_mtd(chip));
> @@ -211,7 +247,7 @@ static int ingenic_nand_attach_chip(struct nand_chip *chip)
>  		return -EINVAL;
>  	}
>  
> -	mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
> +	mtd_set_ooblayout(mtd, nfc->soc_info->oob_layout);
>  
>  	return 0;
>  }
> @@ -407,16 +443,26 @@ static const struct jz_soc_info jz4740_soc_info = {
>  	.data_offset = 0x00000000,
>  	.cmd_offset  = 0x00008000,
>  	.addr_offset = 0x00010000,
> +	.oob_layout = &nand_ooblayout_lp_ops,
> +};
> +
> +static const struct jz_soc_info jz4725b_soc_info = {
> +	.data_offset = 0x00000000,
> +	.cmd_offset  = 0x00008000,
> +	.addr_offset = 0x00010000,
> +	.oob_layout = &jz4725b_ooblayout_ops,
>  };
>  
>  static const struct jz_soc_info jz4780_soc_info = {
>  	.data_offset = 0x00000000,
>  	.cmd_offset  = 0x00400000,
>  	.addr_offset = 0x00800000,
> +	.oob_layout = &nand_ooblayout_lp_ops,
>  };
>  
>  static const struct of_device_id ingenic_nand_dt_match[] = {
>  	{ .compatible = "ingenic,jz4740-nand", .data = &jz4740_soc_info },
> +	{ .compatible = "ingenic,jz4725b-nand", .data = &jz4725b_soc_info },
>  	{ .compatible = "ingenic,jz4780-nand",  .data = &jz4780_soc_info  },
>  	{},
>  };
> diff --git a/drivers/mtd/nand/raw/ingenic/jz4725b_bch.c b/drivers/mtd/nand/raw/ingenic/jz4725b_bch.c
> new file mode 100644
> index 000000000000..66be454be383
> --- /dev/null
> +++ b/drivers/mtd/nand/raw/ingenic/jz4725b_bch.c
> @@ -0,0 +1,251 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * JZ4725B BCH controller driver
> + *
> + * Copyright (C) 2018 Paul Cercueil <paul@...pouillou.net>
> + *
> + * Based on jz4780_bch.c
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +
> +#include "ingenic_ecc.h"
> +
> +#define BCH_BHCR			0x0
> +#define BCH_BHCSR			0x4
> +#define BCH_BHCCR			0x8
> +#define BCH_BHCNT			0xc
> +#define BCH_BHDR			0x10
> +#define BCH_BHPAR0			0x14
> +#define BCH_BHERR0			0x28
> +#define BCH_BHINT			0x24
> +#define BCH_BHINTES			0x3c
> +#define BCH_BHINTEC			0x40
> +#define BCH_BHINTE			0x38
> +
> +#define BCH_BHCR_BSEL_SHIFT		2
> +#define BCH_BHCR_BSEL_MASK		(0x1 << BCH_BHCR_BSEL_SHIFT)
> +#define BCH_BHCR_ENCE			BIT(3)
> +#define BCH_BHCR_INIT			BIT(1)
> +#define BCH_BHCR_BCHE			BIT(0)
> +
> +#define BCH_BHCNT_DEC_COUNT_SHIFT	16
> +#define BCH_BHCNT_DEC_COUNT_MASK	(0x3ff << BCH_BHCNT_DEC_COUNT_SHIFT)
> +#define BCH_BHCNT_ENC_COUNT_SHIFT	0
> +#define BCH_BHCNT_ENC_COUNT_MASK	(0x3ff << BCH_BHCNT_ENC_COUNT_SHIFT)
> +
> +#define BCH_BHERR_INDEX0_SHIFT		0
> +#define BCH_BHERR_INDEX0_MASK		(0x1fff << BCH_BHERR_INDEX0_SHIFT)
> +#define BCH_BHERR_INDEX1_SHIFT		16
> +#define BCH_BHERR_INDEX1_MASK		(0x1fff << BCH_BHERR_INDEX1_SHIFT)
> +
> +#define BCH_BHINT_ERRC_SHIFT		28
> +#define BCH_BHINT_ERRC_MASK		(0xf << BCH_BHINT_ERRC_SHIFT)
> +#define BCH_BHINT_TERRC_SHIFT		16
> +#define BCH_BHINT_TERRC_MASK		(0x7f << BCH_BHINT_TERRC_SHIFT)
> +#define BCH_BHINT_ALL_0			BIT(5)
> +#define BCH_BHINT_ALL_F			BIT(4)
> +#define BCH_BHINT_DECF			BIT(3)
> +#define BCH_BHINT_ENCF			BIT(2)
> +#define BCH_BHINT_UNCOR			BIT(1)
> +#define BCH_BHINT_ERR			BIT(0)
> +
> +/* Timeout for BCH calculation/correction. */
> +#define BCH_TIMEOUT_US			100000
> +
> +static void jz4725b_bch_init(struct ingenic_ecc *bch,
> +			     struct ingenic_ecc_params *params, bool encode)

I don't know the IP but 'encode' looks strange, what is it supposed to
mean?

> +{
> +	u32 reg;
> +
> +	/* Clear interrupt status. */
> +	writel(readl(bch->base + BCH_BHINT), bch->base + BCH_BHINT);
> +
> +	/* Initialise and enable BCH. */
> +	writel(0x1f, bch->base + BCH_BHCCR);
> +	writel(BCH_BHCR_BCHE, bch->base + BCH_BHCSR);
> +
> +	if (params->strength == 8)
> +		writel(BCH_BHCR_BSEL_MASK, bch->base + BCH_BHCSR);
> +	else
> +		writel(BCH_BHCR_BSEL_MASK, bch->base + BCH_BHCCR);

Here you write to BCH_BHCSR or BCH_BHCCR depending on
params->strength...

> +
> +	if (encode)
> +		writel(BCH_BHCR_ENCE, bch->base + BCH_BHCSR);
> +	else
> +		writel(BCH_BHCR_ENCE, bch->base + BCH_BHCCR);

...and here depending on encode.

Can you explain a bit?

> +
> +	writel(BCH_BHCR_INIT, bch->base + BCH_BHCSR);
> +
> +	/* Set up BCH count register. */
> +	reg = params->size << BCH_BHCNT_ENC_COUNT_SHIFT;
> +	reg |= (params->size + params->bytes) << BCH_BHCNT_DEC_COUNT_SHIFT;

Maybe you want to check params->size to fit the bitfield length?

> +	writel(reg, bch->base + BCH_BHCNT);
> +}
> +
> +static void jz4725b_bch_disable(struct ingenic_ecc *bch)
> +{
> +	writel(readl(bch->base + BCH_BHINT), bch->base + BCH_BHINT);
> +	writel(BCH_BHCR_BCHE, bch->base + BCH_BHCCR);

I would add comments, one to say you clear the interrupts, one when you
disable the engine.

> +}
> +
> +static void jz4725b_bch_write_data(struct ingenic_ecc *bch, const u8 *buf,
> +				   size_t size)
> +{
> +	while (size--)
> +		writeb(*buf++, bch->base + BCH_BHDR);
> +}
> +
> +static void jz4725b_bch_read_parity(struct ingenic_ecc *bch, u8 *buf,
> +				    size_t size)
> +{
> +	size_t size32 = size / sizeof(u32);
> +	size_t size8 = size % sizeof(u32);
> +	u32 *dest32;
> +	u8 *dest8;
> +	u32 val, offset = 0;
> +
> +	dest32 = (u32 *)buf;
> +	while (size32--) {
> +		*dest32++ = readl(bch->base + BCH_BHPAR0 + offset);
> +		offset += sizeof(u32);
> +	}
> +
> +	dest8 = (u8 *)dest32;
> +	val = readl(bch->base + BCH_BHPAR0 + offset);
> +	switch (size8) {
> +	case 3:
> +		dest8[2] = (val >> 16) & 0xff;
> +	case 2:
> +		dest8[1] = (val >> 8) & 0xff;
> +	case 1:
> +		dest8[0] = val & 0xff;
> +		break;
> +	}
> +}

Have you tried with _relaxed operators?

> +
> +static bool jz4725b_bch_wait_complete(struct ingenic_ecc *bch, unsigned int irq,
> +				      u32 *status)
> +{
> +	u32 reg;
> +	int ret;
> +
> +	/*
> +	 * While we could use interrupts here and sleep until the operation
> +	 * completes, the controller works fairly quickly (usually a few
> +	 * microseconds) and so the overhead of sleeping until we get an
> +	 * interrupt quite noticeably decreases performance.
> +	 */
> +	ret = readl_poll_timeout(bch->base + BCH_BHINT, reg,
> +				 (reg & irq) == irq, 0, BCH_TIMEOUT_US);

I suppose (reg & irq) is enough?

> +	if (ret)
> +		return false;
> +
> +	if (status)
> +		*status = reg;
> +
> +	writel(reg, bch->base + BCH_BHINT);

space

> +	return true;
> +}
> +
> +static int jz4725b_calculate(struct ingenic_ecc *bch,
> +			     struct ingenic_ecc_params *params,
> +			     const u8 *buf, u8 *ecc_code)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&bch->lock);
> +	jz4725b_bch_init(bch, params, true);
> +	jz4725b_bch_write_data(bch, buf, params->size);
> +
> +	if (jz4725b_bch_wait_complete(bch, BCH_BHINT_ENCF, NULL)) {

I would prefer bch_wait_complete() to return an usual negative error
instead of a boolean.

And maybe a goto could be used in case of error to disable BCH, unlock
the mutex and return.

> +		jz4725b_bch_read_parity(bch, ecc_code, params->bytes);
> +	} else {
> +		dev_err(bch->dev, "timed out while calculating ECC\n");
> +		ret = -ETIMEDOUT;
> +	}
> +
> +	jz4725b_bch_disable(bch);
> +	mutex_unlock(&bch->lock);

Space

> +	return ret;
> +}
> +
> +static int jz4725b_correct(struct ingenic_ecc *bch,
> +			   struct ingenic_ecc_params *params,
> +			   u8 *buf, u8 *ecc_code)
> +{
> +	u32 reg, errors, bit;
> +	unsigned int i;
> +	int ret = 0;
> +
> +	mutex_lock(&bch->lock);
> +
> +	jz4725b_bch_init(bch, params, false);
> +	jz4725b_bch_write_data(bch, buf, params->size);
> +	jz4725b_bch_write_data(bch, ecc_code, params->bytes);
> +
> +	if (!jz4725b_bch_wait_complete(bch, BCH_BHINT_DECF, &reg)) {
> +		dev_err(bch->dev, "timed out while correcting data\n");
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +
> +	if (reg & (BCH_BHINT_ALL_F | BCH_BHINT_ALL_0)) {
> +		/* Data and ECC is all 0xff or 0x00 - nothing to correct */
> +		ret = 0;
> +		goto out;
> +	}
> +
> +	if (reg & BCH_BHINT_UNCOR) {
> +		/* Uncorrectable ECC error */
> +		ret = -EBADMSG;
> +		goto out;
> +	}
> +
> +	errors = (reg & BCH_BHINT_ERRC_MASK) >> BCH_BHINT_ERRC_SHIFT;
> +
> +	/* Correct any detected errors. */
> +	for (i = 0; i < errors; i++) {
> +		if (i & 1) {
> +			bit = (reg & BCH_BHERR_INDEX1_MASK) >> BCH_BHERR_INDEX1_SHIFT;
> +		} else {
> +			reg = readl(bch->base + BCH_BHERR0 + (i * 4));
> +			bit = (reg & BCH_BHERR_INDEX0_MASK) >> BCH_BHERR_INDEX0_SHIFT;
> +		}
> +
> +		buf[(bit >> 3)] ^= BIT(bit & 0x7);
> +	}
> +
> +out:
> +	jz4725b_bch_disable(bch);
> +	mutex_unlock(&bch->lock);
> +	return ret;
> +}
> +
> +static const struct ingenic_ecc_ops jz4725b_bch_ops = {
> +	.disable = jz4725b_bch_disable,
> +	.calculate = jz4725b_calculate,
> +	.correct = jz4725b_correct,
> +};
> +
> +static const struct of_device_id jz4725b_bch_dt_match[] = {
> +	{ .compatible = "ingenic,jz4725b-bch", .data = &jz4725b_bch_ops },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, jz4725b_bch_dt_match);
> +
> +static struct platform_driver jz4725b_bch_driver = {
> +	.probe		= ingenic_ecc_probe,
> +	.driver	= {
> +		.name	= "jz4725b-bch",
> +		.of_match_table = jz4725b_bch_dt_match,
> +	},
> +};
> +module_platform_driver(jz4725b_bch_driver);

Missing MODULE_ macros? (author, license)


Thanks,
Miquèl

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