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Date:   Thu, 9 Jun 2022 13:22:54 +0530
From:   Manivannan Sadhasivam <mani@kernel.org>
To:     Ansuel Smith <ansuelsmth@gmail.com>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linux-mtd@lists.infradead.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/3] mtd: nand: raw: qcom_nandc: add support for
 unprotected spare data pages
Message-ID: <20220609075254.GC2758@thinkpad>
References: <20220608001030.18813-1-ansuelsmth@gmail.com>
 <20220608001030.18813-2-ansuelsmth@gmail.com>
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In-Reply-To: <20220608001030.18813-2-ansuelsmth@gmail.com>
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On Wed, Jun 08, 2022 at 02:10:28AM +0200, Ansuel Smith wrote:
> IPQ8064 nand have special pages where a different layout scheme is used.
> These special page are used by boot partition and on reading them
> lots of warning are reported about wrong ECC data and if written to
> results in broken data and not bootable device.
> 
> The layout scheme used by these special page consist in using 512 bytes
> as the codeword size (even for the last codeword) while writing to CFG0
> register. This forces the NAND controller to unprotect the 4 bytes of
> spare data.
> 
> Since the kernel is unaware of this different layout for these special
> page, it does try to protect the spare data too during read/write and
> warn about CRC errors.
> 
> Add support for this by permitting the user to declare these special
> pages in dts by declaring offset and size of the partition. The driver
> internally will convert these value to nand pages.
> 
> On user read/write the page is checked and if it's a boot page the
> correct layout is used.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> ---
>  drivers/mtd/nand/raw/qcom_nandc.c | 174 +++++++++++++++++++++++++++++-
>  1 file changed, 169 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> index 1a77542c6d67..06ee9a836a3b 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -80,8 +80,10 @@
>  #define	DISABLE_STATUS_AFTER_WRITE	4
>  #define	CW_PER_PAGE			6
>  #define	UD_SIZE_BYTES			9
> +#define	UD_SIZE_BYTES_MASK		GENMASK(18, 9)
>  #define	ECC_PARITY_SIZE_BYTES_RS	19
>  #define	SPARE_SIZE_BYTES		23
> +#define	SPARE_SIZE_BYTES_MASK		GENMASK(26, 23)
>  #define	NUM_ADDR_CYCLES			27
>  #define	STATUS_BFR_READ			30
>  #define	SET_RD_MODE_AFTER_STATUS	31
> @@ -102,6 +104,7 @@
>  #define	ECC_MODE			4
>  #define	ECC_PARITY_SIZE_BYTES_BCH	8
>  #define	ECC_NUM_DATA_BYTES		16
> +#define	ECC_NUM_DATA_BYTES_MASK		GENMASK(25, 16)
>  #define	ECC_FORCE_CLK_OPEN		30
>  
>  /* NAND_DEV_CMD1 bits */
> @@ -418,6 +421,19 @@ struct qcom_nand_controller {
>  	const struct qcom_nandc_props *props;
>  };
>  
> +/*
> + * NAND special boot partitions
> + *
> + * @page_offset:		offset of the partition where spare data is not protected
> + *				by ECC (value in pages)

s/page_offset/offset

> + * @page_offset:		size of the partition where spare data is not protected
> + *				by ECC (value in pages)

s/page_offset/size

> + */
> +struct qcom_nand_boot_partition {
> +	u32 page_offset;
> +	u32 page_size;

same here

> +};
> +
>  /*
>   * NAND chip structure
>   *
> @@ -444,6 +460,13 @@ struct qcom_nand_controller {
>   * @cfg0, cfg1, cfg0_raw..:	NANDc register configurations needed for
>   *				ecc/non-ecc mode for the current nand flash
>   *				device
> + *
> + * @codeword_fixup:		keep track of the current layout used by
> + *				the driver for read/write operation.
> + * @nr_boot_partitions:		count of the boot partitions where spare data is not
> + *				protected by ECC

Align the Kdoc comments w.r.t other members.

> + * @boot_pages:			array of boot partitions where offset and size of the
> + *				boot partitions are stored

s/boot_pages/boot_partitions

>   */
>  struct qcom_nand_host {
>  	struct nand_chip chip;
> @@ -466,6 +489,10 @@ struct qcom_nand_host {
>  	u32 ecc_bch_cfg;
>  	u32 clrflashstatus;
>  	u32 clrreadstatus;
> +
> +	bool codeword_fixup;
> +	int nr_boot_partitions;
> +	struct qcom_nand_boot_partition *boot_partitions;
>  };
>  
>  /*
> @@ -475,6 +502,7 @@ struct qcom_nand_host {
>   * @is_bam - whether NAND controller is using BAM
>   * @is_qpic - whether NAND CTRL is part of qpic IP
>   * @qpic_v2 - flag to indicate QPIC IP version 2
> + * @use_codeword_fixup - whether NAND has different layout for boot partitions
>   * @dev_cmd_reg_start - NAND_DEV_CMD_* registers starting offset
>   */
>  struct qcom_nandc_props {
> @@ -482,6 +510,7 @@ struct qcom_nandc_props {
>  	bool is_bam;
>  	bool is_qpic;
>  	bool qpic_v2;
> +	bool use_codeword_fixup;
>  	u32 dev_cmd_reg_start;
>  };
>  
> @@ -1701,7 +1730,7 @@ qcom_nandc_read_cw_raw(struct mtd_info *mtd, struct nand_chip *chip,
>  	data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1);
>  	oob_size1 = host->bbm_size;
>  
> -	if (qcom_nandc_is_last_cw(ecc, cw)) {
> +	if (qcom_nandc_is_last_cw(ecc, cw) && !host->codeword_fixup) {
>  		data_size2 = ecc->size - data_size1 -
>  			     ((ecc->steps - 1) * 4);
>  		oob_size2 = (ecc->steps * 4) + host->ecc_bytes_hw +
> @@ -1782,7 +1811,7 @@ check_for_erased_page(struct qcom_nand_host *host, u8 *data_buf,
>  	}
>  
>  	for_each_set_bit(cw, &uncorrectable_cws, ecc->steps) {
> -		if (qcom_nandc_is_last_cw(ecc, cw)) {
> +		if (qcom_nandc_is_last_cw(ecc, cw) && !host->codeword_fixup) {
>  			data_size = ecc->size - ((ecc->steps - 1) * 4);
>  			oob_size = (ecc->steps * 4) + host->ecc_bytes_hw;
>  		} else {
> @@ -1940,7 +1969,7 @@ static int read_page_ecc(struct qcom_nand_host *host, u8 *data_buf,
>  	for (i = 0; i < ecc->steps; i++) {
>  		int data_size, oob_size;
>  
> -		if (qcom_nandc_is_last_cw(ecc, i)) {
> +		if (qcom_nandc_is_last_cw(ecc, i) && !host->codeword_fixup) {
>  			data_size = ecc->size - ((ecc->steps - 1) << 2);
>  			oob_size = (ecc->steps << 2) + host->ecc_bytes_hw +
>  				   host->spare_bytes;
> @@ -2037,6 +2066,55 @@ static int copy_last_cw(struct qcom_nand_host *host, int page)
>  	return ret;
>  }
>  
> +static bool
> +qcom_nandc_is_boot_page(struct qcom_nand_host *host, int page)

Move function name to previous line. If it exceeds 100 lines then wrap
arguments.

s/qcom_nandc_is_boot_page/qcom_nandc_is_boot_partition

> +{
> +	struct qcom_nand_boot_partition *boot_partition;
> +	u32 start, end;
> +	int i;
> +
> +	for (i = 0; i < host->nr_boot_partitions; i++) {
> +		boot_partition = &host->boot_partitions[i];
> +		start = boot_partition->page_offset;
> +		end = start + boot_partition->page_size;
> +
> +		/* Boot pages are normally at the start of

Block comments should start with:

	/*
	 * ...

Also, are you sure that only few pages in the partitions have different layout
and not all pages? If not, then this comment needs to be reworded.

> +		 * the nand in various partition.
> +		 * Check the page from the boot page end first
> +		 * to save one extra check and optimize this
> +		 * in case real no-boot partition are used.
> +		 */
> +		if (page < end && page >= start)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static void
> +qcom_nandc_codeword_fixup(struct qcom_nand_host *host, int page)
> +{
> +	bool codeword_fixup = qcom_nandc_is_boot_page(host, page);
> +
> +	/* Skip conf write if we are already in the correct mode */
> +	if (codeword_fixup == host->codeword_fixup)
> +		return;
> +
> +	host->codeword_fixup = codeword_fixup;
> +
> +	host->cw_data = codeword_fixup ? 512 : 516;
> +	host->spare_bytes = host->cw_size - host->ecc_bytes_hw -
> +			    host->bbm_size - host->cw_data;
> +
> +	host->cfg0 &= ~(SPARE_SIZE_BYTES_MASK | UD_SIZE_BYTES_MASK);
> +	host->cfg0 |= host->spare_bytes << SPARE_SIZE_BYTES |
> +		      host->cw_data << UD_SIZE_BYTES;
> +
> +	host->ecc_bch_cfg &= ~ECC_NUM_DATA_BYTES_MASK;
> +	host->ecc_bch_cfg |= host->cw_data << ECC_NUM_DATA_BYTES;
> +	host->ecc_buf_cfg = (codeword_fixup ? 0x1ff : 0x203) << NUM_STEPS;

s/1ff/(512 - 1)
s/203/(516 - 1)

> +}
> +
>  /* implements ecc->read_page() */
>  static int qcom_nandc_read_page(struct nand_chip *chip, uint8_t *buf,
>  				int oob_required, int page)
> @@ -2045,6 +2123,9 @@ static int qcom_nandc_read_page(struct nand_chip *chip, uint8_t *buf,
>  	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
>  	u8 *data_buf, *oob_buf = NULL;
>  
> +	if (host->nr_boot_partitions)
> +		qcom_nandc_codeword_fixup(host, page);
> +
>  	nand_read_page_op(chip, page, 0, NULL, 0);
>  	data_buf = buf;
>  	oob_buf = oob_required ? chip->oob_poi : NULL;
> @@ -2064,6 +2145,9 @@ static int qcom_nandc_read_page_raw(struct nand_chip *chip, uint8_t *buf,
>  	int cw, ret;
>  	u8 *data_buf = buf, *oob_buf = chip->oob_poi;
>  
> +	if (host->nr_boot_partitions)
> +		qcom_nandc_codeword_fixup(host, page);
> +
>  	for (cw = 0; cw < ecc->steps; cw++) {
>  		ret = qcom_nandc_read_cw_raw(mtd, chip, data_buf, oob_buf,
>  					     page, cw);
> @@ -2084,6 +2168,9 @@ static int qcom_nandc_read_oob(struct nand_chip *chip, int page)
>  	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
>  	struct nand_ecc_ctrl *ecc = &chip->ecc;
>  
> +	if (host->nr_boot_partitions)
> +		qcom_nandc_codeword_fixup(host, page);
> +
>  	clear_read_regs(nandc);
>  	clear_bam_transaction(nandc);
>  
> @@ -2104,6 +2191,9 @@ static int qcom_nandc_write_page(struct nand_chip *chip, const uint8_t *buf,
>  	u8 *data_buf, *oob_buf;
>  	int i, ret;
>  
> +	if (host->nr_boot_partitions)
> +		qcom_nandc_codeword_fixup(host, page);
> +
>  	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
>  
>  	clear_read_regs(nandc);
> @@ -2119,7 +2209,7 @@ static int qcom_nandc_write_page(struct nand_chip *chip, const uint8_t *buf,
>  	for (i = 0; i < ecc->steps; i++) {
>  		int data_size, oob_size;
>  
> -		if (qcom_nandc_is_last_cw(ecc, i)) {
> +		if (qcom_nandc_is_last_cw(ecc, i) && !host->codeword_fixup) {
>  			data_size = ecc->size - ((ecc->steps - 1) << 2);
>  			oob_size = (ecc->steps << 2) + host->ecc_bytes_hw +
>  				   host->spare_bytes;
> @@ -2176,6 +2266,9 @@ static int qcom_nandc_write_page_raw(struct nand_chip *chip,
>  	u8 *data_buf, *oob_buf;
>  	int i, ret;
>  
> +	if (host->nr_boot_partitions)
> +		qcom_nandc_codeword_fixup(host, page);
> +
>  	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
>  	clear_read_regs(nandc);
>  	clear_bam_transaction(nandc);
> @@ -2194,7 +2287,7 @@ static int qcom_nandc_write_page_raw(struct nand_chip *chip,
>  		data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1);
>  		oob_size1 = host->bbm_size;
>  
> -		if (qcom_nandc_is_last_cw(ecc, i)) {
> +		if (qcom_nandc_is_last_cw(ecc, i) && !host->codeword_fixup) {
>  			data_size2 = ecc->size - data_size1 -
>  				     ((ecc->steps - 1) << 2);
>  			oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw +
> @@ -2254,6 +2347,9 @@ static int qcom_nandc_write_oob(struct nand_chip *chip, int page)
>  	int data_size, oob_size;
>  	int ret;
>  
> +	if (host->nr_boot_partitions)
> +		qcom_nandc_codeword_fixup(host, page);
> +
>  	host->use_ecc = true;
>  	clear_bam_transaction(nandc);
>  
> @@ -2902,6 +2998,71 @@ static int qcom_nandc_setup(struct qcom_nand_controller *nandc)
>  
>  static const char * const probes[] = { "cmdlinepart", "ofpart", "qcomsmem", NULL };
>  
> +static int qcom_nand_host_parse_boot_partitions(struct qcom_nand_controller *nandc,
> +						struct qcom_nand_host *host,
> +						struct device_node *dn)
> +{
> +	struct nand_chip *chip = &host->chip;
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct qcom_nand_boot_partition *boot_partition;
> +	struct device *dev = nandc->dev;
> +	int partitions_count, i, j, ret;
> +
> +	if (!nandc->props->use_codeword_fixup)
> +		return 0;

Move this check to caller as I suggested previously.

> +
> +	if (!of_find_property(dn, "qcom,boot-partitions", NULL))
> +		return 0;
> +
> +	partitions_count = of_property_count_u32_elems(dn, "qcom,boot-partitions");
> +	if (partitions_count < 0) {

partitions_count <= 0

> +		dev_err(dev, "Error parsing boot partition.");

Add newline at the end of error message

> +		return ret;
> +	}
> +
> +	host->nr_boot_partitions = partitions_count / 2;
> +	host->boot_partitions = devm_kcalloc(dev, host->nr_boot_partitions,
> +					     sizeof(*host->boot_partitions), GFP_KERNEL);
> +	if (!host->boot_partitions)

host->nr_boot_partitions = 0;

> +		return -ENOMEM;
> +
> +	for (i = 0, j = 0; i < host->nr_boot_partitions; i++, j += 2) {
> +		boot_partition = &host->boot_partitions[i];
> +
> +		ret = of_property_read_u32_index(dn, "qcom,boot-partitions", j,
> +						 &boot_partition->page_offset);
> +		if (ret) {
> +			dev_err(dev, "Error parsing boot partition offset at index %d", i);

Add newline at the end of error message. Do the same for all error prints.

> +			return ret;
> +		}
> +
> +		if (boot_partition->page_offset % mtd->writesize) {
> +			dev_err(dev, "Boot partition offset not multiple of writesize at index %i",
> +				i);
> +			return -EINVAL;
> +		}
> +		/* Convert offset to nand pages */

s/pages/partitions

> +		boot_partition->page_offset /= mtd->writesize;

s/page_offset/offset

> +
> +		ret = of_property_read_u32_index(dn, "qcom,boot-partitions", j + 1,
> +						 &boot_partition->page_size);
> +		if (ret) {
> +			dev_err(dev, "Error parsing boot partition size at index %d", i);
> +			return ret;
> +		}
> +
> +		if (boot_partition->page_size % mtd->writesize) {

s/page_size/size here and below

> +			dev_err(dev, "Boot partition size not multiple of writesize at index %i",
> +				i);
> +			return -EINVAL;
> +		}
> +		/* Convert size to nand pages */

s/pages/partitions

Thanks,
Mani

> +		boot_partition->page_size /= mtd->writesize;
> +	}
> +
> +	return 0;
> +}
> +
>  static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
>  					    struct qcom_nand_host *host,
>  					    struct device_node *dn)
> @@ -2970,6 +3131,8 @@ static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
>  	if (ret)
>  		nand_cleanup(chip);
>  
> +	qcom_nand_host_parse_boot_partitions(nandc, host, dn);
> +
>  	return ret;
>  }
>  
> @@ -3135,6 +3298,7 @@ static int qcom_nandc_remove(struct platform_device *pdev)
>  static const struct qcom_nandc_props ipq806x_nandc_props = {
>  	.ecc_modes = (ECC_RS_4BIT | ECC_BCH_8BIT),
>  	.is_bam = false,
> +	.use_codeword_fixup = true,
>  	.dev_cmd_reg_start = 0x0,
>  };
>  
> -- 
> 2.36.1
> 

-- 
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