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Date:   Tue, 28 Sep 2021 17:51:00 +0530
From:   mdalam@codeaurora.org
To:     miquel.raynal@bootlin.com, mani@kernel.org,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     sricharan@codeaurora.org
Subject: Re: [PATCH 3/3] mtd: rawnand: qcom: Add support for page scope read
In-Reply-To: <1631699851-12172-4-git-send-email-mdalam@codeaurora.org>
References: <1631699851-12172-1-git-send-email-mdalam@codeaurora.org>
 <1631699851-12172-4-git-send-email-mdalam@codeaurora.org>
Message-ID: <8765976685ca3a04af1c102a69c9ca63@codeaurora.org>
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On 2021-09-15 15:27, Md Sadre Alam wrote:
> QPIC V2.0 onwards QPIC controller support enhanced read mode
> like page scope read and multi page read.
> 
> In QPIC V1, SW is needed to write EXEC_CMD register for each
> Code word and collect any Status related to that CW before
> issueing EXEC_CMD for next CW.
> 
> Page scope command is truly a page mode command where SW is
> required to issue EXEC_CMD only once for a page. Controller
> HW takes care of Codeword specific details and automatically
> returns status associated with each CW to BAM pipe, dedicated
> for status deposition.
> 
> With this command, SW now can issue one read command for a page
> and upon receiving completion interrupt, can process status,
> that have already been deposited in memory through status BAM pipe.
> 
> Signed-off-by: Md Sadre Alam <mdalam@codeaurora.org>
> ---
>  drivers/mtd/nand/raw/qcom_nandc.c | 77 
> ++++++++++++++++++++++++++++++++++++---
>  1 file changed, 71 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c
> b/drivers/mtd/nand/raw/qcom_nandc.c
> index 07448c4..257dec7e 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -157,6 +157,10 @@
>  #define	OP_FETCH_ID			0xb
>  #define	OP_RESET_DEVICE			0xd
> 
> +/* Auto status val and mask */
> +#define	AUTO_STS_VAL			0x000B000B
> +#define PAGE_SCOPE_READ			BIT(23)
> +
>  /* Default Value for NAND_DEV_CMD_VLD */
>  #define NAND_DEV_CMD_VLD_VAL		(READ_START_VLD | WRITE_START_VLD | \
>  					 ERASE_START_VLD | SEQ_READ_START_VLD)
> @@ -336,6 +340,8 @@ struct nandc_regs {
> 
>  	__le32 erased_cw_detect_cfg_clr;
>  	__le32 erased_cw_detect_cfg_set;
> +
> +	__le32 auto_sts_en;
>  };
> 
>  /*
> @@ -421,6 +427,9 @@ struct qcom_nand_controller {
> 
>  	u32 cmd1, vld;
>  	const struct qcom_nandc_props *props;
> +
> +	__le32 *status_buf;
> +	int sts_buf_size;
>  };
> 
>  /*
> @@ -487,6 +496,7 @@ struct qcom_nandc_props {
>  	bool is_bam;
>  	bool is_qpic;
>  	bool qpic_v2;
> +	bool page_scope;
>  	u32 dev_cmd_reg_start;
>  };
> 
> @@ -656,6 +666,8 @@ static __le32 *offset_to_nandc_reg(struct
> nandc_regs *regs, int offset)
>  		return &regs->cfg1;
>  	case NAND_DEV0_ECC_CFG:
>  		return &regs->ecc_bch_cfg;
> +	case NAND_AUTO_STATUS_EN:
> +		return &regs->auto_sts_en;
>  	case NAND_READ_STATUS:
>  		return &regs->clrreadstatus;
>  	case NAND_DEV_CMD1:
> @@ -756,10 +768,13 @@ static void update_rw_regs(struct qcom_nand_host
> *host, int num_cw, bool read, i
>  	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
> 
>  	if (read) {
> -		if (host->use_ecc)
> +		if (host->use_ecc) {
>  			cmd = OP_PAGE_READ_WITH_ECC | PAGE_ACC | LAST_PAGE;
> -		else
> +			if (nandc->props->qpic_v2 && nandc->props->page_scope)
> +				cmd |= PAGE_SCOPE_READ;
> +		} else {
>  			cmd = OP_PAGE_READ | PAGE_ACC | LAST_PAGE;
> +		}
>  	} else {
>  		cmd = OP_PROGRAM_PAGE | PAGE_ACC | LAST_PAGE;
>  	}
> @@ -788,6 +803,9 @@ static void update_rw_regs(struct qcom_nand_host
> *host, int num_cw, bool read, i
>  	nandc_set_reg(chip, NAND_READ_STATUS, host->clrreadstatus);
>  	nandc_set_reg(chip, NAND_EXEC_CMD, 1);
> 
> +	if (nandc->props->qpic_v2 && nandc->props->page_scope)
> +		nandc_set_reg(chip, NAND_AUTO_STATUS_EN, AUTO_STS_VAL);
> +
>  	if (read)
>  		nandc_set_read_loc(chip, cw, 0, 0, host->use_ecc ?
>  				   host->cw_data : host->cw_size, 1);
> @@ -1040,6 +1058,26 @@ static int prep_adm_dma_desc(struct
> qcom_nand_controller *nandc, bool read,
>  }
> 
>  /*
> + * read_status_data_dma: prepares a DMA descriptor to transfer status 
> from the
> + *			 controller's status registers to buffer 'vaddr'
> + * @reg_off:             offset within the controller's data buffer
> + * @vaddr:               virtual address of the buffer we want to 
> write to
> + * @size:                DMA transaction size in bytes
> + * @flags:               flags to control DMA descriptor preparation
> + */
> +static int read_status_data_dma(struct qcom_nand_controller *nandc,
> int reg_off,
> +				const u8 *vaddr, int size, unsigned int flags)
> +{
> +	struct bam_transaction *bam_txn = nandc->bam_txn;
> +
> +	sg_set_buf(&bam_txn->sts_sgl[bam_txn->sts_sgl_pos],
> +		   vaddr, size);
> +	bam_txn->sts_sgl_pos++;
> +
> +	return 0;
> +}
> +
> +/*
>   * read_reg_dma:	prepares a descriptor to read a given number of
>   *			contiguous registers to the reg_read_buf pointer
>   *
> @@ -1186,13 +1224,20 @@ config_nand_cw_read(struct nand_chip *chip,
> bool use_ecc, int cw)
>  		write_reg_dma(nandc, reg, 4, NAND_BAM_NEXT_SGL);
> 
>  	write_reg_dma(nandc, NAND_FLASH_CMD, 1, NAND_BAM_NEXT_SGL);
> -	write_reg_dma(nandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> 
>  	if (use_ecc) {
> -		read_reg_dma(nandc, NAND_FLASH_STATUS, 2, 0);
> -		read_reg_dma(nandc, NAND_ERASED_CW_DETECT_STATUS, 1,
> -			     NAND_BAM_NEXT_SGL);
> +		if (nandc->props->qpic_v2 && nandc->props->page_scope) {
> +			if (qcom_nandc_is_last_cw(ecc, cw))
> +				write_reg_dma(nandc, NAND_EXEC_CMD, 1,
> +					      NAND_BAM_NEXT_SGL);
> +		} else {
> +			write_reg_dma(nandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +			read_reg_dma(nandc, NAND_FLASH_STATUS, 2, 0);
> +			read_reg_dma(nandc, NAND_ERASED_CW_DETECT_STATUS, 1,
> +				     NAND_BAM_NEXT_SGL);
> +		}
>  	} else {
> +		write_reg_dma(nandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
>  		read_reg_dma(nandc, NAND_FLASH_STATUS, 1, NAND_BAM_NEXT_SGL);
>  	}
>  }
> @@ -1959,6 +2004,8 @@ static int read_page_ecc(struct qcom_nand_host
> *host, u8 *data_buf,
>  	struct nand_ecc_ctrl *ecc = &chip->ecc;
>  	u8 *data_buf_start = data_buf, *oob_buf_start = oob_buf;
>  	int i, ret;
> +	__le32 *status_buf_start = nandc->status_buf;
> +	__le32 *status_buf_cw = nandc->status_buf;
> 
>  	config_nand_page_read(chip);
> 
> @@ -1994,6 +2041,12 @@ static int read_page_ecc(struct qcom_nand_host
> *host, u8 *data_buf,
>  			read_data_dma(nandc, FLASH_BUF_ACC, data_buf,
>  				      data_size, 0);
> 
> +		if (nandc->props->qpic_v2 && nandc->props->page_scope) {
> +			read_status_data_dma(nandc, FLASH_BUF_ACC, (void *)status_buf_cw,
> +					     (nandc->sts_buf_size >> 2), 0);
> +			status_buf_cw += (nandc->sts_buf_size >> 4);
> +		}
> +
>  		/*
>  		 * when ecc is enabled, the controller doesn't read the real
>  		 * or dummy bad block markers in each chunk. To maintain a
> @@ -2025,6 +2078,9 @@ static int read_page_ecc(struct qcom_nand_host
> *host, u8 *data_buf,
>  		return ret;
>  	}
> 
> +	if (nandc->props->qpic_v2 && nandc->props->page_scope)
> +		memmove(nandc->reg_read_buf, status_buf_start, nandc->sts_buf_size);
> +
>  	return parse_read_errors(host, data_buf_start, oob_buf_start, page);
>  }
> 
> @@ -3005,6 +3061,14 @@ static int
> qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
>  		}
>  	}
> 
> +	if (nandc->props->qpic_v2 && nandc->props->page_scope) {
> +		nandc->sts_buf_size = mtd->writesize == SZ_2K ? 48 : 96;
> +		nandc->status_buf = devm_kzalloc(nandc->dev, nandc->sts_buf_size,
> +						 GFP_KERNEL);
> +		if (!nandc->status_buf)
> +			return -ENOMEM;
> +	}
> +
>  	ret = mtd_device_parse_register(mtd, probes, NULL, NULL, 0);
>  	if (ret)
>  		nand_cleanup(chip);
> @@ -3197,6 +3261,7 @@ static const struct qcom_nandc_props 
> sdx55_nandc_props = {
>  	.is_bam = true,
>  	.is_qpic = true,
>  	.qpic_v2 = true,
> +	.page_scope = true,
>  	.dev_cmd_reg_start = 0x7000,
>  };

Ping! Please provide me some updates on this patch.