Patchwork [v6,05/10] mtd: get the ECC info from the Extended Parameter Page

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Submitter Huang Shijie
Date May 17, 2013, 3:17 a.m.
Message ID <1368760654-28754-6-git-send-email-b32955@freescale.com>
Download mbox | patch
Permalink /patch/244485/
State New
Headers show

Comments

Huang Shijie - May 17, 2013, 3:17 a.m.
Since the ONFI 2.1, the onfi spec adds the Extended Parameter Page
to store the ECC info.

The onfi spec tells us that if the nand chip's recommended ECC codeword
size is not 512 bytes, then the @ecc_bits is 0xff. The host _SHOULD_ then
read the Extended ECC information that is part of the extended parameter
page to retrieve the ECC requirements for this device.

This patch implement the reading of the Extended Parameter Page, and parses
the sections for ECC type, and get the ECC info from the ECC section.

Tested this patch with Micron MT29F64G08CBABAWP.

Acked-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Huang Shijie <b32955@freescale.com>
---
 drivers/mtd/nand/nand_base.c |   80 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 80 insertions(+), 0 deletions(-)
Vikram Narayanan - May 17, 2013, 5:36 p.m.
Hello Huang,

On 5/17/2013 8:47 AM, Huang Shijie wrote:
> Since the ONFI 2.1, the onfi spec adds the Extended Parameter Page
> to store the ECC info.
>
<snip>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index b63b731..0b1162a 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -2835,6 +2835,71 @@ static u16 onfi_crc16(u16 crc, u8 const *p, size_t len)
>   	return crc;
>   }
>
> +/* Parse the Extended Parameter Page. */
> +static int nand_flash_detect_ext_param_page(struct mtd_info *mtd,
> +		struct nand_chip *chip, struct nand_onfi_params *p)
> +{
<snip>
> +
> +	/* Read out the Extended Parameter Page. */
> +	chip->read_buf(mtd, (uint8_t *)ep, len);
> +	if ((onfi_crc16(ONFI_CRC_BASE, ((uint8_t *)ep) + 2, len - 2)
> +		!= le16_to_cpu(ep->crc)) || strncmp(ep->sig, "EPPS", 4)) {

 From section 5.7.2.2.
///Byte 2-5: Extended parameter page signature
This field contains the extended parameter page signature. When two or 
more bytes of the signature are valid, then it denotes that a valid copy 
of the extended parameter page is present///

But here you are doing a strict check. What if the first two bytes are 
valid? Or did I misunderstood something?
If not, I'd prefer to take the strncmp to a separate 'if' so, that you 
can do the comparison in the way specified in the ONFI spec.

> +		pr_debug("fail in the CRC.\n");

Also, this is the error for Signature failure as well. Please move the 
signature comparison to a new if to give better error messages.

> +		ret = -EINVAL;
> +		goto ext_out;
> +	}

Regards,
Vikram

Patch

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index b63b731..0b1162a 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2835,6 +2835,71 @@  static u16 onfi_crc16(u16 crc, u8 const *p, size_t len)
 	return crc;
 }
 
+/* Parse the Extended Parameter Page. */
+static int nand_flash_detect_ext_param_page(struct mtd_info *mtd,
+		struct nand_chip *chip, struct nand_onfi_params *p)
+{
+	struct onfi_ext_param_page *ep;
+	struct onfi_ext_section *s;
+	struct onfi_ext_ecc_info *ecc;
+	uint8_t *cursor;
+	int len;
+	int ret;
+	int i;
+
+	len = le16_to_cpu(p->ext_param_page_length) * 16;
+	ep = kmalloc(len, GFP_KERNEL);
+	if (!ep) {
+		ret = -ENOMEM;
+		goto ext_out;
+	}
+
+	/* Send our own NAND_CMD_PARAM. */
+	chip->cmdfunc(mtd, NAND_CMD_PARAM, 0, -1);
+
+	/* Use the Change Read Column command to skip the ONFI param pages. */
+	chip->cmdfunc(mtd, NAND_CMD_RNDOUT,
+			sizeof(*p) * p->num_of_param_pages , -1);
+
+	/* Read out the Extended Parameter Page. */
+	chip->read_buf(mtd, (uint8_t *)ep, len);
+	if ((onfi_crc16(ONFI_CRC_BASE, ((uint8_t *)ep) + 2, len - 2)
+		!= le16_to_cpu(ep->crc)) || strncmp(ep->sig, "EPPS", 4)) {
+		pr_debug("fail in the CRC.\n");
+		ret = -EINVAL;
+		goto ext_out;
+	}
+
+	/* find the ECC section. */
+	cursor = (uint8_t *)(ep + 1);
+	for (i = 0; i < ONFI_EXT_SECTION_MAX; i++) {
+		s = ep->sections + i;
+		if (s->type == ONFI_SECTION_TYPE_2)
+			break;
+		cursor += s->length * 16;
+	}
+	if (i == ONFI_EXT_SECTION_MAX) {
+		pr_debug("We can not find the ECC section.\n");
+		ret = -EINVAL;
+		goto ext_out;
+	}
+
+	/* get the info we want. */
+	ecc = (struct onfi_ext_ecc_info *)cursor;
+
+	if (ecc->codeword_size) {
+		chip->ecc_strength_ds = ecc->ecc_bits;
+		chip->ecc_step_ds = 1 << ecc->codeword_size;
+	}
+
+	pr_info("ONFI extended param page detected.\n");
+	return 0;
+
+ext_out:
+	kfree(ep);
+	return ret;
+}
+
 /*
  * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
  */
@@ -2903,6 +2968,21 @@  static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 	if (p->ecc_bits != 0xff) {
 		chip->ecc_strength_ds = p->ecc_bits;
 		chip->ecc_step_ds = 512;
+	} else if (chip->onfi_version >= 21 &&
+		(onfi_feature(chip) & ONFI_FEATURE_EXT_PARAM_PAGE)) {
+
+		/*
+		 * The nand_flash_detect_ext_param_page() uses the
+		 * Change Read Column command which maybe not supported
+		 * by the chip->cmdfunc. So try to update the chip->cmdfunc
+		 * now. We do not replace user supplied command function.
+		 */
+		if (mtd->writesize > 512 && chip->cmdfunc == nand_command)
+			chip->cmdfunc = nand_command_lp;
+
+		/* The Extended Parameter Page is supported since ONFI 2.1. */
+		if (nand_flash_detect_ext_param_page(mtd, chip, p))
+			pr_info("Failed to detect the extended param page.\n");
 	}
 
 	pr_info("ONFI flash detected\n");