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Date:      Fri, 15 Nov 2013 23:37:33 +0000 (UTC)
From:      Ian Lepore <ian@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r258199 - head/sys/dev/nand
Message-ID:  <201311152337.rAFNbXJp031960@svn.freebsd.org>
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Author: ian
Date: Fri Nov 15 23:37:33 2013
New Revision: 258199
URL: http://svnweb.freebsd.org/changeset/base/258199

Log:
  Search for and validate the ONFI params as specified in the standard.
  
  The ONFI spec states that at least two bytes of the signature ("ONFI")
  must be present, and the CRC must be correct to have a valid parameter
  page.  If the page is not valid there are at least two backup pages where
  the data can also be found.
  
  Submitted by:	Kristof Provost <kristof@sigsegv.be> (cleanup) and me (orig).

Modified:
  head/sys/dev/nand/nand_generic.c

Modified: head/sys/dev/nand/nand_generic.c
==============================================================================
--- head/sys/dev/nand/nand_generic.c	Fri Nov 15 23:35:45 2013	(r258198)
+++ head/sys/dev/nand/nand_generic.c	Fri Nov 15 23:37:33 2013	(r258199)
@@ -319,10 +319,31 @@ check_fail(device_t nandbus)
 	return (0);
 }
 
+static uint16_t
+onfi_crc(const void *buf, size_t buflen)
+{
+	int i, j;
+	uint16_t crc;
+	const uint8_t *bufptr;
+
+	bufptr = buf;
+	crc = 0x4f4e;
+	for (j = 0; j < buflen; j++) {
+		crc ^= *bufptr++ << 8;
+		for (i = 0; i < 8; i++)
+			if (crc & 0x8000)
+				crc = (crc << 1) ^ 0x8005;
+			else
+				crc <<= 1;
+	}
+       return crc;
+}
+
 static int
 onfi_read_parameter(struct nand_chip *chip, struct onfi_params *params)
 {
 	device_t nandbus;
+	int found, sigcount, trycopy;
 
 	nand_debug(NDBG_GEN,"read parameter");
 
@@ -339,16 +360,32 @@ onfi_read_parameter(struct nand_chip *ch
 	if (NANDBUS_START_COMMAND(nandbus))
 		return (ENXIO);
 
-	NANDBUS_READ_BUFFER(nandbus, params, sizeof(struct onfi_params));
-
-	if (memcmp(params->signature, "ONFI", sizeof(params->signature))) {
-		device_printf(chip->dev, "Error: bad signature\n");
-		return (ENXIO);
+	/*
+	 * XXX Bogus DELAY, we really need a nandbus_wait_ready() here, but it's
+	 * not accessible from here (static to nandbus).
+	 */
+	DELAY(1000);
+
+	/*
+	 * The ONFI spec mandates a minimum of three copies of the parameter
+	 * data, so loop up to 3 times trying to find good data.  Each copy is
+	 * validated by a signature of "ONFI" and a crc. There is a very strange
+	 * rule that the signature is valid if any 2 of the 4 bytes are correct.
+	 */
+	for (found= 0, trycopy = 0; !found && trycopy < 3; trycopy++) {
+		NANDBUS_READ_BUFFER(nandbus, params, sizeof(struct onfi_params));
+		sigcount  = params->signature[0] == 'O';
+		sigcount += params->signature[1] == 'N';
+		sigcount += params->signature[2] == 'F';
+		sigcount += params->signature[3] == 'I';
+		if (sigcount < 2)
+			continue;
+		if (onfi_crc(params, 254) != params->crc)
+			continue;
+		found = 1;
 	}
-
-	/* TODO */
-	/* Check CRC */
-	/* Use redundant page if necessary */
+	if (!found)
+		return (ENXIO);
 
 	return (0);
 }

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