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Search for and validate the ONFI params as specified in the standard.

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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).
This commit is contained in:
Ian Lepore 2013-11-15 23:37:33 +00:00
parent 7aa6428bc6
commit 1b45c6cd53
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=258199
1 changed files with 45 additions and 8 deletions
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53
sys/dev/nand/nand_generic.c
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@ -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 *chip, struct onfi_params *params)
if (NANDBUS_START_COMMAND(nandbus))
return (ENXIO);
NANDBUS_READ_BUFFER(nandbus, params, sizeof(struct onfi_params));
/*
* XXX Bogus DELAY, we really need a nandbus_wait_ready() here, but it's
* not accessible from here (static to nandbus).
*/
DELAY(1000);
if (memcmp(params->signature, "ONFI", sizeof(params->signature))) {
device_printf(chip->dev, "Error: bad signature\n");
return (ENXIO);
/*
* 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);
}