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Check the JEDEC vendor ID for correct parity

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Flash chips which can be detected by JEDEC probe routines all have
vendor IDs with correct parity. Use a parity check as additional hint
whether a vendor ID makes sense. Note: Device IDs have no parity
requirements whatsoever.

Corresponding to flashrom svn r231 and coreboot v2 svn r3308.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Peter Stuge <peter@stuge.se>
This commit is contained in:
Carl-Daniel Hailfinger
2008-05-14 12:03:06 +00:00
parent 4e84dfb784
commit a758f5100d
3 changed files with 17 additions and 1 deletions
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13
jedec.c
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@ -27,6 +27,14 @@
#define MAX_REFLASH_TRIES 0x10
/* Check one byte for odd parity */
uint8_t oddparity(uint8_t val)
{
val = (val ^ (val >> 4)) & 0xf;
val = (val ^ (val >> 2)) & 0x3;
return (val ^ (val >> 1)) & 0x1;
}
void toggle_ready_jedec(volatile uint8_t *dst)
{
unsigned int i = 0;
@ -123,7 +131,10 @@ int probe_jedec(struct flashchip *flash)
*(volatile uint8_t *)(bios + 0x5555) = 0xF0;
myusec_delay(40);
printf_debug("%s: id1 0x%x, id2 0x%x\n", __FUNCTION__, largeid1, largeid2);
printf_debug("%s: id1 0x%x, id2 0x%x", __FUNCTION__, largeid1, largeid2);
if (!oddparity(id1))
printf_debug(", id1 parity violation");
printf_debug("\n");
if (largeid1 == flash->manufacture_id && largeid2 == flash->model_id)
return 1;