Check the JEDEC vendor ID for correct parity
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>
diff --git a/jedec.c b/jedec.c
index 9588751..e818294 100644
--- a/jedec.c
+++ b/jedec.c
@@ -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 @@
*(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;