[coreboot] [PATCH] flashrom: Detect non-ID responses

[Carl-Daniel Hailfinger]

When flashrom JEDEC code sends the ID command to the chip, it expects to
see IDs in the default flash location. However, sometimes the chip does
not react to the ID command, either because it doesn't understand the
command or because the command never reached it.
One way to detect this is to compare ID output with flash chip contents
for the same location. If they are identical, there is a high chance
you're not actually seeing ID output. Warn the user in that case.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

Index: flashrom-real-jedec-id/jedec.c
===================================================================
--- flashrom-real-jedec-id/jedec.c	(Revision 470)
+++ flashrom-real-jedec-id/jedec.c	(Arbeitskopie)
@@ -92,6 +92,7 @@
 	volatile uint8_t *bios = flash->virtual_memory;
 	uint8_t id1, id2;
 	uint32_t largeid1, largeid2;
+	uint32_t flashcontent1, flashcontent2;
 
 	/* Issue JEDEC Product ID Entry command */
 	chip_writeb(0xAA, bios + 0x5555);
@@ -133,6 +134,26 @@
 	printf_debug("%s: id1 0x%02x, id2 0x%02x", __FUNCTION__, largeid1, largeid2);
 	if (!oddparity(id1))
 		printf_debug(", id1 parity violation");
+
+	/* Read the product ID location again. We should now see normal flash contents. */
+	flashcontent1 = chip_readb(bios);
+	flashcontent2 = chip_readb(bios + 0x01);
+
+	/* Check if it is a continuation ID, this should be a while loop. */
+	if (flashcontent1 == 0x7F) {
+		flashcontent1 <<= 8;
+		flashcontent1 |= chip_readb(bios + 0x100);
+	}
+	if (flashcontent2 == 0x7F) {
+		flashcontent2 <<= 8;
+		flashcontent2 |= chip_readb(bios + 0x101);
+	}
+
+	if (largeid1 == flashcontent1)
+		printf_debug(", id1 is normal flash content");
+	if (largeid2 == flashcontent2)
+		printf_debug(", id2 is normal flash content");
+
 	printf_debug("\n");
 	if (largeid1 == flash->manufacture_id && largeid2 == flash->model_id)
 		return 1;


-- 
http://www.hailfinger.org/

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