New subject: [PATCH] flashrom: Check the JEDEC vendor ID for correct parity

14 May 2008

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.
Signed-off-by: Carl-Daniel Hailfinger c-d.hailfinger.devel.2006@gmx.net
Index: flashrom-spijedecparity/flash.h
===================================================================

--- flashrom-spijedecparity/flash.h	(Revision 3306)
+++ flashrom-spijedecparity/flash.h	(Arbeitskopie)
@@ -396,6 +396,7 @@
 void it8716f_spi_page_program(int block, uint8_t *buf, uint8_t *bios);
/* jedec.c */
+uint8_t oddparity(uint8_t val);
 void toggle_ready_jedec(volatile uint8_t *dst);
 void data_polling_jedec(volatile uint8_t *dst, uint8_t data);
 void unprotect_jedec(volatile uint8_t *bios);
Index: flashrom-spijedecparity/jedec.c
===================================================================
--- flashrom-spijedecparity/jedec.c	(Revision 3306)
+++ flashrom-spijedecparity/jedec.c	(Arbeitskopie)
@@ -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;
Index: flashrom-spijedecparity/spi.c
===================================================================
--- flashrom-spijedecparity/spi.c	(Revision 3306)
+++ flashrom-spijedecparity/spi.c	(Arbeitskopie)
@@ -71,8 +71,12 @@
    uint32_t manuf_id;
    uint32_t model_id;
    if (!spi_rdid(readarr)) {
+		if (!oddparity(readarr[0]))
+			printf_debug("RDID byte 0 parity violation.\n");
    	/* Check if this is a continuation vendor ID */
    	if (readarr[0] == 0x7f) {
+			if (!oddparity(readarr[1]))
+				printf_debug("RDID byte 1 parity violation.\n");
    		manuf_id = (readarr[0] << 8) | readarr[1];
    		model_id = readarr[2];
    	} else {

    