Refine handling of spi_write_enable() failures to fix chip erases on ichspi

Until the ICH SPI driver can handle preopcodes as standalone opcodes,
we should handle such special opcode failure gracefully on ICH and
compatible chipsets.

This fixes chip erase on almost all ICH+VIA SPI masters.

Thanks to Ali Nadalizadeh for helping track down this bug!

Corresponding to flashrom svn r484.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
diff --git a/sb600spi.c b/sb600spi.c
index 9a3e99d..095fba1 100644
--- a/sb600spi.c
+++ b/sb600spi.c
@@ -68,6 +68,7 @@
 {
 	int rc = 0, i;
 	int total_size = flash->total_size * 1024;
+	int result;
 
 	/* Erase first */
 	printf("Erasing flash before programming... ");
@@ -77,7 +78,9 @@
 	printf("Programming flash");
 	for (i = 0; i < total_size; i++, buf++) {
 		spi_disable_blockprotect();
-		spi_write_enable();
+		result = spi_write_enable();
+		if (result)
+			return result;
 		spi_byte_program(i, *buf);
 		/* wait program complete. */
 		if (i % 0x8000 == 0)