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/it87spi.c b/it87spi.c
index f95f88d..d7f1833 100644
--- a/it87spi.c
+++ b/it87spi.c
@@ -196,11 +196,14 @@
 }
 
 /* Page size is usually 256 bytes */
-static void it8716f_spi_page_program(int block, uint8_t *buf, uint8_t *bios)
+static int it8716f_spi_page_program(int block, uint8_t *buf, uint8_t *bios)
 {
 	int i;
+	int result;
 
-	spi_write_enable();
+	result = spi_write_enable();
+	if (result)
+		return result;
 	OUTB(0x06, it8716f_flashport + 1);
 	OUTB(((2 + (fast_spi ? 1 : 0)) << 4), it8716f_flashport);
 	for (i = 0; i < 256; i++) {
@@ -212,6 +215,7 @@
 	 */
 	while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
 		usleep(1000);
+	return 0;
 }
 
 /*
@@ -222,12 +226,15 @@
 {
 	int total_size = 1024 * flash->total_size;
 	int i;
+	int result;
 
 	fast_spi = 0;
 
 	spi_disable_blockprotect();
 	for (i = 0; i < total_size; i++) {
-		spi_write_enable();
+		result = spi_write_enable();
+		if (result)
+			return result;
 		spi_byte_program(i, buf[i]);
 		while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
 			myusec_delay(10);