Nick: carldani
E-mail: none
Board: sfdp dummy selection patch
Contents: 
Index: sfdp.c
===================================================================
--- sfdp.c	(Revision 1505)
+++ sfdp.c	(Arbeitskopie)
@@ -19,30 +19,45 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include "flash.h"
 #include "spi.h"
 #include "chipdrivers.h"
 
-static int spi_sfdp_read_sfdp_chunk(struct flashctx *flash, uint32_t address, uint8_t *buf, int len)
+static int spi_sfdp_read_sfdp_chunk(struct flashctx *flash, uint32_t address, uint8_t *buf, int len, int dummyread)
 {
 	int i, ret;
+	unsigned char *newbuf;
 	const unsigned char cmd[JEDEC_SFDP_OUTSIZE] = {
 		JEDEC_SFDP,
 		(address >> 16) & 0xff,
 		(address >> 8) & 0xff,
 		(address >> 0) & 0xff,
 		/* FIXME: the following dummy byte explodes on some programmers.
-		 * One possible workaround would be to read the dummy byte
+		 * One workaround is to read the dummy byte
 		 * instead and discard its value.
 		 */
 		0
 	};
 	msg_cspew("%s: addr=0x%x, len=%d, data:\n", __func__, address, len);
-	ret = spi_send_command(flash, sizeof(cmd), len, cmd, buf);
+	/* If dummyread is set, we use dummy read instead of dummy write. */
+	if (!dummyread) {
+		ret = spi_send_command(flash, sizeof(cmd), len, cmd, buf);
+	} else {
+		newbuf = malloc(len + 1);
+		if (!newbuf)
+			return SPI_PROGRAMMER_ERROR;
+		ret = spi_send_command(flash, sizeof(cmd) - 1, len + 1, cmd,
+				       newbuf);
+		memmove(buf, newbuf + 1, len);
+		free(newbuf);
+	}
+	if (ret)
+		return ret;
 	for (i = 0; i < len; i++)
 		msg_cspew(" 0x%02x", buf[i]);
 	msg_cspew("\n");
-	return ret;
+	return 0;
 }
 
 static int spi_sfdp_read_sfdp(struct flashctx *flash, uint32_t address, uint8_t *buf, int len)
@@ -52,14 +67,32 @@ static int spi_sfdp_read_sfdp(struct flashctx *fla
 	 * rest of the structure of the transaction).*/
 	int maxstep = 8;
 	int ret = 0;
-	while (len > 0) {
-		int step = min(len, maxstep);
-		ret = spi_sfdp_read_sfdp_chunk(flash, address, buf, step);
-		if (ret)
-			return ret;
-		address += step;
-		buf += step;
-		len -= step;
+	int i = 0;
+	/* dummyread == -1: no idea which variant works
+	 * dummyread ==  0: dummy write works
+	 * dummyread ==  1: dummy read works
+	 */
+	static int dummyread = -1;
+
+	if (dummyread >= 0)
+		i = dummyread;
+	for (; i < 2; i++) {
+		while (len > 0) {
+			int step = min(len, maxstep);
+			ret = spi_sfdp_read_sfdp_chunk(flash, address, buf,
+						       step, i);
+			if (ret)
+				break;
+			address += step;
+			buf += step;
+			len -= step;
+		}
+		if (dummyread >= 0)
+			break;
+		if (!ret) {
+			dummyread = i;
+			break;
+		}
 	}
 	return ret;
 }