diff --git a/bitbang_spi.c b/bitbang_spi.c
index 8d6a9a1..f60a7e1 100644
--- a/bitbang_spi.c
+++ b/bitbang_spi.c
@@ -1,7 +1,7 @@
 /*
  * This file is part of the flashrom project.
  *
- * Copyright (C) 2009 Carl-Daniel Hailfinger
+ * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -142,24 +142,7 @@
 int bitbang_spi_write_256(struct flashchip *flash, uint8_t *buf)
 {
 	int total_size = 1024 * flash->total_size;
-	int i;
 
 	msg_pdbg("total_size is %d\n", total_size);
-	for (i = 0; i < total_size; i += 256) {
-		int l, r;
-		if (i + 256 <= total_size)
-			l = 256;
-		else
-			l = total_size - i;
-
-		if ((r = spi_nbyte_program(i, &buf[i], l))) {
-			msg_perr("%s: write fail %d\n", __func__, r);
-			return 1;
-		}
-		
-		while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
-			/* loop */;
-	}
-
-	return 0;
+	return spi_write_chunked(flash, buf, 0, total_size, 256);
 }
diff --git a/buspirate_spi.c b/buspirate_spi.c
index dc491e2..524b608 100644
--- a/buspirate_spi.c
+++ b/buspirate_spi.c
@@ -1,7 +1,7 @@
 /*
  * This file is part of the flashrom project.
  *
- * Copyright (C) 2009 Carl-Daniel Hailfinger
+ * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -319,7 +319,6 @@
 int buspirate_spi_write_256(struct flashchip *flash, uint8_t *buf)
 {
 	int total_size = 1024 * flash->total_size;
-	int i;
 
 	spi_disable_blockprotect();
 	/* Erase first. */
@@ -330,25 +329,5 @@
 	}
 	msg_pinfo("done.\n");
 
-	/* FIXME: We could do 12 byte writes, but then we'd have to make sure
-	 * not to cross a 256 byte page boundary. This problem only applies to
-	 * writes, reads can cross page boundaries just fine.
-	 */
-	for (i = 0; i < total_size; i += 8) {
-		int l, r;
-		if (i + 8 <= total_size)
-			l = 8;
-		else
-			l = total_size - i;
-
-		if ((r = spi_nbyte_program(i, &buf[i], l))) {
-			msg_perr("%s: write fail %d\n", __func__, r);
-			return 1;
-		}
-
-		while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
-			/* loop */;
-	}
-
-	return 0;
+	return spi_write_chunked(flash, buf, 0, total_size, 12);
 }
diff --git a/chipdrivers.h b/chipdrivers.h
index 6d5cef0..9537775 100644
--- a/chipdrivers.h
+++ b/chipdrivers.h
@@ -51,6 +51,7 @@
 int spi_nbyte_program(int addr, uint8_t *bytes, int len);
 int spi_nbyte_read(int addr, uint8_t *bytes, int len);
 int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize);
+int spi_write_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize);
 int spi_aai_write(struct flashchip *flash, uint8_t *buf);
 
 /* 82802ab.c */
diff --git a/ft2232_spi.c b/ft2232_spi.c
index 97b4867..111b46d 100644
--- a/ft2232_spi.c
+++ b/ft2232_spi.c
@@ -2,7 +2,7 @@
  * This file is part of the flashrom project.
  *
  * Copyright (C) 2009 Paul Fox <pgf@laptop.org>
- * Copyright (C) 2009 Carl-Daniel Hailfinger
+ * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -288,7 +288,6 @@
 int ft2232_spi_write_256(struct flashchip *flash, uint8_t *buf)
 {
 	int total_size = 1024 * flash->total_size;
-	int i;
 
 	spi_disable_blockprotect();
 	/* Erase first. */
@@ -299,23 +298,7 @@
 	}
 	msg_pinfo("done.\n");
 	msg_pdbg("total_size is %d\n", total_size);
-	for (i = 0; i < total_size; i += 256) {
-		int l, r;
-		if (i + 256 <= total_size)
-			l = 256;
-		else
-			l = total_size - i;
-
-		if ((r = spi_nbyte_program(i, &buf[i], l))) {
-			msg_perr("%s: write fail %d\n", __func__, r);
-			return 1;
-		}
-
-		while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
-			/* loop */;
-	}
-
-	return 0;
+	return spi_write_chunked(flash, buf, 0, total_size, 256);
 }
 
 #endif
diff --git a/ichspi.c b/ichspi.c
index fbe9092..8add13e 100644
--- a/ichspi.c
+++ b/ichspi.c
@@ -5,7 +5,7 @@
  * Copyright (C) 2008 Claus Gindhart <claus.gindhart@kontron.com>
  * Copyright (C) 2008 Dominik Geyer <dominik.geyer@kontron.com>
  * Copyright (C) 2008 coresystems GmbH <info@coresystems.de>
- * Copyright (C) 2009 Carl-Daniel Hailfinger
+ * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -149,8 +149,6 @@
 static int program_opcodes(OPCODES * op);
 static int run_opcode(OPCODE op, uint32_t offset,
 		      uint8_t datalength, uint8_t * data);
-static int ich_spi_write_page(struct flashchip *flash, uint8_t * bytes,
-			      int offset, int maxdata);
 
 /* for pairing opcodes with their required preop */
 struct preop_opcode_pair {
@@ -636,28 +634,6 @@
 	return -1;
 }
 
-static int ich_spi_write_page(struct flashchip *flash, uint8_t * bytes,
-			      int offset, int maxdata)
-{
-	int page_size = flash->page_size;
-	uint32_t remaining = page_size;
-	int towrite;
-
-	msg_pspew("ich_spi_write_page: offset=%d, number=%d, buf=%p\n",
-		     offset, page_size, bytes);
-
-	for (; remaining > 0; remaining -= towrite) {
-		towrite = min(remaining, maxdata);
-		if (spi_nbyte_program(offset + (page_size - remaining),
-				      &bytes[page_size - remaining], towrite)) {
-			msg_perr("Error writing");
-			return 1;
-		}
-	}
-
-	return 0;
-}
-
 int ich_spi_read(struct flashchip *flash, uint8_t * buf, int start, int len)
 {
 	int maxdata = 64;
@@ -670,12 +646,14 @@
 
 int ich_spi_write_256(struct flashchip *flash, uint8_t * buf)
 {
-	int i, j, rc = 0;
+	int i, ret = 0;
 	int total_size = flash->total_size * 1024;
-	int page_size = flash->page_size;
 	int erase_size = 64 * 1024;
 	int maxdata = 64;
 
+	if (spi_controller == SPI_CONTROLLER_VIA)
+		maxdata = 16;
+
 	spi_disable_blockprotect();
 	/* Erase first */
 	msg_pinfo("Erasing flash before programming... ");
@@ -687,19 +665,15 @@
 
 	msg_pinfo("Programming page: \n");
 	for (i = 0; i < total_size / erase_size; i++) {
-		if (spi_controller == SPI_CONTROLLER_VIA)
-			maxdata = 16;
-
-		for (j = 0; j < erase_size / page_size; j++) {
-			ich_spi_write_page(flash,
-			   (void *)(buf + (i * erase_size) + (j * page_size)),
-			   (i * erase_size) + (j * page_size), maxdata);
-		}
+		ret = spi_write_chunked(flash, buf + (i * erase_size),
+					i * erase_size, erase_size, maxdata);
+		if (ret)
+			break;
 	}
 
 	msg_pinfo("\n");
 
-	return rc;
+	return ret;
 }
 
 int ich_spi_send_command(unsigned int writecnt, unsigned int readcnt,
diff --git a/sb600spi.c b/sb600spi.c
index 0cf797c..5fcbd9e 100644
--- a/sb600spi.c
+++ b/sb600spi.c
@@ -4,6 +4,7 @@
  * Copyright (C) 2008 Wang Qingpei <Qingpei.Wang@amd.com>
  * Copyright (C) 2008 Joe Bao <Zheng.Bao@amd.com>
  * Copyright (C) 2008 Advanced Micro Devices, Inc.
+ * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -49,7 +50,6 @@
 /* FIXME: SB600 can write 5 bytes per transaction. */
 int sb600_spi_write_1(struct flashchip *flash, uint8_t *buf)
 {
-	int i;
 	int total_size = flash->total_size * 1024;
 	int result = 0;
 
@@ -63,19 +63,7 @@
 	msg_pinfo("done.\n");
 
 	msg_pinfo("Programming flash");
-	for (i = 0; i < total_size; i++, buf++) {
-		result = spi_nbyte_program(i, buf, 1);
-		if (result) {
-			msg_perr("Write error!\n");
-			return result;
-		}
-
-		/* wait program complete. */
-		if (i % 0x8000 == 0)
-			msg_pspew(".");
-		while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
-			;
-	}
+	result = spi_write_chunked(flash, buf, 0, total_size, 5);
 	msg_pinfo(" done.\n");
 	return result;
 }
diff --git a/spi25.c b/spi25.c
index c6d1b65..5a52f28 100644
--- a/spi25.c
+++ b/spi25.c
@@ -1,7 +1,7 @@
 /*
  * This file is part of the flashrom project.
  *
- * Copyright (C) 2007, 2008, 2009 Carl-Daniel Hailfinger
+ * Copyright (C) 2007, 2008, 2009, 2010 Carl-Daniel Hailfinger
  * Copyright (C) 2008 coresystems GmbH
  *
  * This program is free software; you can redistribute it and/or modify
@@ -874,7 +874,7 @@
 }
 
 /*
- * Read a complete flash chip.
+ * Read a part of the flash chip.
  * Each page is read separately in chunks with a maximum size of chunksize.
  */
 int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize)
@@ -913,6 +913,52 @@
 }
 
 /*
+ * Write a part of the flash chip.
+ * Each page is written separately in chunks with a maximum size of chunksize.
+ */
+int spi_write_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize)
+{
+	int rc = 0;
+	int i, j, starthere, lenhere;
+	/* FIXME: page_size is the wrong variable. We need max_writechunk_size
+	 * in struct flashchip to do this properly. All chips using
+	 * spi_chip_write_256 have page_size set to max_writechunk_size, so
+	 * we're OK for now.
+	 */
+	int page_size = flash->page_size;
+	int towrite;
+
+	/* Warning: This loop has a very unusual condition and body.
+	 * The loop needs to go through each page with at least one affected
+	 * byte. The lowest page number is (start / page_size) since that
+	 * division rounds down. The highest page number we want is the page
+	 * where the last byte of the range lives. That last byte has the
+	 * address (start + len - 1), thus the highest page number is
+	 * (start + len - 1) / page_size. Since we want to include that last
+	 * page as well, the loop condition uses <=.
+	 */
+	for (i = start / page_size; i <= (start + len - 1) / page_size; i++) {
+		/* Byte position of the first byte in the range in this page. */
+		/* starthere is an offset to the base address of the chip. */
+		starthere = max(start, i * page_size);
+		/* Length of bytes in the range in this page. */
+		lenhere = min(start + len, (i + 1) * page_size) - starthere;
+		for (j = 0; j < lenhere; j += chunksize) {
+			towrite = min(chunksize, lenhere - j);
+			rc = spi_nbyte_program(starthere + j, buf + starthere - start + j, towrite);
+			if (rc)
+				break;
+			while (spi_read_status_register() & JEDEC_RDSR_BIT_WIP)
+				programmer_delay(10);
+		}
+		if (rc)
+			break;
+	}
+
+	return rc;
+}
+
+/*
  * Program chip using byte programming. (SLOW!)
  * This is for chips which can only handle one byte writes
  * and for chips where memory mapped programming is impossible