diff --git a/82802ab.c b/82802ab.c
index 2a43813..9e39852 100644
--- a/82802ab.c
+++ b/82802ab.c
@@ -142,8 +142,7 @@
 }
 
 /* chunksize is 1 */
-int write_82802ab(struct flashctx *flash, uint8_t *src, unsigned int start,
-		  unsigned int len)
+int write_82802ab(struct flashctx *flash, const uint8_t *src, unsigned int start, unsigned int len)
 {
 	int i;
 	chipaddr dst = flash->virtual_memory + start;
diff --git a/at45db.c b/at45db.c
index 5c90418..b1a81ef 100644
--- a/at45db.c
+++ b/at45db.c
@@ -460,7 +460,7 @@
 	return at45db_erase(flash, opcode, at45db_convert_addr(addr, page_size), 200000, 100);
 }
 
-static int at45db_fill_buffer1(struct flashctx *flash, uint8_t *bytes, unsigned int off, unsigned int len)
+static int at45db_fill_buffer1(struct flashctx *flash, const uint8_t *bytes, unsigned int off, unsigned int len)
 {
 	const unsigned int page_size = flash->chip->page_size;
 	if ((off + len) > page_size) {
@@ -518,7 +518,7 @@
 	return 0;
 }
 
-static int at45db_program_page(struct flashctx *flash, uint8_t *buf, unsigned int at45db_addr)
+static int at45db_program_page(struct flashctx *flash, const uint8_t *buf, unsigned int at45db_addr)
 {
 	int ret = at45db_fill_buffer1(flash, buf, 0, flash->chip->page_size);
 	if (ret != 0) {
@@ -535,7 +535,7 @@
 	return 0;
 }
 
-int spi_write_at45db(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
+int spi_write_at45db(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	const unsigned int page_size = flash->chip->page_size;
 	const unsigned int total_size = flash->chip->total_size;
diff --git a/chipdrivers.h b/chipdrivers.h
index 851e90a..f270b55 100644
--- a/chipdrivers.h
+++ b/chipdrivers.h
@@ -28,8 +28,8 @@
 #include "flash.h"	/* for chipaddr and flashctx */
 
 /* spi.c */
-int spi_aai_write(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-int spi_chip_write_256(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int spi_aai_write(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
+int spi_chip_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 int spi_chip_read(struct flashctx *flash, uint8_t *buf, unsigned int start, int unsigned len);
 
 /* spi25.c */
@@ -54,12 +54,12 @@
 int spi_block_erase_d8(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 int spi_block_erase_db(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 erasefunc_t *spi_get_erasefn_from_opcode(uint8_t opcode);
-int spi_chip_write_1(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int spi_chip_write_1(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 int spi_byte_program(struct flashctx *flash, unsigned int addr, uint8_t databyte);
-int spi_nbyte_program(struct flashctx *flash, unsigned int addr, uint8_t *bytes, unsigned int len);
+int spi_nbyte_program(struct flashctx *flash, unsigned int addr, const uint8_t *bytes, unsigned int len);
 int spi_nbyte_read(struct flashctx *flash, unsigned int addr, uint8_t *bytes, unsigned int len);
 int spi_read_chunked(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len, unsigned int chunksize);
-int spi_write_chunked(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len, unsigned int chunksize);
+int spi_write_chunked(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len, unsigned int chunksize);
 
 /* spi25_statusreg.c */
 uint8_t spi_read_status_register(struct flashctx *flash);
@@ -107,7 +107,7 @@
 /* opaque.c */
 int probe_opaque(struct flashctx *flash);
 int read_opaque(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-int write_opaque(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int write_opaque(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 int erase_opaque(struct flashctx *flash, unsigned int blockaddr, unsigned int blocklen);
 
 /* at45db.c */
@@ -116,7 +116,7 @@
 int spi_disable_blockprotect_at45db(struct flashctx *flash);
 int spi_read_at45db(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
 int spi_read_at45db_e8(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-int spi_write_at45db(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int spi_write_at45db(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 int spi_erase_at45db_page(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 int spi_erase_at45db_block(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 int spi_erase_at45db_sector(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
@@ -127,7 +127,7 @@
 uint8_t wait_82802ab(struct flashctx *flash);
 int probe_82802ab(struct flashctx *flash);
 int erase_block_82802ab(struct flashctx *flash, unsigned int page, unsigned int pagesize);
-int write_82802ab(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int write_82802ab(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 void print_status_82802ab(uint8_t status);
 int unlock_82802ab(struct flashctx *flash);
 int unlock_28f004s5(struct flashctx *flash);
@@ -140,8 +140,8 @@
 int write_byte_program_jedec(struct flashctx *flash, chipaddr bios, uint8_t *src,
 			     chipaddr dst);
 int probe_jedec(struct flashctx *flash);
-int write_jedec(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-int write_jedec_1(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int write_jedec(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
+int write_jedec_1(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 int erase_sector_jedec(struct flashctx *flash, unsigned int page, unsigned int pagesize);
 int erase_block_jedec(struct flashctx *flash, unsigned int page, unsigned int blocksize);
 int erase_chip_block_jedec(struct flashctx *flash, unsigned int page, unsigned int blocksize);
@@ -150,7 +150,7 @@
 int probe_m29f400bt(struct flashctx *flash);
 int block_erase_m29f400bt(struct flashctx *flash, unsigned int start, unsigned int len);
 int block_erase_chip_m29f400bt(struct flashctx *flash, unsigned int start, unsigned int len);
-int write_m29f400bt(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int write_m29f400bt(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 void protect_m29f400bt(struct flashctx *flash, chipaddr bios);
 
 /* pm49fl00x.c */
@@ -160,7 +160,7 @@
 /* sst28sf040.c */
 int erase_chip_28sf040(struct flashctx *flash, unsigned int addr, unsigned int blocklen);
 int erase_sector_28sf040(struct flashctx *flash, unsigned int address, unsigned int sector_size);
-int write_28sf040(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int write_28sf040(struct flashctx *flash, const uint8_t *buf,unsigned int start, unsigned int len);
 int unprotect_28sf040(struct flashctx *flash);
 int protect_28sf040(struct flashctx *flash);
 
@@ -202,6 +202,6 @@
 int probe_en29lv640b(struct flashctx *flash);
 int block_erase_en29lv640b(struct flashctx *flash, unsigned int start, unsigned int len);
 int block_erase_chip_en29lv640b(struct flashctx *flash, unsigned int start, unsigned int len);
-int write_en29lv640b(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int write_en29lv640b(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 
 #endif /* !__CHIPDRIVERS_H__ */
diff --git a/dummyflasher.c b/dummyflasher.c
index e4dbef8..f0095d1 100644
--- a/dummyflasher.c
+++ b/dummyflasher.c
@@ -96,28 +96,18 @@
 
 static unsigned int spi_write_256_chunksize = 256;
 
-static int dummy_spi_send_command(struct flashctx *flash, unsigned int writecnt,
-				  unsigned int readcnt,
-				  const unsigned char *writearr,
-				  unsigned char *readarr);
-static int dummy_spi_write_256(struct flashctx *flash, uint8_t *buf,
+static int dummy_spi_send_command(struct flashctx *flash, unsigned int writecnt, unsigned int readcnt,
+				  const unsigned char *writearr, unsigned char *readarr);
+static int dummy_spi_write_256(struct flashctx *flash, const uint8_t *buf,
 			       unsigned int start, unsigned int len);
-static void dummy_chip_writeb(const struct flashctx *flash, uint8_t val,
-			      chipaddr addr);
-static void dummy_chip_writew(const struct flashctx *flash, uint16_t val,
-			      chipaddr addr);
-static void dummy_chip_writel(const struct flashctx *flash, uint32_t val,
-			      chipaddr addr);
-static void dummy_chip_writen(const struct flashctx *flash, uint8_t *buf,
-			      chipaddr addr, size_t len);
-static uint8_t dummy_chip_readb(const struct flashctx *flash,
-				const chipaddr addr);
-static uint16_t dummy_chip_readw(const struct flashctx *flash,
-				 const chipaddr addr);
-static uint32_t dummy_chip_readl(const struct flashctx *flash,
-				 const chipaddr addr);
-static void dummy_chip_readn(const struct flashctx *flash, uint8_t *buf,
-			     const chipaddr addr, size_t len);
+static void dummy_chip_writeb(const struct flashctx *flash, uint8_t val, chipaddr addr);
+static void dummy_chip_writew(const struct flashctx *flash, uint16_t val, chipaddr addr);
+static void dummy_chip_writel(const struct flashctx *flash, uint32_t val, chipaddr addr);
+static void dummy_chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len);
+static uint8_t dummy_chip_readb(const struct flashctx *flash, const chipaddr addr);
+static uint16_t dummy_chip_readw(const struct flashctx *flash, const chipaddr addr);
+static uint32_t dummy_chip_readl(const struct flashctx *flash, const chipaddr addr);
+static void dummy_chip_readn(const struct flashctx *flash, uint8_t *buf, const chipaddr addr, size_t len);
 
 static const struct spi_programmer spi_programmer_dummyflasher = {
 	.type		= SPI_CONTROLLER_DUMMY,
@@ -427,26 +417,22 @@
 	msg_pspew("%s: Unmapping 0x%zx bytes at %p\n", __func__, len, virt_addr);
 }
 
-static void dummy_chip_writeb(const struct flashctx *flash, uint8_t val,
-			      chipaddr addr)
+static void dummy_chip_writeb(const struct flashctx *flash, uint8_t val, chipaddr addr)
 {
 	msg_pspew("%s: addr=0x%" PRIxPTR ", val=0x%02x\n", __func__, addr, val);
 }
 
-static void dummy_chip_writew(const struct flashctx *flash, uint16_t val,
-			      chipaddr addr)
+static void dummy_chip_writew(const struct flashctx *flash, uint16_t val, chipaddr addr)
 {
 	msg_pspew("%s: addr=0x%" PRIxPTR ", val=0x%04x\n", __func__, addr, val);
 }
 
-static void dummy_chip_writel(const struct flashctx *flash, uint32_t val,
-			      chipaddr addr)
+static void dummy_chip_writel(const struct flashctx *flash, uint32_t val, chipaddr addr)
 {
 	msg_pspew("%s: addr=0x%" PRIxPTR ", val=0x%08x\n", __func__, addr, val);
 }
 
-static void dummy_chip_writen(const struct flashctx *flash, uint8_t *buf,
-			      chipaddr addr, size_t len)
+static void dummy_chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len)
 {
 	size_t i;
 	msg_pspew("%s: addr=0x%" PRIxPTR ", len=0x%zx, writing data (hex):", __func__, addr, len);
@@ -457,29 +443,25 @@
 	}
 }
 
-static uint8_t dummy_chip_readb(const struct flashctx *flash,
-				const chipaddr addr)
+static uint8_t dummy_chip_readb(const struct flashctx *flash, const chipaddr addr)
 {
 	msg_pspew("%s:  addr=0x%" PRIxPTR ", returning 0xff\n", __func__, addr);
 	return 0xff;
 }
 
-static uint16_t dummy_chip_readw(const struct flashctx *flash,
-				 const chipaddr addr)
+static uint16_t dummy_chip_readw(const struct flashctx *flash, const chipaddr addr)
 {
 	msg_pspew("%s:  addr=0x%" PRIxPTR ", returning 0xffff\n", __func__, addr);
 	return 0xffff;
 }
 
-static uint32_t dummy_chip_readl(const struct flashctx *flash,
-				 const chipaddr addr)
+static uint32_t dummy_chip_readl(const struct flashctx *flash, const chipaddr addr)
 {
 	msg_pspew("%s:  addr=0x%" PRIxPTR ", returning 0xffffffff\n", __func__, addr);
 	return 0xffffffff;
 }
 
-static void dummy_chip_readn(const struct flashctx *flash, uint8_t *buf,
-			     const chipaddr addr, size_t len)
+static void dummy_chip_readn(const struct flashctx *flash, uint8_t *buf, const chipaddr addr, size_t len)
 {
 	msg_pspew("%s:  addr=0x%" PRIxPTR ", len=0x%zx, returning array of 0xff\n", __func__, addr, len);
 	memset(buf, 0xff, len);
@@ -846,8 +828,7 @@
 	return 0;
 }
 
-static int dummy_spi_write_256(struct flashctx *flash, uint8_t *buf,
-			       unsigned int start, unsigned int len)
+static int dummy_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	return spi_write_chunked(flash, buf, start, len,
 				 spi_write_256_chunksize);
diff --git a/en29lv640b.c b/en29lv640b.c
index e79415a..110aa18 100644
--- a/en29lv640b.c
+++ b/en29lv640b.c
@@ -31,8 +31,7 @@
  */
 
 /* chunksize is 1 */
-int write_en29lv640b(struct flashctx *flash, uint8_t *src, unsigned int start,
-		     unsigned int len)
+int write_en29lv640b(struct flashctx *flash, const uint8_t *src, unsigned int start, unsigned int len)
 {
 	int i;
 	chipaddr bios = flash->virtual_memory;
diff --git a/flash.h b/flash.h
index 59f7cd4..2951c4d 100644
--- a/flash.h
+++ b/flash.h
@@ -175,7 +175,7 @@
 
 	int (*printlock) (struct flashctx *flash);
 	int (*unlock) (struct flashctx *flash);
-	int (*write) (struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+	int (*write) (struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 	int (*read) (struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
 	struct voltage {
 		uint16_t min;
@@ -228,7 +228,7 @@
 void chip_writeb(const struct flashctx *flash, uint8_t val, chipaddr addr);
 void chip_writew(const struct flashctx *flash, uint16_t val, chipaddr addr);
 void chip_writel(const struct flashctx *flash, uint32_t val, chipaddr addr);
-void chip_writen(const struct flashctx *flash, uint8_t *buf, chipaddr addr, size_t len);
+void chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len);
 uint8_t chip_readb(const struct flashctx *flash, const chipaddr addr);
 uint16_t chip_readw(const struct flashctx *flash, const chipaddr addr);
 uint32_t chip_readl(const struct flashctx *flash, const chipaddr addr);
@@ -253,8 +253,8 @@
 int max(int a, int b);
 void tolower_string(char *str);
 char *extract_param(const char *const *haystack, const char *needle, const char *delim);
-int verify_range(struct flashctx *flash, uint8_t *cmpbuf, unsigned int start, unsigned int len);
-int need_erase(uint8_t *have, uint8_t *want, unsigned int len, enum write_granularity gran);
+int verify_range(struct flashctx *flash, const uint8_t *cmpbuf, unsigned int start, unsigned int len);
+int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len, enum write_granularity gran);
 char *strcat_realloc(char *dest, const char *src);
 void print_version(void);
 void print_buildinfo(void);
@@ -263,7 +263,7 @@
 int selfcheck(void);
 int doit(struct flashctx *flash, int force, const char *filename, int read_it, int write_it, int erase_it, int verify_it);
 int read_buf_from_file(unsigned char *buf, unsigned long size, const char *filename);
-int write_buf_to_file(unsigned char *buf, unsigned long size, const char *filename);
+int write_buf_to_file(const unsigned char *buf, unsigned long size, const char *filename);
 
 enum test_state {
 	OK = 0,
@@ -327,7 +327,7 @@
 /* layout.c */
 int register_include_arg(char *name);
 int process_include_args(void);
-int read_romlayout(char *name);
+int read_romlayout(const char *name);
 int normalize_romentries(const struct flashctx *flash);
 int build_new_image(const struct flashctx *flash, uint8_t *oldcontents, uint8_t *newcontents);
 void layout_cleanup(void);
diff --git a/flashrom.c b/flashrom.c
index c20461a..9e87164 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -463,8 +463,7 @@
 	flash->pgm->par.chip_writel(flash, val, addr);
 }
 
-void chip_writen(const struct flashctx *flash, uint8_t *buf, chipaddr addr,
-		 size_t len)
+void chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len)
 {
 	flash->pgm->par.chip_writen(flash, buf, addr, len);
 }
@@ -627,7 +626,7 @@
 	return usable_erasefunctions;
 }
 
-int compare_range(uint8_t *wantbuf, uint8_t *havebuf, unsigned int start, unsigned int len)
+static int compare_range(const uint8_t *wantbuf, const uint8_t *havebuf, unsigned int start, unsigned int len)
 {
 	int ret = 0, failcount = 0;
 	unsigned int i;
@@ -671,7 +670,7 @@
  * @len		length of the verified area
  * @return	0 for success, -1 for failure
  */
-int verify_range(struct flashctx *flash, uint8_t *cmpbuf, unsigned int start, unsigned int len)
+int verify_range(struct flashctx *flash, const uint8_t *cmpbuf, unsigned int start, unsigned int len)
 {
 	uint8_t *readbuf = malloc(len);
 	int ret = 0;
@@ -710,7 +709,7 @@
 }
 
 /* Helper function for need_erase() that focuses on granularities of gran bytes. */
-static int need_erase_gran_bytes(uint8_t *have, uint8_t *want, unsigned int len, unsigned int gran)
+static int need_erase_gran_bytes(const uint8_t *have, const uint8_t *want, unsigned int len, unsigned int gran)
 {
 	unsigned int i, j, limit;
 	for (j = 0; j < len / gran; j++) {
@@ -740,7 +739,7 @@
  * @gran	write granularity (enum, not count)
  * @return      0 if no erase is needed, 1 otherwise
  */
-int need_erase(uint8_t *have, uint8_t *want, unsigned int len, enum write_granularity gran)
+int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len, enum write_granularity gran)
 {
 	int result = 0;
 	unsigned int i;
@@ -808,7 +807,7 @@
  * in relation to the max write length of the programmer and the max write
  * length of the chip.
  */
-static unsigned int get_next_write(uint8_t *have, uint8_t *want, unsigned int len,
+static unsigned int get_next_write(const uint8_t *have, const uint8_t *want, unsigned int len,
 			  unsigned int *first_start,
 			  enum write_granularity gran)
 {
@@ -1211,8 +1210,7 @@
 #endif
 }
 
-int write_buf_to_file(unsigned char *buf, unsigned long size,
-		      const char *filename)
+int write_buf_to_file(const unsigned char *buf, unsigned long size, const char *filename)
 {
 #ifdef __LIBPAYLOAD__
 	msg_gerr("Error: No file I/O support in libpayload\n");
@@ -1456,8 +1454,7 @@
 	return 0;
 }
 
-int erase_and_write_flash(struct flashctx *flash, uint8_t *oldcontents,
-			  uint8_t *newcontents)
+int erase_and_write_flash(struct flashctx *flash, uint8_t *oldcontents, uint8_t *newcontents)
 {
 	int k, ret = 1;
 	uint8_t *curcontents;
diff --git a/ichspi.c b/ichspi.c
index 6c394db..190ad5a 100644
--- a/ichspi.c
+++ b/ichspi.c
@@ -1327,8 +1327,7 @@
 	return 0;
 }
 
-static int ich_hwseq_write(struct flashctx *flash, uint8_t *buf,
-			   unsigned int addr, unsigned int len)
+static int ich_hwseq_write(struct flashctx *flash, const uint8_t *buf, unsigned int addr, unsigned int len)
 {
 	uint16_t hsfc;
 	uint16_t timeout = 100 * 60;
diff --git a/it87spi.c b/it87spi.c
index 06bf8db..160c4b6 100644
--- a/it87spi.c
+++ b/it87spi.c
@@ -108,7 +108,7 @@
 				    unsigned char *readarr);
 static int it8716f_spi_chip_read(struct flashctx *flash, uint8_t *buf,
 				 unsigned int start, unsigned int len);
-static int it8716f_spi_chip_write_256(struct flashctx *flash, uint8_t *buf,
+static int it8716f_spi_chip_write_256(struct flashctx *flash, const uint8_t *buf,
 				      unsigned int start, unsigned int len);
 
 static const struct spi_programmer spi_programmer_it87xx = {
@@ -347,8 +347,7 @@
 }
 
 /* Page size is usually 256 bytes */
-static int it8716f_spi_page_program(struct flashctx *flash, uint8_t *buf,
-				    unsigned int start)
+static int it8716f_spi_page_program(struct flashctx *flash, const uint8_t *buf, unsigned int start)
 {
 	unsigned int i;
 	int result;
@@ -393,7 +392,7 @@
 	return 0;
 }
 
-static int it8716f_spi_chip_write_256(struct flashctx *flash, uint8_t *buf,
+static int it8716f_spi_chip_write_256(struct flashctx *flash, const uint8_t *buf,
 				      unsigned int start, unsigned int len)
 {
 	const struct flashchip *chip = flash->chip;
diff --git a/layout.c b/layout.c
index 0e49f19..a12eb28 100644
--- a/layout.c
+++ b/layout.c
@@ -45,7 +45,7 @@
 static int num_include_args = 0; /* the number of valid include_args. */
 
 #ifndef __LIBPAYLOAD__
-int read_romlayout(char *name)
+int read_romlayout(const char *name)
 {
 	FILE *romlayout;
 	char tempstr[256];
@@ -102,7 +102,7 @@
 #endif
 
 /* returns the index of the entry (or a negative value if it is not found) */
-int find_include_arg(const char *const name)
+static int find_include_arg(const char *const name)
 {
 	unsigned int i;
 	for (i = 0; i < num_include_args; i++) {
diff --git a/linux_spi.c b/linux_spi.c
index f0c6404..695032c 100644
--- a/linux_spi.c
+++ b/linux_spi.c
@@ -43,7 +43,7 @@
 				  unsigned char *rxbuf);
 static int linux_spi_read(struct flashctx *flash, uint8_t *buf,
 			  unsigned int start, unsigned int len);
-static int linux_spi_write_256(struct flashctx *flash, uint8_t *buf,
+static int linux_spi_write_256(struct flashctx *flash, const uint8_t *buf,
 			       unsigned int start, unsigned int len);
 
 static const struct spi_programmer spi_programmer_linux = {
@@ -179,8 +179,7 @@
 				(unsigned int)getpagesize());
 }
 
-static int linux_spi_write_256(struct flashctx *flash, uint8_t *buf,
-			       unsigned int start, unsigned int len)
+static int linux_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	return spi_write_chunked(flash, buf, start, len,
 				((unsigned int)getpagesize()) - 4);
diff --git a/m29f400bt.c b/m29f400bt.c
index 8f0329e..c2236e5 100644
--- a/m29f400bt.c
+++ b/m29f400bt.c
@@ -28,8 +28,7 @@
    functions. */
 
 /* chunksize is 1 */
-int write_m29f400bt(struct flashctx *flash, uint8_t *src, unsigned int start,
-		    unsigned int len)
+int write_m29f400bt(struct flashctx *flash, const uint8_t *src, unsigned int start, unsigned int len)
 {
 	int i;
 	chipaddr bios = flash->virtual_memory;
diff --git a/opaque.c b/opaque.c
index 6acaa63..c63919f 100644
--- a/opaque.c
+++ b/opaque.c
@@ -40,7 +40,7 @@
 	return flash->pgm->opaque.read(flash, buf, start, len);
 }
 
-int write_opaque(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
+int write_opaque(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	return flash->pgm->opaque.write(flash, buf, start, len);
 }
diff --git a/programmer.c b/programmer.c
index bf7dca1..1874929 100644
--- a/programmer.c
+++ b/programmer.c
@@ -78,8 +78,7 @@
 	return val;
 }
 
-void fallback_chip_writen(const struct flashctx *flash, uint8_t *buf,
-			  chipaddr addr, size_t len)
+void fallback_chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len)
 {
 	size_t i;
 	for (i = 0; i < len; i++)
diff --git a/programmer.h b/programmer.h
index 4f4cc02..7670784 100644
--- a/programmer.h
+++ b/programmer.h
@@ -542,8 +542,8 @@
 
 	/* Optimized functions for this programmer */
 	int (*read)(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-	int (*write_256)(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-	int (*write_aai)(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+	int (*write_256)(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
+	int (*write_aai)(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 	const void *data;
 };
 
@@ -551,8 +551,8 @@
 			     const unsigned char *writearr, unsigned char *readarr);
 int default_spi_send_multicommand(struct flashctx *flash, struct spi_command *cmds);
 int default_spi_read(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-int default_spi_write_256(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-int default_spi_write_aai(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+int default_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
+int default_spi_write_aai(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 int register_spi_programmer(const struct spi_programmer *programmer);
 
 /* The following enum is needed by ich_descriptor_tool and ich* code as well as in chipset_enable.c. */
@@ -611,7 +611,7 @@
 	/* Specific functions for this programmer */
 	int (*probe) (struct flashctx *flash);
 	int (*read) (struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
-	int (*write) (struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len);
+	int (*write) (struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len);
 	int (*erase) (struct flashctx *flash, unsigned int blockaddr, unsigned int blocklen);
 	const void *data;
 };
@@ -624,7 +624,7 @@
 void noop_chip_writeb(const struct flashctx *flash, uint8_t val, chipaddr addr);
 void fallback_chip_writew(const struct flashctx *flash, uint16_t val, chipaddr addr);
 void fallback_chip_writel(const struct flashctx *flash, uint32_t val, chipaddr addr);
-void fallback_chip_writen(const struct flashctx *flash, uint8_t *buf, chipaddr addr, size_t len);
+void fallback_chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len);
 uint16_t fallback_chip_readw(const struct flashctx *flash, const chipaddr addr);
 uint32_t fallback_chip_readl(const struct flashctx *flash, const chipaddr addr);
 void fallback_chip_readn(const struct flashctx *flash, uint8_t *buf, const chipaddr addr, size_t len);
@@ -632,7 +632,7 @@
 	void (*chip_writeb) (const struct flashctx *flash, uint8_t val, chipaddr addr);
 	void (*chip_writew) (const struct flashctx *flash, uint16_t val, chipaddr addr);
 	void (*chip_writel) (const struct flashctx *flash, uint32_t val, chipaddr addr);
-	void (*chip_writen) (const struct flashctx *flash, uint8_t *buf, chipaddr addr, size_t len);
+	void (*chip_writen) (const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len);
 	uint8_t (*chip_readb) (const struct flashctx *flash, const chipaddr addr);
 	uint16_t (*chip_readw) (const struct flashctx *flash, const chipaddr addr);
 	uint32_t (*chip_readl) (const struct flashctx *flash, const chipaddr addr);
@@ -673,8 +673,8 @@
 extern fdtype sp_fd;
 /* expose serialport_shutdown as it's currently used by buspirate */
 int serialport_shutdown(void *data);
-int serialport_write(unsigned char *buf, unsigned int writecnt);
-int serialport_write_nonblock(unsigned char *buf, unsigned int writecnt, unsigned int timeout, unsigned int *really_wrote);
+int serialport_write(const unsigned char *buf, unsigned int writecnt);
+int serialport_write_nonblock(const unsigned char *buf, unsigned int writecnt, unsigned int timeout, unsigned int *really_wrote);
 int serialport_read(unsigned char *buf, unsigned int readcnt);
 int serialport_read_nonblock(unsigned char *c, unsigned int readcnt, unsigned int timeout, unsigned int *really_read);
 
diff --git a/serial.c b/serial.c
index 126079a..f7d8e5e 100644
--- a/serial.c
+++ b/serial.c
@@ -335,7 +335,7 @@
 	return 0;
 }
 
-int serialport_write(unsigned char *buf, unsigned int writecnt)
+int serialport_write(const unsigned char *buf, unsigned int writecnt)
 {
 #ifdef _WIN32
 	DWORD tmp = 0;
@@ -470,7 +470,7 @@
 /* Tries up to timeout ms to write writecnt characters from the array starting at buf. Returns
  * 0 on success, positive values on temporary errors (e.g. timeouts) and negative ones on permanent errors.
  * If really_wrote is not NULL, this function sets its contents to the number of bytes written successfully. */
-int serialport_write_nonblock(unsigned char *buf, unsigned int writecnt, unsigned int timeout, unsigned int *really_wrote)
+int serialport_write_nonblock(const unsigned char *buf, unsigned int writecnt, unsigned int timeout, unsigned int *really_wrote)
 {
 	int ret = 1;
 	/* disable blocked i/o and declare platform-specific variables */
diff --git a/spi.c b/spi.c
index 94a76a7..d6cbb88 100644
--- a/spi.c
+++ b/spi.c
@@ -88,8 +88,7 @@
 	return spi_read_chunked(flash, buf, start, len, max_data);
 }
 
-int default_spi_write_256(struct flashctx *flash, uint8_t *buf,
-			  unsigned int start, unsigned int len)
+int default_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	unsigned int max_data = flash->pgm->spi.max_data_write;
 	if (max_data == MAX_DATA_UNSPECIFIED) {
@@ -135,8 +134,7 @@
  * .write_256 = spi_chip_write_1
  */
 /* real chunksize is up to 256, logical chunksize is 256 */
-int spi_chip_write_256(struct flashctx *flash, uint8_t *buf, unsigned int start,
-		       unsigned int len)
+int spi_chip_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	return flash->pgm->spi.write_256(flash, buf, start, len);
 }
@@ -162,8 +160,7 @@
 	}
 }
 
-int spi_aai_write(struct flashctx *flash, uint8_t *buf,
-		  unsigned int start, unsigned int len)
+int spi_aai_write(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	return flash->pgm->spi.write_aai(flash, buf, start, len);
 }
diff --git a/spi25.c b/spi25.c
index f660ad1..9763c80 100644
--- a/spi25.c
+++ b/spi25.c
@@ -876,8 +876,7 @@
 	return result;
 }
 
-int spi_nbyte_program(struct flashctx *flash, unsigned int addr, uint8_t *bytes,
-		      unsigned int len)
+int spi_nbyte_program(struct flashctx *flash, unsigned int addr, const uint8_t *bytes, unsigned int len)
 {
 	int result;
 	/* FIXME: Switch to malloc based on len unless that kills speed. */
@@ -983,7 +982,7 @@
  * FIXME: Use the chunk code from Michael Karcher instead.
  * Each page is written separately in chunks with a maximum size of chunksize.
  */
-int spi_write_chunked(struct flashctx *flash, uint8_t *buf, unsigned int start,
+int spi_write_chunked(struct flashctx *flash, const uint8_t *buf, unsigned int start,
 		      unsigned int len, unsigned int chunksize)
 {
 	int rc = 0;
@@ -1032,8 +1031,7 @@
  * (e.g. due to size constraints in IT87* for over 512 kB)
  */
 /* real chunksize is 1, logical chunksize is 1 */
-int spi_chip_write_1(struct flashctx *flash, uint8_t *buf, unsigned int start,
-		     unsigned int len)
+int spi_chip_write_1(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	unsigned int i;
 	int result = 0;
@@ -1049,7 +1047,7 @@
 	return 0;
 }
 
-int default_spi_write_aai(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
+int default_spi_write_aai(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
 	uint32_t pos = start;
 	int result;
diff --git a/sst28sf040.c b/sst28sf040.c
index 52e4256..4d8cb66 100644
--- a/sst28sf040.c
+++ b/sst28sf040.c
@@ -77,8 +77,7 @@
 }
 
 /* chunksize is 1 */
-int write_28sf040(struct flashctx *flash, uint8_t *src, unsigned int start,
-		  unsigned int len)
+int write_28sf040(struct flashctx *flash, const uint8_t *src, unsigned int start, unsigned int len)
 {
 	int i;
 	chipaddr bios = flash->virtual_memory;