Rebrand to flashprog and update URLs

Mostly automated `sed` work. As of now, URLs to the old wiki are broken
either way, so changing them shouldn't hurt. Other URLs (e.g. to mailing
list archives) were hopefully filtered correctly.

Change-Id: I9d43bfd0e675eff2fcbad05f304b9ce9f5006b08
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/flashrom-stable/+/21
diff --git a/flashprog.c b/flashprog.c
new file mode 100644
index 0000000..096453e
--- /dev/null
+++ b/flashprog.c
@@ -0,0 +1,1951 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2000 Silicon Integrated System Corporation
+ * Copyright (C) 2004 Tyan Corp <yhlu@tyan.com>
+ * Copyright (C) 2005-2008 coresystems GmbH
+ * Copyright (C) 2008,2009 Carl-Daniel Hailfinger
+ * Copyright (C) 2016 secunet Security Networks AG
+ * (Written by Nico Huber <nico.huber@secunet.com> for secunet)
+ *
+ * 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
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include "flash.h"
+#include "flashchips.h"
+#include "programmer.h"
+#include "hwaccess_physmap.h"
+#include "chipdrivers.h"
+
+const char flashprog_version[] = FLASHPROG_VERSION;
+const char *chip_to_probe = NULL;
+
+static const struct programmer_entry *programmer = NULL;
+static char *programmer_param = NULL;
+
+/*
+ * Programmers supporting multiple buses can have differing size limits on
+ * each bus. Store the limits for each bus in a common struct.
+ */
+struct decode_sizes max_rom_decode;
+
+/* If nonzero, used as the start address of bottom-aligned flash. */
+unsigned long flashbase;
+
+/* Is writing allowed with this programmer? */
+bool programmer_may_write;
+
+#define SHUTDOWN_MAXFN 32
+static int shutdown_fn_count = 0;
+/** @private */
+static struct shutdown_func_data {
+	int (*func) (void *data);
+	void *data;
+} shutdown_fn[SHUTDOWN_MAXFN];
+/* Initialize to 0 to make sure nobody registers a shutdown function before
+ * programmer init.
+ */
+static bool may_register_shutdown = false;
+
+/* Did we change something or was every erase/write skipped (if any)? */
+static bool all_skipped = true;
+
+static int check_block_eraser(const struct flashctx *flash, int k, int log);
+
+int shutdown_free(void *data)
+{
+	free(data);
+	return 0;
+}
+
+/* Register a function to be executed on programmer shutdown.
+ * The advantage over atexit() is that you can supply a void pointer which will
+ * be used as parameter to the registered function upon programmer shutdown.
+ * This pointer can point to arbitrary data used by said function, e.g. undo
+ * information for GPIO settings etc. If unneeded, set data=NULL.
+ * Please note that the first (void *data) belongs to the function signature of
+ * the function passed as first parameter.
+ */
+int register_shutdown(int (*function) (void *data), void *data)
+{
+	if (shutdown_fn_count >= SHUTDOWN_MAXFN) {
+		msg_perr("Tried to register more than %i shutdown functions.\n",
+			 SHUTDOWN_MAXFN);
+		return 1;
+	}
+	if (!may_register_shutdown) {
+		msg_perr("Tried to register a shutdown function before "
+			 "programmer init.\n");
+		return 1;
+	}
+	shutdown_fn[shutdown_fn_count].func = function;
+	shutdown_fn[shutdown_fn_count].data = data;
+	shutdown_fn_count++;
+
+	return 0;
+}
+
+int register_chip_restore(chip_restore_fn_cb_t func,
+			  struct flashctx *flash, uint8_t status)
+{
+	if (flash->chip_restore_fn_count >= MAX_CHIP_RESTORE_FUNCTIONS) {
+		msg_perr("Tried to register more than %i chip restore"
+		         " functions.\n", MAX_CHIP_RESTORE_FUNCTIONS);
+		return 1;
+	}
+	flash->chip_restore_fn[flash->chip_restore_fn_count].func = func;
+	flash->chip_restore_fn[flash->chip_restore_fn_count].status = status;
+	flash->chip_restore_fn_count++;
+
+	return 0;
+}
+
+static int deregister_chip_restore(struct flashctx *flash)
+{
+	int rc = 0;
+
+	while (flash->chip_restore_fn_count > 0) {
+		int i = --flash->chip_restore_fn_count;
+		rc |= flash->chip_restore_fn[i].func(
+			flash, flash->chip_restore_fn[i].status);
+	}
+
+	return rc;
+}
+
+int programmer_init(const struct programmer_entry *prog, const char *param)
+{
+	int ret;
+
+	if (prog == NULL) {
+		msg_perr("Invalid programmer specified!\n");
+		return -1;
+	}
+	programmer = prog;
+	/* Initialize all programmer specific data. */
+	/* Default to unlimited decode sizes. */
+	max_rom_decode = (const struct decode_sizes) {
+		.parallel	= 0xffffffff,
+		.lpc		= 0xffffffff,
+		.fwh		= 0xffffffff,
+		.spi		= 0xffffffff,
+	};
+	/* Default to top aligned flash at 4 GB. */
+	flashbase = 0;
+	/* Registering shutdown functions is now allowed. */
+	may_register_shutdown = true;
+	/* Default to allowing writes. Broken programmers set this to 0. */
+	programmer_may_write = true;
+
+	if (param) {
+		programmer_param = strdup(param);
+		if (!programmer_param) {
+			msg_perr("Out of memory!\n");
+			return ERROR_FATAL;
+		}
+	} else {
+		programmer_param = NULL;
+	}
+
+	msg_pdbg("Initializing %s programmer\n", programmer->name);
+	ret = programmer->init();
+	if (programmer_param && strlen(programmer_param)) {
+		if (ret != 0) {
+			/* It is quite possible that any unhandled programmer parameter would have been valid,
+			 * but an error in actual programmer init happened before the parameter was evaluated.
+			 */
+			msg_pwarn("Unhandled programmer parameters (possibly due to another failure): %s\n",
+				  programmer_param);
+		} else {
+			/* Actual programmer init was successful, but the user specified an invalid or unusable
+			 * (for the current programmer configuration) parameter.
+			 */
+			msg_perr("Unhandled programmer parameters: %s\n", programmer_param);
+			msg_perr("Aborting.\n");
+			ret = ERROR_FATAL;
+		}
+	}
+	free(programmer_param);
+	programmer_param = NULL;
+	return ret;
+}
+
+/** Calls registered shutdown functions and resets internal programmer-related variables.
+ * Calling it is safe even without previous initialization, but further interactions with programmer support
+ * require a call to programmer_init() (afterwards).
+ *
+ * @return The OR-ed result values of all shutdown functions (i.e. 0 on success). */
+int programmer_shutdown(void)
+{
+	int ret = 0;
+
+	/* Registering shutdown functions is no longer allowed. */
+	may_register_shutdown = false;
+	while (shutdown_fn_count > 0) {
+		int i = --shutdown_fn_count;
+		ret |= shutdown_fn[i].func(shutdown_fn[i].data);
+	}
+	registered_master_count = 0;
+
+	return ret;
+}
+
+void *programmer_map_flash_region(const char *descr, uintptr_t phys_addr, size_t len)
+{
+	void *ret;
+	if (programmer->map_flash_region)
+		ret = programmer->map_flash_region(descr, phys_addr, len);
+	else
+		ret = fallback_map(descr, phys_addr, len);
+	msg_gspew("%s: mapping %s from 0x%0*" PRIxPTR " to 0x%0*" PRIxPTR "\n",
+		  __func__, descr, PRIxPTR_WIDTH, phys_addr, PRIxPTR_WIDTH, (uintptr_t) ret);
+	return ret;
+}
+
+void programmer_unmap_flash_region(void *virt_addr, size_t len)
+{
+	if (programmer->unmap_flash_region)
+		programmer->unmap_flash_region(virt_addr, len);
+	else
+		fallback_unmap(virt_addr, len);
+	msg_gspew("%s: unmapped 0x%0*" PRIxPTR "\n", __func__, PRIxPTR_WIDTH, (uintptr_t)virt_addr);
+}
+
+void programmer_delay(unsigned int usecs)
+{
+	if (usecs > 0) {
+		if (programmer->delay)
+			programmer->delay(usecs);
+		else
+			internal_delay(usecs);
+	}
+}
+
+int read_memmapped(struct flashctx *flash, uint8_t *buf, unsigned int start,
+		   int unsigned len)
+{
+	chip_readn(flash, buf, flash->virtual_memory + start, len);
+
+	return 0;
+}
+
+/* This is a somewhat hacked function similar in some ways to strtok().
+ * It will look for needle with a subsequent '=' in haystack, return a copy of
+ * needle and remove everything from the first occurrence of needle to the next
+ * delimiter from haystack.
+ */
+static char *extract_param(char *const *haystack, const char *needle, const char *delim)
+{
+	char *param_pos, *opt_pos, *rest;
+	char *opt = NULL;
+	int optlen;
+	int needlelen;
+
+	needlelen = strlen(needle);
+	if (!needlelen) {
+		msg_gerr("%s: empty needle! Please report a bug at "
+			 "flashprog@flashprog.org\n", __func__);
+		return NULL;
+	}
+	/* No programmer parameters given. */
+	if (*haystack == NULL)
+		return NULL;
+	param_pos = strstr(*haystack, needle);
+	do {
+		if (!param_pos)
+			return NULL;
+		/* Needle followed by '='? */
+		if (param_pos[needlelen] == '=') {
+			/* Beginning of the string? */
+			if (param_pos == *haystack)
+				break;
+			/* After a delimiter? */
+			if (strchr(delim, *(param_pos - 1)))
+				break;
+		}
+		/* Continue searching. */
+		param_pos++;
+		param_pos = strstr(param_pos, needle);
+	} while (1);
+
+	if (param_pos) {
+		/* Get the string after needle and '='. */
+		opt_pos = param_pos + needlelen + 1;
+		optlen = strcspn(opt_pos, delim);
+		/* Return an empty string if the parameter was empty. */
+		opt = malloc(optlen + 1);
+		if (!opt) {
+			msg_gerr("Out of memory!\n");
+			exit(1);
+		}
+		strncpy(opt, opt_pos, optlen);
+		opt[optlen] = '\0';
+		rest = opt_pos + optlen;
+		/* Skip all delimiters after the current parameter. */
+		rest += strspn(rest, delim);
+		memmove(param_pos, rest, strlen(rest) + 1);
+		/* We could shrink haystack, but the effort is not worth it. */
+	}
+
+	return opt;
+}
+
+char *extract_programmer_param(const char *param_name)
+{
+	return extract_param(&programmer_param, param_name, ",");
+}
+
+/* Returns the number of well-defined erasers for a chip. */
+static unsigned int count_usable_erasers(const struct flashctx *flash)
+{
+	unsigned int usable_erasefunctions = 0;
+	int k;
+	for (k = 0; k < NUM_ERASEFUNCTIONS; k++) {
+		if (!check_block_eraser(flash, k, 0))
+			usable_erasefunctions++;
+	}
+	return usable_erasefunctions;
+}
+
+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;
+	for (i = 0; i < len; i++) {
+		if (wantbuf[i] != havebuf[i]) {
+			/* Only print the first failure. */
+			if (!failcount++)
+				msg_cerr("FAILED at 0x%08x! Expected=0x%02x, Found=0x%02x,",
+					 start + i, wantbuf[i], havebuf[i]);
+		}
+	}
+	if (failcount) {
+		msg_cerr(" failed byte count from 0x%08x-0x%08x: 0x%x\n",
+			 start, start + len - 1, failcount);
+		ret = -1;
+	}
+	return ret;
+}
+
+/* start is an offset to the base address of the flash chip */
+static int check_erased_range(struct flashctx *flash, unsigned int start, unsigned int len)
+{
+	int ret;
+	const uint8_t erased_value = ERASED_VALUE(flash);
+
+	uint8_t *cmpbuf = malloc(len);
+	if (!cmpbuf) {
+		msg_gerr("Out of memory!\n");
+		return -1;
+	}
+	memset(cmpbuf, erased_value, len);
+	ret = verify_range(flash, cmpbuf, start, len);
+
+	free(cmpbuf);
+	return ret;
+}
+
+/*
+ * @cmpbuf	buffer to compare against, cmpbuf[0] is expected to match the
+ *		flash content at location start
+ * @start	offset to the base address of the flash chip
+ * @len		length of the verified area
+ * @return	0 for success, -1 for failure
+ */
+int verify_range(struct flashctx *flash, const uint8_t *cmpbuf, unsigned int start, unsigned int len)
+{
+	if (!len)
+		return -1;
+
+	if (start + len > flash->chip->total_size * 1024) {
+		msg_gerr("Error: %s called with start 0x%x + len 0x%x >"
+			" total_size 0x%x\n", __func__, start, len,
+			flash->chip->total_size * 1024);
+		return -1;
+	}
+
+	uint8_t *readbuf = malloc(len);
+	if (!readbuf) {
+		msg_gerr("Out of memory!\n");
+		return -1;
+	}
+
+	int ret = flash->chip->read(flash, readbuf, start, len);
+	if (ret) {
+		msg_gerr("Verification impossible because read failed "
+			 "at 0x%x (len 0x%x)\n", start, len);
+		ret = -1;
+		goto out_free;
+	}
+
+	ret = compare_range(cmpbuf, readbuf, start, len);
+out_free:
+	free(readbuf);
+	return ret;
+}
+
+size_t gran_to_bytes(const enum write_granularity gran)
+{
+	switch (gran) {
+		case write_gran_1bit:			return 1;
+		case write_gran_1byte:			return 1;
+		case write_gran_1byte_implicit_erase:	return 1;
+		case write_gran_128bytes:		return 128;
+		case write_gran_256bytes:		return 256;
+		case write_gran_264bytes:		return 264;
+		case write_gran_512bytes:		return 512;
+		case write_gran_528bytes:		return 528;
+		case write_gran_1024bytes:		return 1024;
+		case write_gran_1056bytes:		return 1056;
+		default:				return 0;
+	}
+}
+
+/* Helper function for need_erase() that focuses on granularities of gran bytes. */
+static int need_erase_gran_bytes(const uint8_t *have, const uint8_t *want, unsigned int len,
+                                 unsigned int gran, const uint8_t erased_value)
+{
+	unsigned int i, j, limit;
+	for (j = 0; j < len / gran; j++) {
+		limit = min (gran, len - j * gran);
+		/* Are 'have' and 'want' identical? */
+		if (!memcmp(have + j * gran, want + j * gran, limit))
+			continue;
+		/* have needs to be in erased state. */
+		for (i = 0; i < limit; i++)
+			if (have[j * gran + i] != erased_value)
+				return 1;
+	}
+	return 0;
+}
+
+/*
+ * Check if the buffer @have can be programmed to the content of @want without
+ * erasing. This is only possible if all chunks of size @gran are either kept
+ * as-is or changed from an all-ones state to any other state.
+ *
+ * Warning: This function assumes that @have and @want point to naturally
+ * aligned regions.
+ *
+ * @have        buffer with current content
+ * @want        buffer with desired content
+ * @len		length of the checked area
+ * @gran	write granularity (enum, not count)
+ * @return      0 if no erase is needed, 1 otherwise
+ */
+static int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len,
+		      enum write_granularity gran, const uint8_t erased_value)
+{
+	unsigned int i;
+	size_t stride;
+
+	switch (gran) {
+	case write_gran_1bit:
+		for (i = 0; i < len; i++) {
+			if ((have[i] & want[i]) != want[i])
+				return 1;
+		}
+		return 0;
+	case write_gran_1byte:
+		for (i = 0; i < len; i++) {
+			if ((have[i] != want[i]) && (have[i] != erased_value))
+				return 1;
+		}
+		return 0;
+	case write_gran_1byte_implicit_erase:
+		/* Do not erase, handle content changes from anything->0xff by writing 0xff. */
+		return 0;
+	default:
+		stride = gran_to_bytes(gran);
+		if (stride) {
+			return need_erase_gran_bytes(have, want, len, stride, erased_value);
+		}
+		msg_cerr("%s: Unsupported granularity! Please report a bug at "
+			 "flashprog@flashprog.org\n", __func__);
+		return 0;
+	}
+}
+
+/**
+ * Check if the buffer @have needs to be programmed to get the content of @want.
+ * If yes, return 1 and fill in first_start with the start address of the
+ * write operation and first_len with the length of the first to-be-written
+ * chunk. If not, return 0 and leave first_start and first_len undefined.
+ *
+ * Warning: This function assumes that @have and @want point to naturally
+ * aligned regions.
+ *
+ * @have	buffer with current content
+ * @want	buffer with desired content
+ * @len		length of the checked area
+ * @gran	write granularity (enum, not count)
+ * @first_start	offset of the first byte which needs to be written (passed in
+ *		value is increased by the offset of the first needed write
+ *		relative to have/want or unchanged if no write is needed)
+ * @return	length of the first contiguous area which needs to be written
+ *		0 if no write is needed
+ *
+ * FIXME: This function needs a parameter which tells it about coalescing
+ * in relation to the max write length of the programmer and the max write
+ * length of the chip.
+ */
+static unsigned int get_next_write(const uint8_t *have, const uint8_t *want, chipsize_t len,
+				   chipoff_t *first_start, enum write_granularity gran)
+{
+	bool need_write = false;
+	unsigned int rel_start = 0, first_len = 0;
+	unsigned int i, limit;
+
+	const size_t stride = gran_to_bytes(gran);
+	if (!stride) {
+		msg_cerr("%s: Unsupported granularity! Please report a bug at "
+			 "flashprog@flashprog.org\n", __func__);
+		/* Claim that no write was needed. A write with unknown
+		 * granularity is too dangerous to try.
+		 */
+		return 0;
+	}
+	for (i = 0; i < len / stride; i++) {
+		limit = min(stride, len - i * stride);
+		/* Are 'have' and 'want' identical? */
+		if (memcmp(have + i * stride, want + i * stride, limit)) {
+			if (!need_write) {
+				/* First location where have and want differ. */
+				need_write = true;
+				rel_start = i * stride;
+			}
+		} else {
+			if (need_write) {
+				/* First location where have and want
+				 * do not differ anymore.
+				 */
+				break;
+			}
+		}
+	}
+	if (need_write)
+		first_len = min(i * stride - rel_start, len);
+	*first_start += rel_start;
+	return first_len;
+}
+
+void unmap_flash(struct flashctx *flash)
+{
+	if (flash->virtual_registers != (chipaddr)ERROR_PTR) {
+		programmer_unmap_flash_region((void *)flash->virtual_registers, flash->chip->total_size * 1024);
+		flash->physical_registers = 0;
+		flash->virtual_registers = (chipaddr)ERROR_PTR;
+	}
+
+	if (flash->virtual_memory != (chipaddr)ERROR_PTR) {
+		programmer_unmap_flash_region((void *)flash->virtual_memory, flash->chip->total_size * 1024);
+		flash->physical_memory = 0;
+		flash->virtual_memory = (chipaddr)ERROR_PTR;
+	}
+}
+
+int map_flash(struct flashctx *flash)
+{
+	/* Init pointers to the fail-safe state to distinguish them later from legit values. */
+	flash->virtual_memory = (chipaddr)ERROR_PTR;
+	flash->virtual_registers = (chipaddr)ERROR_PTR;
+
+	/* FIXME: This avoids mapping (and unmapping) of flash chip definitions with size 0.
+	 * These are used for various probing-related hacks that would not map successfully anyway and should be
+	 * removed ASAP. */
+	if (flash->chip->total_size == 0)
+		return 0;
+
+	const chipsize_t size = flash->chip->total_size * 1024;
+	uintptr_t base = flashbase ? flashbase : (0xffffffff - size + 1);
+	void *addr = programmer_map_flash_region(flash->chip->name, base, size);
+	if (addr == ERROR_PTR) {
+		msg_perr("Could not map flash chip %s at 0x%0*" PRIxPTR ".\n",
+			 flash->chip->name, PRIxPTR_WIDTH, base);
+		return 1;
+	}
+	flash->physical_memory = base;
+	flash->virtual_memory = (chipaddr)addr;
+
+	/* FIXME: Special function registers normally live 4 MByte below flash space, but it might be somewhere
+	 * completely different on some chips and programmers, or not mappable at all.
+	 * Ignore these problems for now and always report success. */
+	if (flash->chip->feature_bits & FEATURE_REGISTERMAP) {
+		base = 0xffffffff - size - 0x400000 + 1;
+		addr = programmer_map_flash_region("flash chip registers", base, size);
+		if (addr == ERROR_PTR) {
+			msg_pdbg2("Could not map flash chip registers %s at 0x%0*" PRIxPTR ".\n",
+				 flash->chip->name, PRIxPTR_WIDTH, base);
+			return 0;
+		}
+		flash->physical_registers = base;
+		flash->virtual_registers = (chipaddr)addr;
+	}
+	return 0;
+}
+
+/*
+ * Return a string corresponding to the bustype parameter.
+ * Memory is obtained with malloc() and must be freed with free() by the caller.
+ */
+char *flashbuses_to_text(enum chipbustype bustype)
+{
+	char *ret = calloc(1, 1);
+	/*
+	 * FIXME: Once all chipsets and flash chips have been updated, NONSPI
+	 * will cease to exist and should be eliminated here as well.
+	 */
+	if (bustype == BUS_NONSPI) {
+		ret = strcat_realloc(ret, "Non-SPI, ");
+	} else {
+		if (bustype & BUS_PARALLEL)
+			ret = strcat_realloc(ret, "Parallel, ");
+		if (bustype & BUS_LPC)
+			ret = strcat_realloc(ret, "LPC, ");
+		if (bustype & BUS_FWH)
+			ret = strcat_realloc(ret, "FWH, ");
+		if (bustype & BUS_SPI)
+			ret = strcat_realloc(ret, "SPI, ");
+		if (bustype & BUS_PROG)
+			ret = strcat_realloc(ret, "Programmer-specific, ");
+		if (bustype == BUS_NONE)
+			ret = strcat_realloc(ret, "None, ");
+	}
+	/* Kill last comma. */
+	ret[strlen(ret) - 2] = '\0';
+	ret = realloc(ret, strlen(ret) + 1);
+	return ret;
+}
+
+static int init_default_layout(struct flashctx *flash)
+{
+	/* Fill default layout covering the whole chip. */
+	if (flashprog_layout_new(&flash->default_layout) ||
+	    flashprog_layout_add_region(flash->default_layout,
+			0, flash->chip->total_size * 1024 - 1, "complete flash") ||
+	    flashprog_layout_include_region(flash->default_layout, "complete flash"))
+	        return -1;
+	return 0;
+}
+
+int probe_flash(struct registered_master *mst, int startchip, struct flashctx *flash, int force)
+{
+	const struct flashchip *chip;
+	enum chipbustype buses_common;
+	char *tmp;
+
+	for (chip = flashchips + startchip; chip && chip->name; chip++) {
+		if (chip_to_probe && strcmp(chip->name, chip_to_probe) != 0)
+			continue;
+		buses_common = mst->buses_supported & chip->bustype;
+		if (!buses_common)
+			continue;
+		/* Only probe for SPI25 chips by default. */
+		if (chip->bustype == BUS_SPI && !chip_to_probe && chip->spi_cmd_set != SPI25)
+			continue;
+		msg_gdbg("Probing for %s %s, %d kB: ", chip->vendor, chip->name, chip->total_size);
+		if (!chip->probe && !force) {
+			msg_gdbg("failed! flashprog has no probe function for this flash chip.\n");
+			continue;
+		}
+
+		/* Start filling in the dynamic data. */
+		flash->chip = calloc(1, sizeof(*flash->chip));
+		if (!flash->chip) {
+			msg_gerr("Out of memory!\n");
+			return -1;
+		}
+		*flash->chip = *chip;
+		flash->mst = mst;
+
+		if (map_flash(flash) != 0)
+			goto notfound;
+
+		/* We handle a forced match like a real match, we just avoid probing. Note that probe_flash()
+		 * is only called with force=1 after normal probing failed.
+		 */
+		if (force)
+			break;
+
+		if (flash->chip->probe(flash) != 1)
+			goto notfound;
+
+		/* If this is the first chip found, accept it.
+		 * If this is not the first chip found, accept it only if it is
+		 * a non-generic match. SFDP and CFI are generic matches.
+		 * startchip==0 means this call to probe_flash() is the first
+		 * one for this programmer interface (master) and thus no other chip has
+		 * been found on this interface.
+		 */
+		if (startchip == 0 && flash->chip->model_id == SFDP_DEVICE_ID) {
+			msg_cinfo("===\n"
+				  "SFDP has autodetected a flash chip which is "
+				  "not natively supported by flashprog yet.\n");
+			if (count_usable_erasers(flash) == 0)
+				msg_cinfo("The standard operations read and "
+					  "verify should work, but to support "
+					  "erase, write and all other "
+					  "possible features");
+			else
+				msg_cinfo("All standard operations (read, "
+					  "verify, erase and write) should "
+					  "work, but to support all possible "
+					  "features");
+
+			msg_cinfo(" we need to add them manually.\n"
+				  "You can help us by mailing us the output of the following command to "
+				  "flashprog@flashprog.org:\n"
+				  "'flashprog -VV [plus the -p/--programmer parameter]'\n"
+				  "Thanks for your help!\n"
+				  "===\n");
+		}
+
+		/* First flash chip detected on this bus. */
+		if (startchip == 0)
+			break;
+		/* Not the first flash chip detected on this bus, but not a generic match either. */
+		if ((flash->chip->model_id != GENERIC_DEVICE_ID) && (flash->chip->model_id != SFDP_DEVICE_ID))
+			break;
+		/* Not the first flash chip detected on this bus, and it's just a generic match. Ignore it. */
+notfound:
+		unmap_flash(flash);
+		free(flash->chip);
+		flash->chip = NULL;
+	}
+
+	if (!flash->chip)
+		return -1;
+
+	if (init_default_layout(flash) < 0)
+		return -1;
+
+	tmp = flashbuses_to_text(flash->chip->bustype);
+	msg_cinfo("%s %s flash chip \"%s\" (%d kB, %s) ", force ? "Assuming" : "Found",
+		  flash->chip->vendor, flash->chip->name, flash->chip->total_size, tmp);
+	free(tmp);
+#if CONFIG_INTERNAL == 1
+	if (programmer->map_flash_region == physmap)
+		msg_cinfo("mapped at physical address 0x%0*" PRIxPTR ".\n",
+			  PRIxPTR_WIDTH, flash->physical_memory);
+	else
+#endif
+		msg_cinfo("on %s.\n", programmer->name);
+
+	/* Flash registers may more likely not be mapped if the chip was forced.
+	 * Lock info may be stored in registers, so avoid lock info printing. */
+	if (!force)
+		if (flash->chip->printlock)
+			flash->chip->printlock(flash);
+
+	/* Get out of the way for later runs. */
+	unmap_flash(flash);
+
+	/* Return position of matching chip. */
+	return chip - flashchips;
+}
+
+/* Even if an error is found, the function will keep going and check the rest. */
+static int selfcheck_eraseblocks(const struct flashchip *chip)
+{
+	int i, j, k;
+	int ret = 0;
+	unsigned int prev_eraseblock_count = chip->total_size * 1024;
+
+	for (k = 0; k < NUM_ERASEFUNCTIONS; k++) {
+		unsigned int done = 0;
+		struct block_eraser eraser = chip->block_erasers[k];
+		unsigned int curr_eraseblock_count = 0;
+
+		for (i = 0; i < NUM_ERASEREGIONS; i++) {
+			/* Blocks with zero size are bugs in flashchips.c. */
+			if (eraser.eraseblocks[i].count &&
+			    !eraser.eraseblocks[i].size) {
+				msg_gerr("ERROR: Flash chip %s erase function %i region %i has size 0.\n"
+					 "Please report a bug at flashprog@flashprog.org\n",
+					 chip->name, k, i);
+				ret = 1;
+			}
+			/* Blocks with zero count are bugs in flashchips.c. */
+			if (!eraser.eraseblocks[i].count &&
+			    eraser.eraseblocks[i].size) {
+				msg_gerr("ERROR: Flash chip %s erase function %i region %i has count 0.\n"
+					 "Please report a bug at flashprog@flashprog.org\n",
+					 chip->name, k, i);
+				ret = 1;
+			}
+			done += eraser.eraseblocks[i].count *
+				eraser.eraseblocks[i].size;
+			curr_eraseblock_count += eraser.eraseblocks[i].count;
+		}
+		/* Empty eraseblock definition with erase function.  */
+		if (!done && eraser.block_erase)
+			msg_gspew("Strange: Empty eraseblock definition with "
+				  "non-empty erase function. Not an error.\n");
+		if (!done)
+			continue;
+		if (done != chip->total_size * 1024) {
+			msg_gerr("ERROR: Flash chip %s erase function %i "
+				"region walking resulted in 0x%06x bytes total,"
+				" expected 0x%06x bytes.\n"
+				"Please report a bug at flashprog@flashprog.org\n",
+				chip->name, k, done, chip->total_size * 1024);
+			ret = 1;
+		}
+		if (!eraser.block_erase)
+			continue;
+		/* Check if there are identical erase functions for different
+		 * layouts. That would imply "magic" erase functions. The
+		 * easiest way to check this is with function pointers.
+		 */
+		for (j = k + 1; j < NUM_ERASEFUNCTIONS; j++) {
+			if (eraser.block_erase ==
+			    chip->block_erasers[j].block_erase) {
+				msg_gerr("ERROR: Flash chip %s erase function %i and %i are identical.\n"
+					 "Please report a bug at flashprog@flashprog.org\n",
+					 chip->name, k, j);
+				ret = 1;
+			}
+		}
+		if(curr_eraseblock_count > prev_eraseblock_count)
+		{
+			msg_gerr("ERROR: Flash chip %s erase function %i is not in order.\n"
+				 "Please report a bug at flashprog@flashprog.org\n",
+				 chip->name, k);
+			ret = 1;
+		}
+		prev_eraseblock_count = curr_eraseblock_count;
+	}
+	return ret;
+}
+
+static int check_block_eraser(const struct flashctx *flash, int k, int log)
+{
+	struct block_eraser eraser = flash->chip->block_erasers[k];
+
+	if (!eraser.block_erase && !eraser.eraseblocks[0].count) {
+		if (log)
+			msg_cdbg("not defined. ");
+		return 1;
+	}
+	if (!eraser.block_erase && eraser.eraseblocks[0].count) {
+		if (log)
+			msg_cdbg("eraseblock layout is known, but matching "
+				 "block erase function is not implemented. ");
+		return 1;
+	}
+	if (eraser.block_erase && !eraser.eraseblocks[0].count) {
+		if (log)
+			msg_cdbg("block erase function found, but "
+				 "eraseblock layout is not defined. ");
+		return 1;
+	}
+
+	if (flash->chip->bustype == BUS_SPI) {
+		const uint8_t *opcode = spi_get_opcode_from_erasefn(eraser.block_erase);
+		int i;
+		for (i = 0; opcode[i]; i++) {
+			if (!flash->mst->spi.probe_opcode(flash, opcode[i])) {
+				if (log)
+					msg_cdbg("block erase function and layout found "
+						 "but SPI master doesn't support the function. ");
+				return 1;
+			}
+		}
+	}
+	// TODO: Once erase functions are annotated with allowed buses, check that as well.
+	return 0;
+}
+
+/**
+ * @brief Reads the included layout regions into a buffer.
+ *
+ * If there is no layout set in the given flash context, the whole chip will
+ * be read.
+ *
+ * @param flashctx Flash context to be used.
+ * @param buffer   Buffer of full chip size to read into.
+ * @return 0 on success,
+ *	   1 if any read fails.
+ */
+static int read_by_layout(struct flashctx *const flashctx, uint8_t *const buffer)
+{
+	const struct flashprog_layout *const layout = get_layout(flashctx);
+	const struct romentry *entry = NULL;
+
+	while ((entry = layout_next_included(layout, entry))) {
+		const chipoff_t region_start	= entry->start;
+		const chipsize_t region_len	= entry->end - entry->start + 1;
+
+		if (flashctx->chip->read(flashctx, buffer + region_start, region_start, region_len))
+			return 1;
+	}
+	return 0;
+}
+
+/**
+ * @private
+ *
+ * For read-erase-write, `curcontents` and `newcontents` shall point
+ * to buffers of the chip's size. Both are supposed to be prefilled
+ * with at least the included layout regions of the current flash
+ * contents (`curcontents`) and the data to be written to the flash
+ * (`newcontents`).
+ *
+ * For erase, `curcontents` and `newcontents` shall be NULL-pointers.
+ *
+ * The `chipoff_t` values are used internally by `walk_by_layout()`.
+ */
+struct walk_info {
+	uint8_t *curcontents;
+	const uint8_t *newcontents;
+	chipoff_t region_start;
+	chipoff_t region_end;
+	chipoff_t erase_start;
+	chipoff_t erase_end;
+};
+
+struct eraseblock_data {
+	chipoff_t start_addr;
+	chipoff_t end_addr;
+	bool selected;
+	size_t block_num;
+	size_t first_sub_block_index;
+	size_t last_sub_block_index;
+};
+
+struct erase_layout {
+	struct eraseblock_data* layout_list;
+	size_t block_count;
+	const struct block_eraser *eraser;
+};
+
+static bool explicit_erase(const struct walk_info *const info)
+{
+	/* For explicit erase, we are called without new contents. */
+	return !info->newcontents;
+}
+
+static size_t calculate_block_count(const struct block_eraser *const eraser)
+{
+	size_t block_count = 0, i;
+
+	for (i = 0; i < ARRAY_SIZE(eraser->eraseblocks); ++i)
+		block_count += eraser->eraseblocks[i].count;
+
+	return block_count;
+}
+
+static void init_eraseblock(struct erase_layout *layout, size_t idx, size_t block_num,
+		chipoff_t start_addr, chipoff_t end_addr, size_t *sub_block_index)
+{
+	struct eraseblock_data *edata = &layout[idx].layout_list[block_num];
+	edata->start_addr = start_addr;
+	edata->end_addr = end_addr;
+	edata->selected = false;
+	edata->block_num = block_num;
+
+	if (!idx)
+		return;
+	const struct erase_layout *const sub_layout = &layout[idx - 1];
+
+	edata->first_sub_block_index = *sub_block_index;
+	for (; *sub_block_index < sub_layout->block_count; ++*sub_block_index) {
+		if (sub_layout->layout_list[*sub_block_index].end_addr > end_addr)
+			break;
+	}
+	edata->last_sub_block_index = *sub_block_index - 1;
+}
+
+/*
+ * @brief Function to free the created erase_layout
+ *
+ * @param layout pointer to allocated layout
+ * @param erasefn_count number of erase functions for which the layout was created
+ *
+ */
+static void free_erase_layout(struct erase_layout *layout, unsigned int erasefn_count)
+{
+	size_t i;
+
+	if (!layout)
+		return;
+	for (i = 0; i < erasefn_count; i++) {
+		free(layout[i].layout_list);
+	}
+	free(layout);
+}
+
+/*
+ * @brief Function to create an erase layout
+ *
+ * @param	flashctx	flash context
+ * @param	e_layout	address to the pointer to store the layout
+ * @return	0 on success,
+ *		-1 if layout creation fails
+ *
+ * This function creates a layout of which erase functions erase which regions
+ * of the flash chip. This helps to optimally select the erase functions for
+ * erase/write operations.
+ */
+static int create_erase_layout(struct flashctx *const flashctx, struct erase_layout **e_layout)
+{
+	const struct flashchip *chip = flashctx->chip;
+	const size_t erasefn_count = count_usable_erasers(flashctx);
+
+	if (!erasefn_count) {
+		msg_gerr("No erase functions supported\n");
+		return 0;
+	}
+
+	struct erase_layout *layout = calloc(erasefn_count, sizeof(struct erase_layout));
+	if (!layout) {
+		msg_gerr("Out of memory!\n");
+		return -1;
+	}
+
+	size_t layout_idx = 0, eraser_idx;
+	for (eraser_idx = 0; eraser_idx < NUM_ERASEFUNCTIONS; eraser_idx++) {
+		if (check_block_eraser(flashctx, eraser_idx, 0))
+			continue;
+
+		layout[layout_idx].eraser = &chip->block_erasers[eraser_idx];
+		const size_t block_count = calculate_block_count(&chip->block_erasers[eraser_idx]);
+		size_t sub_block_index = 0;
+
+		layout[layout_idx].block_count = block_count;
+		layout[layout_idx].layout_list = (struct eraseblock_data *)calloc(block_count,
+									sizeof(struct eraseblock_data));
+
+		if (!layout[layout_idx].layout_list) {
+			free_erase_layout(layout, layout_idx);
+			return -1;
+		}
+
+		size_t block_num = 0;
+		chipoff_t start_addr = 0;
+
+		int i;
+		for (i = 0; block_num < block_count;  i++) {
+			const struct eraseblock *block = &chip->block_erasers[eraser_idx].eraseblocks[i];
+
+			size_t num;
+			for (num = 0; num < block->count; num++) {
+				chipoff_t end_addr = start_addr + block->size - 1;
+				init_eraseblock(layout, layout_idx, block_num,
+						start_addr, end_addr, &sub_block_index);
+				block_num += 1;
+				start_addr = end_addr + 1;
+			}
+		}
+		layout_idx++;
+	}
+
+	*e_layout = layout;
+	return layout_idx;
+}
+
+/*
+ * @brief	Function to select the list of sectors that need erasing
+ *
+ * @param	flashctx	flash context
+ * @param	layout		erase layout
+ * @param	findex		index of the erase function
+ * @param	block_num	index of the block to erase according to the erase function index
+ * @param	info		current info from walking the regions
+ */
+static void select_erase_functions_rec(const struct flashctx *flashctx, const struct erase_layout *layout,
+				       size_t findex, size_t block_num, const struct walk_info *info)
+{
+	struct eraseblock_data *ll = &layout[findex].layout_list[block_num];
+	if (!findex) {
+		if (ll->start_addr <= info->region_end && ll->end_addr >= info->region_start) {
+			if (explicit_erase(info)) {
+				ll->selected = true;
+				return;
+			}
+			const chipoff_t write_start = MAX(info->region_start, ll->start_addr);
+			const chipoff_t write_end   = MIN(info->region_end, ll->end_addr);
+			const chipsize_t write_len  = write_end - write_start + 1;
+			const uint8_t erased_value  = ERASED_VALUE(flashctx);
+			ll->selected = need_erase(
+				info->curcontents + write_start, info->newcontents + write_start,
+				write_len, flashctx->chip->gran, erased_value);
+		}
+	} else {
+		int count = 0;
+		const int sub_block_start = ll->first_sub_block_index;
+		const int sub_block_end = ll->last_sub_block_index;
+
+		int j;
+		for (j = sub_block_start; j <= sub_block_end; j++) {
+			select_erase_functions_rec(flashctx, layout, findex - 1, j, info);
+			if (layout[findex - 1].layout_list[j].selected)
+				count++;
+		}
+
+		const int total_blocks = sub_block_end - sub_block_start + 1;
+		if (count && count > total_blocks/2) {
+			if (ll->start_addr >= info->region_start && ll->end_addr <= info->region_end) {
+				for (j = sub_block_start; j <= sub_block_end; j++)
+					layout[findex - 1].layout_list[j].selected = false;
+				ll->selected = true;
+			}
+		}
+	}
+}
+
+static void select_erase_functions(const struct flashctx *flashctx, const struct erase_layout *layout,
+				   size_t erasefn_count, const struct walk_info *info)
+{
+	size_t block_num;
+	for (block_num = 0; block_num < layout[erasefn_count - 1].block_count; ++block_num)
+		select_erase_functions_rec(flashctx, layout, erasefn_count - 1, block_num, info);
+}
+
+static int write_range(struct flashctx *const flashctx, const chipoff_t flash_offset,
+		       const uint8_t *const curcontents, const uint8_t *const newcontents,
+		       const chipsize_t len, bool *const skipped)
+{
+	unsigned int writecount = 0;
+	chipoff_t starthere = 0;
+	chipsize_t lenhere = 0;
+
+	while ((lenhere = get_next_write(curcontents + starthere, newcontents + starthere,
+					 len - starthere, &starthere, flashctx->chip->gran))) {
+		if (!writecount++)
+			msg_cdbg("W");
+		if (flashctx->chip->write(flashctx, newcontents + starthere,
+					  flash_offset + starthere, lenhere))
+			return 1;
+		starthere += lenhere;
+		if (skipped)
+			*skipped = false;
+	}
+	return 0;
+}
+
+typedef int (*erasefn_t)(struct flashctx *, unsigned int addr, unsigned int len);
+/* returns 0 on success, 1 to retry with another erase function, 2 for immediate abort */
+typedef int (*per_blockfn_t)(struct flashctx *, const struct walk_info *, erasefn_t);
+
+static int walk_eraseblocks(struct flashctx *const flashctx,
+			    struct erase_layout *const layouts,
+			    const size_t layout_count,
+			    struct walk_info *const info,
+			    const per_blockfn_t per_blockfn)
+{
+	int ret;
+	size_t i, j;
+	bool first = true;
+
+	for (i = 0; i < layout_count; ++i) {
+		const struct erase_layout *const layout = &layouts[i];
+
+		for (j = 0; j < layout->block_count; ++j) {
+			struct eraseblock_data *const eb = &layout->layout_list[j];
+
+			if (eb->start_addr > info->region_end)
+				break;
+			if (eb->end_addr < info->region_start)
+				continue;
+			if (!eb->selected)
+				continue;
+
+			/* Print this for every block except the first one. */
+			if (first)
+				first = false;
+			else
+				msg_cdbg(", ");
+			msg_cdbg("0x%06x-0x%06x:", eb->start_addr, eb->end_addr);
+
+			info->erase_start = eb->start_addr;
+			info->erase_end = eb->end_addr;
+			ret = per_blockfn(flashctx, info, layout->eraser->block_erase);
+			if (ret)
+				return ret;
+
+			/* Clean the erase layout up for future use on other
+			   regions. `.selected` is the only field we alter. */
+			eb->selected = false;
+		}
+	}
+	msg_cdbg("\n");
+	return 0;
+}
+
+static int walk_by_layout(struct flashctx *const flashctx, struct walk_info *const info,
+			  const per_blockfn_t per_blockfn)
+{
+	const bool do_erase = explicit_erase(info) || !(flashctx->chip->feature_bits & FEATURE_NO_ERASE);
+	const struct flashprog_layout *const layout = get_layout(flashctx);
+	struct erase_layout *erase_layouts = NULL;
+	const struct romentry *entry = NULL;
+	int ret = 0, layout_count = 0;
+
+	all_skipped = true;
+	msg_cinfo("Erasing and writing flash chip... ");
+
+	if (do_erase) {
+		layout_count = create_erase_layout(flashctx, &erase_layouts);
+		if (layout_count <= 0)
+			return 1;
+	}
+
+	while ((entry = layout_next_included(layout, entry))) {
+		info->region_start = entry->start;
+		info->region_end   = entry->end;
+
+		if (do_erase) {
+			select_erase_functions(flashctx, erase_layouts, layout_count, info);
+			ret = walk_eraseblocks(flashctx, erase_layouts, layout_count, info, per_blockfn);
+			if (ret) {
+				msg_cerr("FAILED!\n");
+				goto free_ret;
+			}
+		}
+
+		if (info->newcontents) {
+			bool skipped = true;
+			msg_cdbg("0x%06x-0x%06x:", info->region_start, info->region_end);
+			ret = write_range(flashctx, info->region_start,
+					  info->curcontents + info->region_start,
+					  info->newcontents + info->region_start,
+					  info->region_end + 1 - info->region_start, &skipped);
+			if (ret) {
+				msg_cerr("FAILED!\n");
+				goto free_ret;
+			}
+			if (skipped) {
+				msg_cdbg("S\n");
+			} else {
+				msg_cdbg("\n");
+				all_skipped = false;
+			}
+		}
+	}
+	if (all_skipped)
+		msg_cinfo("\nWarning: Chip content is identical to the requested image.\n");
+	msg_cinfo("Erase/write done.\n");
+
+free_ret:
+	free_erase_layout(erase_layouts, layout_count);
+	return ret;
+}
+
+static int erase_block(struct flashctx *const flashctx,
+		       const struct walk_info *const info, const erasefn_t erasefn)
+{
+	const unsigned int erase_len = info->erase_end + 1 - info->erase_start;
+	const bool region_unaligned = info->region_start > info->erase_start ||
+				      info->erase_end > info->region_end;
+	uint8_t *backup_contents = NULL, *erased_contents = NULL;
+	int ret = 1;
+
+	/*
+	 * If the region is not erase-block aligned, merge current flash con-
+	 * tents into a new buffer `backup_contents`.
+	 */
+	if (region_unaligned) {
+		backup_contents = malloc(erase_len);
+		erased_contents = malloc(erase_len);
+		if (!backup_contents || !erased_contents) {
+			msg_cerr("Out of memory!\n");
+			goto _free_ret;
+		}
+		memset(backup_contents, ERASED_VALUE(flashctx), erase_len);
+		memset(erased_contents, ERASED_VALUE(flashctx), erase_len);
+
+		msg_cdbg("R");
+		/* Merge data preceding the current region. */
+		if (info->region_start > info->erase_start) {
+			const chipoff_t start	= info->erase_start;
+			const chipsize_t len	= info->region_start - info->erase_start;
+			if (flashctx->chip->read(flashctx, backup_contents, start, len)) {
+				msg_cerr("Can't read! Aborting.\n");
+				goto _free_ret;
+			}
+		}
+		/* Merge data following the current region. */
+		if (info->erase_end > info->region_end) {
+			const chipoff_t start     = info->region_end + 1;
+			const chipoff_t rel_start = start - info->erase_start; /* within this erase block */
+			const chipsize_t len      = info->erase_end - info->region_end;
+			if (flashctx->chip->read(flashctx, backup_contents + rel_start, start, len)) {
+				msg_cerr("Can't read! Aborting.\n");
+				goto _free_ret;
+			}
+		}
+	}
+
+	all_skipped = false;
+
+	msg_cdbg("E");
+	if (erasefn(flashctx, info->erase_start, erase_len))
+		goto _free_ret;
+	if (check_erased_range(flashctx, info->erase_start, erase_len)) {
+		msg_cerr("ERASE FAILED!\n");
+		goto _free_ret;
+	}
+	if (info->curcontents)
+		memset(info->curcontents + info->erase_start, ERASED_VALUE(flashctx), erase_len);
+
+	if (region_unaligned) {
+		if (write_range(flashctx, info->erase_start, erased_contents, backup_contents, erase_len, NULL))
+			goto _free_ret;
+		if (info->curcontents)
+			memcpy(info->curcontents + info->erase_start, backup_contents, erase_len);
+	}
+
+	ret = 0;
+
+_free_ret:
+	free(erased_contents);
+	free(backup_contents);
+	return ret;
+}
+
+/**
+ * @brief Erases the included layout regions.
+ *
+ * If there is no layout set in the given flash context, the whole chip will
+ * be erased.
+ *
+ * @param flashctx Flash context to be used.
+ * @return 0 on success,
+ *	   1 if all available erase functions failed.
+ */
+static int erase_by_layout(struct flashctx *const flashctx)
+{
+	struct walk_info info = { 0 };
+	return walk_by_layout(flashctx, &info, &erase_block);
+}
+
+/**
+ * @brief Writes the included layout regions from a given image.
+ *
+ * If there is no layout set in the given flash context, the whole image
+ * will be written.
+ *
+ * @param flashctx    Flash context to be used.
+ * @param curcontents A buffer of full chip size with current chip contents of included regions.
+ * @param newcontents The new image to be written.
+ * @return 0 on success,
+ *	   1 if anything has gone wrong.
+ */
+static int write_by_layout(struct flashctx *const flashctx,
+			   void *const curcontents, const void *const newcontents)
+{
+	struct walk_info info;
+	info.curcontents = curcontents;
+	info.newcontents = newcontents;
+	return walk_by_layout(flashctx, &info, erase_block);
+}
+
+/**
+ * @brief Compares the included layout regions with content from a buffer.
+ *
+ * If there is no layout set in the given flash context, the whole chip's
+ * contents will be compared.
+ *
+ * @param flashctx    Flash context to be used.
+ * @param layout      Flash layout information.
+ * @param curcontents A buffer of full chip size to read current chip contents into.
+ * @param newcontents The new image to compare to.
+ * @return 0 on success,
+ *	   1 if reading failed,
+ *	   3 if the contents don't match.
+ */
+static int verify_by_layout(
+		struct flashctx *const flashctx,
+		const struct flashprog_layout *const layout,
+		void *const curcontents, const uint8_t *const newcontents)
+{
+	const struct romentry *entry = NULL;
+
+	while ((entry = layout_next_included(layout, entry))) {
+		const chipoff_t region_start	= entry->start;
+		const chipsize_t region_len	= entry->end - entry->start + 1;
+
+		if (flashctx->chip->read(flashctx, curcontents + region_start, region_start, region_len))
+			return 1;
+		if (compare_range(newcontents + region_start, curcontents + region_start,
+				  region_start, region_len))
+			return 3;
+	}
+	return 0;
+}
+
+static void nonfatal_help_message(void)
+{
+	msg_gerr("Good, writing to the flash chip apparently didn't do anything.\n");
+#if CONFIG_INTERNAL == 1
+	if (programmer == &programmer_internal)
+		msg_gerr("This means we have to add special support for your board, programmer or flash\n"
+			 "chip. Please report this to the mailing list at flashprog@flashprog.org or\n"
+			 "on IRC (see https://www.flashprog.org/Contact for details), thanks!\n"
+			 "-------------------------------------------------------------------------------\n"
+			 "You may now reboot or simply leave the machine running.\n");
+	else
+#endif
+		msg_gerr("Please check the connections (especially those to write protection pins) between\n"
+			 "the programmer and the flash chip. If you think the error is caused by flashprog\n"
+			 "please report this to the mailing list at flashprog@flashprog.org or on IRC\n"
+			 "(see https://www.flashprog.org/Contact for details), thanks!\n");
+}
+
+void emergency_help_message(void)
+{
+	msg_gerr("Your flash chip is in an unknown state.\n");
+#if CONFIG_INTERNAL == 1
+	if (programmer == &programmer_internal)
+		msg_gerr("Get help on IRC (see https://www.flashprog.org/Contact) or mail\n"
+			"flashprog@flashprog.org with the subject \"FAILED: <your board name>\"!\n"
+			"-------------------------------------------------------------------------------\n"
+			"DO NOT REBOOT OR POWEROFF!\n");
+	else
+#endif
+		msg_gerr("Please report this to the mailing list at flashprog@flashprog.org\n"
+			 "or on IRC (see https://www.flashprog.org/Contact for details), thanks!\n");
+}
+
+void list_programmers_linebreak(int startcol, int cols, int paren)
+{
+	const char *pname;
+	int pnamelen;
+	int remaining = 0, firstline = 1;
+	size_t p;
+	int i;
+
+	for (p = 0; p < programmer_table_size; p++) {
+		pname = programmer_table[p]->name;
+		pnamelen = strlen(pname);
+		if (remaining - pnamelen - 2 < 0) {
+			if (firstline)
+				firstline = 0;
+			else
+				msg_ginfo("\n");
+			for (i = 0; i < startcol; i++)
+				msg_ginfo(" ");
+			remaining = cols - startcol;
+		} else {
+			msg_ginfo(" ");
+			remaining--;
+		}
+		if (paren && (p == 0)) {
+			msg_ginfo("(");
+			remaining--;
+		}
+		msg_ginfo("%s", pname);
+		remaining -= pnamelen;
+		if (p < programmer_table_size - 1) {
+			msg_ginfo(",");
+			remaining--;
+		} else {
+			if (paren)
+				msg_ginfo(")");
+		}
+	}
+}
+
+int selfcheck(void)
+{
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < programmer_table_size; i++) {
+		const struct programmer_entry *const p = programmer_table[i];
+		if (p == NULL) {
+			msg_gerr("Programmer with index %d is NULL instead of a valid pointer!\n", i);
+			ret = 1;
+			continue;
+		}
+		if (p->name == NULL) {
+			msg_gerr("All programmers need a valid name, but the one with index %d does not!\n", i);
+			ret = 1;
+			/* This might hide other problems with this programmer, but allows for better error
+			 * messages below without jumping through hoops. */
+			continue;
+		}
+		switch (p->type) {
+		case USB:
+		case PCI:
+		case OTHER:
+			if (p->devs.note == NULL) {
+				if (strcmp("internal", p->name) == 0)
+					break; /* This one has its device list stored separately. */
+				msg_gerr("Programmer %s has neither a device list nor a textual description!\n",
+					 p->name);
+				ret = 1;
+			}
+			break;
+		default:
+			msg_gerr("Programmer %s does not have a valid type set!\n", p->name);
+			ret = 1;
+			break;
+		}
+		if (p->init == NULL) {
+			msg_gerr("Programmer %s does not have a valid init function!\n", p->name);
+			ret = 1;
+		}
+	}
+
+	/* It would be favorable if we could check for the correct layout (especially termination) of various
+	 * constant arrays: flashchips, chipset_enables, board_matches, boards_known, laptops_known.
+	 * They are all defined as externs in this compilation unit so we don't know their sizes which vary
+	 * depending on compiler flags, e.g. the target architecture, and can sometimes be 0.
+	 * For 'flashchips' we export the size explicitly to work around this and to be able to implement the
+	 * checks below. */
+	if (flashchips_size <= 1 || flashchips[flashchips_size - 1].name != NULL) {
+		msg_gerr("Flashchips table miscompilation!\n");
+		ret = 1;
+	} else {
+		for (i = 0; i < flashchips_size - 1; i++) {
+			const struct flashchip *chip = &flashchips[i];
+			if (chip->vendor == NULL || chip->name == NULL || chip->bustype == BUS_NONE) {
+				ret = 1;
+				msg_gerr("ERROR: Some field of flash chip #%d (%s) is misconfigured.\n"
+					 "Please report a bug at flashprog@flashprog.org\n", i,
+					 chip->name == NULL ? "unnamed" : chip->name);
+			}
+			if (selfcheck_eraseblocks(chip)) {
+				ret = 1;
+			}
+		}
+	}
+
+#if CONFIG_INTERNAL == 1
+	ret |= selfcheck_board_enables();
+#endif
+
+	/* TODO: implement similar sanity checks for other arrays where deemed necessary. */
+	return ret;
+}
+
+/* FIXME: This function signature needs to be improved once prepare_flash_access()
+ * has a better function signature.
+ */
+static int chip_safety_check(const struct flashctx *flash, int force,
+			     int read_it, int write_it, int erase_it, int verify_it)
+{
+	const struct flashchip *chip = flash->chip;
+
+	if (!programmer_may_write && (write_it || erase_it)) {
+		msg_perr("Write/erase is not working yet on your programmer in "
+			 "its current configuration.\n");
+		/* --force is the wrong approach, but it's the best we can do
+		 * until the generic programmer parameter parser is merged.
+		 */
+		if (!force)
+			return 1;
+		msg_cerr("Continuing anyway.\n");
+	}
+
+	if (read_it || erase_it || write_it || verify_it) {
+		/* Everything needs read. */
+		if (chip->tested.read == BAD) {
+			msg_cerr("Read is not working on this chip. ");
+			if (!force)
+				return 1;
+			msg_cerr("Continuing anyway.\n");
+		}
+		if (!chip->read) {
+			msg_cerr("flashprog has no read function for this "
+				 "flash chip.\n");
+			return 1;
+		}
+	}
+	if (erase_it || write_it) {
+		/* Write needs erase. */
+		if (chip->tested.erase == NA) {
+			msg_cerr("Erase is not possible on this chip.\n");
+			return 1;
+		}
+		if (chip->tested.erase == BAD) {
+			msg_cerr("Erase is not working on this chip. ");
+			if (!force)
+				return 1;
+			msg_cerr("Continuing anyway.\n");
+		}
+		if(count_usable_erasers(flash) == 0) {
+			msg_cerr("flashprog has no erase function for this "
+				 "flash chip.\n");
+			return 1;
+		}
+	}
+	if (write_it) {
+		if (chip->tested.write == NA) {
+			msg_cerr("Write is not possible on this chip.\n");
+			return 1;
+		}
+		if (chip->tested.write == BAD) {
+			msg_cerr("Write is not working on this chip. ");
+			if (!force)
+				return 1;
+			msg_cerr("Continuing anyway.\n");
+		}
+		if (!chip->write) {
+			msg_cerr("flashprog has no write function for this "
+				 "flash chip.\n");
+			return 1;
+		}
+	}
+	return 0;
+}
+
+int prepare_flash_access(struct flashctx *const flash,
+			 const bool read_it, const bool write_it,
+			 const bool erase_it, const bool verify_it)
+{
+	if (chip_safety_check(flash, flash->flags.force, read_it, write_it, erase_it, verify_it)) {
+		msg_cerr("Aborting.\n");
+		return 1;
+	}
+
+	if (layout_sanity_checks(flash, write_it)) {
+		msg_cerr("Requested regions can not be handled. Aborting.\n");
+		return 1;
+	}
+
+	if (map_flash(flash) != 0)
+		return 1;
+
+	/* Initialize chip_restore_fn_count before chip unlock calls. */
+	flash->chip_restore_fn_count = 0;
+
+	/* Given the existence of read locks, we want to unlock for read,
+	   erase and write. */
+	if (flash->chip->unlock)
+		flash->chip->unlock(flash);
+
+	flash->address_high_byte = -1;
+	flash->in_4ba_mode = false;
+
+	/* Be careful about 4BA chips and broken masters */
+	if (flash->chip->total_size > 16 * 1024 && spi_master_no_4ba_modes(flash)) {
+		/* If we can't use native instructions, bail out */
+		if ((flash->chip->feature_bits & FEATURE_4BA_NATIVE) != FEATURE_4BA_NATIVE
+		    || !spi_master_4ba(flash)) {
+			msg_cerr("Programmer doesn't support this chip. Aborting.\n");
+			return 1;
+		}
+	}
+
+	/* Enable/disable 4-byte addressing mode if flash chip supports it */
+	if (flash->chip->feature_bits & (FEATURE_4BA_ENTER | FEATURE_4BA_ENTER_WREN | FEATURE_4BA_ENTER_EAR7)) {
+		int ret;
+		if (spi_master_4ba(flash))
+			ret = spi_enter_4ba(flash);
+		else
+			ret = spi_exit_4ba(flash);
+		if (ret) {
+			msg_cerr("Failed to set correct 4BA mode! Aborting.\n");
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+void finalize_flash_access(struct flashctx *const flash)
+{
+	deregister_chip_restore(flash);
+	unmap_flash(flash);
+}
+
+/**
+ * @addtogroup flashprog-flash
+ * @{
+ */
+
+/**
+ * @brief Erase the specified ROM chip.
+ *
+ * If a layout is set in the given flash context, only included regions
+ * will be erased.
+ *
+ * @param flashctx The context of the flash chip to erase.
+ * @return 0 on success.
+ */
+int flashprog_flash_erase(struct flashctx *const flashctx)
+{
+	if (prepare_flash_access(flashctx, false, false, true, false))
+		return 1;
+
+	const int ret = erase_by_layout(flashctx);
+
+	finalize_flash_access(flashctx);
+
+	return ret;
+}
+
+/** @} */ /* end flashprog-flash */
+
+/**
+ * @defgroup flashprog-ops Operations
+ * @{
+ */
+
+/**
+ * @brief Read the current image from the specified ROM chip.
+ *
+ * If a layout is set in the specified flash context, only included regions
+ * will be read.
+ *
+ * @param flashctx The context of the flash chip.
+ * @param buffer Target buffer to write image to.
+ * @param buffer_len Size of target buffer in bytes.
+ * @return 0 on success,
+ *         2 if buffer_len is too short for the flash chip's contents,
+ *         or 1 on any other failure.
+ */
+int flashprog_image_read(struct flashctx *const flashctx, void *const buffer, const size_t buffer_len)
+{
+	const size_t flash_size = flashctx->chip->total_size * 1024;
+
+	if (flash_size > buffer_len)
+		return 2;
+
+	if (prepare_flash_access(flashctx, true, false, false, false))
+		return 1;
+
+	msg_cinfo("Reading flash... ");
+
+	int ret = 1;
+	if (read_by_layout(flashctx, buffer)) {
+		msg_cerr("Read operation failed!\n");
+		msg_cinfo("FAILED.\n");
+		goto _finalize_ret;
+	}
+	msg_cinfo("done.\n");
+	ret = 0;
+
+_finalize_ret:
+	finalize_flash_access(flashctx);
+	return ret;
+}
+
+static void combine_image_by_layout(const struct flashctx *const flashctx,
+				    uint8_t *const newcontents, const uint8_t *const oldcontents)
+{
+	const struct flashprog_layout *const layout = get_layout(flashctx);
+	const struct romentry *included;
+	chipoff_t start = 0;
+
+	while ((included = layout_next_included_region(layout, start))) {
+		if (included->start > start) {
+			/* copy everything up to the start of this included region */
+			memcpy(newcontents + start, oldcontents + start, included->start - start);
+		}
+		/* skip this included region */
+		start = included->end + 1;
+		if (start == 0)
+			return;
+	}
+
+	/* copy the rest of the chip */
+	const chipsize_t copy_len = flashctx->chip->total_size * 1024 - start;
+	memcpy(newcontents + start, oldcontents + start, copy_len);
+}
+
+/**
+ * @brief Write the specified image to the ROM chip.
+ *
+ * If a layout is set in the specified flash context, only erase blocks
+ * containing included regions will be touched.
+ *
+ * @param flashctx The context of the flash chip.
+ * @param buffer Source buffer to read image from (may be altered for full verification).
+ * @param buffer_len Size of source buffer in bytes.
+ * @param refbuffer If given, assume flash chip contains same data as `refbuffer`.
+ * @return 0 on success,
+ *         4 if buffer_len doesn't match the size of the flash chip,
+ *         3 if write was tried but nothing has changed,
+ *         2 if write failed and flash contents changed,
+ *         or 1 on any other failure.
+ */
+int flashprog_image_write(struct flashctx *const flashctx, void *const buffer, const size_t buffer_len,
+                         const void *const refbuffer)
+{
+	const size_t flash_size = flashctx->chip->total_size * 1024;
+	const bool verify_all = flashctx->flags.verify_whole_chip;
+	const bool verify = flashctx->flags.verify_after_write;
+	const struct flashprog_layout *const verify_layout =
+		verify_all ? get_default_layout(flashctx) : get_layout(flashctx);
+
+	if (buffer_len != flash_size)
+		return 4;
+
+	int ret = 1;
+
+	uint8_t *const newcontents = buffer;
+	const uint8_t *const refcontents = refbuffer;
+	uint8_t *const curcontents = malloc(flash_size);
+	uint8_t *oldcontents = NULL;
+	if (verify_all)
+		oldcontents = malloc(flash_size);
+	if (!curcontents || (verify_all && !oldcontents)) {
+		msg_gerr("Out of memory!\n");
+		goto _free_ret;
+	}
+
+#if CONFIG_INTERNAL == 1
+	if (programmer == &programmer_internal && cb_check_image(newcontents, flash_size) < 0) {
+		if (flashctx->flags.force_boardmismatch) {
+			msg_pinfo("Proceeding anyway because user forced us to.\n");
+		} else {
+			msg_perr("Aborting. You can override this with "
+				 "-p internal:boardmismatch=force.\n");
+			goto _free_ret;
+		}
+	}
+#endif
+
+	if (prepare_flash_access(flashctx, false, true, false, verify))
+		goto _free_ret;
+
+	/* If given, assume flash chip contains same data as `refcontents`. */
+	if (refcontents) {
+		msg_cinfo("Assuming old flash chip contents as ref-file...\n");
+		memcpy(curcontents, refcontents, flash_size);
+		if (oldcontents)
+			memcpy(oldcontents, refcontents, flash_size);
+	} else {
+		/*
+		 * Read the whole chip to be able to check whether regions need to be
+		 * erased and to give better diagnostics in case write fails.
+		 * The alternative is to read only the regions which are to be
+		 * preserved, but in that case we might perform unneeded erase which
+		 * takes time as well.
+		 */
+		msg_cinfo("Reading old flash chip contents... ");
+		if (verify_all) {
+			if (flashctx->chip->read(flashctx, oldcontents, 0, flash_size)) {
+				msg_cinfo("FAILED.\n");
+				goto _finalize_ret;
+			}
+			memcpy(curcontents, oldcontents, flash_size);
+		} else {
+			if (read_by_layout(flashctx, curcontents)) {
+				msg_cinfo("FAILED.\n");
+				goto _finalize_ret;
+			}
+		}
+		msg_cinfo("done.\n");
+	}
+
+	if (write_by_layout(flashctx, curcontents, newcontents)) {
+		msg_cerr("Uh oh. Erase/write failed. ");
+		ret = 2;
+		if (verify_all) {
+			msg_cerr("Checking if anything has changed.\n");
+			msg_cinfo("Reading current flash chip contents... ");
+			if (!flashctx->chip->read(flashctx, curcontents, 0, flash_size)) {
+				msg_cinfo("done.\n");
+				if (!memcmp(oldcontents, curcontents, flash_size)) {
+					nonfatal_help_message();
+					goto _finalize_ret;
+				}
+				msg_cerr("Apparently at least some data has changed.\n");
+			} else
+				msg_cerr("Can't even read anymore!\n");
+			emergency_help_message();
+			goto _finalize_ret;
+		} else {
+			msg_cerr("\n");
+		}
+		emergency_help_message();
+		goto _finalize_ret;
+	}
+
+	/* Verify only if we actually changed something. */
+	if (verify && !all_skipped) {
+		msg_cinfo("Verifying flash... ");
+
+		/* Work around chips which need some time to calm down. */
+		programmer_delay(1000*1000);
+
+		if (verify_all)
+			combine_image_by_layout(flashctx, newcontents, oldcontents);
+		ret = verify_by_layout(flashctx, verify_layout, curcontents, newcontents);
+		/* If we tried to write, and verification now fails, we
+		   might have an emergency situation. */
+		if (ret)
+			emergency_help_message();
+		else
+			msg_cinfo("VERIFIED.\n");
+	} else {
+		/* We didn't change anything. */
+		ret = 0;
+	}
+
+_finalize_ret:
+	finalize_flash_access(flashctx);
+_free_ret:
+	free(oldcontents);
+	free(curcontents);
+	return ret;
+}
+
+/**
+ * @brief Verify the ROM chip's contents with the specified image.
+ *
+ * If a layout is set in the specified flash context, only included regions
+ * will be verified.
+ *
+ * @param flashctx The context of the flash chip.
+ * @param buffer Source buffer to verify with.
+ * @param buffer_len Size of source buffer in bytes.
+ * @return 0 on success,
+ *         3 if the chip's contents don't match,
+ *         2 if buffer_len doesn't match the size of the flash chip,
+ *         or 1 on any other failure.
+ */
+int flashprog_image_verify(struct flashctx *const flashctx, const void *const buffer, const size_t buffer_len)
+{
+	const struct flashprog_layout *const layout = get_layout(flashctx);
+	const size_t flash_size = flashctx->chip->total_size * 1024;
+
+	if (buffer_len != flash_size)
+		return 2;
+
+	const uint8_t *const newcontents = buffer;
+	uint8_t *const curcontents = malloc(flash_size);
+	if (!curcontents) {
+		msg_gerr("Out of memory!\n");
+		return 1;
+	}
+
+	int ret = 1;
+
+	if (prepare_flash_access(flashctx, false, false, false, true))
+		goto _free_ret;
+
+	msg_cinfo("Verifying flash... ");
+	ret = verify_by_layout(flashctx, layout, curcontents, newcontents);
+	if (!ret)
+		msg_cinfo("VERIFIED.\n");
+
+	finalize_flash_access(flashctx);
+_free_ret:
+	free(curcontents);
+	return ret;
+}
+
+/** @} */ /* end flashprog-ops */