flash: ROM support

The only reason to define a read-only region is that gdb needs
a complete memory map to choose hard or soft breakpoints properly.

Change-Id: I9d05cb6b91f054ad5cc9333af6b14eb433dbdc99
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/5106
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins

doc/openocd.texi

@@ -6178,6 +6178,16 @@ flash bank vbank1 virtual 0x9fc00000 0 0 0 \
 @end example
 @end deffn
 
+@deffn {Flash Driver} read_only
+A stub driver without write and erase.
+Use to define a ROM region for the gdb memory map.
+
+@example
+flash bank $_CHIPNAME.sysrom read_only 0x1ff00000 0xedc0 0 0 \
+           $_TARGETNAME
+@end example
+@end deffn
+
 @subsection External Flash
 
 @deffn {Flash Driver} {cfi}

src/flash/nor/Makefile.am

@@ -60,6 +60,7 @@ NOR_DRIVERS = \
 	%D%/psoc5lp.c \
 	%D%/psoc6.c \
 	%D%/qn908x.c \
+	%D%/read_only.c \
 	%D%/renesas_rpchf.c \
 	%D%/rp2xxx.c \
 	%D%/rsl10.c \

src/flash/nor/core.c

@@ -44,6 +44,11 @@ int flash_driver_protect(struct flash_bank *bank, int set, unsigned int first,
 	int retval;
 	unsigned int num_blocks;
 
+	if (!bank->driver->protect) {
+		LOG_ERROR("Flash protection is not supported");
+		return ERROR_FLASH_OPER_UNSUPPORTED;
+	}
+
 	if (bank->num_prot_blocks)
 		num_blocks = bank->num_prot_blocks;
 	else
@@ -59,11 +64,6 @@ int flash_driver_protect(struct flash_bank *bank, int set, unsigned int first,
 	/* force "set" to 0/1 */
 	set = !!set;
 
-	if (!bank->driver->protect) {
-		LOG_ERROR("Flash protection is not supported.");
-		return ERROR_FLASH_OPER_UNSUPPORTED;
-	}
-
 	/* DANGER!
 	 *
 	 * We must not use any cached information about protection state!!!!

src/flash/nor/core.h

@@ -84,6 +84,8 @@ struct flash_bank {
 	target_addr_t base; /**< The base address of this bank */
 	uint32_t size; /**< The size of this chip bank, in bytes */
 
+	bool read_only; /**< a ROM region - mainly to list in gdb memory map */
+
 	unsigned int chip_width; /**< Width of the chip in bytes (1,2,4 bytes) */
 	unsigned int bus_width; /**< Maximum bus width, in bytes (1,2,4 bytes) */
 

src/flash/nor/driver.h

@@ -292,6 +292,7 @@ extern const struct flash_driver psoc5lp_flash;
 extern const struct flash_driver psoc5lp_nvl_flash;
 extern const struct flash_driver psoc6_flash;
 extern const struct flash_driver qn908x_flash;
+extern const struct flash_driver read_only_flash;
 extern const struct flash_driver renesas_rpchf_flash;
 extern const struct flash_driver rp2xxx_flash;
 extern const struct flash_driver rsl10_flash;

src/flash/nor/drivers.c

@@ -71,6 +71,7 @@ static const struct flash_driver * const flash_drivers[] = {
 	&psoc5lp_nvl_flash,
 	&psoc6_flash,
 	&qn908x_flash,
+	&read_only_flash,
 	&renesas_rpchf_flash,
 	&rp2xxx_flash,
 	&rsl10_flash,

src/flash/nor/read_only.c

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ * Copyright (C) 2019 by Tomas Vanek <vanekt@fbl.cz>
+ *
+ * To declare a read-only region for GDB memory map.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "imp.h"
+
+FLASH_BANK_COMMAND_HANDLER(rom_bank_command)
+{
+	bank->read_only = true;
+	return ERROR_OK;
+}
+
+static int rom_erase(struct flash_bank *bank, unsigned int first, unsigned int last)
+{
+	LOG_ERROR("Erase of read-only memory refused");
+	return ERROR_FAIL;
+}
+
+static int rom_write(struct flash_bank *bank, const uint8_t *buffer,
+		uint32_t offset, uint32_t count)
+{
+	LOG_ERROR("Write to read-only memory refused");
+	return ERROR_FAIL;
+}
+
+static int rom_probe(struct flash_bank *bank)
+{
+	return ERROR_OK;
+}
+
+const struct flash_driver read_only_flash = {
+	.name = "read_only",
+	.flash_bank_command = rom_bank_command,
+	.erase = rom_erase,
+	.write = rom_write,
+	.read = default_flash_read,
+	.probe = rom_probe,
+	.auto_probe = rom_probe,
+	.erase_check = default_flash_blank_check,
+
+	// ROM driver doesn't set driver_priv, free(NULL) makes no harm
+	.free_driver_priv = default_flash_free_driver_priv,
+};

src/server/gdb_server.c

@@ -2004,52 +2004,58 @@ static int gdb_memory_map(struct connection *connection,
 				"length=\"" TARGET_ADDR_FMT "\"/>\n",
 				ram_start, p->base - ram_start);
 
-		/* Report adjacent groups of same-size sectors.  So for
-		 * example top boot CFI flash will list an initial region
-		 * with several large sectors (maybe 128KB) and several
-		 * smaller ones at the end (maybe 32KB).  STR7 will have
-		 * regions with 8KB, 32KB, and 64KB sectors; etc.
-		 */
-		for (unsigned int j = 0; j < p->num_sectors; j++) {
-
-			/* Maybe start a new group of sectors. */
-			if (sector_size == 0) {
-				if (p->sectors[j].offset + p->sectors[j].size > p->size) {
-					LOG_WARNING("The flash sector at offset 0x%08" PRIx32
-						" overflows the end of %s bank.",
-						p->sectors[j].offset, p->name);
-					LOG_WARNING("The rest of bank will not show in gdb memory map.");
-					break;
-				}
-				target_addr_t start;
-				start = p->base + p->sectors[j].offset;
-				xml_printf(&retval, &xml, &pos, &size,
-					"<memory type=\"flash\" "
-					"start=\"" TARGET_ADDR_FMT "\" ",
-					start);
-				sector_size = p->sectors[j].size;
-				group_len = sector_size;
-			} else {
-				group_len += sector_size; /* equal to p->sectors[j].size */
-			}
-
-			/* Does this finish a group of sectors?
-			 * If not, continue an already-started group.
-			 */
-			if (j < p->num_sectors - 1
-					&& p->sectors[j + 1].size == sector_size
-					&& p->sectors[j + 1].offset == p->sectors[j].offset + sector_size
-					&& p->sectors[j + 1].offset + p->sectors[j + 1].size <= p->size)
-				continue;
-
+		if (p->read_only) {
 			xml_printf(&retval, &xml, &pos, &size,
-				"length=\"0x%x\">\n"
-				"<property name=\"blocksize\">"
-				"0x%x</property>\n"
-				"</memory>\n",
-				group_len,
-				sector_size);
-			sector_size = 0;
+				"<memory type=\"rom\" start=\"" TARGET_ADDR_FMT "\" "
+				"length=\"0x%x\"/>\n",
+				p->base, p->size);
+		} else {
+			/* Report adjacent groups of same-size sectors.  So for
+			 * example top boot CFI flash will list an initial region
+			 * with several large sectors (maybe 128KB) and several
+			 * smaller ones at the end (maybe 32KB).  STR7 will have
+			 * regions with 8KB, 32KB, and 64KB sectors; etc.
+			 */
+			for (unsigned int j = 0; j < p->num_sectors; j++) {
+				// Maybe start a new group of sectors
+				if (sector_size == 0) {
+					if (p->sectors[j].offset + p->sectors[j].size > p->size) {
+						LOG_WARNING("The flash sector at offset 0x%08" PRIx32
+							" overflows the end of %s bank.",
+							p->sectors[j].offset, p->name);
+						LOG_WARNING("The rest of bank will not show in gdb memory map.");
+						break;
+					}
+					target_addr_t start;
+					start = p->base + p->sectors[j].offset;
+					xml_printf(&retval, &xml, &pos, &size,
+						"<memory type=\"flash\" "
+						"start=\"" TARGET_ADDR_FMT "\" ",
+						start);
+					sector_size = p->sectors[j].size;
+					group_len = sector_size;
+				} else {
+					group_len += sector_size; /* equal to p->sectors[j].size */
+				}
+
+				/* Does this finish a group of sectors?
+				 * If not, continue an already-started group.
+				 */
+				if (j < p->num_sectors - 1
+						&& p->sectors[j + 1].size == sector_size
+						&& p->sectors[j + 1].offset == p->sectors[j].offset + sector_size
+						&& p->sectors[j + 1].offset + p->sectors[j + 1].size <= p->size)
+					continue;
+
+				xml_printf(&retval, &xml, &pos, &size,
+					"length=\"0x%x\">\n"
+					"<property name=\"blocksize\">"
+					"0x%x</property>\n"
+					"</memory>\n",
+					group_len,
+					sector_size);
+				sector_size = 0;
+			}
 		}
 
 		ram_start = p->base + p->size;