flash: read only alias

Similar as virtual flash but has write/erase suppressed.

'virtual' flash driver name check in flash_free_all_banks()
was replaced by a customized free_driver_priv()

Change-Id: I528760aad0ba55ebc57fc1fabfdfdf07c92cac94
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/5107
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins

doc/openocd.texi

@@ -6160,7 +6160,7 @@ Some drivers also activate driver-specific commands.
 This is a special driver that maps a previously defined bank to another
 address. All bank settings will be copied from the master physical bank.
 
-The @var{virtual} driver defines one mandatory parameters,
+The @var{virtual} driver defines one mandatory parameter,
 
 @itemize
 @item @var{master_bank} The bank that this virtual address refers to.
@@ -6178,6 +6178,18 @@ flash bank vbank1 virtual 0x9fc00000 0 0 0 \
 @end example
 @end deffn
 
+@deffn {Flash Driver} ro_alias
+Similar as @var{virtual} driver but suppresses write
+and erase. Use to build a complete memory map for gdb.
+Bank size will be copied from the master physical bank.
+
+The @var{virtual} driver defines one mandatory parameter,
+
+@itemize
+@item @var{master_bank} The bank that this virtual address refers to.
+@end itemize
+@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.

src/flash/nor/core.c

@@ -223,15 +223,8 @@ void flash_free_all_banks(void)
 		else
 			LOG_WARNING("Flash driver of %s does not support free_driver_priv()", bank->name);
 
-		/* For 'virtual' flash driver bank->sectors and bank->prot_blocks pointers are copied from
-		 * master flash_bank structure. They point to memory locations allocated by master flash driver
-		 * so master driver is responsible for releasing them.
-		 * Avoid UB caused by double-free memory corruption if flash bank is 'virtual'. */
-
-		if (strcmp(bank->driver->name, "virtual") != 0) {
-			free(bank->sectors);
-			free(bank->prot_blocks);
-		}
+		free(bank->sectors);
+		free(bank->prot_blocks);
 
 		free(bank->name);
 		free(bank);

src/flash/nor/driver.h

@@ -294,6 +294,7 @@ 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 ro_alias_flash;
 extern const struct flash_driver rp2xxx_flash;
 extern const struct flash_driver rsl10_flash;
 extern const struct flash_driver sh_qspi_flash;

src/flash/nor/drivers.c

@@ -72,6 +72,7 @@ static const struct flash_driver * const flash_drivers[] = {
 	&psoc6_flash,
 	&qn908x_flash,
 	&read_only_flash,
+	&ro_alias_flash,
 	&renesas_rpchf_flash,
 	&rp2xxx_flash,
 	&rsl10_flash,

src/flash/nor/virtual.c

@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
-/***************************************************************************
- *   Copyright (C) 2010 by Spencer Oliver                                  *
- *   spen@spen-soft.co.uk                                                  *
- ***************************************************************************/
+/*
+ * Copyright (C) 2010 by Spencer Oliver <spen@spen-soft.co.uk>
+ *
+ * Copyright (C) 2019 by Tomas Vanek <vanekt@fbl.cz>
+ */
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
@@ -31,6 +32,9 @@ static void virtual_update_bank_info(struct flash_bank *bank)
 
 	/* update the info we do not have */
 	bank->size = master_bank->size;
+	if (bank->read_only)
+		return;
+
 	bank->chip_width = master_bank->chip_width;
 	bank->bus_width = master_bank->bus_width;
 	bank->erased_value = master_bank->erased_value;
@@ -187,6 +191,19 @@ static int virtual_flash_read(struct flash_bank *bank,
 	return master_bank->driver->read(master_bank, buffer, offset, count);
 }
 
+void virtual_flash_free_driver_priv(struct flash_bank *bank)
+{
+	free(bank->driver_priv);
+	bank->driver_priv = NULL;
+
+	/* For 'virtual' flash driver bank->sectors and bank->prot_blocks pointers are copied from
+	 * master flash_bank structure. They point to memory locations allocated by master flash driver
+	 * so master driver is responsible for releasing them.
+	 * Avoid UB caused by double-free memory corruption if flash bank is 'virtual'. */
+	bank->sectors = NULL;
+	bank->prot_blocks = NULL;
+}
+
 const struct flash_driver virtual_flash = {
 	.name = "virtual",
 	.flash_bank_command = virtual_flash_bank_command,
@@ -199,5 +216,62 @@ const struct flash_driver virtual_flash = {
 	.erase_check = virtual_blank_check,
 	.protect_check = virtual_protect_check,
 	.info = virtual_info,
-	.free_driver_priv = default_flash_free_driver_priv,
+	.free_driver_priv = virtual_flash_free_driver_priv,
+};
+
+FLASH_BANK_COMMAND_HANDLER(ro_alias_bank_command)
+{
+	if (CMD_ARGC < 7)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	// get the master flash bank
+	const char *bank_name = CMD_ARGV[6];
+	struct flash_bank *master_bank = get_flash_bank_by_name_noprobe(bank_name);
+
+	if (!master_bank) {
+		LOG_ERROR("master flash bank '%s' does not exist", bank_name);
+		return ERROR_FLASH_OPERATION_FAILED;
+	}
+
+	// save master bank name - use this to get settings later
+	bank->driver_priv = strdup(bank_name);
+
+	bank->read_only = true;
+
+	return ERROR_OK;
+}
+
+static int ro_alias_erase(struct flash_bank *bank,
+	unsigned int first, unsigned int last)
+{
+	char *bank_name = bank->driver_priv;
+
+	LOG_ERROR("Erase of read-only flash alias refused. Use master flash bank '%s'",
+			bank_name);
+
+	return ERROR_FAIL;
+}
+
+static int ro_alias_write(struct flash_bank *bank, const uint8_t *buffer,
+		uint32_t offset, uint32_t count)
+{
+	char *bank_name = bank->driver_priv;
+
+	LOG_ERROR("Write to read-only flash alias refused. Use master flash bank '%s'",
+			bank_name);
+
+	return ERROR_FAIL;
+}
+
+const struct flash_driver ro_alias_flash = {
+	.name = "ro_alias",
+	.flash_bank_command = ro_alias_bank_command,
+	.erase = ro_alias_erase,
+	.write = ro_alias_write,
+	.read = virtual_flash_read,
+	.probe = virtual_probe,
+	.auto_probe = virtual_auto_probe,
+	.erase_check = virtual_blank_check,
+	.info = virtual_info,
+	.free_driver_priv = virtual_flash_free_driver_priv,
 };