flash/stm32l4x: introduce flash programming without loader

this capability permits to program the flash if we cannot reserve a workarea.

the introduction the command 'stm32l4x flashloader <bank_id> [enable|disable]'
helps to automatically skip using the flashloader if needed.

Change-Id: Id29213c85ee5c7c487cfee21554f5a7ea50db6c9
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6273
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Tested-by: jenkins

doc/openocd.texi

@@ -7344,6 +7344,13 @@ Unlocks the entire stm32 device.
 The @var{num} parameter is a value shown by @command{flash banks}.
 @end deffn
 
+@deffn Command {stm32l4x flashloader} num [@option{enable} | @option{disable}]
+Enables or disables the flashloader usage (enabled by default),
+when disabled it will fall back to direct memory access to program the Flash or OTP memories.
+if neither @option{enabled} nor @option{disable} are specified, the command will display
+the current configuration.
+@end deffn
+
 @deffn {Command} {stm32l4x mass_erase} num
 Mass erases the entire stm32l4x device.
 The @var{num} parameter is a value shown by @command{flash banks}.

src/flash/nor/stm32l4x.c

@@ -116,6 +116,7 @@
 /* Erase time can be as high as 25ms, 10x this and assume it's toast... */
 
 #define FLASH_ERASE_TIMEOUT 250
+#define FLASH_WRITE_TIMEOUT 50
 
 
 /* relevant STM32L4 flags ****************************************************/
@@ -223,6 +224,7 @@ struct stm32l4_flash_bank {
 	uint32_t flash_regs_base;
 	const uint32_t *flash_regs;
 	bool otp_enabled;
+	bool use_flashloader;
 	enum stm32l4_rdp rdp;
 	bool tzen;
 	uint32_t optr;
@@ -545,6 +547,7 @@ FLASH_BANK_COMMAND_HANDLER(stm32l4_flash_bank_command)
 	stm32l4_info->probed = false;
 	stm32l4_info->otp_enabled = false;
 	stm32l4_info->user_bank_size = bank->size;
+	stm32l4_info->use_flashloader = true;
 
 	return ERROR_OK;
 }
@@ -1362,6 +1365,49 @@ static int stm32l4_write_block(struct flash_bank *bank, const uint8_t *buffer,
 	return retval;
 }
 
+/* Count is in double-words */
+static int stm32l4_write_block_without_loader(struct flash_bank *bank, const uint8_t *buffer,
+				uint32_t offset, uint32_t count)
+{
+	struct target *target = bank->target;
+	uint32_t address = bank->base + offset;
+	int retval = ERROR_OK;
+
+	/* wait for BSY bit */
+	retval = stm32l4_wait_status_busy(bank, FLASH_WRITE_TIMEOUT);
+	if (retval != ERROR_OK)
+		return retval;
+
+	/* set PG in FLASH_CR */
+	retval = stm32l4_write_flash_reg_by_index(bank, STM32_FLASH_CR_INDEX, FLASH_PG);
+	if (retval != ERROR_OK)
+		return retval;
+
+
+	/* write directly to flash memory */
+	const uint8_t *src = buffer;
+	while (count--) {
+		retval = target_write_memory(target, address, 4, 2, src);
+		if (retval != ERROR_OK)
+			return retval;
+
+		/* wait for BSY bit */
+		retval = stm32l4_wait_status_busy(bank, FLASH_WRITE_TIMEOUT);
+		if (retval != ERROR_OK)
+			return retval;
+
+		src += 8;
+		address += 8;
+	}
+
+	/* reset PG in FLASH_CR */
+	retval = stm32l4_write_flash_reg_by_index(bank, STM32_FLASH_CR_INDEX, 0);
+	if (retval != ERROR_OK)
+		return retval;
+
+	return retval;
+}
+
 static int stm32l4_write(struct flash_bank *bank, const uint8_t *buffer,
 	uint32_t offset, uint32_t count)
 {
@@ -1434,6 +1480,7 @@ static int stm32l4_write(struct flash_bank *bank, const uint8_t *buffer,
 	if (retval != ERROR_OK)
 		goto err_lock;
 
+	if (stm32l4_info->use_flashloader) {
 		/* For TrustZone enabled devices, when TZEN is set and RDP level is 0.5,
 		 * the debug is possible only in non-secure state.
 		 * Thus means the flashloader will run in non-secure mode,
@@ -1442,6 +1489,13 @@ static int stm32l4_write(struct flash_bank *bank, const uint8_t *buffer,
 			LOG_INFO("RDP level is 0.5, the work-area should reside in non-secure RAM");
 
 		retval = stm32l4_write_block(bank, buffer, offset, count / 8);
+	}
+
+	if (!stm32l4_info->use_flashloader || retval == ERROR_TARGET_RESOURCE_NOT_AVAILABLE) {
+		LOG_INFO("falling back to single memory accesses");
+		retval = stm32l4_write_block_without_loader(bank, buffer, offset, count / 8);
+	}
+
 
 err_lock:
 	retval2 = stm32l4_write_flash_reg_by_index(bank, STM32_FLASH_CR_INDEX, FLASH_LOCK);
@@ -2017,6 +2071,26 @@ COMMAND_HANDLER(stm32l4_handle_trustzone_command)
 	return stm32l4_perform_obl_launch(bank);
 }
 
+COMMAND_HANDLER(stm32l4_handle_flashloader_command)
+{
+	if (CMD_ARGC < 1 || CMD_ARGC > 2)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	struct flash_bank *bank;
+	int retval = CALL_COMMAND_HANDLER(flash_command_get_bank, 0, &bank);
+	if (retval != ERROR_OK)
+		return retval;
+
+	struct stm32l4_flash_bank *stm32l4_info = bank->driver_priv;
+
+	if (CMD_ARGC == 2)
+		COMMAND_PARSE_ENABLE(CMD_ARGV[1], stm32l4_info->use_flashloader);
+
+	command_print(CMD, "FlashLoader usage is %s", stm32l4_info->use_flashloader ? "enabled" : "disabled");
+
+	return ERROR_OK;
+}
+
 COMMAND_HANDLER(stm32l4_handle_option_load_command)
 {
 	if (CMD_ARGC != 1)
@@ -2222,6 +2296,13 @@ static const struct command_registration stm32l4_exec_command_handlers[] = {
 		.usage = "bank_id",
 		.help = "Unlock entire protected flash device.",
 	},
+	{
+		.name = "flashloader",
+		.handler = stm32l4_handle_flashloader_command,
+		.mode = COMMAND_EXEC,
+		.usage = "<bank_id> [enable|disable]",
+		.help = "Configure the flashloader usage",
+	},
 	{
 		.name = "mass_erase",
 		.handler = stm32l4_handle_mass_erase_command,