refactor(plat/arm): update NV flags on image load/authentication failure

Erasing the FIP TOC header present in a flash is replaced by updating NV
flags with an error code on image load/authentication failure.
BL1 component uses these NV flags to detect whether a firmware update is
needed or not.
These NV flags get cleared once the firmware update gets completed.
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I6232a0db07c89b2373b7b9d28acd37df6203d914

plat/arm/board/fvp/fvp_bl1_setup.c

 /*
- * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
 #include <assert.h>
+#include <errno.h>
 
 #include <bl1/bl1.h>
 #include <common/tbbr/tbbr_img_def.h>
 #include <drivers/arm/smmu_v3.h>
 #include <drivers/arm/sp805.h>
+#include <lib/mmio.h>
 #include <plat/arm/common/arm_config.h>
 #include <plat/arm/common/plat_arm.h>
 #include <plat/arm/common/arm_def.h>
@@ -61,6 +63,12 @@ void bl1_platform_setup(void)
 
 __dead2 void bl1_plat_fwu_done(void *client_cookie, void *reserved)
 {
+	uint32_t nv_flags = mmio_read_32(V2M_SYS_NVFLAGS_ADDR);
+
+	/* Clear the NV flags register. */
+	mmio_write_32((V2M_SYSREGS_BASE + V2M_SYS_NVFLAGSCLR),
+		      nv_flags);
+
 	/* Setup the watchdog to reset the system as soon as possible */
 	sp805_refresh(ARM_SP805_TWDG_BASE, 1U);
 
@@ -124,3 +132,15 @@ int bl1_plat_handle_post_image_load(unsigned int image_id)
 	return 0;
 }
 #endif /* MEASURED_BOOT */
+
+/*******************************************************************************
+ * The following function checks if Firmware update is needed by checking error
+ * reported in NV flag.
+ ******************************************************************************/
+bool plat_arm_bl1_fwu_needed(void)
+{
+	int32_t nv_flags = (int32_t)mmio_read_32(V2M_SYS_NVFLAGS_ADDR);
+
+	/* if image load/authentication failed */
+	return ((nv_flags == -EAUTH) || (nv_flags == -ENOENT));
+}

plat/arm/board/fvp/fvp_err.c

 /*
- * Copyright (c) 2019-2020, Arm Limited. All rights reserved.
+ * Copyright (c) 2019-2021, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,6 +9,7 @@
 #include <common/debug.h>
 #include <drivers/arm/sp805.h>
 #include <drivers/cfi/v2m_flash.h>
+#include <lib/mmio.h>
 #include <plat/arm/common/plat_arm.h>
 #include <platform_def.h>
 
@@ -17,25 +18,8 @@
  */
 __dead2 void plat_arm_error_handler(int err)
 {
-	int ret;
-
-	switch (err) {
-	case -ENOENT:
-	case -EAUTH:
-		/* Image load or authentication error. Erase the ToC */
-		INFO("Erasing FIP ToC from flash...\n");
-		(void)nor_unlock(PLAT_ARM_FLASH_IMAGE_BASE);
-		ret = nor_word_program(PLAT_ARM_FLASH_IMAGE_BASE, 0);
-		if (ret != 0) {
-			ERROR("Cannot erase ToC\n");
-		} else {
-			INFO("Done\n");
-		}
-		break;
-	default:
-		/* Unexpected error */
-		break;
-	}
+	/* Propagate the err code in the NV-flags register */
+	mmio_write_32(V2M_SYS_NVFLAGS_ADDR, (uint32_t)err);
 
 	console_flush();