logging: allow storing log history in flash

When CONFIG_LOG_BACKEND_RPC_HISTORY_STORAGE_FCB option
is set, define the "log_history" flash partition and enable
storing the log history using Flash Circular Buffer.

Signed-off-by: Damian Krolik <[email protected]>

subsys/logging/CMakeLists.txt

@@ -9,4 +9,5 @@ if (CONFIG_LOG_FORWARDER_RPC OR CONFIG_LOG_BACKEND_RPC)
     zephyr_library_sources_ifdef(CONFIG_LOG_FORWARDER_RPC log_forwarder_rpc.c)
     zephyr_library_sources_ifdef(CONFIG_LOG_BACKEND_RPC log_backend_rpc.c)
     zephyr_library_sources_ifdef(CONFIG_LOG_BACKEND_RPC_HISTORY_STORAGE_RAM log_backend_rpc_history_ram.c)
+    zephyr_library_sources_ifdef(CONFIG_LOG_BACKEND_RPC_HISTORY_STORAGE_FCB log_backend_rpc_history_fcb.c)
 endif()

subsys/logging/Kconfig

@@ -53,6 +53,14 @@ choice LOG_BACKEND_RPC_HISTORY_STORAGE_CHOICE
 config LOG_BACKEND_RPC_HISTORY_STORAGE_RAM
 	bool "RAM buffer"
 
+config LOG_BACKEND_RPC_HISTORY_STORAGE_FCB
+	bool "Flash Circular Buffer"
+	help
+	  Stores the log history in Flash Circular Buffer located in the "log_history"
+	  flash partition. Note that enabling this option may significantly increase
+	  the flash wear, so this option is not meant the production environments,
+	  and extra caution should be taken when using this functionality.
+
 endchoice # LOG_BACKEND_RPC_HISTORY_STORAGE_CHOICE
 
 config LOG_BACKEND_RPC_HISTORY_UPLOAD_THREAD_STACK_SIZE
@@ -64,12 +72,17 @@ config LOG_BACKEND_RPC_HISTORY_UPLOAD_CHUNK_SIZE
 	default 1024
 
 config LOG_BACKEND_RPC_HISTORY_SIZE
-	int "Log history size"
-	depends on LOG_BACKEND_RPC_HISTORY_STORAGE_RAM
-	default 16384
+	hex "Log history size"
+	default 0x4000 if LOG_BACKEND_RPC_HISTORY_STORAGE_RAM
+	default 0x8000 if LOG_BACKEND_RPC_HISTORY_STORAGE_FCB
 	help
 	  Size of the ring buffer used to store the log history, in bytes.
 
+config LOG_BACKEND_RPC_HISTORY_STORAGE_FCB_NUM_SECTORS
+	int "Log history FCB maximum number of flash sectors"
+	default 64
+	depends on LOG_BACKEND_RPC_HISTORY_STORAGE_FCB
+
 endif # LOG_BACKEND_RPC_HISTORY
 
 config LOG_BACKEND_RPC_CRASH_LOG

subsys/logging/log_backend_rpc_history_fcb.c

@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#include "log_backend_rpc_history.h"
+
+#include <zephyr/fs/fcb.h>
+#include <zephyr/sys/util.h>
+
+#define LOG_HISTORY_MAGIC 0x7d2ac863
+#define LOG_HISTORY_AREA FIXED_PARTITION_ID(log_history)
+
+static struct fcb fcb;
+static struct flash_sector fcb_sectors[CONFIG_LOG_BACKEND_RPC_HISTORY_STORAGE_FCB_NUM_SECTORS];
+static struct fcb_entry last_popped;
+static bool erase_oldest;
+static K_MUTEX_DEFINE(fcb_lock);
+
+void log_rpc_history_init(void)
+{
+	int rc;
+	uint32_t sector_cnt = ARRAY_SIZE(fcb_sectors);
+
+	rc = flash_area_get_sectors(LOG_HISTORY_AREA, &sector_cnt, fcb_sectors);
+
+	if (rc) {
+		goto out;
+	}
+
+	fcb.f_magic = LOG_HISTORY_MAGIC;
+	fcb.f_sectors = fcb_sectors;
+	fcb.f_sector_cnt = (uint8_t)sector_cnt;
+	erase_oldest = true;
+
+	rc = fcb_init(LOG_HISTORY_AREA, &fcb);
+
+	if (rc) {
+		goto out;
+	}
+
+	rc = fcb_clear(&fcb);
+
+out:
+	__ASSERT_NO_MSG(rc == 0);
+}
+
+void log_rpc_history_push(const union log_msg_generic *msg)
+{
+	int rc;
+	size_t len;
+	struct fcb_entry entry;
+
+	len = log_msg_generic_get_wlen(&msg->buf) * sizeof(uint32_t);
+
+	k_mutex_lock(&fcb_lock, K_FOREVER);
+	rc = fcb_append(&fcb, len, &entry);
+
+	if (rc == -ENOSPC && erase_oldest) {
+		/*
+		 * The log history FCB is full but overwriting is enabled.
+		 * Erase the oldest FCB page and try again.
+		 * Note that the "last popped" location is cleared so that the next log transfer
+		 * starts from the updated oldest log message.
+		 */
+		rc = fcb_rotate(&fcb);
+
+		if (rc) {
+			goto out;
+		}
+
+		memset(&last_popped, 0, sizeof(last_popped));
+		rc = fcb_append(&fcb, len, &entry);
+	}
+
+	if (rc) {
+		goto out;
+	}
+
+	rc = flash_area_write(fcb.fap, FCB_ENTRY_FA_DATA_OFF(entry), msg, len);
+
+	if (rc) {
+		goto out;
+	}
+
+	rc = fcb_append_finish(&fcb, &entry);
+
+out:
+	k_mutex_unlock(&fcb_lock);
+
+#ifdef LOG_HISTORY_DEBUG
+	__ASSERT_NO_MSG(rc == 0);
+#endif
+}
+
+void log_rpc_history_set_overwriting(bool overwriting)
+{
+	k_mutex_lock(&fcb_lock, K_FOREVER);
+
+	erase_oldest = overwriting;
+
+	k_mutex_unlock(&fcb_lock);
+}
+
+union log_msg_generic *log_rpc_history_pop(void)
+{
+	int rc;
+	struct fcb_entry entry = last_popped;
+	union log_msg_generic *msg = NULL;
+
+	k_mutex_lock(&fcb_lock, K_FOREVER);
+	rc = fcb_getnext(&fcb, &entry);
+
+	if (rc) {
+		rc = 0;
+		goto out;
+	}
+
+	msg = (union log_msg_generic *)k_malloc(entry.fe_data_len);
+
+	if (!msg) {
+		goto out;
+	}
+
+	rc = flash_area_read(fcb.fap, FCB_ENTRY_FA_DATA_OFF(entry), msg, entry.fe_data_len);
+
+	if (rc) {
+		goto out;
+	}
+
+	last_popped = entry;
+
+	while (fcb.f_oldest != last_popped.fe_sector) {
+		rc = fcb_rotate(&fcb);
+
+		if (rc) {
+			goto out;
+		}
+	}
+
+out:
+	k_mutex_unlock(&fcb_lock);
+
+#ifdef LOG_HISTORY_DEBUG
+	__ASSERT_NO_MSG(rc == 0);
+#endif
+
+	return msg;
+}
+
+void log_rpc_history_free(const union log_msg_generic *msg)
+{
+	k_free((void *)msg);
+}

subsys/partition_manager/CMakeLists.txt

@@ -135,6 +135,10 @@ if(CONFIG_WIFI_NRF70 AND CONFIG_NRF_WIFI_PATCHES_EXT_FLASH_STORE)
   ncs_add_partition_manager_config(pm.yml.wifi)
 endif()
 
+if(CONFIG_LOG_BACKEND_RPC_HISTORY_STORAGE_FCB)
+    ncs_add_partition_manager_config(pm.yml.log_history)
+endif()
+
 # We are using partition manager if we are a child image or if we are
 # the root image and the 'partition_manager' target exists.
 zephyr_compile_definitions(

subsys/partition_manager/pm.yml.log_history

@@ -0,0 +1,7 @@
+#include <zephyr/autoconf.h>
+
+log_history:
+  size: CONFIG_LOG_BACKEND_RPC_HISTORY_SIZE
+  placement:
+    before: [end]
+    align: {start: CONFIG_FPROTECT_BLOCK_SIZE}