drivers: retained_mem: Add optional mutex disablement

Adds an optional Kconfig to disable use of mutexes in the retained
memory driver.

Signed-off-by: Jamie McCrae <[email protected]>

Author: nordicjm

drivers/retained_mem/Kconfig

@@ -15,6 +15,15 @@ config RETAINED_MEM_INIT_PRIORITY
 	help
 	  Retained memory devices initialization priority,
 
+config RETAINED_MEM_MUTEXES
+	int "Retained memory mutex support"
+	default y
+	depends on MULTITHREADING
+	help
+	  Use mutexes to prevent issues with concurrent retained memory access.
+	  Should only be disabled whereby retained memory access is required
+	  in an ISR or for special use cases.
+
 module = RETAINED_MEM
 module-str = retained_mem
 source "subsys/logging/Kconfig.template.log_config"

drivers/retained_mem/retained_mem_nrf_gpregret.c

@@ -16,7 +16,7 @@
 
 LOG_MODULE_REGISTER(retained_mem_nrf_gpregret, CONFIG_RETAINED_MEM_LOG_LEVEL);
 
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 struct nrf_gpregret_data {
 	struct k_mutex lock;
 };
@@ -29,7 +29,7 @@ struct nrf_gpregret_config {
 
 static inline void nrf_gpregret_lock_take(const struct device *dev)
 {
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 	struct nrf_gpregret_data *data = dev->data;
 
 	k_mutex_lock(&data->lock, K_FOREVER);
@@ -40,7 +40,7 @@ static inline void nrf_gpregret_lock_take(const struct device *dev)
 
 static inline void nrf_gpregret_lock_release(const struct device *dev)
 {
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 	struct nrf_gpregret_data *data = dev->data;
 
 	k_mutex_unlock(&data->lock);
@@ -51,7 +51,7 @@ static inline void nrf_gpregret_lock_release(const struct device *dev)
 
 static int nrf_gpregret_init(const struct device *dev)
 {
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 	struct nrf_gpregret_data *data = dev->data;
 
 	k_mutex_init(&data->lock);
@@ -115,7 +115,7 @@ static const struct retained_mem_driver_api nrf_gpregret_api = {
 };
 
 #define NRF_GPREGRET_DEVICE(inst)						\
-	IF_ENABLED(CONFIG_MULTITHREADING,					\
+	IF_ENABLED(CONFIG_RETAINED_MEM_MUTEXES,					\
 		   (static struct nrf_gpregret_data nrf_gpregret_data_##inst;)	\
 	)									\
 	static const struct nrf_gpregret_config nrf_gpregret_config_##inst = {	\
@@ -125,7 +125,7 @@ static const struct retained_mem_driver_api nrf_gpregret_api = {
 	DEVICE_DT_INST_DEFINE(inst,						\
 			      &nrf_gpregret_init,				\
 			      NULL,						\
-			      COND_CODE_1(CONFIG_MULTITHREADING,		\
+			      COND_CODE_1(CONFIG_RETAINED_MEM_MUTEXES,		\
 					  (&nrf_gpregret_data_##inst), (NULL)	\
 			      ),						\
 			      &nrf_gpregret_config_##inst,			\

drivers/retained_mem/retained_mem_zephyr_ram.c

@@ -16,7 +16,7 @@
 
 LOG_MODULE_REGISTER(retained_mem_zephyr_ram, CONFIG_RETAINED_MEM_LOG_LEVEL);
 
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 struct zephyr_retained_mem_ram_data {
 	struct k_mutex lock;
 };
@@ -29,7 +29,7 @@ struct zephyr_retained_mem_ram_config {
 
 static inline void zephyr_retained_mem_ram_lock_take(const struct device *dev)
 {
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 	struct zephyr_retained_mem_ram_data *data = dev->data;
 
 	k_mutex_lock(&data->lock, K_FOREVER);
@@ -40,7 +40,7 @@ static inline void zephyr_retained_mem_ram_lock_take(const struct device *dev)
 
 static inline void zephyr_retained_mem_ram_lock_release(const struct device *dev)
 {
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 	struct zephyr_retained_mem_ram_data *data = dev->data;
 
 	k_mutex_unlock(&data->lock);
@@ -51,7 +51,7 @@ static inline void zephyr_retained_mem_ram_lock_release(const struct device *dev
 
 static int zephyr_retained_mem_ram_init(const struct device *dev)
 {
-#ifdef CONFIG_MULTITHREADING
+#ifdef CONFIG_RETAINED_MEM_MUTEXES
 	struct zephyr_retained_mem_ram_data *data = dev->data;
 
 	k_mutex_init(&data->lock);
@@ -116,7 +116,7 @@ static const struct retained_mem_driver_api zephyr_retained_mem_ram_api = {
 };
 
 #define ZEPHYR_RETAINED_MEM_RAM_DEVICE(inst)							\
-	IF_ENABLED(CONFIG_MULTITHREADING,							\
+	IF_ENABLED(CONFIG_RETAINED_MEM_MUTEXES,							\
 		   (static struct zephyr_retained_mem_ram_data					\
 		    zephyr_retained_mem_ram_data_##inst;)					\
 	)											\
@@ -128,7 +128,7 @@ static const struct retained_mem_driver_api zephyr_retained_mem_ram_api = {
 	DEVICE_DT_INST_DEFINE(inst,								\
 			      &zephyr_retained_mem_ram_init,					\
 			      NULL,								\
-			      COND_CODE_1(CONFIG_MULTITHREADING,				\
+			      COND_CODE_1(CONFIG_RETAINED_MEM_MUTEXES,				\
 					  (&zephyr_retained_mem_ram_data_##inst), (NULL)	\
 			      ),								\
 			      &zephyr_retained_mem_ram_config_##inst,				\