retention: Allow disabling mutex support

Changes the Kconfig option to allow disabling mutex support, this is to allow other Kconfig options to disable the feature. Also adds an optional dts option which can be used to disable muted support for a specific retention area. Signed-off-by: Jamie McCrae <[email protected]>
zephyrproject-rtos · Jun 15, 2023 · 5b34cb5 · 5b34cb5
1 parent bab35a5
commit 5b34cb5
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Showing 3 changed files with 38 additions and 6 deletions.
diff --git a/dts/bindings/retention/zephyr,retention.yaml b/dts/bindings/retention/zephyr,retention.yaml
@@ -64,3 +64,9 @@ properties:
       16-bit CRC, 4 for 32-bit CRC). Default is to not use a checksum.
     type: int
     default: 0
+
+  no-mutex:
+    description: |
+      If specified, will disable mutex protection, should only be enabled if
+      this is a requirement for a particular retention area.
+    type: boolean
diff --git a/subsys/retention/Kconfig b/subsys/retention/Kconfig
@@ -20,13 +20,22 @@ config RETENTION_INIT_PRIORITY
 	  priorities for retained memory drivers.
 
 config RETENTION_MUTEXES
-	bool "Retention mutex support"
+	bool
 	default y
 	depends on MULTITHREADING
+	depends on !RETENTION_MUTEX_FORCE_DISABLE
+
+config RETENTION_MUTEX_FORCE_DISABLE
+	bool "Disable retention mutex support"
+	depends on MULTITHREADING
 	help
-	  Use mutexes to prevent issues with concurrent retention device
-	  access. Should only be disabled whereby retained memory access is
-	  required in an ISR or for special use cases.
+	  Disable use of mutexes which prevent issues with concurrent retention
+	  device access. This option should should only be enabled when
+	  retention device access is required in an ISR or for special use
+	  cases.
+
+	  Note that this can also be enforced on a per-partition basis by
+	  setting the ``no-mutex;`` device tree property instead.
 
 config RETENTION_BUFFER_SIZE
 	int "Retention stack buffer sizes"

diff --git a/subsys/retention/retention.c b/subsys/retention/retention.c
@@ -41,6 +41,9 @@ struct retention_config {
 	size_t offset;
 	size_t size;
 	size_t reserved_size;
+#ifdef CONFIG_RETENTION_MUTEXES
+	bool mutex;
+#endif
 	uint8_t checksum_size;
 	uint8_t prefix_len;
 	uint8_t prefix[];
@@ -50,8 +53,11 @@ static inline void retention_lock_take(const struct device *dev)
 {
 #ifdef CONFIG_RETENTION_MUTEXES
 	struct retention_data *data = dev->data;
+	const struct retention_config *config = dev->config;
 
-	k_mutex_lock(&data->lock, K_FOREVER);
+	if (config->mutex) {
+		k_mutex_lock(&data->lock, K_FOREVER);
+	}
 #else
 	ARG_UNUSED(dev);
 #endif
@@ -61,8 +67,11 @@ static inline void retention_lock_release(const struct device *dev)
 {
 #ifdef CONFIG_RETENTION_MUTEXES
 	struct retention_data *data = dev->data;
+	const struct retention_config *config = dev->config;
 
-	k_mutex_unlock(&data->lock);
+	if (config->mutex) {
+		k_mutex_unlock(&data->lock);
+	}
 #else
 	ARG_UNUSED(dev);
 #endif
@@ -376,6 +385,13 @@ static const struct retention_api retention_api = {
 	.clear = retention_clear,
 };
 
+#ifdef CONFIG_RETENTION_MUTEXES
+#define RETENTION_MUTEX(inst)									\
+	.mutex = COND_CODE_1(DT_INST_NODE_HAS_PROP(inst, no_mutex), (false), (true))
+#else
+#define RETENTION_MUTEX(inst)
+#endif
+
 #define RETENTION_DEVICE(inst)									\
 	static struct retention_data								\
 		retention_data_##inst = {							\
@@ -393,6 +409,7 @@ static const struct retention_api retention_api = {
 		.prefix_len = COND_CODE_1(DT_INST_NODE_HAS_PROP(inst, prefix),			\
 					  (DT_INST_PROP_LEN(inst, prefix)), (0)),		\
 		.prefix = DT_INST_PROP_OR(inst, prefix, {0}),					\
+		RETENTION_MUTEX(inst)								\
 	};											\
 	DEVICE_DT_INST_DEFINE(inst,								\
 			      &retention_init,							\