drivers/segger:Add config option to allow defining the macro as variable

we are using segger RTT protocol over shared memory for two core log/trace: one is NuttX another Linux/Windows. But the base address of shared memory can only be known at runtime, so we change SEGGER_RTT_UNCACHED_OFF from macro to global variable, and update to the correct g_segger_offset after the shared memory is initialized by:
g_segger_offset = (uintptr_t)ishmem - (uintptr_t)&_SEGGER_RTT;

Signed-off-by: liwenxiang1 <liwenxiang1@xiaomi.com>

drivers/segger/Kconfig

@@ -33,9 +33,16 @@ config SEGGER_RTT_CPU_CACHE_LINE_SIZE
 	---help---
 		Largest cache line size (in bytes) in the target system.
 
+config SEGGER_RTT_UNCACHED_OFF_VARIABLE
+	bool
+	default n
+	---help---
+		Converting the macro for Segger RTT uncached offset to variable representation
+
 config SEGGER_RTT_UNCACHED_OFF
 	int "Segger RTT uncached offset"
 	default 0
+	depends on !SEGGER_RTT_UNCACHED_OFF_VARIABLE
 	---help---
 		Address alias where RTT CB and buffers can be accessed uncached
 

drivers/segger/config/SEGGER_RTT_Conf.h

@@ -41,6 +41,10 @@
 extern struct rspinlock_s g_segger_lock;
 #endif
 
+#ifdef CONFIG_SEGGER_RTT_UNCACHED_OFF_VARIABLE
+extern ptrdiff_t g_segger_offset;
+#endif
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -53,7 +57,11 @@ extern struct rspinlock_s g_segger_lock;
 
 /* Address alias where RTT CB and buffers can be accessed uncached */
 
-#define SEGGER_RTT_UNCACHED_OFF         CONFIG_SEGGER_RTT_UNCACHED_OFF
+#ifdef CONFIG_SEGGER_RTT_UNCACHED_OFF_VARIABLE
+#  define SEGGER_RTT_UNCACHED_OFF         g_segger_offset
+#else
+#  define SEGGER_RTT_UNCACHED_OFF         CONFIG_SEGGER_RTT_UNCACHED_OFF
+#endif
 
 /* Number of up-buffers (T->H) available on this target */
 

drivers/segger/segger.c

@@ -31,6 +31,7 @@
  ****************************************************************************/
 
 struct rspinlock_s g_segger_lock = RSPINLOCK_INITIALIZER;
+ptrdiff_t g_segger_offset = PTRDIFF_MAX;
 
 /****************************************************************************
  * Public Functions