Changes between Version 32 and Version 33 of WikiStart

Timestamp:

Oct 10, 2014, 2:54:53 PM (10 years ago)

Author:

alain

Comment:

--

WikiStart

@@ -7 +7 @@
 == __B) Peripherals Drivers__ ==
 
-The GIET_VM supports two types of peripheral components:
- * '''External peripherals''' are located in one single cluster identified by the [X_IO,Y_IO] global variables. 
- * '''Internal peripherals''', such as ICU, XCU, DMA or MMC, are replicated in all clusters.
+The GIET_VM supports two types of peripheral components: '''External peripherals''' are located in one single cluster identified by the [X_IO,Y_IO] variables, '''Internal peripherals''' are replicated in all clusters.
 
-Each driver xxx_driver define two low-level functions ''_xxx_get_register()'' and ''_xxx_set_register()
-to access the peripheral addressable registers. These functions are in charge to compute the physical addresses, taking into account the cluster extension if required.
+Each driver xxx_driver define two low-level functions ''_xxx_get_register()'' and ''_xxx_set_register()''
+to access the peripheral addressable registers. These functions are in charge to compute the physical addresses, taking into account the cluster extension if required. 
+
+ * '''External peripherals''': Accesses use virtual addresses if the MMU (Memory management Unit) is activated, or physical addresses if it is not. In this case, the physical address is computed as pbase = SEG_XXX_BASE + cluster_io << 32.
+
+ * '''Internal peripherals''': Accesses use virtual addresses, and the MMU must be activated. The peripheral virtual base address is computed as vbase = SEG_XXX_BASE + cluster_xy * CLUSTER_INCREMENT. 
+
+The SEG_XXX_BASE , X_IO, Y_IO, and CLUSTER_INCREMENT vatiables must be defined in the ''hard_config.h" file.
 
  === [wiki:bdv_driver     BDV  (Block Device controller)]