powerpc/85xx: introduce and document CONFIG_SYS_CCSRBAR macros

Introduce the CONFIG_SYS_CCSRBAR_PHYS_HIGH and CONFIG_SYS_CCSRBAR_PHYS_LOW
macros, which contain the high and low portions of CONFIG_SYS_CCSRBAR_PHYS.
This is necessary for the assembly-language code that relocates CCSR, since
the assembler does not understand 64-bit constants.

CONFIG_SYS_CCSRBAR_PHYS is automatically defined from the
CONFIG_SYS_CCSRBAR_PHYS_HIGH and CONFIG_SYS_CCSRBAR_PHYS_LOW macros, so it
should not be defined in a board header file.  Similarly,
CONFIG_SYS_CCSRBAR_DEFAULT is defined for each SOC in config_mpc85xx.h, so
it should also not be defined in the board header file.

CONFIG_SYS_CCSR_DO_NOT_RELOCATE is a "short-cut" macro that guarantees that
CONFIG_SYS_CCSRBAR_PHYS is set to the same value as CONFIG_SYS_CCSRBAR_DEFAULT,
and so CCSR will not be relocated.

Since CONFIG_SYS_CCSRBAR_DEFAULT is locked to a fixed value, multi-stage U-Boot
builds (e.g. NAND) are required to relocate CCSR only during the last stage
(i.e. the "real" U-Boot).  All other stages should define
CONFIG_SYS_CCSR_DO_NOT_RELOCATE to ensure that CCSR is not relocated.

README is updated with descriptions of all the CONFIG_SYS_CCSRBAR_xxx macros.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/include/mpc85xx.h b/include/mpc85xx.h
index 2495b99..11d8985 100644
--- a/include/mpc85xx.h
+++ b/include/mpc85xx.h
@@ -26,4 +26,46 @@
 #define SCCR_DFBRG10    0x00000002      /* BRGCLK division by 64 */
 #define SCCR_DFBRG11    0x00000003      /* BRGCLK division by 256 */
 
+/*
+ * Define default values for some CCSR macros to make header files cleaner*
+ *
+ * To completely disable CCSR relocation in a board header file, define
+ * CONFIG_SYS_CCSR_DO_NOT_RELOCATE.  This will force CONFIG_SYS_CCSRBAR_PHYS
+ * to a value that is the same as CONFIG_SYS_CCSRBAR.
+ */
+
+#ifdef CONFIG_SYS_CCSRBAR_PHYS
+#error "Do not define CONFIG_SYS_CCSRBAR_PHYS directly.  Use \
+CONFIG_SYS_CCSRBAR_PHYS_LOW and/or CONFIG_SYS_CCSRBAR_PHYS_HIGH instead."
+#endif
+
+#ifdef CONFIG_SYS_CCSR_DO_NOT_RELOCATE
+#undef CONFIG_SYS_CCSRBAR_PHYS_HIGH
+#undef CONFIG_SYS_CCSRBAR_PHYS_LOW
+#define CONFIG_SYS_CCSRBAR_PHYS_HIGH	0
+#endif
+
+#ifndef CONFIG_SYS_CCSRBAR
+#define CONFIG_SYS_CCSRBAR 		CONFIG_SYS_CCSRBAR_DEFAULT
+#endif
+
+#ifndef CONFIG_SYS_CCSRBAR_PHYS_HIGH
+#ifdef CONFIG_PHYS_64BIT
+#define CONFIG_SYS_CCSRBAR_PHYS_HIGH	0xf
+#else
+#define CONFIG_SYS_CCSRBAR_PHYS_HIGH	0
+#endif
+#endif
+
+#ifndef CONFIG_SYS_CCSRBAR_PHYS_LOW
+#define CONFIG_SYS_CCSRBAR_PHYS_LOW 	CONFIG_SYS_CCSRBAR_DEFAULT
+#endif
+
+#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH * 1ull) << 32 | \
+				 CONFIG_SYS_CCSRBAR_PHYS_LOW)
+
+#ifndef CONFIG_SYS_IMMR
+#define CONFIG_SYS_IMMR 		CONFIG_SYS_CCSRBAR
+#endif
+
 #endif	/* __MPC85xx_H__ */