ARM: uniphier: check DT to determine whether to initialize SBC

If CONFIG_MICRO_SUPPORT_CARD is enabled, U-Boot initialize SBC
(System Bus Controller), which may not be really necessary.

Check the "socionext,uniphier-system-bus" node in DT run-time.
If and only if it is found and its "status" property is okay,
initialize the SBC block.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/mach-uniphier/Makefile

@@ -18,13 +18,14 @@ ifndef CONFIG_SYSRESET
 obj-y += reset.o
 endif
 
-obj-$(CONFIG_MICRO_SUPPORT_CARD) += sbc/ micro-support-card.o
+obj-$(CONFIG_MICRO_SUPPORT_CARD) += micro-support-card.o
 obj-y += pinctrl-glue.o
 obj-$(CONFIG_MMC) += mmc-first-dev.o
 obj-y += fdt-fixup.o
 
 endif
 
+obj-y += sbc/
 obj-y += soc-info.o
 obj-y += boot-device/
 obj-y += clk/

arch/arm/mach-uniphier/sbc/Makefile

@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0+
 
+obj-					+= dummy.o
+
+ifndef CONFIG_SPL_BUILD
 obj-y					+= sbc.o
 
 obj-$(CONFIG_ARCH_UNIPHIER_LD4)		+= sbc-ld4.o
@@ -9,3 +12,4 @@ obj-$(CONFIG_ARCH_UNIPHIER_LD6B)	+= sbc-pxs2.o
 obj-$(CONFIG_ARCH_UNIPHIER_LD11)	+= sbc-ld11.o
 obj-$(CONFIG_ARCH_UNIPHIER_LD20)	+= sbc-ld11.o
 obj-$(CONFIG_ARCH_UNIPHIER_PXS3)	+= sbc-pxs2.o
+endif

arch/arm/mach-uniphier/sbc/sbc-ld11.c

@@ -12,6 +12,9 @@
 
 void uniphier_ld11_sbc_init(void)
 {
+	if (!uniphier_sbc_is_enabled())
+		return;
+
 	uniphier_sbc_init_savepin();
 
 	/* necessary for ROM boot ?? */

arch/arm/mach-uniphier/sbc/sbc-ld4.c

@@ -13,6 +13,9 @@ void uniphier_ld4_sbc_init(void)
 {
 	u32 tmp;
 
+	if (!uniphier_sbc_is_enabled())
+		return;
+
 	uniphier_sbc_init_savepin();
 
 	/* system bus output enable */

arch/arm/mach-uniphier/sbc/sbc-pxs2.c

@@ -10,6 +10,9 @@
 
 void uniphier_pxs2_sbc_init(void)
 {
+	if (!uniphier_sbc_is_enabled())
+		return;
+
 	uniphier_sbc_init_savepin();
 
 	/* necessary for ROM boot ?? */

arch/arm/mach-uniphier/sbc/sbc-regs.h

@@ -84,4 +84,6 @@ static inline int boot_is_swapped(void)
 }
 #endif
 
+int uniphier_sbc_is_enabled(void);
+
 #endif	/* ARCH_SBC_REGS_H */

arch/arm/mach-uniphier/sbc/sbc.c

@@ -5,7 +5,9 @@
  *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
  */
 
+#include <common.h>
 #include <linux/io.h>
+#include <asm/global_data.h>
 
 #include "../init.h"
 #include "sbc-regs.h"
@@ -31,6 +33,20 @@
 #define SBCTRL2_SAVEPIN_MEM_VALUE	0x34000009
 #define SBCTRL4_SAVEPIN_MEM_VALUE	0x02110210
 
+int uniphier_sbc_is_enabled(void)
+{
+	DECLARE_GLOBAL_DATA_PTR;
+	const void *fdt = gd->fdt_blob;
+	int offset;
+
+	offset = fdt_node_offset_by_compatible(fdt, 0,
+					       "socionext,uniphier-system-bus");
+	if (offset < 0)
+		return 0;
+
+	return fdtdec_get_is_enabled(fdt, offset);
+}
+
 static void __uniphier_sbc_init(int savepin)
 {
 	/*