[PATCH] of: arm: powerpc: Restrict memory@0 node handling to affected platforms

[Leif Lindholm]

In order to deal with a firmware bug on a specific ppc32 platform
(longtrail), early_init_dt_scan_memory() looks for a node called
memory@0 on all platforms, for all nodes lacking a device_type.
Restrict this quirk to ppc32 and the arm mach-ux500 platforms (one of
which has depended on this special handling).

Signed-off-by: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Cc: Lee Jones <lee.jones@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
---
 arch/arm/mach-ux500/Kconfig |    1 +
 arch/powerpc/Kconfig        |    1 +
 drivers/of/Kconfig          |    3 +++
 drivers/of/fdt.c            |   10 +++++++++-
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-ux500/Kconfig b/arch/arm/mach-ux500/Kconfig
index b41a42d..e6b0c3b 100644
--- a/arch/arm/mach-ux500/Kconfig
+++ b/arch/arm/mach-ux500/Kconfig
@@ -13,6 +13,7 @@ config ARCH_U8500
 	select CLKSRC_NOMADIK_MTU
 	select HAVE_ARM_SCU if SMP
 	select HAVE_ARM_TWD if SMP
+	select OF_MEMORY_AT_0_QUIRK
 	select PINCTRL
 	select PINCTRL_ABX500
 	select PINCTRL_NOMADIK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e099899..d78452d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -3,6 +3,7 @@ source "arch/powerpc/platforms/Kconfig.cputype"
 config PPC32
 	bool
 	default y if !PPC64
+	select OF_MEMORY_AT_0_QUIRK
 
 config 32BIT
 	bool
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 889005f..230c747 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -77,4 +77,7 @@ config OF_RESERVED_MEM
 	help
 	  Helpers to allow for reservation of memory regions
 
+config OF_MEMORY_AT_0_QUIRK
+	def_bool n
+
 endmenu # OF
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index fa16a91..1b80b94 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -887,14 +887,22 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 
 	/* We are scanning "memory" nodes only */
 	if (type == NULL) {
+#ifdef CONFIG_OF_MEMORY_AT_0_QUIRK
 		/*
 		 * The longtrail doesn't have a device_type on the
 		 * /memory node, so look for the node called /memory@0.
+		 * Converted to generic quirk to handle later platforms
+		 * with inforrect DTs that work only because of this
+		 * special handling.
 		 */
 		if (depth != 1 || strcmp(uname, "memory@0") != 0)
 			return 0;
-	} else if (strcmp(type, "memory") != 0)
+#else
+		return 0;
+#endif
+	} else if (strcmp(type, "memory") != 0) {
 		return 0;
+	}
 
 	reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
 	if (reg == NULL)
-- 
1.7.10.4

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