[Buildroot] [PATCH 4/5 v2] linux: simplify adding new extensions

[Yann E. MORIN]

Curently, all three linux extensions follow the same layout:
  - test if the extension is enabled
  - add itself to linux' patch-dependencies
  - declare a macro, added as the pre-patch hook

Except for the macro, all can be commonalised.

Add a simple infrastructure for that:
  - extensions declare themselves in the list of extensions
  - extensions define their macro
  - the infra adds them to the patch-dependencies and pre-patch
    hooks as appropriate

Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 linux/linux.mk | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/linux/linux.mk b/linux/linux.mk
index b1aca41..2917857 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -333,6 +333,13 @@ endef
 # included here *must* be in the same directory!
 include $(sort $(wildcard linux/linux-ext-*.mk))
 
+LINUX_PATCH_DEPENDENCIES += $(foreach ext,$(LINUX_EXTENSIONS),\
+	$(if $(BR2_LINUX_KERNEL_EXT_$(call UPPERCASE,$(ext))),$(ext)))
+
+LINUX_PRE_PATCH_HOOKS += $(foreach ext,$(LINUX_EXTENSIONS),\
+	$(if $(BR2_LINUX_KERNEL_EXT_$(call UPPERCASE,$(ext))),\
+		$(call UPPERCASE,$(ext))_PREPARE_KERNEL))
+
 $(eval $(kconfig-package))
 
 # Support for rebuilding the kernel after the cpio archive has
-- 
1.9.1