Patchwork [2/6] Rework support for the device tree

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Submitter Maxime Ripard
Date July 17, 2012, 12:27 p.m.
Message ID <1342528042-10038-3-git-send-email-maxime.ripard@free-electrons.com>
Download mbox | patch
Permalink /patch/171409/
State Superseded
Headers show

Comments

Maxime Ripard - July 17, 2012, 12:27 p.m.
This patch introduces some support for device tree-enabled kernels.

It replaces the former BR2_LINUX_KERNEL_DTS_FILE option that was
microblaze-only, that was quite limited. This option was quite
limited, first obviously because it was restricted to microblaze,
but also because it targetted only external device tree source files,
and allowed only to build simpleImages using the custom image name
mechanism.

This patch adds a much more generic one, that can work on basically
every architecture that supports device tree. It allows to build
both device tree source file that comes with the kernel source or to
set the path to the device tree file to use so that one can use a
custom device tree.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
 linux/Config.in |   59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 linux/linux.mk  |   21 ++++++++++++++++++++
 2 files changed, 80 insertions(+)
Arnout Vandecappelle - July 27, 2012, 7:45 p.m.
On 07/17/12 14:27, Maxime Ripard wrote:
> This patch introduces some support for device tree-enabled kernels.
>
> It replaces the former BR2_LINUX_KERNEL_DTS_FILE option that was
> microblaze-only, that was quite limited. This option was quite
> limited, first obviously because it was restricted to microblaze,
> but also because it targetted only external device tree source files,
> and allowed only to build simpleImages using the custom image name
> mechanism.
>
> This patch adds a much more generic one, that can work on basically
> every architecture that supports device tree. It allows to build
> both device tree source file that comes with the kernel source or to
> set the path to the device tree file to use so that one can use a
> custom device tree.
>
> Signed-off-by: Maxime Ripard<maxime.ripard@free-electrons.com>

Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

  Really nice!

  The BR2_LINUX_KERNEL_DTB_IS_SELF_BUILT part actually belongs to
patch 4/6, but that's a minor detail.

  Regards,
  Arnout

Patch

diff --git a/linux/Config.in b/linux/Config.in
index 550371d..9b63ab3 100644
--- a/linux/Config.in
+++ b/linux/Config.in
@@ -124,6 +124,65 @@  config BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE
 	help
 	  Path to the kernel configuration file
 
+config BR2_LINUX_KERNEL_DTS_SUPPORT
+	bool "Device tree support"
+	help
+	  Compile a device tree source into a device tree blob.
+	  Select the dts file to compile in the options below.
+
+if BR2_LINUX_KERNEL_DTS_SUPPORT
+
+# We have mainly three cases when it comes to device tree support:
+#   1) We don't want any support at all. Then the ..DTS_SUPPORT
+#      variable won't be set
+#   2) We want device tree support, so we need the user to enter
+#      the device tree name or the the path to the custom device
+#      he uses, but the kernel abstracts this from us and only
+#      build an image that looks like a regular kernel image. In
+#      this case, we only need to derive the kernel image name from
+#      the given device tree name, and all the rest is as usual
+#   3) We want device tree support, but the kernel requires us to
+#      build the device tree blob separately. In this case, some
+#      more logic will be needed.
+# The variable below address the second case, were you only want
+# limited actions from buildroot.
+config BR2_LINUX_KERNEL_DTB_IS_SELF_BUILT
+       bool
+
+choice
+	prompt "Device tree source"
+	default BR2_LINUX_KERNEL_USE_INTREE_DTS
+
+config BR2_LINUX_KERNEL_USE_INTREE_DTS
+	bool "Use a device tree present in the kernel."
+	help
+	   Use a device tree source distributed with
+	   the kernel sources. The dts files are located
+           in the arch/<arch>/boot/dts folder.
+
+config BR2_LINUX_KERNEL_USE_CUSTOM_DTS
+	bool "Use a custom device tree file"
+	help
+	  Use a custom device tree file, i.e, a device
+	  tree file that does not belong to the kernel
+	  source tree.
+endchoice
+
+config BR2_LINUX_KERNEL_INTREE_DTS_NAME
+	string "Device Tree Source file name"
+	depends on BR2_LINUX_KERNEL_USE_INTREE_DTS
+	help
+	 Name of the device tree source file, without
+	 the trailing .dts
+
+config BR2_LINUX_KERNEL_CUSTOM_DTS_PATH
+	string "Device Tree Source file path"
+	depends on BR2_LINUX_KERNEL_USE_CUSTOM_DTS
+	help
+	  Path to the device tree source file
+
+endif
+
 #
 # Binary format
 #
diff --git a/linux/linux.mk b/linux/linux.mk
index 09c8e79..9b4abf1 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -46,6 +46,12 @@  LINUX_MAKE_FLAGS = \
 # going to be installed in the target filesystem.
 LINUX_VERSION_PROBED = $(shell $(MAKE) $(LINUX_MAKE_FLAGS) -C $(LINUX_DIR) --no-print-directory -s kernelrelease)
 
+ifeq ($(BR2_LINUX_KERNEL_USE_INTREE_DTS),y)
+KERNEL_DTS_NAME = $(BR2_LINUX_KERNEL_INTREE_DTS_NAME)
+else ifeq ($(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),y)
+KERNEL_DTS_NAME = $(basename $(notdir $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)))
+endif
+
 ifeq ($(BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM),y)
 LINUX_IMAGE_NAME=$(call qstrip,$(BR2_LINUX_KERNEL_IMAGE_TARGET_NAME))
 else
@@ -153,13 +159,27 @@  define LINUX_CONFIGURE_CMDS
 	yes '' | $(TARGET_MAKE_ENV) $(MAKE1) $(LINUX_MAKE_FLAGS) -C $(@D) oldconfig
 endef
 
+ifeq ($(BR2_LINUX_KERNEL_DTS_SUPPORT),y)
+ifeq ($(BR2_LINUX_KERNEL_DTB_IS_SELF_BUILT),)
+define LINUX_BUILD_DTB
+	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(KERNEL_DTS_NAME).dtb
+endef
+define LINUX_INSTALL_DTB
+	cp $(KERNEL_ARCH_PATH)/boot/$(KERNEL_DTS_NAME).dtb $(BINARIES_DIR)/
+endef
+endif
+endif
+
 # Compilation. We make sure the kernel gets rebuilt when the
 # configuration has changed.
 define LINUX_BUILD_CMDS
+	$(if $(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),
+		cp $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) $(KERNEL_ARCH_PATH)/boot/dts/)
 	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_IMAGE_NAME)
 	@if grep -q "CONFIG_MODULES=y" $(@D)/.config; then 	\
 		$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) modules ;	\
 	fi
+	$(LINUX_BUILD_DTB)
 endef
 
 
@@ -175,6 +195,7 @@  endef
 
 define LINUX_INSTALL_TARGET_CMDS
 	$(LINUX_INSTALL_KERNEL_IMAGE_TO_TARGET)
+	$(LINUX_INSTALL_DTB)
 	# Install modules and remove symbolic links pointing to build
 	# directories, not relevant on the target
 	@if grep -q "CONFIG_MODULES=y" $(@D)/.config; then 	\