[PATCH v7 2/2] docs: Integrate rustdoc generation into htmldocs

[Carlos Bilbao <carlos.bilbao@amd.com>]

Change target `make htmldocs` to combine RST Sphinx and the generation of
Rust documentation, when support is available and .config exists.

Reviewed-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Carlos Bilbao <carlos.bilbao@amd.com>
---
 Documentation/Makefile | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 023fa658a0a8..3c375c34fd81 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -59,6 +59,12 @@ PAPEROPT_letter = -D latex_paper_size=letter
 KERNELDOC       = $(srctree)/scripts/kernel-doc
 KERNELDOC_CONF  = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC)
 ALLSPHINXOPTS   =  $(KERNELDOC_CONF) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS)
+ifneq ($(wildcard $(srctree)/.config),)
+ifeq ($(CONFIG_RUST),y)
+	# Let Sphinx know we will include rustdoc
+	ALLSPHINXOPTS   +=  -t rustdoc
+endif
+endif
 # the i18n builder cannot share the environment and doctrees with the others
 I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
 
@@ -95,6 +101,20 @@ htmldocs:
 	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))
 
+# If Rust support is available and .config exists, add rustdoc generated contents.
+# If there are any, the errors from this make rustdoc will be displayed but
+# won't stop the execution of htmldocs
+
+ifneq ($(wildcard $(srctree)/.config),)
+ifeq ($(CONFIG_RUST),y)
+	$(Q)$(MAKE) rustdoc || true
+else
+	@echo "   Skipping Rust documentation since CONFIG_RUST is not y."
+endif
+else
+	@echo "   Skipping Rust documentation since .config was not found."
+endif
+
 texinfodocs:
 	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,texinfo,$(var),texinfo,$(var)))
-- 
2.34.1