doc: document <foo>_DEVICES / _PERMISSIONS

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

docs/manual/adding-packages-gentargets.txt

@@ -38,7 +38,15 @@ system is based on hand-written Makefiles or shell scripts.
 24: 	$(INSTALL) -d -m 0755 $(TARGET_DIR)/etc/foo.d
 25: endef
 26:
-27: $(eval $(call GENTARGETS))
+27: define LIBFOO_DEVICES
+28: 	/dev/foo  c  666  0  0  42  0  -  -  -
+29: endef
+30:
+31: define LIBFOO_PERMISSIONS
+32: 	/bin/foo  f  4755  0  0  -  -  -  -  -
+33: endef
+34:
+35: $(eval $(call GENTARGETS))
 --------------------------------
 
 The Makefile begins on line 6 to 8 with metadata information: the
@@ -75,7 +83,7 @@ All these steps rely on the +$(@D)+ variable, which
 contains the directory where the source code of the package has been
 extracted.
 
-Finally, on line 27, we call the +GENTARGETS+ which
+Finally, on line 35, we call the +GENTARGETS+ which
 generates, according to the variables defined previously, all the
 Makefile code necessary to make your package working.
 
@@ -188,6 +196,13 @@ information is (assuming the package name is +libfoo+) :
   variables are executed to install the package into the target
   directory.
 
+* +LIBFOO_DEVICES+ lists the device files to be created by Buildroot
+  when using the static device table. The syntax to use is the
+  makedevs one.
+
+* +LIBFOO_PERMISSIONS+ lists the changes of permissions to be done at
+  the end of the build process. The syntax is once again the makedevs one.
+
 The recommended way to define these variables is to use the following
 syntax: