firmware: Add firmware installation to modules_install, add firmware_install

For 'make modules_install', install any firmware required by
the modules which are being installed.

Also add a 'make firmware_install' target which doesn't depend on the
configuration, but installs _all_ available in-kernel-tree firmware into
$(INSTALL_FW_PATH), which defaults to /lib/firmware. This is intended
for distributors to make arch-independent (and config-independent)
packages containing firmware.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/firmware/Makefile b/firmware/Makefile
index cc25f56..3742fee 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -9,13 +9,22 @@
 
 fw-external-y := $(subst ",,$(CONFIG_EXTRA_FIRMWARE))
 
-# If CONFIG_FIRMWARE_IN_KERNEL is not set, then don't include any firmware
-ifneq ($(CONFIG_FIRMWARE_IN_KERNEL),y)
-fw-shipped-y :=
-endif
+# There are three cases to care about:
+# 1. Building kernel with CONFIG_FIRMWARE_IN_KERNEL=y -- $(fw-shipped-y) should
+#    include the firmware files to include, according to .config
+# 2. 'make modules_install', which will install firmware for modules, and 
+#    _also_ for the in-kernel drivers when CONFIG_FIRMWARE_IN_KERNEL=n
+# 3. 'make firmware_install', which installs all firmware, unconditionally.
 
-firmware-y    := $(fw-external-y) $(fw-shipped-y)
-firmware-dirs := $(sort $(patsubst %,$(objtree)/$(obj)/%/,$(dir $(firmware-y) $(fw-shipped-))))
+# For the former two cases we want $(fw-shipped-y) and $(fw-shipped-m) to be
+# accurate. In the latter case it doesn't matter -- it'll use $(fw-shipped-all).
+# But be aware that the config file might not be included at all.
+
+
+fw-shipped-all := $(fw-shipped-y) $(fw-shipped-m) $(fw-shipped-)
+
+# Directories which we _might_ need to create, so we have a rule for them.
+firmware-dirs := $(sort $(patsubst %,$(objtree)/$(obj)/%/,$(dir $(fw-external-y) $(fw-shipped-all))))
 
 quiet_cmd_mkdir = MKDIR   $(patsubst $(objtree)/%,%,$@)
       cmd_mkdir = mkdir -p $@
@@ -81,7 +90,8 @@
 $(firmware-dirs):
 	$(call cmd,mkdir)
 
-obj-y := $(patsubst %,%.gen.o, $(firmware-y))
+obj-y				 += $(patsubst %,%.gen.o, $(fw-external-y))
+obj-$(CONFIG_FIRMWARE_IN_KERNEL) += $(patsubst %,%.gen.o, $(fw-shipped-y))
 
 # Remove .S files and binaries created from ihex
 # (during 'make clean' .config isn't included so they're all in $(fw-shipped-))