firmware: Restore support for built-in firmware

Commit 5620a0d1aac ("firmware: delete in-kernel firmware") removed the
entire firmware directory.  Unfortunately it thereby also removed the
support for built-in firmware.

This restores the ability to build firmware directly into the kernel by
pruning the original Makefile to the necessary minimum.  The default for
EXTRA_FIRMWARE_DIR is now the standard directory /lib/firmware/.

Fixes: 5620a0d1aac ("firmware: delete in-kernel firmware")
Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Acked-by: Greg K-H <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 71 insertions, 5 deletions

diff --git a/Makefile b/Makefile
index 7e2ca4971a39..9f86816c41fd 100644
--- a/Makefile
+++ b/Makefile
@@ -562,7 +562,7 @@ scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
 
 # Objects we will link into vmlinux / subdirs we need to visit
 init-y          := init/
-drivers-y       := drivers/ sound/
+drivers-y       := drivers/ sound/ firmware/
 net-y           := net/
 libs-y          := lib/
 core-y          := usr/
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index f046d21de57d..1a5f6a157a57 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -140,13 +140,10 @@ config EXTRA_FIRMWARE
 config EXTRA_FIRMWARE_DIR
         string "Firmware blobs root directory"
         depends on EXTRA_FIRMWARE != ""
-        default "firmware"
+        default "/lib/firmware"
         help
           This option controls the directory in which the kernel build system
           looks for the firmware files listed in the EXTRA_FIRMWARE option.
-          The default is firmware/ in the kernel source tree, but by changing
-          this option you can point it elsewhere, such as /lib/firmware/ or
-          some other directory containing the firmware files.
 
 config FW_LOADER_USER_HELPER
         bool
diff --git a/firmware/.gitignore b/firmware/.gitignore
new file mode 100644
index 000000000000..d9c69017bc9a
--- /dev/null
+++ b/firmware/.gitignore
@@ -0,0 +1,6 @@
+*.gen.S
+*.fw
+*.bin
+*.csp
+*.dsp
+ihex2fw
diff --git a/firmware/Makefile b/firmware/Makefile
new file mode 100644
index 000000000000..fa0808853883
--- /dev/null
+++ b/firmware/Makefile
@@ -0,0 +1,63 @@
+#
+# kbuild file for firmware/
+#
+
+# Create $(fwabs) from $(CONFIG_EXTRA_FIRMWARE_DIR) -- if it doesn't have a
+# leading /, it's relative to $(srctree).
+fwdir := $(subst $(quote),,$(CONFIG_EXTRA_FIRMWARE_DIR))
+fwabs := $(addprefix $(srctree)/,$(filter-out /%,$(fwdir)))$(filter /%,$(fwdir))
+
+fw-external-y := $(subst $(quote),,$(CONFIG_EXTRA_FIRMWARE))
+
+quiet_cmd_fwbin = MK_FW   $@
+      cmd_fwbin = FWNAME="$(patsubst firmware/%.gen.S,%,$@)";                \
+                  FWSTR="$(subst /,_,$(subst .,_,$(subst -,_,$(patsubst      \
+                                firmware/%.gen.S,%,$@))))";                  \
+                  ASM_WORD=$(if $(CONFIG_64BIT),.quad,.long);                \
+                  ASM_ALIGN=$(if $(CONFIG_64BIT),3,2);                       \
+                  PROGBITS=$(if $(CONFIG_ARM),%,@)progbits;                  \
+                  echo "/* Generated by firmware/Makefile */"           > $@;\
+                  echo "    .section .rodata"                           >>$@;\
+                  echo "    .p2align $${ASM_ALIGN}"                     >>$@;\
+                  echo "_fw_$${FWSTR}_bin:"                             >>$@;\
+                  echo "    .incbin \"$(2)\""                           >>$@;\
+                  echo "_fw_end:"                                       >>$@;\
+                  echo "   .section .rodata.str,\"aMS\",$${PROGBITS},1" >>$@;\
+                  echo "    .p2align $${ASM_ALIGN}"                     >>$@;\
+                  echo "_fw_$${FWSTR}_name:"                            >>$@;\
+                  echo "    .string \"$$FWNAME\""                       >>$@;\
+                  echo "    .section .builtin_fw,\"a\",$${PROGBITS}"    >>$@;\
+                  echo "    .p2align $${ASM_ALIGN}"                     >>$@;\
+                  echo "    $${ASM_WORD} _fw_$${FWSTR}_name"            >>$@;\
+                  echo "    $${ASM_WORD} _fw_$${FWSTR}_bin"             >>$@;\
+                  echo "    $${ASM_WORD} _fw_end - _fw_$${FWSTR}_bin"   >>$@;
+
+# One of these files will change, or come into existence, whenever
+# the configuration changes between 32-bit and 64-bit. The .S files
+# need to change when that happens.
+wordsize_deps := $(wildcard include/config/64bit.h include/config/32bit.h \
+                include/config/ppc32.h include/config/ppc64.h \
+                include/config/superh32.h include/config/superh64.h \
+                include/config/x86_32.h include/config/x86_64.h \
+                firmware/Makefile)
+
+$(patsubst %,$(obj)/%.gen.S, $(fw-external-y)): %: $(wordsize_deps) \
+                include/config/extra/firmware/dir.h
+        $(call cmd,fwbin,$(fwabs)/$(patsubst $(obj)/%.gen.S,%,$@))
+
+# The .o files depend on the binaries directly; the .S files don't.
+$(patsubst %,$(obj)/%.gen.o, $(fw-external-y)): $(obj)/%.gen.o: $(fwdir)/%
+
+obj-y                            += $(patsubst %,%.gen.o, $(fw-external-y))
+
+ifeq ($(KBUILD_SRC),)
+# Makefile.build only creates subdirectories for O= builds, but external
+# firmware might live outside the kernel source tree
+_dummy := $(foreach d,$(addprefix $(obj)/,$(dir $(fw-external-y))), $(shell [ -d $(d) ] || mkdir -p $(d)))
+endif
+
+targets := $(patsubst $(obj)/%,%, \
+                                $(shell find $(obj) -name \*.gen.S 2>/dev/null))
+# Without this, built-in.o won't be created when it's empty, and the
+# final vmlinux link will fail.
+obj- := dummy