cpupower: change binding's makefile to use -lcpupower

Originally I believed I needed the .o files to make the bindings. The
linking failed due to a missing .so link in Fedora or by using make
install-lib from the cpupower directory. Amend the makefile and the
README.

Big thanks to Wander Lairson Costa <wander@redhat.com> for the help.

Link: https://lore.kernel.org/r/20250429204711.127274-1-jwyatt@redhat.com
Signed-off-by: "John B. Wyatt IV" <jwyatt@redhat.com>
Signed-off-by: "John B. Wyatt IV" <sageofredondo@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: John B. Wyatt IV

tools/power/cpupower/bindings/python/Makefile

@@ -1,22 +1,20 @@
 # SPDX-License-Identifier: GPL-2.0-only
 # Makefile for libcpupower's Python bindings
 #
-# This Makefile expects you have already run the makefile for cpupower to build
-# the .o files in the lib directory for the bindings to be created.
+# This Makefile expects you have already run `make install-lib` in the lib
+# directory for the bindings to be created.
 
 CC := gcc
 HAVE_SWIG := $(shell if which swig >/dev/null 2>&1; then echo 1; else echo 0; fi)
 HAVE_PYCONFIG := $(shell if which python-config >/dev/null 2>&1; then echo 1; else echo 0; fi)
 
-LIB_DIR := ../../lib
 PY_INCLUDE = $(firstword $(shell python-config --includes))
-OBJECTS_LIB = $(wildcard $(LIB_DIR)/*.o)
 INSTALL_DIR = $(shell python3 -c "import site; print(site.getsitepackages()[0])")
 
 all: _raw_pylibcpupower.so
 
 _raw_pylibcpupower.so: raw_pylibcpupower_wrap.o
-	$(CC) -shared $(OBJECTS_LIB) raw_pylibcpupower_wrap.o -o _raw_pylibcpupower.so
+	$(CC) -shared -lcpupower raw_pylibcpupower_wrap.o -o _raw_pylibcpupower.so
 
 raw_pylibcpupower_wrap.o: raw_pylibcpupower_wrap.c
 	$(CC) -fPIC -c raw_pylibcpupower_wrap.c $(PY_INCLUDE)

tools/power/cpupower/bindings/python/README

@@ -5,18 +5,21 @@ libcpupower (aside from the libcpupower object files).
 requirements
 ------------
 
-* You need the object files in the libcpupower directory compiled by
-cpupower's makefile.
+* If you are building completely from upstream; please install libcpupower by
+running `make install-lib` within the cpupower directory. This installs the
+libcpupower.so file and symlinks needed. Otherwise, please make sure a symlink
+to libcpupower.so exists in your library path from your distribution's
+packages.
 * The SWIG program must be installed.
-* The Python's development libraries installed.
+* The Python's development libraries must be installed.
 
 Please check that your version of SWIG is compatible with the version of Python
 installed on your machine by checking the SWIG changelog on their website.
 https://swig.org/
 
 Note that while SWIG itself is GPL v3+ licensed; the resulting output,
-the bindings code: is permissively licensed + the license of libcpupower's .o
-files. For these bindings that means GPL v2.
+the bindings code: is permissively licensed + the license of libcpupower's
+library files. For these bindings that means GPL v2.
 
 Please see https://swig.org/legal.html and the discussion [1] for more details.