selftests: amd-pstate: Add test trigger for amd-pstate driver

Add amd-pstate test trigger in kselftest, it will load/unload
amd-pstate-ut module to test some cases etc.

Signed-off-by: Meng Li <[e-mail]>
Acked-by: Huang Rui <[e-mail]>
Reviewed-by: Shuah Khan <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 TARGETS += alsa
+TARGETS += amd-pstate
 TARGETS += arm64
 TARGETS += bpf
 TARGETS += breakpoints

tools/testing/selftests/amd-pstate/Makefile

···
+# SPDX-License-Identifier: GPL-2.0-only
+# Makefile for amd-pstate/ function selftests
+
+# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
+all:
+
+TEST_PROGS := amd-pstate-ut.sh
+
+include ../lib.mk

tools/testing/selftests/amd-pstate/amd-pstate-ut.sh

···
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+# amd-pstate-ut is a test module for testing the amd-pstate driver.
+# It can only run on x86 architectures and current cpufreq driver
+# must be amd-pstate.
+# (1) It can help all users to verify their processor support
+# (SBIOS/Firmware or Hardware).
+# (2) Kernel can have a basic function test to avoid the kernel
+# regression during the update.
+# (3) We can introduce more functional or performance tests to align
+# the result together, it will benefit power and performance scale optimization.
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+# amd-pstate-ut only run on x86/x86_64 AMD systems.
+ARCH=$(uname -m 2>/dev/null | sed -e 's/i.86/x86/' -e 's/x86_64/x86/')
+VENDOR=$(cat /proc/cpuinfo | grep -m 1 'vendor_id' | awk '{print $NF}')
+
+if ! echo "$ARCH" | grep -q x86; then
+	echo "$0 # Skipped: Test can only run on x86 architectures."
+	exit $ksft_skip
+fi
+
+if ! echo "$VENDOR" | grep -iq amd; then
+	echo "$0 # Skipped: Test can only run on AMD CPU."
+	echo "$0 # Current cpu vendor is $VENDOR."
+	exit $ksft_skip
+fi
+
+scaling_driver=$(cat /sys/devices/system/cpu/cpufreq/policy0/scaling_driver)
+if [ "$scaling_driver" != "amd-pstate" ]; then
+	echo "$0 # Skipped: Test can only run on amd-pstate driver."
+	echo "$0 # Current cpufreq scaling drvier is $scaling_driver."
+	exit $ksft_skip
+fi
+
+msg="Skip all tests:"
+if [ ! -w /dev ]; then
+    echo $msg please run this as root >&2
+    exit $ksft_skip
+fi
+
+if ! /sbin/modprobe -q -n amd-pstate-ut; then
+	echo "amd-pstate-ut: module amd-pstate-ut is not found [SKIP]"
+	exit $ksft_skip
+fi
+if /sbin/modprobe -q amd-pstate-ut; then
+	/sbin/modprobe -q -r amd-pstate-ut
+	echo "amd-pstate-ut: ok"
+else
+	echo "amd-pstate-ut: [FAIL]"
+	exit 1
+fi

tools/testing/selftests/amd-pstate/config

···
+CONFIG_X86_AMD_PSTATE_UT=m