libtimeinstate: add getCpuFreqs() function

Currently the KernelCpuUidFreqTimeReader reads the first line of
/proc/uid_time_in_state to determine a device's available CPU
frequencies, but libtimeinstate already reads this information from
sysfs files that are supported upstream. Add a function to provide
this information to libtimeinstate's users & eliminate the need to
read the proc file for this data.
Add a sanity check in libtimeinstate_test to confirm that
getCpuFreqs() and getUidCpuFreqTimes() report the same number of
frequencies for each cluster.

Bug: 138317993
Test: libtimeinstate_test passes
Change-Id: I3e8c632d14bbeb552d7e52bd83a9b4a64dec408d
Signed-off-by: Connor O'Brien <connoro@google.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/libs/cputimeinstate/testtimeinstate.cpp b/libs/cputimeinstate/testtimeinstate.cpp
index c0cd3e07ff..30722de0c1 100644
--- a/libs/cputimeinstate/testtimeinstate.cpp
+++ b/libs/cputimeinstate/testtimeinstate.cpp
@@ -351,5 +351,16 @@ TEST(TimeInStateTest, RemoveUid) {
     ASSERT_EQ(allConcurrentTimes->find(uid), allConcurrentTimes->end());
 }
 
+TEST(TimeInStateTest, GetCpuFreqs) {
+    auto freqs = getCpuFreqs();
+    ASSERT_TRUE(freqs.has_value());
+
+    auto times = getUidCpuFreqTimes(0);
+    ASSERT_TRUE(times.has_value());
+
+    ASSERT_EQ(freqs->size(), times->size());
+    for (size_t i = 0; i < freqs->size(); ++i) EXPECT_EQ((*freqs)[i].size(), (*times)[i].size());
+}
+
 } // namespace bpf
 } // namespace android