cpufreq/amd-pstate: Move perf values into a union

By storing perf values in a union all the writes and reads can
be done atomically, removing the need for some concurrency protections.

While making this change, also drop the cached frequency values,
using inline helpers to calculate them on demand from perf value.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Author: superm1

drivers/cpufreq/amd-pstate-ut.c

@@ -129,6 +129,7 @@ static void amd_pstate_ut_check_perf(u32 index)
 	struct cppc_perf_caps cppc_perf;
 	struct cpufreq_policy *policy = NULL;
 	struct amd_cpudata *cpudata = NULL;
+	union perf_cached cur_perf;
 
 	for_each_possible_cpu(cpu) {
 		policy = cpufreq_cpu_get(cpu);
@@ -162,19 +163,20 @@ static void amd_pstate_ut_check_perf(u32 index)
 			lowest_perf = AMD_CPPC_LOWEST_PERF(cap1);
 		}
 
-		if (highest_perf != READ_ONCE(cpudata->highest_perf) && !cpudata->hw_prefcore) {
+		cur_perf = READ_ONCE(cpudata->perf);
+		if (highest_perf != cur_perf.highest_perf && !cpudata->hw_prefcore) {
 			pr_err("%s cpu%d highest=%d %d highest perf doesn't match\n",
-				__func__, cpu, highest_perf, cpudata->highest_perf);
+				__func__, cpu, highest_perf, cur_perf.highest_perf);
 			goto skip_test;
 		}
-		if ((nominal_perf != READ_ONCE(cpudata->nominal_perf)) ||
-			(lowest_nonlinear_perf != READ_ONCE(cpudata->lowest_nonlinear_perf)) ||
-			(lowest_perf != READ_ONCE(cpudata->lowest_perf))) {
+		if (nominal_perf != cur_perf.nominal_perf ||
+		   (lowest_nonlinear_perf != cur_perf.lowest_nonlinear_perf) ||
+		   (lowest_perf != cur_perf.lowest_perf)) {
 			amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
 			pr_err("%s cpu%d nominal=%d %d lowest_nonlinear=%d %d lowest=%d %d, they should be equal!\n",
-				__func__, cpu, nominal_perf, cpudata->nominal_perf,
-				lowest_nonlinear_perf, cpudata->lowest_nonlinear_perf,
-				lowest_perf, cpudata->lowest_perf);
+				__func__, cpu, nominal_perf, cur_perf.nominal_perf,
+				lowest_nonlinear_perf, cur_perf.lowest_nonlinear_perf,
+				lowest_perf, cur_perf.lowest_perf);
 			goto skip_test;
 		}