cpufreq: amd-pstate: Add AMD P-State performance attributes

Introduce sysfs attributes to get the different level AMD P-State
performances.

Signed-off-by: Huang Rui <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/cpufreq/amd-pstate.c

···
 	return sprintf(&buf[0], "%u\n", freq);
 }
 
+/*
+ * In some of ASICs, the highest_perf is not the one in the _CPC table, so we
+ * need to expose it to sysfs.
+ */
+static ssize_t show_amd_pstate_highest_perf(struct cpufreq_policy *policy,
+					    char *buf)
+{
+	u32 perf;
+	struct amd_cpudata *cpudata = policy->driver_data;
+
+	perf = READ_ONCE(cpudata->highest_perf);
+
+	return sprintf(&buf[0], "%u\n", perf);
+}
+
 cpufreq_freq_attr_ro(amd_pstate_max_freq);
 cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
+
+cpufreq_freq_attr_ro(amd_pstate_highest_perf);
 
 static struct freq_attr *amd_pstate_attr[] = {
 	&amd_pstate_max_freq,
 	&amd_pstate_lowest_nonlinear_freq,
+	&amd_pstate_highest_perf,
 	NULL,
 };