ACPI / CPPC: Add support for guaranteed performance

The Continuous Performance Control package may contain an optional
guaranteed performance field.

Add support to read guaranteed performance from _CPC.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/cppc_acpi.c

@@ -1061,9 +1061,9 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
 {
 	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
 	struct cpc_register_resource *highest_reg, *lowest_reg,
-		*lowest_non_linear_reg, *nominal_reg,
+		*lowest_non_linear_reg, *nominal_reg, *guaranteed_reg,
 		*low_freq_reg = NULL, *nom_freq_reg = NULL;
-	u64 high, low, nom, min_nonlinear, low_f = 0, nom_f = 0;
+	u64 high, low, guaranteed, nom, min_nonlinear, low_f = 0, nom_f = 0;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
 	struct cppc_pcc_data *pcc_ss_data = NULL;
 	int ret = 0, regs_in_pcc = 0;
@@ -1079,6 +1079,7 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
 	nominal_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
 	low_freq_reg = &cpc_desc->cpc_regs[LOWEST_FREQ];
 	nom_freq_reg = &cpc_desc->cpc_regs[NOMINAL_FREQ];
+	guaranteed_reg = &cpc_desc->cpc_regs[GUARANTEED_PERF];
 
 	/* Are any of the regs PCC ?*/
 	if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
@@ -1107,6 +1108,9 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
 	cpc_read(cpunum, nominal_reg, &nom);
 	perf_caps->nominal_perf = nom;
 
+	cpc_read(cpunum, guaranteed_reg, &guaranteed);
+	perf_caps->guaranteed_perf = guaranteed;
+
 	cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
 	perf_caps->lowest_nonlinear_perf = min_nonlinear;
 

include/acpi/cppc_acpi.h

@@ -104,6 +104,7 @@ enum cppc_regs {
  * today.
  */
 struct cppc_perf_caps {
+	u32 guaranteed_perf;
 	u32 highest_perf;
 	u32 nominal_perf;
 	u32 lowest_perf;