1 files changed, 49 insertions, 2 deletions

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 217a782c3e55..d4244e7d0e38 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1051,6 +1051,48 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 }
 
 /**
+ * cppc_get_desired_perf - Get the value of desired performance register.
+ * @cpunum: CPU from which to get desired performance.
+ * @desired_perf: address of a variable to store the returned desired performance
+ *
+ * Return: 0 for success, -EIO otherwise.
+ */
+int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
+	struct cpc_register_resource *desired_reg;
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+
+	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+
+	if (CPC_IN_PCC(desired_reg)) {
+		int ret = 0;
+
+		if (pcc_ss_id < 0)
+			return -EIO;
+
+		pcc_ss_data = pcc_data[pcc_ss_id];
+
+		down_write(&pcc_ss_data->pcc_lock);
+
+		if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
+			cpc_read(cpunum, desired_reg, desired_perf);
+		else
+			ret = -EIO;
+
+		up_write(&pcc_ss_data->pcc_lock);
+
+		return ret;
+	}
+
+	cpc_read(cpunum, desired_reg, desired_perf);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
+
+/**
  * cppc_get_perf_caps - Get a CPUs performance capabilities.
  * @cpunum: CPU from which to get capabilities info.
  * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
@@ -1108,8 +1150,13 @@ 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;
+	if (guaranteed_reg->type != ACPI_TYPE_BUFFER  ||
+	    IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) {
+		perf_caps->guaranteed_perf = 0;
+	} else {
+		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;