1 files changed, 43 insertions, 1 deletions

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index bc1454789a06..3b299b28a8af 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -100,6 +100,16 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
 				(cpc)->cpc_entry.reg.space_id ==	\
 				ACPI_ADR_SPACE_PLATFORM_COMM)
 
+/* Check if a CPC register is in SystemMemory */
+#define CPC_IN_SYSTEM_MEMORY(cpc) ((cpc)->type == ACPI_TYPE_BUFFER &&	\
+				(cpc)->cpc_entry.reg.space_id ==	\
+				ACPI_ADR_SPACE_SYSTEM_MEMORY)
+
+/* Check if a CPC register is in SystemIo */
+#define CPC_IN_SYSTEM_IO(cpc) ((cpc)->type == ACPI_TYPE_BUFFER &&	\
+				(cpc)->cpc_entry.reg.space_id ==	\
+				ACPI_ADR_SPACE_SYSTEM_IO)
+
 /* Evaluates to True if reg is a NULL register descriptor */
 #define IS_NULL_REG(reg) ((reg)->space_id ==  ACPI_ADR_SPACE_SYSTEM_MEMORY && \
 				(reg)->address == 0 &&			\
@@ -424,6 +434,24 @@ bool acpi_cpc_valid(void)
 }
 EXPORT_SYMBOL_GPL(acpi_cpc_valid);
 
+bool cppc_allow_fast_switch(void)
+{
+	struct cpc_register_resource *desired_reg;
+	struct cpc_desc *cpc_ptr;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		cpc_ptr = per_cpu(cpc_desc_ptr, cpu);
+		desired_reg = &cpc_ptr->cpc_regs[DESIRED_PERF];
+		if (!CPC_IN_SYSTEM_MEMORY(desired_reg) &&
+				!CPC_IN_SYSTEM_IO(desired_reg))
+			return false;
+	}
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(cppc_allow_fast_switch);
+
 /**
  * acpi_get_psd_map - Map the CPUs in the freq domain of a given cpu
  * @cpu: Find all CPUs that share a domain with cpu.
@@ -736,6 +764,11 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 				if (gas_t->address) {
 					void __iomem *addr;
 
+					if (!osc_cpc_flexible_adr_space_confirmed) {
+						pr_debug("Flexible address space capability not supported\n");
+						goto out_free;
+					}
+
 					addr = ioremap(gas_t->address, gas_t->bit_width/8);
 					if (!addr)
 						goto out_free;
@@ -758,6 +791,10 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 						 gas_t->address);
 					goto out_free;
 				}
+				if (!osc_cpc_flexible_adr_space_confirmed) {
+					pr_debug("Flexible address space capability not supported\n");
+					goto out_free;
+				}
 			} else {
 				if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
 					/* Support only PCC, SystemMemory, SystemIO, and FFH type regs. */
@@ -1447,6 +1484,9 @@ EXPORT_SYMBOL_GPL(cppc_set_perf);
  * transition latency for performance change requests. The closest we have
  * is the timing information from the PCCT tables which provides the info
  * on the number and frequency of PCC commands the platform can handle.
+ *
+ * If desired_reg is in the SystemMemory or SystemIo ACPI address space,
+ * then assume there is no latency.
  */
 unsigned int cppc_get_transition_latency(int cpu_num)
 {
@@ -1472,7 +1512,9 @@ unsigned int cppc_get_transition_latency(int cpu_num)
 		return CPUFREQ_ETERNAL;
 
 	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
-	if (!CPC_IN_PCC(desired_reg))
+	if (CPC_IN_SYSTEM_MEMORY(desired_reg) || CPC_IN_SYSTEM_IO(desired_reg))
+		return 0;
+	else if (!CPC_IN_PCC(desired_reg))
 		return CPUFREQ_ETERNAL;
 
 	if (pcc_ss_id < 0)