ACPI: CPPC: Add helper to get the highest performance value

Add support for getting the highest performance to the
generic CPPC driver. This enables downstream drivers
such as amd-pstate to discover and use these values.

Refer to Chapter 8.4.6.1.1.1. Highest Performance of ACPI
Specification 6.5 for details on continuous performance control
of CPPC (linked below).

Tested-by: Oleksandr Natalenko <[email protected]>
Reviewed-by: Mario Limonciello <[email protected]>
Reviewed-by: Wyes Karny <[email protected]>
Reviewed-by: Perry Yuan <[email protected]>
Acked-by: Huang Rui <[email protected]>
Signed-off-by: Meng Li <[email protected]>
Link: https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html?highlight=cppc#highest-performance
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 3a0995f8bce8..930b6afba6f4 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -139,6 +139,7 @@ struct cppc_cpudata {
 #ifdef CONFIG_ACPI_CPPC_LIB
 extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
 extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
+extern int cppc_get_highest_perf(int cpunum, u64 *highest_perf);
 extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
 extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
 extern int cppc_set_enable(int cpu, bool enable);
@@ -167,6 +168,10 @@ static inline int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
 {
 	return -ENOTSUPP;
 }
+static inline int cppc_get_highest_perf(int cpunum, u64 *highest_perf)
+{
+	return -ENOTSUPP;
+}
 static inline int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
 {
 	return -ENOTSUPP;