[PATCH 2/6] ACPI: Add CPPC v4 definitions

Mario Limonciello (AMD)
2026-04-27T03:55:31Z

ACPI 6.6 introduced new optional package values for
`OSPMNominalPerformanceRegister` and
`ResourcePriorityRegisters`.

Add these into the defines. As they're not used right now they are not
wired up to anything at this time.

Link: https://uefi.org/specs/ACPI/6.6/08_Processor_Configuration_and_Control.html#cpc-continuous-performance-control
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
drivers/acpi/cppc_acpi.c | 16 ++++++++++++----
include/acpi/cppc_acpi.h | 13 +++++++++----
2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 2e91c5a977611..cbfebc50b6eab 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -755,14 +755,15 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
*/
if ((cpc_rev == CPPC_V2_REV && num_ent != CPPC_V2_NUM_ENT) ||
(cpc_rev == CPPC_V3_REV && num_ent != CPPC_V3_NUM_ENT) ||
- (cpc_rev > CPPC_V3_REV && num_ent <= CPPC_V3_NUM_ENT)) {
+ (cpc_rev == CPPC_V4_REV && num_ent != CPPC_V4_NUM_ENT) ||
+ (cpc_rev > CPPC_V4_REV && num_ent <= CPPC_V4_NUM_ENT)) {
pr_debug("Unexpected number of _CPC return package entries (%d) for CPU:%d\n",
num_ent, pr->id);
goto out_free;
}
- if (cpc_rev > CPPC_V3_REV) {
- num_ent = CPPC_V3_NUM_ENT;
- cpc_rev = CPPC_V3_REV;
+ if (cpc_rev > CPPC_V4_REV) {
+ num_ent = CPPC_V4_NUM_ENT;
+ cpc_rev = CPPC_V4_REV;
}

cpc_ptr->num_entries = num_ent;
@@ -845,6 +846,13 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)

cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_BUFFER;
memcpy(&cpc_ptr->cpc_regs[i-2].cpc_entry.reg, gas_t, sizeof(*gas_t));
+ } else if (cpc_obj->type == ACPI_TYPE_PACKAGE) {
+ /*
+ * CPPC v4 ResourcePriorityRegisters is a Package.
+ * Store NULL for now as it's not wired up to anything.
+ */
+ cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_PACKAGE;
+ cpc_ptr->cpc_regs[i-2].cpc_entry.pkg_data = NULL;
} else {
pr_debug("Invalid entry type (%d) in _CPC for CPU:%d\n",
i, pr->id);
diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index d1f02ceec4f98..38bf9013c6e2e 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -17,16 +17,18 @@
#include <acpi/pcc.h>
#include <acpi/processor.h>

-/* CPPCv2 and CPPCv3 support */
+/* CPPC support */
#define CPPC_V2_REV 2
#define CPPC_V3_REV 3
+#define CPPC_V4_REV 4
#define CPPC_V2_NUM_ENT 21
#define CPPC_V3_NUM_ENT 23
+#define CPPC_V4_NUM_ENT 25

#define PCC_CMD_COMPLETE_MASK (1 << 0)
#define PCC_ERROR_MASK (1 << 2)

-#define MAX_CPC_REG_ENT 21
+#define MAX_CPC_REG_ENT 23

/* CPPC specific PCC commands. */
#define CMD_READ 0
@@ -60,8 +62,8 @@ struct cpc_reg {

/*
* Each entry in the CPC table is either
- * of type ACPI_TYPE_BUFFER or
- * ACPI_TYPE_INTEGER.
+ * of type ACPI_TYPE_BUFFER, ACPI_TYPE_INTEGER,
+ * or ACPI_TYPE_PACKAGE (for CPPC v4 ResourcePriorityRegisters).
*/
struct cpc_register_resource {
acpi_object_type type;
@@ -69,6 +71,7 @@ struct cpc_register_resource {
union {
struct cpc_reg reg;
u64 int_value;
+ void *pkg_data;
} cpc_entry;
};

@@ -109,6 +112,8 @@ enum cppc_regs {
REFERENCE_PERF,
LOWEST_FREQ,
NOMINAL_FREQ,
+ OSPM_NOMINAL_PERF,
+ RESOURCE_PRIO,
};

/*
--
2.43.0