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ACPI: CPPC: Add support for CPPC v4

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CPPC v4 (ACPI 6.6, Section 8.4.6) adds two optional entries to the
_CPC package:

1. OSPM Nominal Performance (8.4.6.1.2.6): A write-only register that
   lets OSPM inform the platform what it considers nominal performance.
   The platform classifies performance above this level as boost and
   below as throttle for its power/thermal decisions.

2. Resource Priority (8.4.6.1.2.7): A Package of Resource Priority
   Register Descriptor sub-packages that allow OSPM to set relative
   priority among processors for shared resources (boost, throttle,
   L2/L3 cache, memory bandwidth). Parsing the full structure is not
   yet supported; such entries are marked as unsupported.

Add v4 _CPC table parsing (25 entries) and update REG_OPTIONAL to
mark the two new registers as optional.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://patch.msgid.link/20260527194626.185286-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Sumit Gupta
2026-05-28 01:16:25 +05:30
committed by Rafael J. Wysocki
parent e43ffb69e0
commit 71e1815113
2 changed files with 23 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/acpi/cppc_acpi.c
View File

@@ -134,7 +134,7 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
* cpc_regs[] with the corresponding index. 0 means mandatory and 1
* means optional.
*/
#define REG_OPTIONAL (0x1FC7D0)
#define REG_OPTIONAL (0x7FC7D0)
/*
* Use the index of the register in per-cpu cpc_regs[] to check if
@@ -751,18 +751,19 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
/*
* Disregard _CPC if the number of entries in the return package is not
* as expected, but support future revisions being proper supersets of
* the v3 and only causing more entries to be returned by _CPC.
* the v4 and only causing more entries to be returned by _CPC.
*/
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 +846,16 @@ 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 && (i - 2) == RESOURCE_PRIORITY) {
/*
* ACPI 6.6, s8.4.6.1.2.7 defines Resource Priority as a
* Package of Resource Priority Register Descriptor sub-packages.
* Parsing the full structure is not yet supported.
* Mark the register as unsupported for now.
*/
pr_debug("CPU:%d Resource Priority not supported\n", pr->id);
cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_INTEGER;
cpc_ptr->cpc_regs[i-2].cpc_entry.int_value = 0;
} else {
pr_debug("Invalid entry type (%d) in _CPC for CPU:%d\n",
i, pr->id);

8
include/acpi/cppc_acpi.h
View File

@@ -17,16 +17,18 @@
#include <acpi/pcc.h>
#include <acpi/processor.h>
/* CPPCv2 and CPPCv3 support */
/* CPPCv2, CPPCv3 and CPPCv4 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
@@ -109,6 +111,8 @@ enum cppc_regs {
REFERENCE_PERF,
LOWEST_FREQ,
NOMINAL_FREQ,
OSPM_NOMINAL_PERF,
RESOURCE_PRIORITY,
};
/*