[PATCH 1/8] ACPI: CPPC: Prepare cpc_register_resource for Package-type entries

[Lifeng Zheng]

CPPC v4 (ACPI 6.6, Section 8.4.6.1.2.7) introduces the Resource
Priority entry, which is a Package of sub-packages rather than a
plain Integer or Buffer register.  The existing cpc_register_resource
union only accommodates Integer and Buffer (register descriptor)
fields.

Add a Package variant to the cpc_entry union so that nested
structures such as RESOURCE_PRIORITY can store their element count
and a dynamically allocated array of child cpc_register_resource
descriptors.

Update the CPC_SUPPORTED() macro to recognise Package-type entries
with a non-zero element count, and switch the unsupported-Package
fallback from a zero Integer to an empty Package (count = 0,
elements = NULL) so that CPC_SUPPORTED() correctly reports such
entries as unsupported.

No functional change intended; the new Package fields are not yet
consumed by any caller.

Signed-off-by: Lifeng Zheng <zhenglifeng1@xxxxxxxxxx>
---
 drivers/acpi/cppc_acpi.c | 19 +++++++++++++------
 include/acpi/cppc_acpi.h |  8 ++++++++
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 9f572f481241..d7e654f2a66c 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -124,10 +124,16 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
 				(reg)->bit_offset == 0 &&		\
 				(reg)->access_width == 0)
 
-/* Evaluates to True if an optional cpc field is supported */
-#define CPC_SUPPORTED(cpc) ((cpc)->type == ACPI_TYPE_INTEGER ?		\
-				!!(cpc)->cpc_entry.int_value :		\
-				!IS_NULL_REG(&(cpc)->cpc_entry.reg))
+/*
+ * Evaluates to True if an optional cpc field is supported.
+ * Integer: non-zero value; Buffer: non-NULL register; Package: non-empty.
+ */
+#define CPC_SUPPORTED(cpc) (((cpc)->type == ACPI_TYPE_INTEGER &&	\
+			     !!(cpc)->cpc_entry.int_value) ||		\
+			    ((cpc)->type == ACPI_TYPE_BUFFER &&		\
+			     !IS_NULL_REG(&(cpc)->cpc_entry.reg)) ||	\
+			    ((cpc)->type == ACPI_TYPE_PACKAGE &&	\
+			     (cpc)->cpc_entry.package.count != 0))
 
 /*
  * Each bit indicates the optionality of the register in per-cpu
@@ -859,8 +865,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 			 * 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;
+			cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_PACKAGE;
+			cpc_ptr->cpc_regs[i-2].cpc_entry.package.count = 0;
+			cpc_ptr->cpc_regs[i-2].cpc_entry.package.elements = 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 8693890a7275..1839582b80be 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -71,6 +71,14 @@ struct cpc_register_resource {
 	union {
 		struct cpc_reg reg;
 		u64 int_value;
+		/*
+		 * CPPC v4: nested Package (e.g. RESOURCE_PRIORITY),
+		 * elements dynamically allocated
+		 */
+		struct {
+			u32 count;
+			struct cpc_register_resource *elements;
+		} package;
 	} cpc_entry;
 };
 
-- 
2.33.0