[RFC PATCH 2/5] x86/hygon: Add Family 0x18 node enumeration API header

[Lin Wang]

Introduce a small Hygon-only node helper header.

The header provides prototypes for DF misc/link accessors, node and socket
counters, DFID/family-model helpers used by external users, and CPU/channel
translation helpers shared by amd_nb, EDAC, and ATL code. It is built under
CONFIG_AMD_NODE and consumed without extending AMD-only data structures.

Signed-off-by: Lin Wang <wanglin@xxxxxxxxxxxxxx>
---
 MAINTAINERS                       |   3 +
 arch/x86/include/asm/hygon/node.h | 148 ++++++++++++++++++++++++++++++
 2 files changed, 151 insertions(+)
 create mode 100644 arch/x86/include/asm/hygon/node.h

diff --git a/MAINTAINERS b/MAINTAINERS
index c3fe46d7c4bc..2a6cf33a34e2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11865,8 +11865,11 @@ F:	drivers/input/touchscreen/hycon-hy46xx.c
 
 HYGON PROCESSOR SUPPORT
 M:	Pu Wen <puwen@xxxxxxxx>
+M:	Lin Wang <wanglin@xxxxxxxxxxxxxx>
 L:	linux-kernel@xxxxxxxxxxxxxxx
 S:	Maintained
+F:	arch/x86/include/asm/hygon/
+F:	arch/x86/kernel/hygon_node.c
 F:	arch/x86/kernel/cpu/hygon.c
 
 HYNIX HI556 SENSOR DRIVER
diff --git a/arch/x86/include/asm/hygon/node.h b/arch/x86/include/asm/hygon/node.h
new file mode 100644
index 000000000000..fce9ff8ba27d
--- /dev/null
+++ b/arch/x86/include/asm/hygon/node.h
@@ -0,0 +1,148 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_X86_HYGON_NODE_H
+#define _ASM_X86_HYGON_NODE_H
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+#include <asm/processor.h>
+#include <asm/topology.h>
+
+struct pci_dev;
+
+#define HYGON_MAX_SOCKETS	8
+
+#ifdef CONFIG_AMD_NODE
+
+/**
+ * hygon_node_num() - total node entries (CDD + IOD)
+ *
+ * Hygon Fam18h enumerates nodes by walking DF misc (F3) devices rather than
+ * using the fixed 00:18..1f scheme used by AMD. Returns the total count of
+ * CDD and IOD nodes, which sizes amd_nb[] and amd_roots[].
+ */
+u16 hygon_node_num(void);
+
+/**
+ * hygon_cdd_num() - number of compute dies (CDD)
+ *
+ * DF IDs >= 4 represent compute dies (CDD). DF IDs < 4 represent IO dies
+ * (IOD). EDAC instances must be sized by CDD count, not total node count,
+ * because IOD nodes have no UMC.
+ */
+u16 hygon_cdd_num(void);
+
+/**
+ * hygon_socket_num() - number of sockets
+ */
+u16 hygon_socket_num(void);
+
+/**
+ * hygon_f18h_model() - return Hygon Fam18h model byte, or 0 if not Hygon Fam18h
+ */
+u8 hygon_f18h_model(void);
+
+/**
+ * hygon_node_get_func() - get PCI dev for a Hygon node DF function
+ * @node: logical node index (0..hygon_node_num()-1)
+ * @func: PCI function number (3 for DF misc, 4 for DF link)
+ *
+ * Returns a reference-counted pci_dev pointer. Caller must call
+ * pci_dev_put() when done.
+ */
+struct pci_dev *hygon_node_get_func(u16 node, u8 func);
+
+/**
+ * hygon_node_socket() - get socket ID for a logical node
+ * @node: logical node index (0..hygon_node_num()-1)
+ *
+ * Returns the hardware socket ID for @node (0..hygon_socket_num()-1).
+ * Used by amd_smn_init() to assign per-socket SMN root devices to the
+ * per-node amd_roots[] array. Returns U8_MAX on error.
+ */
+u8 hygon_node_socket(u16 node);
+
+/**
+ * hygon_get_dfid() - read DF ID for a Hygon DF misc device
+ * @misc: PCI dev for DF misc (function 3)
+ * @dfid: output DF ID
+ */
+int hygon_get_dfid(struct pci_dev *misc, u8 *dfid);
+
+/**
+ * hygon_cpu_to_logical_node() - map CPU to dense logical node ID (O(1))
+ * @cpu: CPU index
+ *
+ * Hygon Fam18h exposes sparse physical node IDs (CPUID 8000001E[7:0]).
+ * This function translates the per-CPU physical node ID into a contiguous
+ * logical node ID (0..hygon_cdd_num()-1) that aligns with EDAC instance
+ * numbering and amd_nb[] indexing.
+ *
+ * Return: logical node id on success, negative errno on failure.
+ */
+int hygon_cpu_to_logical_node(unsigned int cpu);
+
+#else /* !CONFIG_AMD_NODE */
+static inline u16 hygon_node_num(void)
+{
+	return 0;
+}
+
+static inline u16 hygon_cdd_num(void)
+{
+	return 0;
+}
+
+static inline u16 hygon_socket_num(void)
+{
+	return 0;
+}
+
+static inline u8 hygon_f18h_model(void)
+{
+	return 0;
+}
+
+static inline struct pci_dev *hygon_node_get_func(u16 node, u8 func)
+{
+	return NULL;
+}
+
+static inline u8 hygon_node_socket(u16 node)
+{
+	return U8_MAX;
+}
+
+static inline int hygon_get_dfid(struct pci_dev *misc, u8 *dfid)
+{
+	return -ENODEV;
+}
+
+static inline int hygon_cpu_to_logical_node(unsigned int cpu)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_AMD_NODE */
+
+/**
+ * hygon_f18h_m4h() - check Hygon family 18h model 4h..fh
+ */
+static inline bool hygon_f18h_m4h(void)
+{
+	u8 m = hygon_f18h_model();
+
+	return m >= 0x4 && m <= 0xf;
+}
+
+/**
+ * hygon_f18h_m10h() - check Hygon family 18h model 10h..1fh
+ */
+static inline bool hygon_f18h_m10h(void)
+{
+	u8 m = hygon_f18h_model();
+
+	return m >= 0x10;
+}
+
+
+#endif /* _ASM_X86_HYGON_NODE_H */
-- 
2.43.0