x86, uv: Add function retrieving node controller revision number

Add function for determining the revision id of the SGI UV
node controller chip (HUB). This function is needed in a
subsequent patch.

Signed-off-by: Jack Steiner <[e-mail]>
LKML-Reference: <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/include/asm/uv/uv_hub.h

···
 	uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
 }
 
+/*
+ * Get the minimum revision number of the hub chips within the partition.
+ *     1 - initial rev 1.0 silicon
+ *     2 - rev 2.0 production silicon
+ */
+static inline int uv_get_min_hub_revision_id(void)
+{
+	extern int uv_min_hub_revision_id;
+
+	return uv_min_hub_revision_id;
+}
+
 #endif /* CONFIG_X86_64 */
 #endif /* _ASM_X86_UV_UV_HUB_H */

arch/x86/kernel/apic/x2apic_uv_x.c

···
 
 static enum uv_system_type uv_system_type;
 static u64 gru_start_paddr, gru_end_paddr;
+int uv_min_hub_revision_id;
+EXPORT_SYMBOL_GPL(uv_min_hub_revision_id);
 
 static inline bool is_GRU_range(u64 start, u64 end)
 {
···
 	mmr = early_ioremap(UV_LOCAL_MMR_BASE | UVH_NODE_ID, sizeof(*mmr));
 	node_id.v = *mmr;
 	early_iounmap(mmr, sizeof(*mmr));
+
+	/* Currently, all blades have same revision number */
+	uv_min_hub_revision_id = node_id.s.revision;
+
 	return node_id.s.node_id;
 }