[PATCH 07/38] MIPS: SGI-IP27: choose the node address layout at runtime

[Imre Kaloz]

A Bedrock node owns twice the address space a Hub node does, putting
the nasid one bit higher. Take the shift and the node size from the
generation detected at boot; head.S runs before that and keeps Hub's
values.

Signed-off-by: Imre Kaloz <kaloz@xxxxxxxxxx>
---
 arch/mips/include/asm/sn/addrs.h     | 12 +++++++++++-
 arch/mips/include/asm/sn/sn0/addrs.h |  8 ++++----
 arch/mips/include/asm/sn/sn1/addrs.h | 22 ++++++++++++++++++++++
 3 files changed, 37 insertions(+), 5 deletions(-)
 create mode 100644 arch/mips/include/asm/sn/sn1/addrs.h

diff --git a/arch/mips/include/asm/sn/addrs.h b/arch/mips/include/asm/sn/addrs.h
index 51161fd5130b..499615abd501 100644
--- a/arch/mips/include/asm/sn/addrs.h
+++ b/arch/mips/include/asm/sn/addrs.h
@@ -20,7 +20,6 @@
 
 #if defined(CONFIG_SGI_IP27)
 #include <asm/sn/sn0/addrs.h>
-#elif defined(CONFIG_SGI_IP35)
 #include <asm/sn/sn1/addrs.h>
 #endif
 
@@ -39,6 +38,17 @@
 
 extern bool system_is_ip35;
 
+#define NASID_SHFT		(system_is_ip35 ? SN1_NASID_SHFT :	\
+				 SN0_NASID_SHFT)
+#define NODE_SIZE_BITS		(system_is_ip35 ? SN1_NODE_SIZE_BITS :	\
+				 SN0_NODE_SIZE_BITS)
+
+#else /* __ASSEMBLER__ */
+
+/* The entry paths run before prom_init() reads the hub's part number. */
+#define NASID_SHFT		SN0_NASID_SHFT
+#define NODE_SIZE_BITS		SN0_NODE_SIZE_BITS
+
 #endif /* __ASSEMBLER__ */
 
 
diff --git a/arch/mips/include/asm/sn/sn0/addrs.h b/arch/mips/include/asm/sn/sn0/addrs.h
index a28158a91ecf..f1a161913ae4 100644
--- a/arch/mips/include/asm/sn/sn0/addrs.h
+++ b/arch/mips/include/asm/sn/sn0/addrs.h
@@ -50,12 +50,12 @@
 
 #ifdef CONFIG_SGI_SN_N_MODE
 
-#define NODE_SIZE_BITS		31
+#define SN0_NODE_SIZE_BITS	31
 #define BWIN_SIZE_BITS		28
 
 #define NASID_BITS		9
 #define NASID_BITMASK		(0x1ffLL)
-#define NASID_SHFT		31
+#define SN0_NASID_SHFT		31
 #define NASID_META_BITS		5
 #define NASID_LOCAL_BITS	4
 
@@ -64,12 +64,12 @@
 
 #else /* !defined(CONFIG_SGI_SN_N_MODE), assume that M-mode is desired */
 
-#define NODE_SIZE_BITS		32
+#define SN0_NODE_SIZE_BITS	32
 #define BWIN_SIZE_BITS		29
 
 #define NASID_BITMASK		(0xffLL)
 #define NASID_BITS		8
-#define NASID_SHFT		32
+#define SN0_NASID_SHFT		32
 #define NASID_META_BITS		4
 #define NASID_LOCAL_BITS	4
 
diff --git a/arch/mips/include/asm/sn/sn1/addrs.h b/arch/mips/include/asm/sn/sn1/addrs.h
new file mode 100644
index 000000000000..58878a5b4710
--- /dev/null
+++ b/arch/mips/include/asm/sn/sn1/addrs.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * SN1 (Bedrock) address space layout.
+ *
+ * Copyright (C) 2026 Imre Kaloz <kaloz@xxxxxxxxxx>
+ */
+#ifndef _ASM_SN_SN1_ADDRS_H
+#define _ASM_SN_SN1_ADDRS_H
+
+#ifdef CONFIG_SGI_SN_N_MODE
+
+#define SN1_NODE_SIZE_BITS	32
+#define SN1_NASID_SHFT		32
+
+#else /* !defined(CONFIG_SGI_SN_N_MODE), assume that M-mode is desired */
+
+#define SN1_NODE_SIZE_BITS	33
+#define SN1_NASID_SHFT		33
+
+#endif /* !defined(CONFIG_SGI_SN_N_MODE) */
+
+#endif /* _ASM_SN_SN1_ADDRS_H */
-- 
2.47.3