[RFC/RFT PATCH v3 1/1] arc: add sparsemem support

[Mike Rapoport]

From: Mike Rapoport <rppt at linux.ibm.com>

Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>
---
 arch/arc/Kconfig                 | 10 ++++++++++
 arch/arc/include/asm/sparsemem.h | 13 +++++++++++++
 arch/arc/mm/init.c               |  6 +++++-
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 arch/arc/include/asm/sparsemem.h

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index ba00c4e1e1c2..2e3c02e9b657 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -48,6 +48,7 @@ config ARC
 	select PCI_SYSCALL if PCI
 	select PERF_USE_VMALLOC if ARC_CACHE_VIPT_ALIASING
 	select HAVE_ARCH_JUMP_LABEL if ISA_ARCV2 && !CPU_ENDIAN_BE32
+	select SPARSEMEM_STATIC if SPARSEMEM
 
 config ARCH_HAS_CACHE_LINE_SIZE
 	def_bool y
@@ -67,8 +68,15 @@ config GENERIC_CSUM
 config ARCH_DISCONTIGMEM_ENABLE
 	def_bool n
 
+config ARCH_SPARSEMEM_ENABLE
+	def_bool n
+
 config ARCH_FLATMEM_ENABLE
 	def_bool y
+	depends on !HIGHMEM
+
+config ARCH_SELECT_MEMORY_MODEL
+	def_bool n
 
 config MMU
 	def_bool y
@@ -508,6 +516,8 @@ config LINUX_RAM_BASE
 config HIGHMEM
 	bool "High Memory Support"
 	select ARCH_DISCONTIGMEM_ENABLE
+	select ARCH_SPARSEMEM_ENABLE
+	select ARCH_SELECT_MEMORY_MODEL
 	help
 	  With ARC 2G:2G address split, only upper 2G is directly addressable by
 	  kernel. Enable this to potentially allow access to rest of 2G and PAE
diff --git a/arch/arc/include/asm/sparsemem.h b/arch/arc/include/asm/sparsemem.h
new file mode 100644
index 000000000000..1156b9934c74
--- /dev/null
+++ b/arch/arc/include/asm/sparsemem.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ARC_SPARSEMEM_H
+#define _ASM_ARC_SPARSEMEM_H
+
+#ifdef CONFIG_ARC_HAS_PAE40
+#define MAX_PHYSMEM_BITS	40
+#define SECTION_SIZE_BITS	32
+#else
+#define MAX_PHYSMEM_BITS	32
+#define SECTION_SIZE_BITS	27
+#endif
+
+#endif /* _ASM_ARC_SPARSEMEM_H */
diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index 3a35b82a718e..60e3808a4e19 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -153,7 +153,11 @@ void __init setup_arch_memory(void)
 	 * DISCONTIGMEM in turns requires multiple nodes. node 0 above is
 	 * populated with normal memory zone while node 1 only has highmem
 	 */
+#ifdef CONFIG_DISCONTIGMEM
 	node_set_online(1);
+#elif defined(CONFIG_SPARSEMEM)
+	sparse_init();
+#endif
 
 	min_high_pfn = PFN_DOWN(high_mem_start);
 	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
@@ -162,7 +166,7 @@ void __init setup_arch_memory(void)
 
 	high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
 	kmap_init();
-#endif
+#endif /* CONFIG_HIGHMEM */
 
 	free_area_init(max_zone_pfn);
 }
-- 
2.26.2