sh: memory hot-add for sparsemem users support.

This enables simple hotplug support for sparsemem users. Presently
this only permits memory being added in to node 0 on ZONE_NORMAL.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/Kconfig

@@ -331,6 +331,14 @@ config ARCH_POPULATES_NODE_MAP
 config ARCH_SELECT_MEMORY_MODEL
 	def_bool y
 
+config ARCH_ENABLE_MEMORY_HOTPLUG
+	def_bool y
+	depends on SPARSEMEM
+
+config ARCH_MEMORY_PROBE
+	def_bool y
+	depends on MEMORY_HOTPLUG
+
 choice
 	prompt "Kernel page size"
 	default PAGE_SIZE_4KB

arch/sh/mm/init.c

@@ -265,3 +265,45 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	printk("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 }
 #endif
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+void online_page(struct page *page)
+{
+	ClearPageReserved(page);
+	init_page_count(page);
+	__free_page(page);
+	totalram_pages++;
+	num_physpages++;
+}
+
+int arch_add_memory(int nid, u64 start, u64 size)
+{
+	pg_data_t *pgdat;
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	int ret;
+
+	pgdat = NODE_DATA(nid);
+
+	/* We only have ZONE_NORMAL, so this is easy.. */
+	ret = __add_pages(pgdat->node_zones + ZONE_NORMAL, start_pfn, nr_pages);
+	if (unlikely(ret))
+		printk("%s: Failed, __add_pages() == %d\n", __FUNCTION__, ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(arch_add_memory);
+
+int remove_memory(u64 start, u64 size)
+{
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(remove_memory);
+
+int memory_add_physaddr_to_nid(u64 addr)
+{
+	/* Node 0 for now.. */
+	return 0;
+}
+EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
+#endif

mm/Kconfig

@@ -117,7 +117,7 @@ config MEMORY_HOTPLUG
 	bool "Allow for memory hot-add"
 	depends on SPARSEMEM || X86_64_ACPI_NUMA
 	depends on HOTPLUG && !SOFTWARE_SUSPEND && ARCH_ENABLE_MEMORY_HOTPLUG
-	depends on (IA64 || X86 || PPC64)
+	depends on (IA64 || X86 || PPC64 || SUPERH)
 
 comment "Memory hotplug is currently incompatible with Software Suspend"
 	depends on SPARSEMEM && HOTPLUG && SOFTWARE_SUSPEND