csky: MMU and page table management

This patch adds files related to memory management and here is our
memory-layout:

   Fixmap       : 0xffc02000 – 0xfffff000       (4 MB - 12KB)
   Pkmap        : 0xff800000 – 0xffc00000       (4 MB)
   Vmalloc      : 0xf0200000 – 0xff000000       (238 MB)
   Lowmem       : 0x80000000 – 0xc0000000       (1GB)

abiv1 CPU (CK610) is VIPT cache and it doesn't support highmem.
abiv2 CPUs are all PIPT cache and they could support highmem.

Lowmem is directly mapped by msa0 & msa1 reg, and we needn't setup
memory page table for it.

Link:https://lore.kernel.org/lkml/20180518215548.GH17671@n2100.armlinux.org.uk/
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 48 insertions, 0 deletions

diff --git a/arch/csky/mm/ioremap.c b/arch/csky/mm/ioremap.c
new file mode 100644
index 000000000000..7ad3ff103f4a
--- /dev/null
+++ b/arch/csky/mm/ioremap.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/io.h>
+
+#include <asm/pgtable.h>
+
+void __iomem *ioremap(phys_addr_t addr, size_t size)
+{
+	phys_addr_t last_addr;
+	unsigned long offset, vaddr;
+	struct vm_struct *area;
+	pgprot_t prot;
+
+	last_addr = addr + size - 1;
+	if (!size || last_addr < addr)
+		return NULL;
+
+	offset = addr & (~PAGE_MASK);
+	addr &= PAGE_MASK;
+	size = PAGE_ALIGN(size + offset);
+
+	area = get_vm_area_caller(size, VM_ALLOC, __builtin_return_address(0));
+	if (!area)
+		return NULL;
+
+	vaddr = (unsigned long)area->addr;
+
+	prot = __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE |
+			_PAGE_GLOBAL | _CACHE_UNCACHED);
+
+	if (ioremap_page_range(vaddr, vaddr + size, addr, prot)) {
+		free_vm_area(area);
+		return NULL;
+	}
+
+	return (void __iomem *)(vaddr + offset);
+}
+EXPORT_SYMBOL(ioremap);
+
+void iounmap(void __iomem *addr)
+{
+	vunmap((void *)((unsigned long)addr & PAGE_MASK));
+}
+EXPORT_SYMBOL(iounmap);