OpenRISC: Memory management

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 137 insertions, 0 deletions

diff --git a/arch/openrisc/mm/ioremap.c b/arch/openrisc/mm/ioremap.c
new file mode 100644
index 000000000000..62b08ef392be
--- /dev/null
+++ b/arch/openrisc/mm/ioremap.c
@@ -0,0 +1,137 @@
+/*
+ * OpenRISC ioremap.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/vmalloc.h>
+#include <linux/io.h>
+#include <asm/pgalloc.h>
+#include <asm/kmap_types.h>
+#include <asm/fixmap.h>
+#include <asm/bug.h>
+#include <asm/pgtable.h>
+#include <linux/sched.h>
+#include <asm/tlbflush.h>
+
+extern int mem_init_done;
+
+static unsigned int fixmaps_used __initdata;
+
+/*
+ * Remap an arbitrary physical address space into the kernel virtual
+ * address space. Needed when the kernel wants to access high addresses
+ * directly.
+ *
+ * NOTE! We need to allow non-page-aligned mappings too: we will obviously
+ * have to convert them into an offset in a page-aligned mapping, but the
+ * caller shouldn't need to know that small detail.
+ */
+void __iomem *__init_refok
+__ioremap(phys_addr_t addr, unsigned long size, pgprot_t prot)
+{
+	phys_addr_t p;
+	unsigned long v;
+	unsigned long offset, last_addr;
+	struct vm_struct *area = NULL;
+
+	/* Don't allow wraparound or zero size */
+	last_addr = addr + size - 1;
+	if (!size || last_addr < addr)
+		return NULL;
+
+	/*
+	 * Mappings have to be page-aligned
+	 */
+	offset = addr & ~PAGE_MASK;
+	p = addr & PAGE_MASK;
+	size = PAGE_ALIGN(last_addr + 1) - p;
+
+	if (likely(mem_init_done)) {
+		area = get_vm_area(size, VM_IOREMAP);
+		if (!area)
+			return NULL;
+		v = (unsigned long)area->addr;
+	} else {
+		if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
+			return NULL;
+		v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
+		fixmaps_used += (size >> PAGE_SHIFT);
+	}
+
+	if (ioremap_page_range(v, v + size, p, prot)) {
+		if (likely(mem_init_done))
+			vfree(area->addr);
+		else
+			fixmaps_used -= (size >> PAGE_SHIFT);
+		return NULL;
+	}
+
+	return (void __iomem *)(offset + (char *)v);
+}
+
+void iounmap(void *addr)
+{
+	/* If the page is from the fixmap pool then we just clear out
+	 * the fixmap mapping.
+	 */
+	if (unlikely((unsigned long)addr > FIXADDR_START)) {
+		/* This is a bit broken... we don't really know
+		 * how big the area is so it's difficult to know
+		 * how many fixed pages to invalidate...
+		 * just flush tlb and hope for the best...
+		 * consider this a FIXME
+		 *
+		 * Really we should be clearing out one or more page
+		 * table entries for these virtual addresses so that
+		 * future references cause a page fault... for now, we
+		 * rely on two things:
+		 *   i)  this code never gets called on known boards
+		 *   ii) invalid accesses to the freed areas aren't made
+		 */
+		flush_tlb_all();
+		return;
+	}
+
+	return vfree((void *)(PAGE_MASK & (unsigned long)addr));
+}
+
+/**
+ * OK, this one's a bit tricky... ioremap can get called before memory is
+ * initialized (early serial console does this) and will want to alloc a page
+ * for its mapping.  No userspace pages will ever get allocated before memory
+ * is initialized so this applies only to kernel pages.  In the event that
+ * this is called before memory is initialized we allocate the page using
+ * the memblock infrastructure.
+ */
+
+pte_t __init_refok *pte_alloc_one_kernel(struct mm_struct *mm,
+					 unsigned long address)
+{
+	pte_t *pte;
+
+	if (likely(mem_init_done)) {
+		pte = (pte_t *) __get_free_page(GFP_KERNEL | __GFP_REPEAT);
+	} else {
+		pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+#if 0
+		/* FIXME: use memblock... */
+		pte = (pte_t *) __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
+#endif
+	}
+
+	if (pte)
+		clear_page(pte);
+	return pte;
+}