Ioremap for 32-bit kernel.

2 files changed, 178 insertions, 2 deletions

diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index 5976ee150..aa1d667f5 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -9,8 +9,8 @@
 
 O_TARGET := mm.o
 
-export-objs			+= umap.o
-obj-y				+= extable.o init.o fault.o loadmmu.o
+export-objs			+= ioremap.o umap.o
+obj-y				+= extable.o init.o ioremap.o fault.o loadmmu.o
 
 obj-$(CONFIG_CPU_R3000)		+= r2300.o
 obj-$(CONFIG_CPU_R4300)		+= r4xx0.o
diff --git a/arch/mips/mm/ioremap.c b/arch/mips/mm/ioremap.c
new file mode 100644
index 000000000..97bb6a734
--- /dev/null
+++ b/arch/mips/mm/ioremap.c
@@ -0,0 +1,176 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * (C) Copyright 1995 1996 Linus Torvalds
+ * (C) Copyright 2001 Ralf Baechle
+ */
+#include <linux/module.h>
+#include <asm/addrspace.h>
+#include <asm/byteorder.h>
+
+#include <linux/vmalloc.h>
+#include <asm/io.h>
+#include <asm/pgalloc.h>
+
+static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
+	unsigned long phys_addr, unsigned long flags)
+{
+	unsigned long end;
+	pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | __READABLE
+	                           | __WRITEABLE | flags);
+
+	address &= ~PMD_MASK;
+	end = address + size;
+	if (end > PMD_SIZE)
+		end = PMD_SIZE;
+	if (address >= end)
+		BUG();
+	do {
+		if (!pte_none(*pte)) {
+			printk("remap_area_pte: page already exists\n");
+			BUG();
+		}
+		set_pte(pte, mk_pte_phys(phys_addr, pgprot));
+		address += PAGE_SIZE;
+		phys_addr += PAGE_SIZE;
+		pte++;
+	} while (address && (address < end));
+}
+
+static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
+	unsigned long phys_addr, unsigned long flags)
+{
+	unsigned long end;
+
+	address &= ~PGDIR_MASK;
+	end = address + size;
+	if (end > PGDIR_SIZE)
+		end = PGDIR_SIZE;
+	phys_addr -= address;
+	if (address >= end)
+		BUG();
+	do {
+		pte_t * pte = pte_alloc(&init_mm, pmd, address);
+		if (!pte)
+			return -ENOMEM;
+		remap_area_pte(pte, address, end - address, address + phys_addr, flags);
+		address = (address + PMD_SIZE) & PMD_MASK;
+		pmd++;
+	} while (address && (address < end));
+	return 0;
+}
+
+static int remap_area_pages(unsigned long address, unsigned long phys_addr,
+				 unsigned long size, unsigned long flags)
+{
+	int error;
+	pgd_t * dir;
+	unsigned long end = address + size;
+
+	phys_addr -= address;
+	dir = pgd_offset(&init_mm, address);
+	flush_cache_all();
+	if (address >= end)
+		BUG();
+	spin_lock(&init_mm.page_table_lock);
+	do {
+		pmd_t *pmd;
+		pmd = pmd_alloc(&init_mm, dir, address);
+		error = -ENOMEM;
+		if (!pmd)
+			break;
+		if (remap_area_pmd(pmd, address, end - address,
+					 phys_addr + address, flags))
+			break;
+		error = 0;
+		address = (address + PGDIR_SIZE) & PGDIR_MASK;
+		dir++;
+	} while (address && (address < end));
+	spin_unlock(&init_mm.page_table_lock);
+	flush_tlb_all();
+	return error;
+}
+
+/*
+ * Generic mapping function (not visible outside):
+ */
+
+/*
+ * 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.
+ */
+
+#define IS_LOW512(addr) (!((unsigned long)(addr) & ~0x1fffffffUL))
+
+void * __ioremap(unsigned long phys_addr, unsigned long size)
+{
+	void * addr;
+	struct vm_struct * area;
+	unsigned long offset, last_addr, flags = _CACHE_UNCACHED;
+
+	/* Don't allow wraparound or zero size */
+	last_addr = phys_addr + size - 1;
+	if (!size || last_addr < phys_addr)
+		return NULL;
+
+	/*
+	 * Map objects in the low 512mb of address space using KSEG1, otherwise
+	 * map using page tables.
+	 */
+	if (IS_LOW512(phys_addr) && IS_LOW512(phys_addr + size - 1))
+		return (void *) KSEG1ADDR(phys_addr);
+
+	/*
+	 * Don't allow anybody to remap normal RAM that we're using..
+	 */
+	if (phys_addr < virt_to_phys(high_memory)) {
+		char *t_addr, *t_end;
+		struct page *page;
+
+		t_addr = __va(phys_addr);
+		t_end = t_addr + (size - 1);
+	   
+		for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
+			if(!PageReserved(page))
+				return NULL;
+	}
+
+	/*
+	 * Mappings have to be page-aligned
+	 */
+	offset = phys_addr & ~PAGE_MASK;
+	phys_addr &= PAGE_MASK;
+	size = PAGE_ALIGN(last_addr) - phys_addr;
+
+	/*
+	 * Ok, go for it..
+	 */
+	area = get_vm_area(size, VM_IOREMAP);
+	if (!area)
+		return NULL;
+	addr = area->addr;
+	if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
+		vfree(addr);
+		return NULL;
+	}
+
+	return (void *) (offset + (char *)addr);
+}
+
+#define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == KSEG1)
+
+void iounmap(void *addr)
+{
+	if (!IS_KSEG1(addr))
+		return vfree((void *) (PAGE_MASK & (unsigned long) addr));
+}
+
+EXPORT_SYMBOL(__ioremap);
+EXPORT_SYMBOL(iounmap);