patch-2.2.8 linux/arch/arm/mm/ioremap.c

• Lines: 150
• Date: Sat May 8 11:06:56 1999
• Orig file: v2.2.7/linux/arch/arm/mm/ioremap.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.2.7/linux/arch/arm/mm/ioremap.c linux/arch/arm/mm/ioremap.c
@@ -0,0 +1,149 @@
+/*
+ * arch/arm/mm/ioremap.c
+ *
+ * Re-map IO memory to kernel address space so that we can access it.
+ *
+ * (C) Copyright 1995 1996 Linus Torvalds
+ *
+ * Hacked for ARM by Phil Blundell <philb@gnu.org>
+ * Hacked to allow all architectures to build, and various cleanups
+ * by Russell King
+ */
+
+/*
+ * This allows a driver to remap an arbitrary region of bus memory into
+ * virtual space.  One should *only* use readl, writel, memcpy_toio and
+ * so on with such remapped areas.
+ *
+ * Because the ARM only has a 32-bit address space we can't address the
+ * whole of the (physical) PCI space at once.  PCI huge-mode addressing
+ * allows us to circumvent this restriction by splitting PCI space into
+ * two 2GB chunks and mapping only one at a time into processor memory.
+ * We use MMU protection domains to trap any attempt to access the bank
+ * that is not currently mapped.  (This isn't fully implemented yet.)
+ *
+ * DC21285 currently has a bug in that the PCI address extension
+ * register affects the address of any writes waiting in the outbound
+ * FIFO.  Unfortunately, it is not possible to tell the DC21285 to
+ * flush this - flushing the area causes the bus to lock.
+ */
+
+#include <linux/vmalloc.h>
+#include <asm/io.h>
+
+static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
+	unsigned long phys_addr, pgprot_t pgprot)
+{
+	unsigned long end;
+
+	address &= ~PMD_MASK;
+	end = address + size;
+	if (end > PMD_SIZE)
+		end = PMD_SIZE;
+	do {
+		if (!pte_none(*pte))
+			printk("remap_area_pte: page already exists\n");
+		set_pte(pte, mk_pte_phys(phys_addr, pgprot));
+		address += PAGE_SIZE;
+		phys_addr += PAGE_SIZE;
+		pte++;
+	} while (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;
+	pgprot_t pgprot;
+
+	address &= ~PGDIR_MASK;
+	end = address + size;
+
+	if (end > PGDIR_SIZE)
+		end = PGDIR_SIZE;
+
+	phys_addr -= address;
+	pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
+	do {
+		pte_t * pte = pte_alloc_kernel(pmd, address);
+		if (!pte)
+			return -ENOMEM;
+		remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
+		address = (address + PMD_SIZE) & PMD_MASK;
+		pmd++;
+	} while (address < end);
+	return 0;
+}
+
+static int remap_area_pages(unsigned long address, unsigned long phys_addr,
+				 unsigned long size, unsigned long flags)
+{
+	pgd_t * dir;
+	unsigned long end = address + size;
+
+	phys_addr -= address;
+	dir = pgd_offset(&init_mm, address);
+	flush_cache_all();
+	while (address < end) {
+		pmd_t *pmd = pmd_alloc_kernel(dir, address);
+		if (!pmd)
+			return -ENOMEM;
+		if (remap_area_pmd(pmd, address, end - address,
+					 phys_addr + address, flags))
+			return -ENOMEM;
+		set_pgdir(address, *dir);
+		address = (address + PGDIR_SIZE) & PGDIR_MASK;
+		dir++;
+	}
+	flush_tlb_all();
+	return 0;
+}
+
+/*
+ * 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.
+ *
+ * 'flags' are the extra L_PTE_ flags that you want to specify for this
+ * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
+ */
+void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
+{
+	void * addr;
+	struct vm_struct * area;
+	unsigned long offset;
+
+	/*
+	 * Mappings have to be page-aligned
+	 */
+	offset = phys_addr & ~PAGE_MASK;
+	size = PAGE_ALIGN(size + offset);
+
+	/*
+	 * Don't allow mappings that wrap..
+	 */
+	if (!size || size > phys_addr + size)
+		return NULL;
+
+	/*
+	 * Ok, go for it..
+	 */
+	area = get_vm_area(size);
+	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);
+}
+
+void iounmap(void *addr)
+{
+	return vfree((void *) (PAGE_MASK & (unsigned long) addr));
+}