patch-2.0.21-2.1.0 linux/arch/i386/mm/ioremap.c

• Lines: 110
• Date: Wed Sep 25 12:12:50 1996
• Orig file: lx2.0/v2.0.21/linux/arch/i386/mm/ioremap.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file lx2.0/v2.0.21/linux/arch/i386/mm/ioremap.c linux/arch/i386/mm/ioremap.c
@@ -0,0 +1,109 @@
+/*
+ * arch/i386/mm/ioremap.c
+ *
+ * Re-map IO memory to kernel address space so that we can access it.
+ * This is needed for high PCI addresses that aren't mapped in the
+ * 640k-1MB IO memory area on PC's
+ *
+ * (C) Copyright 1995 1996 Linus Torvalds
+ */
+
+#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)
+{
+	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, PAGE_KERNEL));
+		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 end;
+
+	address &= ~PGDIR_MASK;
+	end = address + size;
+	if (end > PGDIR_SIZE)
+		end = PGDIR_SIZE;
+	phys_addr -= address;
+	do {
+		pte_t * pte = pte_alloc_kernel(pmd, address);
+		if (!pte)
+			return -ENOMEM;
+		remap_area_pte(pte, address, end - address, address + phys_addr);
+		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)
+{
+	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))
+			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.
+ */
+void * ioremap(unsigned long phys_addr, unsigned long size)
+{
+	void * addr;
+	struct vm_struct * area;
+
+	if (phys_addr < virt_to_phys(high_memory))
+		return phys_to_virt(phys_addr);
+	if (phys_addr & ~PAGE_MASK)
+		return NULL;
+	size = PAGE_ALIGN(size);
+	if (!size || size > phys_addr + size)
+		return NULL;
+	area = get_vm_area(size);
+	if (!area)
+		return NULL;
+	addr = area->addr;
+	if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size)) {
+		vfree(addr);
+		return NULL;
+	}
+	return addr;
+}
+
+void iounmap(void *addr)
+{
+	if (addr > high_memory)
+		return vfree(addr);
+}