1 files changed, 97 insertions, 0 deletions

diff --git a/arch/i386/mm/boot_ioremap.c b/arch/i386/mm/boot_ioremap.c
new file mode 100644
index 000000000000..523b30634e0a
--- /dev/null
+++ b/arch/i386/mm/boot_ioremap.c
@@ -0,0 +1,97 @@
+/*
+ * arch/i386/mm/boot_ioremap.c
+ * 
+ * Re-map functions for early boot-time before paging_init() when the 
+ * boot-time pagetables are still in use
+ *
+ * Written by Dave Hansen <haveblue@us.ibm.com>
+ */
+
+
+/*
+ * We need to use the 2-level pagetable functions, but CONFIG_X86_PAE
+ * keeps that from happenning.  If anyone has a better way, I'm listening.
+ *
+ * boot_pte_t is defined only if this all works correctly
+ */
+
+#include <linux/config.h>
+#undef CONFIG_X86_PAE
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <linux/init.h>
+#include <linux/stddef.h>
+
+/* 
+ * I'm cheating here.  It is known that the two boot PTE pages are 
+ * allocated next to each other.  I'm pretending that they're just
+ * one big array. 
+ */
+
+#define BOOT_PTE_PTRS (PTRS_PER_PTE*2)
+#define boot_pte_index(address) \
+             (((address) >> PAGE_SHIFT) & (BOOT_PTE_PTRS - 1))
+
+static inline boot_pte_t* boot_vaddr_to_pte(void *address)
+{
+        boot_pte_t* boot_pg = (boot_pte_t*)pg0;
+        return &boot_pg[boot_pte_index((unsigned long)address)];
+}
+
+/*
+ * This is only for a caller who is clever enough to page-align
+ * phys_addr and virtual_source, and who also has a preference
+ * about which virtual address from which to steal ptes
+ */
+static void __boot_ioremap(unsigned long phys_addr, unsigned long nrpages, 
+                    void* virtual_source)
+{
+        boot_pte_t* pte;
+        int i;
+        char *vaddr = virtual_source;
+
+        pte = boot_vaddr_to_pte(virtual_source);
+        for (i=0; i < nrpages; i++, phys_addr += PAGE_SIZE, pte++) {
+                set_pte(pte, pfn_pte(phys_addr>>PAGE_SHIFT, PAGE_KERNEL));
+                __flush_tlb_one(&vaddr[i*PAGE_SIZE]);
+        }
+}
+
+/* the virtual space we're going to remap comes from this array */
+#define BOOT_IOREMAP_PAGES 4
+#define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE)
+static __initdata char boot_ioremap_space[BOOT_IOREMAP_SIZE]
+                       __attribute__ ((aligned (PAGE_SIZE)));
+
+/*
+ * This only applies to things which need to ioremap before paging_init()
+ * bt_ioremap() and plain ioremap() are both useless at this point.
+ * 
+ * When used, we're still using the boot-time pagetables, which only
+ * have 2 PTE pages mapping the first 8MB
+ *
+ * There is no unmap.  The boot-time PTE pages aren't used after boot.
+ * If you really want the space back, just remap it yourself.
+ * boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE)
+ */
+__init void* boot_ioremap(unsigned long phys_addr, unsigned long size)
+{
+        unsigned long last_addr, offset;
+        unsigned int nrpages;
+        
+        last_addr = phys_addr + size - 1;
+
+        /* page align the requested address */
+        offset = phys_addr & ~PAGE_MASK;
+        phys_addr &= PAGE_MASK;
+        size = PAGE_ALIGN(last_addr) - phys_addr;
+        
+        nrpages = size >> PAGE_SHIFT;
+        if (nrpages > BOOT_IOREMAP_PAGES)
+                return NULL;
+        
+        __boot_ioremap(phys_addr, nrpages, boot_ioremap_space);
+
+        return &boot_ioremap_space[offset];
+}