[ARM] 3705/1: add supersection support to ioremap()

Patch from Lennert Buytenhek

Analogous to the previous patch that allows ioremap() to use section
mappings, this patch allows ioremap() to use supersection mappings.
Original patch by Deepak Saxena.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 63 insertions, 3 deletions

diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 6aa13d59c858..7eac87f05180 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -33,8 +33,8 @@
 #include <asm/sizes.h>
 
 /*
- * Used by ioremap() and iounmap() code to mark section-mapped I/O regions
- * in vm_struct->flags field.
+ * Used by ioremap() and iounmap() code to mark (super)section-mapped
+ * I/O regions in vm_struct->flags field.
  */
 #define VM_ARM_SECTION_MAPPING  0x80000000
 
@@ -233,6 +233,54 @@ remap_area_sections(unsigned long virt, unsigned long pfn,
 
         return 0;
 }
+
+static int
+remap_area_supersections(unsigned long virt, unsigned long pfn,
+                         unsigned long size, unsigned long flags)
+{
+        unsigned long prot, addr = virt, end = virt + size;
+        pgd_t *pgd;
+
+        /*
+         * Remove and free any PTE-based mapping, and
+         * sync the current kernel mapping.
+         */
+        unmap_area_sections(virt, size);
+
+        prot = PMD_TYPE_SECT | PMD_SECT_SUPER | PMD_SECT_AP_WRITE |
+                        PMD_DOMAIN(DOMAIN_IO) |
+                        (flags & (L_PTE_CACHEABLE | L_PTE_BUFFERABLE));
+
+        /*
+         * ARMv6 and above need XN set to prevent speculative prefetches
+         * hitting IO.
+         */
+        if (cpu_architecture() >= CPU_ARCH_ARMv6)
+                prot |= PMD_SECT_XN;
+
+        pgd = pgd_offset_k(virt);
+        do {
+                unsigned long super_pmd_val, i;
+
+                super_pmd_val = __pfn_to_phys(pfn) | prot;
+                super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
+
+                for (i = 0; i < 8; i++) {
+                        pmd_t *pmd = pmd_offset(pgd, addr);
+
+                        pmd[0] = __pmd(super_pmd_val);
+                        pmd[1] = __pmd(super_pmd_val);
+                        flush_pmd_entry(pmd);
+
+                        addr += PGDIR_SIZE;
+                        pgd++;
+                }
+
+                pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
+        } while (addr < end);
+
+        return 0;
+}
 #endif
 
 
@@ -255,6 +303,13 @@ __ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
         int err;
         unsigned long addr;
         struct vm_struct * area;
+        unsigned int cr = get_cr();
+
+        /*
+         * High mappings must be supersection aligned
+         */
+        if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
+                return NULL;
 
         area = get_vm_area(size, VM_IOREMAP);
         if (!area)
@@ -262,7 +317,12 @@ __ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
         addr = (unsigned long)area->addr;
 
 #ifndef CONFIG_SMP
-        if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
+        if ((((cpu_architecture() >= CPU_ARCH_ARMv6) && (cr & CR_XP)) ||
+               cpu_is_xsc3()) &&
+               !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
+                area->flags |= VM_ARM_SECTION_MAPPING;
+                err = remap_area_supersections(addr, pfn, size, flags);
+        } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
                 area->flags |= VM_ARM_SECTION_MAPPING;
                 err = remap_area_sections(addr, pfn, size, flags);
         } else