Pull button into test branch
[linux-drm-fsl-dcu.git] / arch / sh / mm / cache-sh4.c
index 94c05d09c3f7e046077f93f2416f3ac4484dafcf..c6955157c9897fc20d43567d09622fcfe6ab2d79 100644 (file)
  * arch/sh/mm/cache-sh4.c
  *
  * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
- * Copyright (C) 2001, 2002, 2003, 2004, 2005  Paul Mundt
+ * Copyright (C) 2001 - 2006  Paul Mundt
  * Copyright (C) 2003  Richard Curnow
  *
  * 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.
  */
-
 #include <linux/init.h>
-#include <linux/mman.h>
 #include <linux/mm.h>
-#include <linux/threads.h>
-#include <asm/addrspace.h>
-#include <asm/page.h>
-#include <asm/pgtable.h>
-#include <asm/processor.h>
-#include <asm/cache.h>
-#include <asm/io.h>
-#include <asm/uaccess.h>
-#include <asm/pgalloc.h>
+#include <linux/io.h>
+#include <linux/mutex.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 
-extern void __flush_cache_4096(unsigned long addr, unsigned long phys,
+/*
+ * The maximum number of pages we support up to when doing ranged dcache
+ * flushing. Anything exceeding this will simply flush the dcache in its
+ * entirety.
+ */
+#define MAX_DCACHE_PAGES       64      /* XXX: Tune for ways */
+
+static void __flush_dcache_segment_1way(unsigned long start,
+                                       unsigned long extent);
+static void __flush_dcache_segment_2way(unsigned long start,
+                                       unsigned long extent);
+static void __flush_dcache_segment_4way(unsigned long start,
+                                       unsigned long extent);
+
+static void __flush_cache_4096(unsigned long addr, unsigned long phys,
                               unsigned long exec_offset);
-extern void __flush_cache_4096_all(unsigned long start);
-static void __flush_cache_4096_all_ex(unsigned long start);
-extern void __flush_dcache_all(void);
-static void __flush_dcache_all_ex(void);
+
+/*
+ * This is initialised here to ensure that it is not placed in the BSS.  If
+ * that were to happen, note that cache_init gets called before the BSS is
+ * cleared, so this would get nulled out which would be hopeless.
+ */
+static void (*__flush_dcache_segment_fn)(unsigned long, unsigned long) =
+       (void (*)(unsigned long, unsigned long))0xdeadbeef;
+
+static void compute_alias(struct cache_info *c)
+{
+       c->alias_mask = ((c->sets - 1) << c->entry_shift) & ~(PAGE_SIZE - 1);
+       c->n_aliases = (c->alias_mask >> PAGE_SHIFT) + 1;
+}
+
+static void __init emit_cache_params(void)
+{
+       printk("PVR=%08x CVR=%08x PRR=%08x\n",
+               ctrl_inl(CCN_PVR),
+               ctrl_inl(CCN_CVR),
+               ctrl_inl(CCN_PRR));
+       printk("I-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+               cpu_data->icache.ways,
+               cpu_data->icache.sets,
+               cpu_data->icache.way_incr);
+       printk("I-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+               cpu_data->icache.entry_mask,
+               cpu_data->icache.alias_mask,
+               cpu_data->icache.n_aliases);
+       printk("D-cache : n_ways=%d n_sets=%d way_incr=%d\n",
+               cpu_data->dcache.ways,
+               cpu_data->dcache.sets,
+               cpu_data->dcache.way_incr);
+       printk("D-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
+               cpu_data->dcache.entry_mask,
+               cpu_data->dcache.alias_mask,
+               cpu_data->dcache.n_aliases);
+
+       if (!__flush_dcache_segment_fn)
+               panic("unknown number of cache ways\n");
+}
 
 /*
  * SH-4 has virtually indexed and physically tagged cache.
  */
 
-struct semaphore p3map_sem[4];
+/* Worst case assumed to be 64k cache, direct-mapped i.e. 4 synonym bits. */
+#define MAX_P3_MUTEXES 16
+
+struct mutex p3map_mutex[MAX_P3_MUTEXES];
 
 void __init p3_cache_init(void)
 {
-       if (remap_area_pages(P3SEG, 0, PAGE_SIZE*4, _PAGE_CACHABLE))
+       int i;
+
+       compute_alias(&cpu_data->icache);
+       compute_alias(&cpu_data->dcache);
+
+       switch (cpu_data->dcache.ways) {
+       case 1:
+               __flush_dcache_segment_fn = __flush_dcache_segment_1way;
+               break;
+       case 2:
+               __flush_dcache_segment_fn = __flush_dcache_segment_2way;
+               break;
+       case 4:
+               __flush_dcache_segment_fn = __flush_dcache_segment_4way;
+               break;
+       default:
+               __flush_dcache_segment_fn = NULL;
+               break;
+       }
+
+       emit_cache_params();
+
+       if (ioremap_page_range(P3SEG, P3SEG + (PAGE_SIZE * 4), 0, PAGE_KERNEL))
                panic("%s failed.", __FUNCTION__);
 
-       sema_init (&p3map_sem[0], 1);
-       sema_init (&p3map_sem[1], 1);
-       sema_init (&p3map_sem[2], 1);
-       sema_init (&p3map_sem[3], 1);
+       for (i = 0; i < cpu_data->dcache.n_aliases; i++)
+               mutex_init(&p3map_mutex[i]);
 }
 
 /*
@@ -91,7 +156,6 @@ void __flush_purge_region(void *start, int size)
        }
 }
 
-
 /*
  * No write back please
  */
@@ -110,46 +174,6 @@ void __flush_invalidate_region(void *start, int size)
        }
 }
 
-static void __flush_dcache_all_ex(void)
-{
-       unsigned long addr, end_addr, entry_offset;
-
-       end_addr = CACHE_OC_ADDRESS_ARRAY +
-               (cpu_data->dcache.sets << cpu_data->dcache.entry_shift) *
-                cpu_data->dcache.ways;
-
-       entry_offset = 1 << cpu_data->dcache.entry_shift;
-       for (addr = CACHE_OC_ADDRESS_ARRAY;
-            addr < end_addr;
-            addr += entry_offset) {
-               ctrl_outl(0, addr);
-       }
-}
-
-static void __flush_cache_4096_all_ex(unsigned long start)
-{
-       unsigned long addr, entry_offset;
-       int i;
-
-       entry_offset = 1 << cpu_data->dcache.entry_shift;
-       for (i = 0; i < cpu_data->dcache.ways;
-            i++, start += cpu_data->dcache.way_incr) {
-               for (addr = CACHE_OC_ADDRESS_ARRAY + start;
-                    addr < CACHE_OC_ADDRESS_ARRAY + 4096 + start;
-                    addr += entry_offset) {
-                       ctrl_outl(0, addr);
-               }
-       }
-}
-
-void flush_cache_4096_all(unsigned long start)
-{
-       if (cpu_data->dcache.ways == 1)
-               __flush_cache_4096_all(start);
-       else
-               __flush_cache_4096_all_ex(start);
-}
-
 /*
  * Write back the range of D-cache, and purge the I-cache.
  *
@@ -180,32 +204,33 @@ void flush_cache_sigtramp(unsigned long addr)
 
        local_irq_save(flags);
        jump_to_P2();
+
        for (i = 0; i < cpu_data->icache.ways;
             i++, index += cpu_data->icache.way_incr)
                ctrl_outl(0, index);    /* Clear out Valid-bit */
+
        back_to_P1();
+       wmb();
        local_irq_restore(flags);
 }
 
 static inline void flush_cache_4096(unsigned long start,
                                    unsigned long phys)
 {
-       unsigned long flags;
+       unsigned long flags, exec_offset = 0;
 
        /*
-        * SH7751, SH7751R, and ST40 have no restriction to handle cache.
-        * (While SH7750 must do that at P2 area.)
+        * All types of SH-4 require PC to be in P2 to operate on the I-cache.
+        * Some types of SH-4 require PC to be in P2 to operate on the D-cache.
         */
-       if ((cpu_data->flags & CPU_HAS_P2_FLUSH_BUG)
-          || start < CACHE_OC_ADDRESS_ARRAY) {
-               local_irq_save(flags);
-               __flush_cache_4096(start | SH_CACHE_ASSOC,
-                                  P1SEGADDR(phys), 0x20000000);
-               local_irq_restore(flags);
-       } else {
-               __flush_cache_4096(start | SH_CACHE_ASSOC,
-                                  P1SEGADDR(phys), 0);
-       }
+       if ((cpu_data->flags & CPU_HAS_P2_FLUSH_BUG) ||
+           (start < CACHE_OC_ADDRESS_ARRAY))
+               exec_offset = 0x20000000;
+
+       local_irq_save(flags);
+       __flush_cache_4096(start | SH_CACHE_ASSOC,
+                          P1SEGADDR(phys), exec_offset);
+       local_irq_restore(flags);
 }
 
 /*
@@ -216,15 +241,19 @@ void flush_dcache_page(struct page *page)
 {
        if (test_bit(PG_mapped, &page->flags)) {
                unsigned long phys = PHYSADDR(page_address(page));
+               unsigned long addr = CACHE_OC_ADDRESS_ARRAY;
+               int i, n;
 
                /* Loop all the D-cache */
-               flush_cache_4096(CACHE_OC_ADDRESS_ARRAY,          phys);
-               flush_cache_4096(CACHE_OC_ADDRESS_ARRAY | 0x1000, phys);
-               flush_cache_4096(CACHE_OC_ADDRESS_ARRAY | 0x2000, phys);
-               flush_cache_4096(CACHE_OC_ADDRESS_ARRAY | 0x3000, phys);
+               n = cpu_data->dcache.n_aliases;
+               for (i = 0; i < n; i++, addr += 4096)
+                       flush_cache_4096(addr, phys);
        }
+
+       wmb();
 }
 
+/* TODO: Selective icache invalidation through IC address array.. */
 static inline void flush_icache_all(void)
 {
        unsigned long flags, ccr;
@@ -237,16 +266,19 @@ static inline void flush_icache_all(void)
        ccr |= CCR_CACHE_ICI;
        ctrl_outl(ccr, CCR);
 
+       /*
+        * back_to_P1() will take care of the barrier for us, don't add
+        * another one!
+        */
+
        back_to_P1();
        local_irq_restore(flags);
 }
 
 void flush_dcache_all(void)
 {
-       if (cpu_data->dcache.ways == 1)
-               __flush_dcache_all();
-       else
-               __flush_dcache_all_ex();
+       (*__flush_dcache_segment_fn)(0UL, cpu_data->dcache.way_size);
+       wmb();
 }
 
 void flush_cache_all(void)
@@ -255,9 +287,121 @@ void flush_cache_all(void)
        flush_icache_all();
 }
 
+static void __flush_cache_mm(struct mm_struct *mm, unsigned long start,
+                            unsigned long end)
+{
+       unsigned long d = 0, p = start & PAGE_MASK;
+       unsigned long alias_mask = cpu_data->dcache.alias_mask;
+       unsigned long n_aliases = cpu_data->dcache.n_aliases;
+       unsigned long select_bit;
+       unsigned long all_aliases_mask;
+       unsigned long addr_offset;
+       pgd_t *dir;
+       pmd_t *pmd;
+       pud_t *pud;
+       pte_t *pte;
+       int i;
+
+       dir = pgd_offset(mm, p);
+       pud = pud_offset(dir, p);
+       pmd = pmd_offset(pud, p);
+       end = PAGE_ALIGN(end);
+
+       all_aliases_mask = (1 << n_aliases) - 1;
+
+       do {
+               if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) {
+                       p &= PMD_MASK;
+                       p += PMD_SIZE;
+                       pmd++;
+
+                       continue;
+               }
+
+               pte = pte_offset_kernel(pmd, p);
+
+               do {
+                       unsigned long phys;
+                       pte_t entry = *pte;
+
+                       if (!(pte_val(entry) & _PAGE_PRESENT)) {
+                               pte++;
+                               p += PAGE_SIZE;
+                               continue;
+                       }
+
+                       phys = pte_val(entry) & PTE_PHYS_MASK;
+
+                       if ((p ^ phys) & alias_mask) {
+                               d |= 1 << ((p & alias_mask) >> PAGE_SHIFT);
+                               d |= 1 << ((phys & alias_mask) >> PAGE_SHIFT);
+
+                               if (d == all_aliases_mask)
+                                       goto loop_exit;
+                       }
+
+                       pte++;
+                       p += PAGE_SIZE;
+               } while (p < end && ((unsigned long)pte & ~PAGE_MASK));
+               pmd++;
+       } while (p < end);
+
+loop_exit:
+       addr_offset = 0;
+       select_bit = 1;
+
+       for (i = 0; i < n_aliases; i++) {
+               if (d & select_bit) {
+                       (*__flush_dcache_segment_fn)(addr_offset, PAGE_SIZE);
+                       wmb();
+               }
+
+               select_bit <<= 1;
+               addr_offset += PAGE_SIZE;
+       }
+}
+
+/*
+ * Note : (RPC) since the caches are physically tagged, the only point
+ * of flush_cache_mm for SH-4 is to get rid of aliases from the
+ * D-cache.  The assumption elsewhere, e.g. flush_cache_range, is that
+ * lines can stay resident so long as the virtual address they were
+ * accessed with (hence cache set) is in accord with the physical
+ * address (i.e. tag).  It's no different here.  So I reckon we don't
+ * need to flush the I-cache, since aliases don't matter for that.  We
+ * should try that.
+ *
+ * Caller takes mm->mmap_sem.
+ */
 void flush_cache_mm(struct mm_struct *mm)
 {
-       flush_cache_all();
+       /*
+        * If cache is only 4k-per-way, there are never any 'aliases'.  Since
+        * the cache is physically tagged, the data can just be left in there.
+        */
+       if (cpu_data->dcache.n_aliases == 0)
+               return;
+
+       /*
+        * Don't bother groveling around the dcache for the VMA ranges
+        * if there are too many PTEs to make it worthwhile.
+        */
+       if (mm->nr_ptes >= MAX_DCACHE_PAGES)
+               flush_dcache_all();
+       else {
+               struct vm_area_struct *vma;
+
+               /*
+                * In this case there are reasonably sized ranges to flush,
+                * iterate through the VMA list and take care of any aliases.
+                */
+               for (vma = mm->mmap; vma; vma = vma->vm_next)
+                       __flush_cache_mm(mm, vma->vm_start, vma->vm_end);
+       }
+
+       /* Only touch the icache if one of the VMAs has VM_EXEC set. */
+       if (mm->exec_vm)
+               flush_icache_all();
 }
 
 /*
@@ -266,27 +410,40 @@ void flush_cache_mm(struct mm_struct *mm)
  * ADDR: Virtual Address (U0 address)
  * PFN: Physical page number
  */
-void flush_cache_page(struct vm_area_struct *vma, unsigned long address, unsigned long pfn)
+void flush_cache_page(struct vm_area_struct *vma, unsigned long address,
+                     unsigned long pfn)
 {
        unsigned long phys = pfn << PAGE_SHIFT;
+       unsigned int alias_mask;
+
+       alias_mask = cpu_data->dcache.alias_mask;
 
        /* We only need to flush D-cache when we have alias */
-       if ((address^phys) & CACHE_ALIAS) {
+       if ((address^phys) & alias_mask) {
                /* Loop 4K of the D-cache */
                flush_cache_4096(
-                       CACHE_OC_ADDRESS_ARRAY | (address & CACHE_ALIAS),
+                       CACHE_OC_ADDRESS_ARRAY | (address & alias_mask),
                        phys);
                /* Loop another 4K of the D-cache */
                flush_cache_4096(
-                       CACHE_OC_ADDRESS_ARRAY | (phys & CACHE_ALIAS),
+                       CACHE_OC_ADDRESS_ARRAY | (phys & alias_mask),
                        phys);
        }
 
-       if (vma->vm_flags & VM_EXEC)
-               /* Loop 4K (half) of the I-cache */
+       alias_mask = cpu_data->icache.alias_mask;
+       if (vma->vm_flags & VM_EXEC) {
+               /*
+                * Evict entries from the portion of the cache from which code
+                * may have been executed at this address (virtual).  There's
+                * no need to evict from the portion corresponding to the
+                * physical address as for the D-cache, because we know the
+                * kernel has never executed the code through its identity
+                * translation.
+                */
                flush_cache_4096(
-                       CACHE_IC_ADDRESS_ARRAY | (address & 0x1000),
+                       CACHE_IC_ADDRESS_ARRAY | (address & alias_mask),
                        phys);
+       }
 }
 
 /*
@@ -301,69 +458,31 @@ void flush_cache_page(struct vm_area_struct *vma, unsigned long address, unsigne
 void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
                       unsigned long end)
 {
-       unsigned long p = start & PAGE_MASK;
-       pgd_t *dir;
-       pmd_t *pmd;
-       pud_t *pud;
-       pte_t *pte;
-       pte_t entry;
-       unsigned long phys;
-       unsigned long d = 0;
+       /*
+        * If cache is only 4k-per-way, there are never any 'aliases'.  Since
+        * the cache is physically tagged, the data can just be left in there.
+        */
+       if (cpu_data->dcache.n_aliases == 0)
+               return;
 
        /*
         * Don't bother with the lookup and alias check if we have a
         * wide range to cover, just blow away the dcache in its
         * entirety instead. -- PFM.
         */
-       if (((end - start) >> PAGE_SHIFT) >= 64) {
+       if (((end - start) >> PAGE_SHIFT) >= MAX_DCACHE_PAGES)
                flush_dcache_all();
-
-               if (vma->vm_flags & VM_EXEC)
-                       flush_icache_all();
-
-               return;
-       }
-
-       dir = pgd_offset(vma->vm_mm, p);
-       pud = pud_offset(dir, p);
-       pmd = pmd_offset(pud, p);
-       end = PAGE_ALIGN(end);
-
-       do {
-               if (pmd_none(*pmd) || pmd_bad(*pmd)) {
-                       p &= ~((1 << PMD_SHIFT) -1);
-                       p += (1 << PMD_SHIFT);
-                       pmd++;
-                       continue;
-               }
-               pte = pte_offset_kernel(pmd, p);
-               do {
-                       entry = *pte;
-                       if ((pte_val(entry) & _PAGE_PRESENT)) {
-                               phys = pte_val(entry)&PTE_PHYS_MASK;
-                               if ((p^phys) & CACHE_ALIAS) {
-                                       d |= 1 << ((p & CACHE_ALIAS)>>12);
-                                       d |= 1 << ((phys & CACHE_ALIAS)>>12);
-                                       if (d == 0x0f)
-                                               goto loop_exit;
-                               }
-                       }
-                       pte++;
-                       p += PAGE_SIZE;
-               } while (p < end && ((unsigned long)pte & ~PAGE_MASK));
-               pmd++;
-       } while (p < end);
- loop_exit:
-       if (d & 1)
-               flush_cache_4096_all(0);
-       if (d & 2)
-               flush_cache_4096_all(0x1000);
-       if (d & 4)
-               flush_cache_4096_all(0x2000);
-       if (d & 8)
-               flush_cache_4096_all(0x3000);
-       if (vma->vm_flags & VM_EXEC)
+       else
+               __flush_cache_mm(vma->vm_mm, start, end);
+
+       if (vma->vm_flags & VM_EXEC) {
+               /*
+                * TODO: Is this required???  Need to look at how I-cache
+                * coherency is assured when new programs are loaded to see if
+                * this matters.
+                */
                flush_icache_all();
+       }
 }
 
 /*
@@ -377,5 +496,273 @@ void flush_icache_user_range(struct vm_area_struct *vma,
                             struct page *page, unsigned long addr, int len)
 {
        flush_cache_page(vma, addr, page_to_pfn(page));
+       mb();
+}
+
+/**
+ * __flush_cache_4096
+ *
+ * @addr:  address in memory mapped cache array
+ * @phys:  P1 address to flush (has to match tags if addr has 'A' bit
+ *         set i.e. associative write)
+ * @exec_offset: set to 0x20000000 if flush has to be executed from P2
+ *               region else 0x0
+ *
+ * The offset into the cache array implied by 'addr' selects the
+ * 'colour' of the virtual address range that will be flushed.  The
+ * operation (purge/write-back) is selected by the lower 2 bits of
+ * 'phys'.
+ */
+static void __flush_cache_4096(unsigned long addr, unsigned long phys,
+                              unsigned long exec_offset)
+{
+       int way_count;
+       unsigned long base_addr = addr;
+       struct cache_info *dcache;
+       unsigned long way_incr;
+       unsigned long a, ea, p;
+       unsigned long temp_pc;
+
+       dcache = &cpu_data->dcache;
+       /* Write this way for better assembly. */
+       way_count = dcache->ways;
+       way_incr = dcache->way_incr;
+
+       /*
+        * Apply exec_offset (i.e. branch to P2 if required.).
+        *
+        * FIXME:
+        *
+        *      If I write "=r" for the (temp_pc), it puts this in r6 hence
+        *      trashing exec_offset before it's been added on - why?  Hence
+        *      "=&r" as a 'workaround'
+        */
+       asm volatile("mov.l 1f, %0\n\t"
+                    "add   %1, %0\n\t"
+                    "jmp   @%0\n\t"
+                    "nop\n\t"
+                    ".balign 4\n\t"
+                    "1:  .long 2f\n\t"
+                    "2:\n" : "=&r" (temp_pc) : "r" (exec_offset));
+
+       /*
+        * We know there will be >=1 iteration, so write as do-while to avoid
+        * pointless nead-of-loop check for 0 iterations.
+        */
+       do {
+               ea = base_addr + PAGE_SIZE;
+               a = base_addr;
+               p = phys;
+
+               do {
+                       *(volatile unsigned long *)a = p;
+                       /*
+                        * Next line: intentionally not p+32, saves an add, p
+                        * will do since only the cache tag bits need to
+                        * match.
+                        */
+                       *(volatile unsigned long *)(a+32) = p;
+                       a += 64;
+                       p += 64;
+               } while (a < ea);
+
+               base_addr += way_incr;
+       } while (--way_count != 0);
 }
 
+/*
+ * Break the 1, 2 and 4 way variants of this out into separate functions to
+ * avoid nearly all the overhead of having the conditional stuff in the function
+ * bodies (+ the 1 and 2 way cases avoid saving any registers too).
+ */
+static void __flush_dcache_segment_1way(unsigned long start,
+                                       unsigned long extent_per_way)
+{
+       unsigned long orig_sr, sr_with_bl;
+       unsigned long base_addr;
+       unsigned long way_incr, linesz, way_size;
+       struct cache_info *dcache;
+       register unsigned long a0, a0e;
+
+       asm volatile("stc sr, %0" : "=r" (orig_sr));
+       sr_with_bl = orig_sr | (1<<28);
+       base_addr = ((unsigned long)&empty_zero_page[0]);
+
+       /*
+        * The previous code aligned base_addr to 16k, i.e. the way_size of all
+        * existing SH-4 D-caches.  Whilst I don't see a need to have this
+        * aligned to any better than the cache line size (which it will be
+        * anyway by construction), let's align it to at least the way_size of
+        * any existing or conceivable SH-4 D-cache.  -- RPC
+        */
+       base_addr = ((base_addr >> 16) << 16);
+       base_addr |= start;
+
+       dcache = &cpu_data->dcache;
+       linesz = dcache->linesz;
+       way_incr = dcache->way_incr;
+       way_size = dcache->way_size;
+
+       a0 = base_addr;
+       a0e = base_addr + extent_per_way;
+       do {
+               asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
+               asm volatile("movca.l r0, @%0\n\t"
+                            "ocbi @%0" : : "r" (a0));
+               a0 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "ocbi @%0" : : "r" (a0));
+               a0 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "ocbi @%0" : : "r" (a0));
+               a0 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "ocbi @%0" : : "r" (a0));
+               asm volatile("ldc %0, sr" : : "r" (orig_sr));
+               a0 += linesz;
+       } while (a0 < a0e);
+}
+
+static void __flush_dcache_segment_2way(unsigned long start,
+                                       unsigned long extent_per_way)
+{
+       unsigned long orig_sr, sr_with_bl;
+       unsigned long base_addr;
+       unsigned long way_incr, linesz, way_size;
+       struct cache_info *dcache;
+       register unsigned long a0, a1, a0e;
+
+       asm volatile("stc sr, %0" : "=r" (orig_sr));
+       sr_with_bl = orig_sr | (1<<28);
+       base_addr = ((unsigned long)&empty_zero_page[0]);
+
+       /* See comment under 1-way above */
+       base_addr = ((base_addr >> 16) << 16);
+       base_addr |= start;
+
+       dcache = &cpu_data->dcache;
+       linesz = dcache->linesz;
+       way_incr = dcache->way_incr;
+       way_size = dcache->way_size;
+
+       a0 = base_addr;
+       a1 = a0 + way_incr;
+       a0e = base_addr + extent_per_way;
+       do {
+               asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1" : :
+                            "r" (a0), "r" (a1));
+               a0 += linesz;
+               a1 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1" : :
+                            "r" (a0), "r" (a1));
+               a0 += linesz;
+               a1 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1" : :
+                            "r" (a0), "r" (a1));
+               a0 += linesz;
+               a1 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1" : :
+                            "r" (a0), "r" (a1));
+               asm volatile("ldc %0, sr" : : "r" (orig_sr));
+               a0 += linesz;
+               a1 += linesz;
+       } while (a0 < a0e);
+}
+
+static void __flush_dcache_segment_4way(unsigned long start,
+                                       unsigned long extent_per_way)
+{
+       unsigned long orig_sr, sr_with_bl;
+       unsigned long base_addr;
+       unsigned long way_incr, linesz, way_size;
+       struct cache_info *dcache;
+       register unsigned long a0, a1, a2, a3, a0e;
+
+       asm volatile("stc sr, %0" : "=r" (orig_sr));
+       sr_with_bl = orig_sr | (1<<28);
+       base_addr = ((unsigned long)&empty_zero_page[0]);
+
+       /* See comment under 1-way above */
+       base_addr = ((base_addr >> 16) << 16);
+       base_addr |= start;
+
+       dcache = &cpu_data->dcache;
+       linesz = dcache->linesz;
+       way_incr = dcache->way_incr;
+       way_size = dcache->way_size;
+
+       a0 = base_addr;
+       a1 = a0 + way_incr;
+       a2 = a1 + way_incr;
+       a3 = a2 + way_incr;
+       a0e = base_addr + extent_per_way;
+       do {
+               asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "movca.l r0, @%2\n\t"
+                            "movca.l r0, @%3\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1\n\t"
+                            "ocbi @%2\n\t"
+                            "ocbi @%3\n\t" : :
+                            "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+               a0 += linesz;
+               a1 += linesz;
+               a2 += linesz;
+               a3 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "movca.l r0, @%2\n\t"
+                            "movca.l r0, @%3\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1\n\t"
+                            "ocbi @%2\n\t"
+                            "ocbi @%3\n\t" : :
+                            "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+               a0 += linesz;
+               a1 += linesz;
+               a2 += linesz;
+               a3 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "movca.l r0, @%2\n\t"
+                            "movca.l r0, @%3\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1\n\t"
+                            "ocbi @%2\n\t"
+                            "ocbi @%3\n\t" : :
+                            "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+               a0 += linesz;
+               a1 += linesz;
+               a2 += linesz;
+               a3 += linesz;
+               asm volatile("movca.l r0, @%0\n\t"
+                            "movca.l r0, @%1\n\t"
+                            "movca.l r0, @%2\n\t"
+                            "movca.l r0, @%3\n\t"
+                            "ocbi @%0\n\t"
+                            "ocbi @%1\n\t"
+                            "ocbi @%2\n\t"
+                            "ocbi @%3\n\t" : :
+                            "r" (a0), "r" (a1), "r" (a2), "r" (a3));
+               asm volatile("ldc %0, sr" : : "r" (orig_sr));
+               a0 += linesz;
+               a1 += linesz;
+               a2 += linesz;
+               a3 += linesz;
+       } while (a0 < a0e);
+}