[ARM] Feroceon: add highmem support to L2 cache handling code

The choice is between looping over the physical range and performing
single cache line operations, or to map highmem pages somewhere, as
cache range ops are possible only on virtual addresses.

Because L2 range ops are much faster, we go with the later by factoring
the physical-to-virtual address conversion and use a fixmap entry for it
in the HIGHMEM case.

Possible future optimizations to avoid the pte setup cost:

 - do the pte setup for highmem pages only

 - determine a threshold for doing a line-by-line processing on physical
   addresses when the range is small

Signed-off-by: Nicolas Pitre <nico@marvell.com>

2 files changed, 38 insertions, 17 deletions

diff --git a/arch/arm/include/asm/kmap_types.h b/arch/arm/include/asm/kmap_types.h
index 45def13ee17a..d16ec97ec9a9 100644
--- a/arch/arm/include/asm/kmap_types.h
+++ b/arch/arm/include/asm/kmap_types.h
@@ -18,6 +18,7 @@ enum km_type {
         KM_IRQ1,
         KM_SOFTIRQ0,
         KM_SOFTIRQ1,
+        KM_L2_CACHE,
         KM_TYPE_NR
 };
 
diff --git a/arch/arm/mm/cache-feroceon-l2.c b/arch/arm/mm/cache-feroceon-l2.c
index 80cd207cbaea..d6dd83826f8a 100644
--- a/arch/arm/mm/cache-feroceon-l2.c
+++ b/arch/arm/mm/cache-feroceon-l2.c
@@ -14,8 +14,12 @@
 
 #include <linux/init.h>
 #include <asm/cacheflush.h>
+#include <asm/kmap_types.h>
+#include <asm/fixmap.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
 #include <plat/cache-feroceon-l2.h>
-
+#include "mm.h"
 
 /*
  * Low-level cache maintenance operations.
@@ -34,14 +38,36 @@
  * The range operations require two successive cp15 writes, in
  * between which we don't want to be preempted.
  */
+
+static inline unsigned long l2_start_va(unsigned long paddr)
+{
+#ifdef CONFIG_HIGHMEM
+        /*
+         * Let's do our own fixmap stuff in a minimal way here.
+         * Because range ops can't be done on physical addresses,
+         * we simply install a virtual mapping for it only for the
+         * TLB lookup to occur, hence no need to flush the untouched
+         * memory mapping.  This is protected with the disabling of
+         * interrupts by the caller.
+         */
+        unsigned long idx = KM_L2_CACHE + KM_TYPE_NR * smp_processor_id();
+        unsigned long vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+        set_pte_ext(TOP_PTE(vaddr), pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL), 0);
+        local_flush_tlb_kernel_page(vaddr);
+        return vaddr + (paddr & ~PAGE_MASK);
+#else
+        return __phys_to_virt(paddr);
+#endif
+}
+
 static inline void l2_clean_pa(unsigned long addr)
 {
         __asm__("mcr p15, 1, %0, c15, c9, 3" : : "r" (addr));
 }
 
-static inline void l2_clean_mva_range(unsigned long start, unsigned long end)
+static inline void l2_clean_pa_range(unsigned long start, unsigned long end)
 {
-        unsigned long flags;
+        unsigned long va_start, va_end, flags;
 
         /*
          * Make sure 'start' and 'end' reference the same page, as
@@ -51,17 +77,14 @@ static inline void l2_clean_mva_range(unsigned long start, unsigned long end)
         BUG_ON((start ^ end) >> PAGE_SHIFT);
 
         raw_local_irq_save(flags);
+        va_start = l2_start_va(start);
+        va_end = va_start + (end - start);
         __asm__("mcr p15, 1, %0, c15, c9, 4\n\t"
                 "mcr p15, 1, %1, c15, c9, 5"
-                : : "r" (start), "r" (end));
+                : : "r" (va_start), "r" (va_end));
         raw_local_irq_restore(flags);
 }
 
-static inline void l2_clean_pa_range(unsigned long start, unsigned long end)
-{
-        l2_clean_mva_range(__phys_to_virt(start), __phys_to_virt(end));
-}
-
 static inline void l2_clean_inv_pa(unsigned long addr)
 {
         __asm__("mcr p15, 1, %0, c15, c10, 3" : : "r" (addr));
@@ -72,9 +95,9 @@ static inline void l2_inv_pa(unsigned long addr)
         __asm__("mcr p15, 1, %0, c15, c11, 3" : : "r" (addr));
 }
 
-static inline void l2_inv_mva_range(unsigned long start, unsigned long end)
+static inline void l2_inv_pa_range(unsigned long start, unsigned long end)
 {
-        unsigned long flags;
+        unsigned long va_start, va_end, flags;
 
         /*
          * Make sure 'start' and 'end' reference the same page, as
@@ -84,17 +107,14 @@ static inline void l2_inv_mva_range(unsigned long start, unsigned long end)
         BUG_ON((start ^ end) >> PAGE_SHIFT);
 
         raw_local_irq_save(flags);
+        va_start = l2_start_va(start);
+        va_end = va_start + (end - start);
         __asm__("mcr p15, 1, %0, c15, c11, 4\n\t"
                 "mcr p15, 1, %1, c15, c11, 5"
-                : : "r" (start), "r" (end));
+                : : "r" (va_start), "r" (va_end));
         raw_local_irq_restore(flags);
 }
 
-static inline void l2_inv_pa_range(unsigned long start, unsigned long end)
-{
-        l2_inv_mva_range(__phys_to_virt(start), __phys_to_virt(end));
-}
-
 
 /*
  * Linux primitives.