ARM: cache-l2x0: avoid taking spinlock for every iteration

Taking the spinlock for every iteration is very expensive; instead,
batch iterations up into 4K blocks, releasing and reacquiring the
spinlock between each block.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 52 insertions, 13 deletions

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index b480f1d3591f..c1b7bfff47f4 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -31,14 +31,10 @@ static DEFINE_SPINLOCK(l2x0_lock);
 static inline void sync_writel(unsigned long val, unsigned long reg,
                                unsigned long complete_mask)
 {
-        unsigned long flags;
-
-        spin_lock_irqsave(&l2x0_lock, flags);
         writel(val, l2x0_base + reg);
         /* wait for the operation to complete */
         while (readl(l2x0_base + reg) & complete_mask)
                 ;
-        spin_unlock_irqrestore(&l2x0_lock, flags);
 }
 
 static inline void cache_sync(void)
@@ -48,15 +44,20 @@ static inline void cache_sync(void)
 
 static inline void l2x0_inv_all(void)
 {
+        unsigned long flags;
+
         /* invalidate all ways */
+        spin_lock_irqsave(&l2x0_lock, flags);
         sync_writel(0xff, L2X0_INV_WAY, 0xff);
         cache_sync();
+        spin_unlock_irqrestore(&l2x0_lock, flags);
 }
 
 static void l2x0_inv_range(unsigned long start, unsigned long end)
 {
-        unsigned long addr;
+        unsigned long flags;
 
+        spin_lock_irqsave(&l2x0_lock, flags);
         if (start & (CACHE_LINE_SIZE - 1)) {
                 start &= ~(CACHE_LINE_SIZE - 1);
                 sync_writel(start, L2X0_CLEAN_INV_LINE_PA, 1);
@@ -68,29 +69,67 @@ static void l2x0_inv_range(unsigned long start, unsigned long end)
                 sync_writel(end, L2X0_CLEAN_INV_LINE_PA, 1);
         }
 
-        for (addr = start; addr < end; addr += CACHE_LINE_SIZE)
-                sync_writel(addr, L2X0_INV_LINE_PA, 1);
+        while (start < end) {
+                unsigned long blk_end = start + min(end - start, 4096UL);
+
+                while (start < blk_end) {
+                        sync_writel(start, L2X0_INV_LINE_PA, 1);
+                        start += CACHE_LINE_SIZE;
+                }
+
+                if (blk_end < end) {
+                        spin_unlock_irqrestore(&l2x0_lock, flags);
+                        spin_lock_irqsave(&l2x0_lock, flags);
+                }
+        }
         cache_sync();
+        spin_unlock_irqrestore(&l2x0_lock, flags);
 }
 
 static void l2x0_clean_range(unsigned long start, unsigned long end)
 {
-        unsigned long addr;
+        unsigned long flags;
 
+        spin_lock_irqsave(&l2x0_lock, flags);
         start &= ~(CACHE_LINE_SIZE - 1);
-        for (addr = start; addr < end; addr += CACHE_LINE_SIZE)
-                sync_writel(addr, L2X0_CLEAN_LINE_PA, 1);
+        while (start < end) {
+                unsigned long blk_end = start + min(end - start, 4096UL);
+
+                while (start < blk_end) {
+                        sync_writel(start, L2X0_CLEAN_LINE_PA, 1);
+                        start += CACHE_LINE_SIZE;
+                }
+
+                if (blk_end < end) {
+                        spin_unlock_irqrestore(&l2x0_lock, flags);
+                        spin_lock_irqsave(&l2x0_lock, flags);
+                }
+        }
         cache_sync();
+        spin_unlock_irqrestore(&l2x0_lock, flags);
 }
 
 static void l2x0_flush_range(unsigned long start, unsigned long end)
 {
-        unsigned long addr;
+        unsigned long flags;
 
+        spin_lock_irqsave(&l2x0_lock, flags);
         start &= ~(CACHE_LINE_SIZE - 1);
-        for (addr = start; addr < end; addr += CACHE_LINE_SIZE)
-                sync_writel(addr, L2X0_CLEAN_INV_LINE_PA, 1);
+        while (start < end) {
+                unsigned long blk_end = start + min(end - start, 4096UL);
+
+                while (start < blk_end) {
+                        sync_writel(start, L2X0_CLEAN_INV_LINE_PA, 1);
+                        start += CACHE_LINE_SIZE;
+                }
+
+                if (blk_end < end) {
+                        spin_unlock_irqrestore(&l2x0_lock, flags);
+                        spin_lock_irqsave(&l2x0_lock, flags);
+                }
+        }
         cache_sync();
+        spin_unlock_irqrestore(&l2x0_lock, flags);
 }
 
 void __init l2x0_init(void __iomem *base, __u32 aux_val, __u32 aux_mask)