ARM: change ARM_DMA_ZONE_SIZE into a variable

Having this value defined at compile time prevents multiple machines with
conflicting definitions to coexist.  Move it to a variable in preparation
for having a per machine value selected at run time.  This is relevant
only when CONFIG_ZONE_DMA is selected.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>

2 files changed, 22 insertions, 12 deletions

diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index 42005542932..fcf15de8cad 100644
--- a/arch/arm/include/asm/dma.h
+++ b/arch/arm/include/asm/dma.h
@@ -6,10 +6,13 @@
 /*
  * This is the maximum virtual address which can be DMA'd from.
  */
-#ifndef ARM_DMA_ZONE_SIZE
-#define MAX_DMA_ADDRESS 0xffffffff
+#ifndef CONFIG_ZONE_DMA
+#define MAX_DMA_ADDRESS 0xffffffffUL
 #else
-#define MAX_DMA_ADDRESS (PAGE_OFFSET + ARM_DMA_ZONE_SIZE)
+#define MAX_DMA_ADDRESS ({ \
+        extern unsigned long arm_dma_zone_size; \
+        arm_dma_zone_size ? \
+                (PAGE_OFFSET + arm_dma_zone_size) : 0xffffffffUL; })
 #endif
 
 #ifdef CONFIG_ISA_DMA_API
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 17d6cd0c57e..4a8a01e0c3a 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -28,6 +28,7 @@
 #include <asm/sizes.h>
 #include <asm/tlb.h>
 #include <asm/fixmap.h>
+#include <asm/memory.h>
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
@@ -212,6 +213,14 @@ static void __init arm_bootmem_init(unsigned long start_pfn,
 }
 
 #ifdef CONFIG_ZONE_DMA
+
+#ifdef ARM_DMA_ZONE_SIZE
+unsigned long arm_dma_zone_size = ARM_DMA_ZONE_SIZE;
+#else
+unsigned long arm_dma_zone_size __read_mostly;
+#endif
+EXPORT_SYMBOL(arm_dma_zone_size);
+
 /*
  * The DMA mask corresponding to the maximum bus address allocatable
  * using GFP_DMA.  The default here places no restriction on DMA
@@ -275,19 +284,17 @@ static void __init arm_bootmem_free(unsigned long min, unsigned long max_low,
 #endif
         }
 
-#ifdef ARM_DMA_ZONE_SIZE
-#ifndef CONFIG_ZONE_DMA
-#error ARM_DMA_ZONE_SIZE set but no DMA zone to limit allocations
-#endif
-
+#ifdef CONFIG_ZONE_DMA
         /*
          * Adjust the sizes according to any special requirements for
          * this machine type.
          */
-        arm_adjust_dma_zone(zone_size, zhole_size,
-                ARM_DMA_ZONE_SIZE >> PAGE_SHIFT);
-
-        arm_dma_limit = PHYS_OFFSET + ARM_DMA_ZONE_SIZE - 1;
+        if (arm_dma_zone_size) {
+                arm_adjust_dma_zone(zone_size, zhole_size,
+                        arm_dma_zone_size >> PAGE_SHIFT);
+                arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
+        } else
+                arm_dma_limit = 0xffffffff;
 #endif
 
         free_area_init_node(0, zone_size, min, zhole_size);