ARM: integrate CMA with DMA-mapping subsystem

This patch adds support for CMA to dma-mapping subsystem for ARM
architecture. By default a global CMA area is used, but specific devices
are allowed to have their private memory areas if required (they can be
created with dma_declare_contiguous() function during board
initialisation).

Contiguous memory areas reserved for DMA are remapped with 2-level page
tables on boot. Once a buffer is requested, a low memory kernel mapping
is updated to to match requested memory access type.

GFP_ATOMIC allocations are performed from special pool which is created
early during boot. This way remapping page attributes is not needed on
allocation time.

CMA has been enabled unconditionally for ARMv6+ systems.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 8f5813bbffb5..c21d06c7dd7e 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -20,6 +20,7 @@
 #include <linux/highmem.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
+#include <linux/dma-contiguous.h>
 
 #include <asm/mach-types.h>
 #include <asm/memblock.h>
@@ -226,6 +227,17 @@ static void __init arm_adjust_dma_zone(unsigned long *size, unsigned long *hole,
 }
 #endif
 
+void __init setup_dma_zone(struct machine_desc *mdesc)
+{
+#ifdef CONFIG_ZONE_DMA
+        if (mdesc->dma_zone_size) {
+                arm_dma_zone_size = mdesc->dma_zone_size;
+                arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
+        } else
+                arm_dma_limit = 0xffffffff;
+#endif
+}
+
 static void __init arm_bootmem_free(unsigned long min, unsigned long max_low,
         unsigned long max_high)
 {
@@ -273,12 +285,9 @@ static void __init arm_bootmem_free(unsigned long min, unsigned long max_low,
          * Adjust the sizes according to any special requirements for
          * this machine type.
          */
-        if (arm_dma_zone_size) {
+        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);
@@ -364,6 +373,12 @@ void __init arm_memblock_init(struct meminfo *mi, struct machine_desc *mdesc)
         if (mdesc->reserve)
                 mdesc->reserve();
 
+        /*
+         * reserve memory for DMA contigouos allocations,
+         * must come from DMA area inside low memory
+         */
+        dma_contiguous_reserve(min(arm_dma_limit, arm_lowmem_limit));
+
         arm_memblock_steal_permitted = false;
         memblock_allow_resize();
         memblock_dump_all();