xtensa: enable HAVE_DMA_CONTIGUOUS

Enable HAVE_DMA_CONTIGUOUS, reserve contiguous memory at bootmem_init,
use dma_alloc_from_contiguous and dma_release_from_contiguous in
xtensa_dma_alloc/free.
This allows for big contiguous DMA buffer allocation from designated
area configured in the device tree.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Kconfig

@@ -15,6 +15,7 @@ config XTENSA
 	select GENERIC_SCHED_CLOCK
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_API_DEBUG
+	select HAVE_DMA_CONTIGUOUS
 	select HAVE_EXIT_THREAD
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUTEX_CMPXCHG if !MMU

arch/xtensa/include/asm/Kbuild

@@ -3,6 +3,7 @@ generic-y += bug.h
 generic-y += clkdev.h
 generic-y += cputime.h
 generic-y += div64.h
+generic-y += dma-contiguous.h
 generic-y += emergency-restart.h
 generic-y += errno.h
 generic-y += exec.h

arch/xtensa/kernel/pci-dma.c

@@ -15,6 +15,7 @@
  * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
  */
 
+#include <linux/dma-contiguous.h>
 #include <linux/gfp.h>
 #include <linux/highmem.h>
 #include <linux/mm.h>
@@ -146,6 +147,8 @@ static void *xtensa_dma_alloc(struct device *dev, size_t size,
 {
 	unsigned long ret;
 	unsigned long uncached = 0;
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	struct page *page = NULL;
 
 	/* ignore region speicifiers */
 
@@ -153,11 +156,18 @@ static void *xtensa_dma_alloc(struct device *dev, size_t size,
 
 	if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
 		flag |= GFP_DMA;
-	ret = (unsigned long)__get_free_pages(flag, get_order(size));
 
-	if (ret == 0)
+	if (gfpflags_allow_blocking(flag))
+		page = dma_alloc_from_contiguous(dev, count, get_order(size));
+
+	if (!page)
+		page = alloc_pages(flag, get_order(size));
+
+	if (!page)
 		return NULL;
 
+	ret = (unsigned long)page_address(page);
+
 	/* We currently don't support coherent memory outside KSEG */
 
 	BUG_ON(ret < XCHAL_KSEG_CACHED_VADDR ||
@@ -170,16 +180,19 @@ static void *xtensa_dma_alloc(struct device *dev, size_t size,
 	return (void *)uncached;
 }
 
-static void xtensa_dma_free(struct device *hwdev, size_t size, void *vaddr,
+static void xtensa_dma_free(struct device *dev, size_t size, void *vaddr,
 			    dma_addr_t dma_handle, unsigned long attrs)
 {
 	unsigned long addr = (unsigned long)vaddr +
 		XCHAL_KSEG_CACHED_VADDR - XCHAL_KSEG_BYPASS_VADDR;
+	struct page *page = virt_to_page(addr);
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
 	BUG_ON(addr < XCHAL_KSEG_CACHED_VADDR ||
 	       addr > XCHAL_KSEG_CACHED_VADDR + XCHAL_KSEG_SIZE - 1);
 
-	free_pages(addr, get_order(size));
+	if (!dma_release_from_contiguous(dev, page, count))
+		__free_pages(page, get_order(size));
 }
 
 static dma_addr_t xtensa_map_page(struct device *dev, struct page *page,

arch/xtensa/mm/init.c

@@ -26,6 +26,7 @@
 #include <linux/nodemask.h>
 #include <linux/mm.h>
 #include <linux/of_fdt.h>
+#include <linux/dma-contiguous.h>
 
 #include <asm/bootparam.h>
 #include <asm/page.h>
@@ -60,6 +61,7 @@ void __init bootmem_init(void)
 	max_low_pfn = min(max_pfn, MAX_LOW_PFN);
 
 	memblock_set_current_limit(PFN_PHYS(max_low_pfn));
+	dma_contiguous_reserve(PFN_PHYS(max_low_pfn));
 
 	memblock_dump_all();
 }