MIPS: DMA: Add cma support

Adds cma support to the MIPS architecture.

cma uses memblock. However, mips uses bootmem.
bootmem is informed about any regions reserved by memblock

dma api is modified to use cma reserved memory regions when available

Tested using cma_test. cma_test is a simple driver that assigns blocks
of memory from cma reserved sections.
Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: catalin.marinas@arm.com
Cc: will.deacon@arm.com
Cc: tglx@linutronix.de
Cc: mingo@redhat.com
Cc: hpa@zytor.com
Cc: arnd@arndb.de
Cc: gregkh@linuxfoundation.org
Cc: m.szyprowski@samsung.com
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-arch@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7360/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -29,6 +29,7 @@ config MIPS
 	select GENERIC_ATOMIC64 if !64BIT
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select HAVE_DMA_ATTRS
+	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DMA_API_DEBUG
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW

arch/mips/include/asm/Kbuild

 # MIPS headers
 generic-y += cputime.h
 generic-y += current.h
+generic-y += dma-contiguous.h
 generic-y += emergency-restart.h
 generic-y += hash.h
 generic-y += local64.h

arch/mips/kernel/setup.c

@@ -24,6 +24,8 @@
 #include <linux/debugfs.h>
 #include <linux/kexec.h>
 #include <linux/sizes.h>
+#include <linux/device.h>
+#include <linux/dma-contiguous.h>
 
 #include <asm/addrspace.h>
 #include <asm/bootinfo.h>
@@ -476,6 +478,7 @@ static void __init bootmem_init(void)
  *  o bootmem_init()
  *  o sparse_init()
  *  o paging_init()
+ *  o dma_continguous_reserve()
  *
  * At this stage the bootmem allocator is ready to use.
  *
@@ -609,6 +612,7 @@ static void __init request_crashkernel(struct resource *res)
 
 static void __init arch_mem_init(char **cmdline_p)
 {
+	struct memblock_region *reg;
 	extern void plat_mem_setup(void);
 
 	/* call board setup routine */
@@ -675,6 +679,11 @@ static void __init arch_mem_init(char **cmdline_p)
 	sparse_init();
 	plat_swiotlb_setup();
 	paging_init();
+
+	dma_contiguous_reserve(PFN_PHYS(max_low_pfn));
+	/* Tell bootmem about cma reserved memblock section */
+	for_each_memblock(reserved, reg)
+		reserve_bootmem(reg->base, reg->size, BOOTMEM_DEFAULT);
 }
 
 static void __init resource_init(void)

arch/mips/mm/dma-default.c

@@ -16,6 +16,7 @@
 #include <linux/string.h>
 #include <linux/gfp.h>
 #include <linux/highmem.h>
+#include <linux/dma-contiguous.h>
 
 #include <asm/cache.h>
 #include <asm/cpu-type.h>
@@ -128,23 +129,30 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size,
 	dma_addr_t * dma_handle, gfp_t gfp, struct dma_attrs *attrs)
 {
 	void *ret;
+	struct page *page = NULL;
+	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
 	if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
 		return ret;
 
 	gfp = massage_gfp_flags(dev, gfp);
 
-	ret = (void *) __get_free_pages(gfp, get_order(size));
-
-	if (ret) {
-		memset(ret, 0, size);
-		*dma_handle = plat_map_dma_mem(dev, ret, size);
-
-		if (!plat_device_is_coherent(dev)) {
-			dma_cache_wback_inv((unsigned long) ret, size);
-			if (!hw_coherentio)
-				ret = UNCAC_ADDR(ret);
-		}
+	if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC))
+		page = dma_alloc_from_contiguous(dev,
+					count, get_order(size));
+	if (!page)
+		page = alloc_pages(gfp, get_order(size));
+
+	if (!page)
+		return NULL;
+
+	ret = page_address(page);
+	memset(ret, 0, size);
+	*dma_handle = plat_map_dma_mem(dev, ret, size);
+	if (!plat_device_is_coherent(dev)) {
+		dma_cache_wback_inv((unsigned long) ret, size);
+		if (!hw_coherentio)
+			ret = UNCAC_ADDR(ret);
 	}
 
 	return ret;
@@ -164,6 +172,8 @@ static void mips_dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 {
 	unsigned long addr = (unsigned long) vaddr;
 	int order = get_order(size);
+	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	struct page *page = NULL;
 
 	if (dma_release_from_coherent(dev, order, vaddr))
 		return;
@@ -173,7 +183,10 @@ static void mips_dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 	if (!plat_device_is_coherent(dev) && !hw_coherentio)
 		addr = CAC_ADDR(addr);
 
-	free_pages(addr, get_order(size));
+	page = virt_to_page((void *) addr);
+
+	if (!dma_release_from_contiguous(dev, page, count))
+		__free_pages(page, get_order(size));
 }
 
 static inline void __dma_sync_virtual(void *addr, size_t size,