drivers: dma-mapping: allow dma_common_mmap() for NOMMU

Currently, internals of dma_common_mmap() is compiled out if build is
done for either NOMMU or target which explicitly says it does not
have/want coherent DMA mmap. It turned out that dma_common_mmap() can
be handy in NOMMU setup (at least for ARM).

This patch converts exitent NOMMU targets to use ARCH_NO_COHERENT_DMA_MMAP,
thus when CONFIG_MMU is gone from dma_common_mmap() their behaviour stays
unchanged.

ARM is not converted to ARCH_NO_COHERENT_DMA_MMAP because it 1)
already has mmap callback which can handle (at some extent) NOMMU 2)
already defines dummy pgprot_noncached() for NOMMU build.

c6x and frv stay untouched since they already have ARCH_NO_COHERENT_DMA_MMAP.

Cc: Steven Miao <realmz6@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index 10e7c022e8cf..ce1e02b567c3 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -227,7 +227,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
                     void *cpu_addr, dma_addr_t dma_addr, size_t size)
 {
         int ret = -ENXIO;
-#if defined(CONFIG_MMU) && !defined(CONFIG_ARCH_NO_COHERENT_DMA_MMAP)
+#ifndef CONFIG_ARCH_NO_COHERENT_DMA_MMAP
         unsigned long user_count = vma_pages(vma);
         unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
         unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr));
@@ -244,7 +244,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
                                       user_count << PAGE_SHIFT,
                                       vma->vm_page_prot);
         }
-#endif  /* CONFIG_MMU && !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
+#endif  /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
 
         return ret;
 }