xtensa: support DMA to high memory

- don't bugcheck if high memory page is passed to xtensa_map_page;
- turn empty dcache flush macros into functions so that they could be
  passed as function parameters;
- use kmap_atomic to map high memory pages for cache invalidation/
  flushing performed by xtensa_sync_single_for_{cpu,device}.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

diff --git a/arch/xtensa/include/asm/cacheflush.h b/arch/xtensa/include/asm/cacheflush.h
index 7158881..397d6a1 100644 (file)
--- a/arch/xtensa/include/asm/cacheflush.h
+++ b/arch/xtensa/include/asm/cacheflush.h
@@ -55,9 +55,14 @@ extern void __flush_dcache_range(unsigned long, unsigned long);
 extern void __flush_invalidate_dcache_page(unsigned long);
 extern void __flush_invalidate_dcache_range(unsigned long, unsigned long);
 #else
-# define __flush_dcache_range(p,s)             do { } while(0)
-# define __flush_dcache_page(p)                        do { } while(0)
-# define __flush_invalidate_dcache_page(p)     __invalidate_dcache_page(p)
+static inline void __flush_dcache_page(unsigned long va)
+{
+}
+static inline void __flush_dcache_range(unsigned long va, unsigned long sz)
+{
+}
+# define __flush_invalidate_dcache_all()       __invalidate_dcache_all()
+# define __flush_invalidate_dcache_page(p)     __invalidate_dcache_page(p)
 # define __flush_invalidate_dcache_range(p,s)  __invalidate_dcache_range(p,s)
 #endif
 

diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index fb75ebf..cd66698 100644 (file)
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -15,14 +15,15 @@
  * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
  */
 
-#include <linux/types.h>
-#include <linux/mm.h>
-#include <linux/string.h>
-#include <linux/pci.h>
 #include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
 #include <linux/module.h>
-#include <asm/io.h>
+#include <linux/pci.h>
+#include <linux/string.h>
+#include <linux/types.h>
 #include <asm/cacheflush.h>
+#include <asm/io.h>
 
 void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
                    enum dma_data_direction dir)
@@ -47,17 +48,36 @@ void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 }
 EXPORT_SYMBOL(dma_cache_sync);
 
+static void do_cache_op(dma_addr_t dma_handle, size_t size,
+                       void (*fn)(unsigned long, unsigned long))
+{
+       unsigned long off = dma_handle & (PAGE_SIZE - 1);
+       unsigned long pfn = PFN_DOWN(dma_handle);
+       struct page *page = pfn_to_page(pfn);
+
+       if (!PageHighMem(page))
+               fn((unsigned long)bus_to_virt(dma_handle), size);
+       else
+               while (size > 0) {
+                       size_t sz = min_t(size_t, size, PAGE_SIZE - off);
+                       void *vaddr = kmap_atomic(page);
+
+                       fn((unsigned long)vaddr + off, sz);
+                       kunmap_atomic(vaddr);
+                       off = 0;
+                       ++page;
+                       size -= sz;
+               }
+}
+
 static void xtensa_sync_single_for_cpu(struct device *dev,
                                       dma_addr_t dma_handle, size_t size,
                                       enum dma_data_direction dir)
 {
-       void *vaddr;
-
        switch (dir) {
        case DMA_BIDIRECTIONAL:
        case DMA_FROM_DEVICE:
-               vaddr = bus_to_virt(dma_handle);
-               __invalidate_dcache_range((unsigned long)vaddr, size);
+               do_cache_op(dma_handle, size, __invalidate_dcache_range);
                break;
 
        case DMA_NONE:
@@ -73,13 +93,11 @@ static void xtensa_sync_single_for_device(struct device *dev,
                                          dma_addr_t dma_handle, size_t size,
                                          enum dma_data_direction dir)
 {
-       void *vaddr;
-
        switch (dir) {
        case DMA_BIDIRECTIONAL:
        case DMA_TO_DEVICE:
-               vaddr = bus_to_virt(dma_handle);
-               __flush_dcache_range((unsigned long)vaddr, size);
+               if (XCHAL_DCACHE_IS_WRITEBACK)
+                       do_cache_op(dma_handle, size, __flush_dcache_range);
                break;
 
        case DMA_NONE:
@@ -171,7 +189,6 @@ static dma_addr_t xtensa_map_page(struct device *dev, struct page *page,
 {
        dma_addr_t dma_handle = page_to_phys(page) + offset;
 
-       BUG_ON(PageHighMem(page));
        xtensa_sync_single_for_device(dev, dma_handle, size, dir);
        return dma_handle;
 }