[PATCH 19/21] ARM: dma-mapping: use generic form of arch_sync_dma_* helpers

[Arnd Bergmann]

From: Arnd Bergmann <a...@arndb.de>

As the final step of the conversion to generic arch_sync_dma_*
helpers, change the Arm implementation to look the same as the
new generic version, by calling the dmac_{clean,inv,flush}_area
low-level functions instead of the abstracted dmac_{map,unmap}_area
version.

On ARMv6/v7, this invalidates the caches after a DMA transfer from
a device because of speculative prefetching, while on earlier versions
it only needs to do this before the transfer.

This should not change any of the current behavior.

FIXME: address CONFIG_DMA_CACHE_RWFO properly.

Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
 arch/arm/mm/dma-mapping-nommu.c | 11 +++----
 arch/arm/mm/dma-mapping.c       | 53 +++++++++++++++++++++++----------
 2 files changed, 43 insertions(+), 21 deletions(-)

diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
index cfd9c933d2f0..12b5c6ae93fc 100644
--- a/arch/arm/mm/dma-mapping-nommu.c
+++ b/arch/arm/mm/dma-mapping-nommu.c
@@ -16,12 +16,13 @@
 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
 {
-       dmac_map_area(__va(paddr), size, dir);
-
-       if (dir == DMA_FROM_DEVICE)
+       if (dir == DMA_FROM_DEVICE) {
+               dmac_inv_range(__va(paddr), __va(paddr + size));
                outer_inv_range(paddr, paddr + size);
-       else
+       } else {
+               dmac_clean_range(__va(paddr), __va(paddr + size));
                outer_clean_range(paddr, paddr + size);
+       }
 }
 
 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
@@ -29,7 +30,7 @@ void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
 {
        if (dir != DMA_TO_DEVICE) {
                outer_inv_range(paddr, paddr + size);
-               dmac_unmap_area(__va(paddr), size, dir);
+               dmac_inv_range(__va(paddr), __va(paddr));
        }
 }
 
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index ce4b74f34a58..cc702cb27ae7 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -623,8 +623,7 @@ static void __arm_dma_free(struct device *dev, size_t size, 
void *cpu_addr,
 }
 
 static void dma_cache_maint(phys_addr_t paddr,
-       size_t size, enum dma_data_direction dir,
-       void (*op)(const void *, size_t, int))
+       size_t size, void (*op)(const void *, const void *))
 {
        unsigned long pfn = PFN_DOWN(paddr);
        unsigned long offset = paddr % PAGE_SIZE;
@@ -647,18 +646,18 @@ static void dma_cache_maint(phys_addr_t paddr,
 
                        if (cache_is_vipt_nonaliasing()) {
                                vaddr = kmap_atomic(page);
-                               op(vaddr + offset, len, dir);
+                               op(vaddr + offset, vaddr + offset + len);
                                kunmap_atomic(vaddr);
                        } else {
                                vaddr = kmap_high_get(page);
                                if (vaddr) {
-                                       op(vaddr + offset, len, dir);
+                                       op(vaddr + offset, vaddr + offset + 
len);
                                        kunmap_high(page);
                                }
                        }
                } else {
                        vaddr = page_address(page) + offset;
-                       op(vaddr, len, dir);
+                       op(vaddr, vaddr + len);
                }
                offset = 0;
                pfn++;
@@ -666,6 +665,18 @@ static void dma_cache_maint(phys_addr_t paddr,
        } while (left);
 }
 
+static bool arch_sync_dma_cpu_needs_post_dma_flush(void)
+{
+       if (IS_ENABLED(CONFIG_CPU_V6) ||
+           IS_ENABLED(CONFIG_CPU_V6K) ||
+           IS_ENABLED(CONFIG_CPU_V7) ||
+           IS_ENABLED(CONFIG_CPU_V7M))
+               return true;
+
+       /* FIXME: runtime detection */
+       return false;
+}
+
 /*
  * Make an area consistent for devices.
  * Note: Drivers should NOT use this function directly.
@@ -674,25 +685,35 @@ static void dma_cache_maint(phys_addr_t paddr,
 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
 {
-       dma_cache_maint(paddr, size, dir, dmac_map_area);
-
-       if (dir == DMA_FROM_DEVICE) {
-               outer_inv_range(paddr, paddr + size);
-       } else {
+       switch (dir) {
+       case DMA_TO_DEVICE:
+               dma_cache_maint(paddr, size, dmac_clean_range);
                outer_clean_range(paddr, paddr + size);
+               break;
+       case DMA_FROM_DEVICE:
+               dma_cache_maint(paddr, size, dmac_inv_range);
+               outer_inv_range(paddr, paddr + size);
+               break;
+       case DMA_BIDIRECTIONAL:
+               if (arch_sync_dma_cpu_needs_post_dma_flush()) {
+                       dma_cache_maint(paddr, size, dmac_clean_range);
+                       outer_clean_range(paddr, paddr + size);
+               } else {
+                       dma_cache_maint(paddr, size, dmac_flush_range);
+                       outer_flush_range(paddr, paddr + size);
+               }
+               break;
+       default:
+               break;
        }
-       /* FIXME: non-speculating: flush on bidirectional mappings? */
 }
 
 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
 {
-       /* FIXME: non-speculating: not required */
-       /* in any case, don't bother invalidating if DMA to device */
-       if (dir != DMA_TO_DEVICE) {
+       if (dir != DMA_TO_DEVICE && arch_sync_dma_cpu_needs_post_dma_flush()) {
                outer_inv_range(paddr, paddr + size);
-
-               dma_cache_maint(paddr, size, dir, dmac_unmap_area);
+               dma_cache_maint(paddr, size, dmac_inv_range);
        }
 
        /*
-- 
2.39.2