MIPS: Support per-device DMA coherence
On some MIPS systems, a subset of devices may have DMA coherent with CPU
caches. For example in systems including a MIPS I/O Coherence Unit
(IOCU), some devices may be connected to that IOCU whilst others are
not.
Prior to this patch, we have a plat_device_is_coherent() function but no
implementation which does anything besides return a global true or
false, optionally chosen at runtime. For devices such as those described
above this is insufficient.
Fix this by tracking DMA coherence on a per-device basis with a
dma_coherent field in struct dev_archdata. Setting this from
arch_setup_dma_ops() takes care of devices which set the dma-coherent
property via device tree, and any PCI devices beneath a bridge described
in DT, automatically.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14349/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 78ac033..88cfaf8 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -1935,8 +1935,12 @@
__local_flush_icache_user_range = local_r4k_flush_icache_user_range;
#if defined(CONFIG_DMA_NONCOHERENT) || defined(CONFIG_DMA_MAYBE_COHERENT)
+# if defined(CONFIG_DMA_PERDEV_COHERENT)
+ if (0) {
+# else
if ((coherentio == IO_COHERENCE_ENABLED) ||
((coherentio == IO_COHERENCE_DEFAULT) && hw_coherentio)) {
+# endif
_dma_cache_wback_inv = (void *)cache_noop;
_dma_cache_wback = (void *)cache_noop;
_dma_cache_inv = (void *)cache_noop;
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 7ae4c55..46d5696 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -24,7 +24,7 @@
#include <dma-coherence.h>
-#ifdef CONFIG_DMA_MAYBE_COHERENT
+#if defined(CONFIG_DMA_MAYBE_COHERENT) && !defined(CONFIG_DMA_PERDEV_COHERENT)
/* User defined DMA coherency from command line. */
enum coherent_io_user_state coherentio = IO_COHERENCE_DEFAULT;
EXPORT_SYMBOL_GPL(coherentio);