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@xxxxxxxxxx>
---
arch/mips/Kconfig | 4 ++++
arch/mips/include/asm/device.h | 5 +++++
arch/mips/include/asm/dma-coherence.h | 4 +++-
arch/mips/include/asm/dma-mapping.h | 10 ++++++++++
arch/mips/include/asm/mach-generic/dma-coherence.h | 4 ++++
arch/mips/mm/c-r4k.c | 4 ++++
arch/mips/mm/dma-default.c | 2 +-
7 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 6c5133f..49eb902 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1097,6 +1097,10 @@ config DMA_MAYBE_COHERENT
select DMA_NONCOHERENT
bool
+config DMA_PERDEV_COHERENT
+ bool
+ select DMA_MAYBE_COHERENT
+
config DMA_COHERENT
bool
diff --git a/arch/mips/include/asm/device.h b/arch/mips/include/asm/device.h
index c94fafb..21c2082 100644
--- a/arch/mips/include/asm/device.h
+++ b/arch/mips/include/asm/device.h
@@ -11,6 +11,11 @@ struct dma_map_ops;
struct dev_archdata {
/* DMA operations on that device */
struct dma_map_ops *dma_ops;
+
+#ifdef CONFIG_DMA_PERDEV_COHERENT
+ /* Non-zero if DMA is coherent with CPU caches */
+ bool dma_coherent;
+#endif
};
struct pdev_archdata {
diff --git a/arch/mips/include/asm/dma-coherence.h b/arch/mips/include/asm/dma-coherence.h
index 4fbce79..72d0eab 100644
--- a/arch/mips/include/asm/dma-coherence.h
+++ b/arch/mips/include/asm/dma-coherence.h
@@ -15,7 +15,9 @@ enum coherent_io_user_state {
IO_COHERENCE_DISABLED,
};
-#ifdef CONFIG_DMA_MAYBE_COHERENT
+#if defined(CONFIG_DMA_PERDEV_COHERENT)
+/* Don't provide (hw_)coherentio to avoid misuse */
+#elif defined(CONFIG_DMA_MAYBE_COHERENT)
extern enum coherent_io_user_state coherentio;
extern int hw_coherentio;
#else
diff --git a/arch/mips/include/asm/dma-mapping.h b/arch/mips/include/asm/dma-mapping.h
index 12fa79e..7aa71b9 100644
--- a/arch/mips/include/asm/dma-mapping.h
+++ b/arch/mips/include/asm/dma-mapping.h
@@ -32,4 +32,14 @@ static inline void dma_mark_clean(void *addr, size_t size) {}
extern void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
enum dma_data_direction direction);
+#define arch_setup_dma_ops arch_setup_dma_ops
+static inline void arch_setup_dma_ops(struct device *dev, u64 dma_base,
+ u64 size, const struct iommu_ops *iommu,
+ bool coherent)
+{
+#ifdef CONFIG_DMA_PERDEV_COHERENT
+ dev->archdata.dma_coherent = coherent;
+#endif
+}
+
#endif /* _ASM_DMA_MAPPING_H */
diff --git a/arch/mips/include/asm/mach-generic/dma-coherence.h b/arch/mips/include/asm/mach-generic/dma-coherence.h
index 8484f82..61addb1 100644
--- a/arch/mips/include/asm/mach-generic/dma-coherence.h
+++ b/arch/mips/include/asm/mach-generic/dma-coherence.h
@@ -49,6 +49,9 @@ static inline int plat_dma_supported(struct device *dev, u64 mask)
static inline int plat_device_is_coherent(struct device *dev)
{
+#ifdef CONFIG_DMA_PERDEV_COHERENT
+ return dev->archdata.dma_coherent;
+#else
switch (coherentio) {
default:
case IO_COHERENCE_DEFAULT:
@@ -58,6 +61,7 @@ static inline int plat_device_is_coherent(struct device *dev)
case IO_COHERENCE_DISABLED:
return 0;
}
+#endif
}
#ifndef plat_post_dma_flush
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index c48deab..7529096 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -1917,8 +1917,12 @@ void r4k_cache_init(void)
local_flush_icache_range = local_r4k_flush_icache_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 6540355..9f51ee8 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);
--
2.9.3
