Commit 20d33064 authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
Browse files

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: default avatarPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14349/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent cfa93fb9

arch/mips/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -1099,6 +1099,10 @@ config DMA_MAYBE_COHERENT 
	select DMA_NONCOHERENT

	bool



config DMA_PERDEV_COHERENT

	bool

	select DMA_MAYBE_COHERENT



config DMA_COHERENT

	bool

arch/mips/include/asm/device.h

+5 −0
Original line number Diff line number Diff line
@@ -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 {

arch/mips/include/asm/dma-coherence.h

+3 −1
Original line number Diff line number Diff line
@@ -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

arch/mips/include/asm/dma-mapping.h

+10 −0
Original line number Diff line number Diff line
@@ -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 */

arch/mips/include/asm/mach-generic/dma-coherence.h

+4 −0
Original line number Diff line number Diff line
@@ -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

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