linux-kernel - Re: [PATCH v9 01/18] arm: make SWIOTLB available

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Date:	Wed, 30 Oct 2013 01:17:14 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	<xen-devel@...ts.xensource.com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <Ian.Campbell@...rix.com>,
	<will.deacon@....com>
Subject: Re: [PATCH v9 01/18] arm: make SWIOTLB available

On Tue, 29 Oct 2013, Russell King - ARM Linux wrote:
> So... what I'm saying is please fix xgmac to use the DMA API properly
> rather than working around such problems. :)
 
OK.
Would the appended patch fix your concerns?

---

arm: make SWIOTLB available

IOMMU_HELPER is needed because SWIOTLB calls iommu_is_span_boundary,
provided by lib/iommu_helper.c.

Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

Changes in v9:
- remove uneeded include asm/cacheflush.h;
- just return 0 if !dev->dma_mask in dma_capable.

---
 arch/arm/Kconfig                   |    6 ++++++
 arch/arm/include/asm/dma-mapping.h |   33 +++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1ad6fb6..b08374f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1872,6 +1872,12 @@ config CC_STACKPROTECTOR
 	  neutralized via a kernel panic.
 	  This feature requires gcc version 4.2 or above.
 
+config SWIOTLB
+	def_bool y
+
+config IOMMU_HELPER
+	def_bool SWIOTLB
+
 config XEN_DOM0
 	def_bool y
 	depends on XEN
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 5b579b9..1ad2c17 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -86,6 +86,39 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
 }
 #endif
 
+static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+	unsigned int offset = paddr & ~PAGE_MASK;
+	return pfn_to_dma(dev, __phys_to_pfn(paddr)) + offset;
+}
+
+static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
+{
+	unsigned int offset = dev_addr & ~PAGE_MASK;
+	return __pfn_to_phys(dma_to_pfn(dev, dev_addr)) + offset;
+}
+
+static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
+{
+	u64 limit, mask;
+
+	if (!dev->dma_mask)
+		return 0;
+
+	mask = *dev->dma_mask;
+
+	limit = (mask + 1) & ~mask;
+	if (limit && size > limit)
+		return 0;
+
+	if ((addr | (addr + size - 1)) & ~mask)
+		return 0;
+
+	return 1;
+}
+
+static inline void dma_mark_clean(void *addr, size_t size) { }
+
 /*
  * DMA errors are defined by all-bits-set in the DMA address.
  */
-- 
1.7.2.5

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