Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754036Ab2FMLws (ORCPT ); Wed, 13 Jun 2012 07:52:48 -0400 Received: from mailout2.samsung.com ([203.254.224.25]:26821 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753951Ab2FMLvQ (ORCPT ); Wed, 13 Jun 2012 07:51:16 -0400 X-AuditID: cbfee61b-b7fcc6d000003a7a-11-4fd87eab7d48 From: Marek Szyprowski To: linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Marek Szyprowski , Kyungmin Park , Arnd Bergmann , Russell King - ARM Linux , Chunsang Jeong , Krishna Reddy , Benjamin Herrenschmidt , Konrad Rzeszutek Wilk , Hiroshi Doyu , Subash Patel , Sumit Semwal , Abhinav Kochhar , Tomasz Stanislawski Subject: [PATCHv2 3/6] common: dma-mapping: introduce dma_get_sgtable() function Date: Wed, 13 Jun 2012 13:50:15 +0200 Message-id: <1339588218-24398-4-git-send-email-m.szyprowski@samsung.com> X-Mailer: git-send-email 1.7.10 In-reply-to: <1339588218-24398-1-git-send-email-m.szyprowski@samsung.com> References: <1339588218-24398-1-git-send-email-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrOJMWRmVeSWpSXmKPExsVy+t9jAd3VdTf8DV7d57To2PWVxeLyrjls DkwenzfJBTBGcdmkpOZklqUW6dslcGW0rn7JVnBMrmLXkzWsDYzLJbsYOTkkBEwkzvVPY4Kw xSQu3FvP1sXIxSEksIhRYtGyPhYIp4tJ4tv+J2wgVWwChhJdb7vAbBGBGYwSu/rSQIqYBfax SHRuPsHYxcjBISwQINF0jhWkhkVAVWL1j99g9bwCHhLLP+1mh9gmL/H0fh9YnFPAU+L3s31g VwgB1fyedph5AiPvAkaGVYyiqQXJBcVJ6blGesWJucWleel6yfm5mxjB3n8mvYNxVYPFIUYB DkYlHt4MYFAIsSaWFVfmHmKU4GBWEuF9lg0U4k1JrKxKLcqPLyrNSS0+xCjNwaIkzttkfcFf SCA9sSQ1OzW1ILUIJsvEwSnVwLhaXk+xsdxpS2XDrTDt5TO4TBunPm/s2XRY7078n7L83GXL jtrlWds9mthR8DxnYfv3C0knnh9Z/u+uiFRqlUFOnbuyc6X9kce7IpPWeV2uKFb7dNeEVfpo fHXdmbe/ZYqTVrxSnV5arRSzUmemyeLPUi2zdCuP3rIMbynNKNF/Lu8/uVRHWYmlOCPRUIu5 qDgRAK4V3U76AQAA X-TM-AS-MML: No Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4058 Lines: 102 This patch adds dma_get_sgtable() function which is required to let drivers to share the buffers allocated by DMA-mapping subsystem. Right now the driver gets a dma address of the allocated buffer and the kernel virtual mapping for it. If it wants to share it with other device (= map into its dma address space) it usually hacks around kernel virtual addresses to get pointers to pages or assumes that both devices share the DMA address space. Both solutions are just hacks for the special cases, which should be avoided in the final version of buffer sharing. To solve this issue in a generic way, a new call to DMA mapping has been introduced - dma_get_sgtable(). It allocates a scatter-list which describes the allocated buffer and lets the driver(s) to use it with other device(s) by calling dma_map_sg() on it. This patch provides a generic implementation based on virt_to_page() call. Architectures which require more sophisticated translation might provide their own get_sgtable() methods. Signed-off-by: Marek Szyprowski Reviewed-by: Kyungmin Park --- drivers/base/dma-mapping.c | 18 ++++++++++++++++++ include/asm-generic/dma-mapping-common.h | 18 ++++++++++++++++++ include/linux/dma-mapping.h | 3 +++ 3 files changed, 39 insertions(+), 0 deletions(-) diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index 6f3676f..49785c1 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -217,4 +217,22 @@ void dmam_release_declared_memory(struct device *dev) } EXPORT_SYMBOL(dmam_release_declared_memory); +/* + * Create scatter-list for the already allocated DMA buffer. + */ +int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt, + void *cpu_addr, dma_addr_t handle, size_t size) +{ + struct page *page = virt_to_page(cpu_addr); + int ret; + + ret = sg_alloc_table(sgt, 1, GFP_KERNEL); + if (unlikely(ret)) + return ret; + + sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0); + return 0; +} +EXPORT_SYMBOL(dma_common_get_sgtable); + #endif diff --git a/include/asm-generic/dma-mapping-common.h b/include/asm-generic/dma-mapping-common.h index 2e248d8..34841c6 100644 --- a/include/asm-generic/dma-mapping-common.h +++ b/include/asm-generic/dma-mapping-common.h @@ -176,4 +176,22 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, #define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, NULL) #define dma_unmap_sg(d, s, n, r) dma_unmap_sg_attrs(d, s, n, r, NULL) +int +dma_common_get_sgtable(struct device *dev, struct sg_table *sgt, + void *cpu_addr, dma_addr_t dma_addr, size_t size); + +static inline int +dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr, + dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs) +{ + struct dma_map_ops *ops = get_dma_ops(dev); + BUG_ON(!ops); + if (ops->get_sgtable) + return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size, + attrs); + return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr, size); +} + +#define dma_get_sgtable(d, t, v, h, s) dma_get_sgtable_attrs(d, t, v, h, s, NULL) + #endif diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index dfc099e..94af418 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -18,6 +18,9 @@ struct dma_map_ops { int (*mmap)(struct device *, struct vm_area_struct *, void *, dma_addr_t, size_t, struct dma_attrs *attrs); + int (*get_sgtable)(struct device *dev, struct sg_table *sgt, void *, + dma_addr_t, size_t, struct dma_attrs *attrs); + dma_addr_t (*map_page)(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, -- 1.7.1.569.g6f426 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/