Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756398AbcCaMbR (ORCPT ); Thu, 31 Mar 2016 08:31:17 -0400 Received: from down.free-electrons.com ([37.187.137.238]:42009 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754429AbcCaM3w (ORCPT ); Thu, 31 Mar 2016 08:29:52 -0400 From: Boris Brezillon To: David Woodhouse , Brian Norris , linux-mtd@lists.infradead.org, Andrew Morton , Dave Gordon Cc: Mark Brown , linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Vinod Koul , Dan Williams , dmaengine@vger.kernel.org, Mauro Carvalho Chehab , Hans Verkuil , Laurent Pinchart , linux-media@vger.kernel.org, Boris Brezillon , Richard Weinberger , Herbert Xu , "David S. Miller" , linux-crypto@vger.kernel.org, Vignesh R , linux-mm@kvack.org, Joerg Roedel , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH 4/4] mtd: provide helper to prepare buffers for DMA operations Date: Thu, 31 Mar 2016 14:29:44 +0200 Message-Id: <1459427384-21374-5-git-send-email-boris.brezillon@free-electrons.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1459427384-21374-1-git-send-email-boris.brezillon@free-electrons.com> References: <1459427384-21374-1-git-send-email-boris.brezillon@free-electrons.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4151 Lines: 133 Some NAND controller drivers are making use of DMA to transfer data from the controller to the buffer passed by the MTD user. Provide a generic mtd_map/unmap_buf() implementation to avoid open coded (and sometime erroneous) implementations. Signed-off-by: Boris Brezillon --- drivers/mtd/mtdcore.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/mtd/mtd.h | 25 +++++++++++++++++++ 2 files changed, 91 insertions(+) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 3096251..4c20f33 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -1253,6 +1253,72 @@ void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size) } EXPORT_SYMBOL_GPL(mtd_kmalloc_up_to); +#ifdef CONFIG_HAS_DMA +/** + * mtd_map_buf - create an SG table and prepare it for DMA operations + * + * @mtd: mtd device description object pointer + * @dev: device handling the DMA operation + * @buf: buf used to create the SG table + * @len: length of buf + * @constraints: optional constraints to take into account when creating + * the SG table. Can be NULL if no specific constraints + * are required. + * @dir: direction of the DMA operation + * + * This function should be used when an MTD driver wants to do DMA operations + * on a buffer passed by the MTD layer. This functions takes care of + * vmallocated buffer constraints, and return and sg_table that you can safely + * use. + */ +int mtd_map_buf(struct mtd_info *mtd, struct device *dev, + struct sg_table *sgt, const void *buf, size_t len, + const struct sg_constraints *constraints, + enum dma_data_direction dir) +{ + int ret; + + ret = sg_alloc_table_from_buf(sgt, buf, len, constraints, GFP_KERNEL); + if (ret) + return ret; + + ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir); + if (!ret) + ret = -ENOMEM; + + if (ret < 0) { + sg_free_table(sgt); + return ret; + } + + sgt->nents = ret; + + return 0; +} +EXPORT_SYMBOL_GPL(mtd_map_buf); + +/** + * mtd_unmap_buf - unmap an SG table and release its resources + * + * @mtd: mtd device description object pointer + * @dev: device handling the DMA operation + * @sgt: SG table + * @dir: direction of the DMA operation + * + * This function unmaps a previously mapped SG table and release SG table + * resources. Should be called when your DMA operation is done. + */ +void mtd_unmap_buf(struct mtd_info *mtd, struct device *dev, + struct sg_table *sgt, enum dma_data_direction dir) +{ + if (sgt->orig_nents) { + dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir); + sg_free_table(sgt); + } +} +EXPORT_SYMBOL_GPL(mtd_unmap_buf); +#endif /* !CONFIG_HAS_DMA */ + #ifdef CONFIG_PROC_FS /*====================================================================*/ diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index 7712721..15cff85 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -24,6 +24,7 @@ #include #include #include +#include #include @@ -410,6 +411,30 @@ extern void register_mtd_user (struct mtd_notifier *new); extern int unregister_mtd_user (struct mtd_notifier *old); void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size); +#ifdef CONFIG_HAS_DMA +int mtd_map_buf(struct mtd_info *mtd, struct device *dev, + struct sg_table *sgt, const void *buf, size_t len, + const struct sg_constraints *constraints, + enum dma_data_direction dir); +void mtd_unmap_buf(struct mtd_info *mtd, struct device *dev, + struct sg_table *sgt, enum dma_data_direction dir); +#else +static inline int mtd_map_buf(struct mtd_info *mtd, struct device *dev, + struct sg_table *sgt, const void *buf, + size_t len, + const struct sg_constraints *constraints + enum dma_data_direction dir) +{ + return -ENOTSUPP; +} + +static void mtd_unmap_buf(struct mtd_info *mtd, struct device *dev, + struct sg_table *sgt, enum dma_data_direction dir) +{ + return -ENOTSUPP; +} +#endif + void mtd_erase_callback(struct erase_info *instr); static inline int mtd_is_bitflip(int err) { -- 2.5.0