Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751909AbaFAHKt (ORCPT ); Sun, 1 Jun 2014 03:10:49 -0400 Received: from si-002-i45.relay.mailchannels.net ([184.154.112.210]:16859 "EHLO relay.mailchannels.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751107AbaFAHKr (ORCPT ); Sun, 1 Jun 2014 03:10:47 -0400 X-Sender-Id: totalchoicehosting|x-authuser|billaue X-Sender-Id: totalchoicehosting|x-authuser|billaue X-MC-Relay: Neutral X-MailChannels-SenderId: totalchoicehosting%7Cx-authuser%7Cbillaue X-MailChannels-Auth-Id: totalchoicehosting From: Eli Billauer To: tj@kernel.org Cc: devel@driverdev.osuosl.org, gregkh@linuxfoundation.org, bhelgaas@google.com, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, shuah.kh@samsung.com, iommu@lists.linux-foundation.org, discuss@x86-64.org, Eli Billauer Subject: [PATCH v2 1/4] dma-mapping: Add devm_ interface for dma_map_single() Date: Sun, 1 Jun 2014 10:01:14 +0300 Message-Id: <1401606077-1739-2-git-send-email-eli.billauer@gmail.com> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1401606077-1739-1-git-send-email-eli.billauer@gmail.com> References: <1401606077-1739-1-git-send-email-eli.billauer@gmail.com> X-AuthUser: billaue Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org dmam_map_single() and dmam_unmap_single() are the managed counterparts for the respective dma_* functions. Note that dmam_map_single() returns a status value rather than the DMA handle. The DMA handle is passed to the caller through a pointer in the arguments. The reason for this API change is that dmam_map_single() allocates memory, which may fail even if the DMA mapping is successful. On the other hand, it seems like there's no platform-independent value for dma_handle that can be used to indicate an error. This leaves dmam_map_single() with no safe way to tell its caller that the memory allocation has failed, except for returning a status as an int. Trying to keep close to the non-devres API could also tempt programmers into using dma_mapping_error() on the dmam_* functions. This would work incorrectly on platforms, for which dma_mapping_error() ignores its argument, and always returns success. Thanks to Tejun Heo for suggesting this API. Signed-off-by: Eli Billauer --- Documentation/driver-model/devres.txt | 2 + drivers/base/dma-mapping.c | 86 +++++++++++++++++++++++++++++++++ include/linux/dma-mapping.h | 6 ++- 3 files changed, 93 insertions(+), 1 deletions(-) diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt index e1a2707..13b8be0 100644 --- a/Documentation/driver-model/devres.txt +++ b/Documentation/driver-model/devres.txt @@ -266,6 +266,8 @@ DMA dmam_declare_coherent_memory() dmam_pool_create() dmam_pool_destroy() + dmam_map_single() + dmam_unmap_single() PCI pcim_enable_device() : after success, all PCI ops become managed diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index 0ce39a3..f76ea0f 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -19,6 +19,7 @@ struct dma_devres { size_t size; void *vaddr; dma_addr_t dma_handle; + enum dma_data_direction direction; }; static void dmam_coherent_release(struct device *dev, void *res) @@ -267,3 +268,88 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, return ret; } EXPORT_SYMBOL(dma_common_mmap); + +static int dmam_map_match(struct device *dev, void *res, void *match_data) +{ + struct dma_devres *this = res, *match = match_data; + + if (this->dma_handle == match->dma_handle) { + WARN_ON(this->size != match->size || + this->direction != match->direction); + return 1; + } + return 0; +} + +static void dmam_map_single_release(struct device *dev, void *res) +{ + struct dma_devres *this = res; + + dma_unmap_single(dev, this->dma_handle, this->size, this->direction); +} + +/** + * dmam_map_single - Managed dma_map_single() + * @dev: Device to map DMA region for + * @ptr: Pointer to region + * @size: Size to map + * @direction: The mapping's direction + * @ret_dma_handle: Pointer to return the value of the DMA handle + * + * Managed dma_map_single(). The region mapped using this + * function will be automatically unmapped on driver detach. + * + * RETURNED VALUE: + * 0 is returned on success + * -EIO if the DMA mapping failed + * -ENOMEM on failure to allocate memory for internal data structure + */ +int dmam_map_single(struct device *dev, void *ptr, size_t size, + enum dma_data_direction direction, + dma_addr_t *ret_dma_handle) + +{ + struct dma_devres *dr; + dma_addr_t dma_handle; + + dr = devres_alloc(dmam_map_single_release, sizeof(*dr), GFP_KERNEL); + if (!dr) + return -ENOMEM; + + dma_handle = dma_map_single(dev, ptr, size, direction); + if (dma_mapping_error(dev, dma_handle)) { + devres_free(dr); + return -EIO; + } + + *ret_dma_handle = dma_handle; + + dr->vaddr = ptr; + dr->dma_handle = dma_handle; + dr->size = size; + dr->direction = direction; + + devres_add(dev, dr); + + return 0; /* Success */ +} +EXPORT_SYMBOL(dmam_map_single); + +/** + * dmam_unmap_single - Managed dma_unmap_single() + * @dev: Device to map DMA region for + * @dma_handle: DMA handle of the region to unmap + * @size: Size to unmap + * @direction: The mapping's direction + * + * Managed dma_unmap_single(). + */ +void dmam_unmap_single(struct device *dev, dma_addr_t dma_handle, + size_t size, enum dma_data_direction direction) +{ + struct dma_devres match_data = { size, NULL, dma_handle, direction }; + + WARN_ON(devres_release(dev, dmam_map_single_release, dmam_map_match, + &match_data)); +} +EXPORT_SYMBOL(dmam_unmap_single); diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index fd4aee2..cad63de 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -233,7 +233,11 @@ static inline void dmam_release_declared_memory(struct device *dev) { } #endif /* ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY */ - +int dmam_map_single(struct device *dev, void *ptr, size_t size, + enum dma_data_direction direction, + dma_addr_t *ret_dma_handle); +void dmam_unmap_single(struct device *dev, dma_addr_t dma_handle, + size_t size, enum dma_data_direction direction); #ifndef CONFIG_HAVE_DMA_ATTRS struct dma_attrs; -- 1.7.2.3 -- 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/