From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29D41C43461 for ; Mon, 14 Sep 2020 15:04:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7175920732 for ; Mon, 14 Sep 2020 15:04:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="s2+O7HbR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7175920732 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E60B36B005C; Mon, 14 Sep 2020 11:04:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E0E0D6B0062; Mon, 14 Sep 2020 11:04:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CAF8C6B006C; Mon, 14 Sep 2020 11:04:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id B40816B005C for ; Mon, 14 Sep 2020 11:04:54 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4BCB9180ACC5F for ; Mon, 14 Sep 2020 15:04:54 +0000 (UTC) X-FDA: 77261989308.18.scent32_24091d727109 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id CF22A100EC697 for ; Mon, 14 Sep 2020 15:04:51 +0000 (UTC) X-HE-Tag: scent32_24091d727109 X-Filterd-Recvd-Size: 8941 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Mon, 14 Sep 2020 15:04:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=I03vZyMCQXixsKgB+vAi29QqwSDPgVkGV9+ViaS1CMg=; b=s2+O7HbRaaMGrNRetpOniwlx5p 4zrt8B58bME1ofMoXH7Bu9HYSWDUmdmcRgtceEr3NgHfL3XugiyB2tqRvEfFRwg27Lt0NYX9qh7P/ 0FfTh+Xxrd4rzkb7xmi89hmk+KzUg4UvLAGmV2YAv6yTLygrJ/K8XL3YOzs+bEp3rmhADdd2weYNo HHdR9RQfuZrvLOwnfbM7kdAvrnB+v5trSodoIhNTg6ZIEdjTqirpBGnMwcJur9gkuPCb0BBGS0TQP WKw6O4lbPPpAxWpm0XDzc3CqrgG22CYBXJwRxiHYzL48GpVzTVwp/++JkQ2X5YyOCSA58sk9iA7eh UEvO26Tg==; Received: from 089144214092.atnat0023.highway.a1.net ([89.144.214.92] helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHq1i-0002aX-Sy; Mon, 14 Sep 2020 15:04:19 +0000 From: Christoph Hellwig To: Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Ben Skeggs , Marek Szyprowski , Tomasz Figa , Matt Porter , iommu@lists.linux-foundation.org Cc: Stefan Richter , linux1394-devel@lists.sourceforge.net, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, netdev@vger.kernel.org, linux-scsi@vger.kernel.org, linux-mm@kvack.org, alsa-devel@alsa-project.org Subject: [PATCH 08/17] dma-mapping: add a new dma_alloc_noncoherent API Date: Mon, 14 Sep 2020 16:44:24 +0200 Message-Id: <20200914144433.1622958-9-hch@lst.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200914144433.1622958-1-hch@lst.de> References: <20200914144433.1622958-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: CF22A100EC697 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Add a new API to allocate and free memory that is guaranteed to be addressable by a device, but which potentially is not cache coherent for DMA. To transfer ownership to and from the device, the existing streaming DMA API calls dma_sync_single_for_device and dma_sync_single_for_cpu must be used. For now the new calls are implemented on top of dma_alloc_attrs just like the old-noncoherent API, but once all drivers are switched to the new API it will be replaced with a better working implementation that is available on all architectures. Signed-off-by: Christoph Hellwig --- Documentation/core-api/dma-api.rst | 75 ++++++++++++++---------------- include/linux/dma-mapping.h | 12 +++++ 2 files changed, 48 insertions(+), 39 deletions(-) diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/= dma-api.rst index 90239348b30f6f..ea0413276ddb70 100644 --- a/Documentation/core-api/dma-api.rst +++ b/Documentation/core-api/dma-api.rst @@ -516,48 +516,56 @@ routines, e.g.::: } =20 =20 -Part II - Advanced dma usage ----------------------------- +Part II - Non-coherent DMA allocations +-------------------------------------- =20 -Warning: These pieces of the DMA API should not be used in the -majority of cases, since they cater for unlikely corner cases that -don't belong in usual drivers. +These APIs allow to allocate pages in the kernel direct mapping that are +guaranteed to be DMA addressable. This means that unlike dma_alloc_cohe= rent, +virt_to_page can be called on the resulting address, and the resulting +struct page can be used for everything a struct page is suitable for. =20 -If you don't understand how cache line coherency works between a -processor and an I/O device, you should not be using this part of the -API at all. +If you don't understand how cache line coherency works between a process= or and +an I/O device, you should not be using this part of the API. =20 :: =20 void * - dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle= , - gfp_t flag, unsigned long attrs) + dma_alloc_noncoherent(struct device *dev, size_t size, + dma_addr_t *dma_handle, enum dma_data_direction dir, + gfp_t gfp) =20 -Identical to dma_alloc_coherent() except that when the -DMA_ATTR_NON_CONSISTENT flags is passed in the attrs argument, the -platform will choose to return either consistent or non-consistent memor= y -as it sees fit. By using this API, you are guaranteeing to the platform -that you have all the correct and necessary sync points for this memory -in the driver should it choose to return non-consistent memory. +This routine allocates a region of bytes of consistent memory. I= t +returns a pointer to the allocated region (in the processor's virtual ad= dress +space) or NULL if the allocation failed. The returned memory may or may= not +be in the kernels direct mapping. Drivers must not call virt_to_page on +the returned memory region. =20 -Note: where the platform can return consistent memory, it will -guarantee that the sync points become nops. +It also returns a which may be cast to an unsigned integer = the +same width as the bus and given to the device as the DMA address base of +the region. =20 -Warning: Handling non-consistent memory is a real pain. You should -only use this API if you positively know your driver will be -required to work on one of the rare (usually non-PCI) architectures -that simply cannot make consistent memory. +The dir parameter specified if data is read and/or written by the device= , +see dma_map_single() for details. + +The gfp parameter allows the caller to specify the ``GFP_`` flags (see +kmalloc()) for the allocation, but rejects flags used to specify a memor= y +zone such as GFP_DMA or GFP_HIGHMEM. + +Before giving the memory to the device, dma_sync_single_for_device() nee= ds +to be called, and before reading memory written by the device, +dma_sync_single_for_cpu(), just like for streaming DMA mappings that are +reused. =20 :: =20 void - dma_free_attrs(struct device *dev, size_t size, void *cpu_addr, - dma_addr_t dma_handle, unsigned long attrs) + dma_free_noncoherent(struct device *dev, size_t size, void *cpu_addr, + dma_addr_t dma_handle, enum dma_data_direction dir) =20 -Free memory allocated by the dma_alloc_attrs(). All common -parameters must be identical to those otherwise passed to dma_free_coher= ent, -and the attrs argument must be identical to the attrs passed to -dma_alloc_attrs(). +Free a region of memory previously allocated using dma_alloc_noncoherent= (). +dev, size and dma_handle and dir must all be the same as those passed in= to +dma_alloc_noncoherent(). cpu_addr must be the virtual address returned = by +the dma_alloc_noncoherent(). =20 :: =20 @@ -575,17 +583,6 @@ memory or doing partial flushes. into the width returned by this call. It will also always be a power of two for easy alignment. =20 -:: - - void - dma_cache_sync(struct device *dev, void *vaddr, size_t size, - enum dma_data_direction direction) - -Do a partial sync of memory that was allocated by dma_alloc_attrs() with -the DMA_ATTR_NON_CONSISTENT flag starting at virtual address vaddr and -continuing on for size. Again, you *must* observe the cache line -boundaries when doing this. - =20 Part III - Debug drivers use of the DMA-API ------------------------------------------- diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index df0bff2ea750e0..4e1de194b45cbf 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -389,6 +389,18 @@ static inline unsigned long dma_get_merge_boundary(s= truct device *dev) } #endif /* CONFIG_HAS_DMA */ =20 +static inline void *dma_alloc_noncoherent(struct device *dev, size_t siz= e, + dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp) +{ + return dma_alloc_attrs(dev, size, dma_handle, gfp, + DMA_ATTR_NON_CONSISTENT); +} +static inline void dma_free_noncoherent(struct device *dev, size_t size, + void *vaddr, dma_addr_t dma_handle, enum dma_data_direction dir) +{ + dma_free_attrs(dev, size, vaddr, dma_handle, DMA_ATTR_NON_CONSISTENT); +} + static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *= ptr, size_t size, enum dma_data_direction dir, unsigned long attrs) { --=20 2.28.0