From patchwork Mon Sep 14 14:44:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11774069 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D59FD14B7 for ; Mon, 14 Sep 2020 15:05:58 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9439B20732 for ; Mon, 14 Sep 2020 15:05:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="XKhdGuVg"; 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 9439B20732 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=OZhVA/9BDbgM24CWE0OZCU3+sRxsaFgbMo/rCgkGXuw=; b=XKhdGuVghhvT9uJd/WwSHwbSi sR6SEbFzVZ+AGViVhblgcFUNRPGWv1KT+IbwmdKgH947bX1dUVwaWIv2vgWfyPy8diyLf+Zy49UNB nD/jESRuvJGVVzK6S9cT232EXQu7BrvcDBglaA4SwiK92rRT6iLXvrwyBOp/OBLwxCZgMcyxafh+k Goe8sxXI5LLsfsiednLlY2h7oOUNB03LhgrqmNRi6nxUEN6TLaF8VSELv1sB081NSbCh1zS+61aYt 6oexyOFsUf+jtKfVcgVkosSRQ9mMHzMYhf5tDaTALwOkpVCjXOeSjLtmzs8/c2cp6v2Umzmrqb2fL hF0E6xiPw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHq1n-00085v-9R; Mon, 14 Sep 2020 15:04:23 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHq1k-00085Q-AR for linux-arm-kernel@merlin.infradead.org; Mon, 14 Sep 2020 15:04:20 +0000 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 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-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, linux-samsung-soc@vger.kernel.org, linux-scsi@vger.kernel.org, linux-parisc@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, Stefan Richter , netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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.::: } -Part II - Advanced dma usage ----------------------------- +Part II - Non-coherent DMA allocations +-------------------------------------- -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_coherent, +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. -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 processor and +an I/O device, you should not be using this part of the API. :: 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) -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 memory -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. It +returns a pointer to the allocated region (in the processor's virtual address +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. -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. -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 memory +zone such as GFP_DMA or GFP_HIGHMEM. + +Before giving the memory to the device, dma_sync_single_for_device() needs +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. :: 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) -Free memory allocated by the dma_alloc_attrs(). All common -parameters must be identical to those otherwise passed to dma_free_coherent, -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 into +dma_alloc_noncoherent(). cpu_addr must be the virtual address returned by +the dma_alloc_noncoherent(). :: @@ -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. -:: - - 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. - 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(struct device *dev) } #endif /* CONFIG_HAS_DMA */ +static inline void *dma_alloc_noncoherent(struct device *dev, size_t size, + 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) {