From: Claire Chang <tientzu@chromium.org>
To: robh+dt@kernel.org, frowand.list@gmail.com, hch@lst.de,
m.szyprowski@samsung.com, robin.murphy@arm.com
Cc: treding@nvidia.com, gregkh@linuxfoundation.org,
saravanak@google.com, suzuki.poulose@arm.com,
dan.j.williams@intel.com, heikki.krogerus@linux.intel.com,
bgolaszewski@baylibre.com, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
tfiga@chromium.org, drinkcat@chromium.org,
Claire Chang <tientzu@chromium.org>
Subject: [PATCH 3/4] dt-bindings: of: Add plumbing for bounced DMA pool
Date: Mon, 13 Jul 2020 17:12:10 +0800 [thread overview]
Message-ID: <20200713091211.2183368-4-tientzu@chromium.org> (raw)
In-Reply-To: <20200713091211.2183368-1-tientzu@chromium.org>
Introduce the new compatible string, bounced-dma-pool, for bounced DMA.
One can specify the address and length of the bounced memory region by
bounced-dma-pool in the device tree.
Signed-off-by: Claire Chang <tientzu@chromium.org>
---
.../reserved-memory/reserved-memory.txt | 36 +++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
index 4dd20de6977f..45b3134193ea 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
@@ -51,6 +51,24 @@ compatible (optional) - standard definition
used as a shared pool of DMA buffers for a set of devices. It can
be used by an operating system to instantiate the necessary pool
management subsystem if necessary.
+ - bounced-dma-pool: This indicates a region of memory meant to be used
+ as a pool of DMA bounce buffers for a given device. When using this,
+ the no-map and reusable properties must not be set, so the operating
+ system can create a virtual mapping that will be used for
+ synchronization. Also, there must be a bounced-dma property in the
+ device node to specify the indexes of reserved-memory nodes. One can
+ specify two reserved-memory nodes in the device tree. One with
+ shared-dma-pool to handle the coherent DMA buffer allocation, and
+ another one with bounced-dma-pool for regular DMA to/from system
+ memory, which would be subject to bouncing. The main purpose for
+ bounced DMA is to mitigate the lack of DMA access control on systems
+ without an IOMMU, which could result in the DMA accessing the system
+ memory at unexpected times and/or unexpected addresses, possibly
+ leading to data leakage or corruption. The feature on its own provides
+ a basic level of protection against the DMA overwriting buffer
+ contents at unexpected times. However, to protect against general data
+ leakage and system memory corruption, the system needs to provide a
+ way to restrict the DMA to a predefined memory region.
- vendor specific string in the form <vendor>,[<device>-]<usage>
no-map (optional) - empty property
- Indicates the operating system must not create a virtual mapping
@@ -117,6 +135,17 @@ one for multimedia processing (named multimedia-memory@77000000, 64MiB).
compatible = "acme,multimedia-memory";
reg = <0x77000000 0x4000000>;
};
+
+ wifi_bounced_dma_mem_region: wifi_bounced_dma_mem_region {
+ compatible = "bounced-dma-pool";
+ reg = <0x50000000 0x4000000>;
+ };
+
+ wifi_coherent_mem_region: wifi_coherent_mem_region {
+ compatible = "shared-dma-pool";
+ reg = <0x54000000 0x400000>;
+ };
+
};
/* ... */
@@ -135,4 +164,11 @@ one for multimedia processing (named multimedia-memory@77000000, 64MiB).
memory-region = <&multimedia_reserved>;
/* ... */
};
+
+ pcie_wifi: pcie_wifi@0,0 {
+ memory-region = <&wifi_bounced_dma_mem_region>,
+ <&wifi_coherent_mem_region>;
+ bounced-dma = <0>, <1>;
+ /* ... */
+ };
};
--
2.27.0.383.g050319c2ae-goog
next prev parent reply other threads:[~2020-07-13 9:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 9:12 [PATCH 0/4] Bounced DMA support Claire Chang
2020-07-13 9:12 ` [PATCH 1/4] dma-mapping: Add bounced DMA ops Claire Chang
2020-07-13 11:55 ` Robin Murphy
2020-07-14 11:01 ` Christoph Hellwig
2020-07-15 3:46 ` Claire Chang
2020-07-15 9:04 ` Claire Chang
2020-07-28 5:05 ` Claire Chang
2020-07-13 9:12 ` [PATCH 2/4] dma-mapping: Add bounced DMA pool Claire Chang
2020-07-13 9:12 ` Claire Chang [this message]
2020-07-13 9:12 ` [PATCH 4/4] of: Add plumbing for " Claire Chang
2020-07-13 11:39 ` [PATCH 0/4] Bounced DMA support Robin Murphy
2020-07-15 3:43 ` Claire Chang
2020-07-15 17:53 ` Robin Murphy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200713091211.2183368-4-tientzu@chromium.org \
--to=tientzu@chromium.org \
--cc=bgolaszewski@baylibre.com \
--cc=dan.j.williams@intel.com \
--cc=devicetree@vger.kernel.org \
--cc=drinkcat@chromium.org \
--cc=frowand.list@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=hch@lst.de \
--cc=heikki.krogerus@linux.intel.com \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=robh+dt@kernel.org \
--cc=robin.murphy@arm.com \
--cc=saravanak@google.com \
--cc=suzuki.poulose@arm.com \
--cc=tfiga@chromium.org \
--cc=treding@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).