linux-kernel - [PATCH v7 1/8] dmaengine: add DMA_PREP_LOCK and DMA_PREP

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Message-Id: <20250311-qce-cmd-descr-v7-1-db613f5d9c9f@linaro.org>
Date: Tue, 11 Mar 2025 10:25:32 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Thara Gopinath <thara.gopinath@...il.com>, 
 Herbert Xu <herbert@...dor.apana.org.au>, 
 "David S. Miller" <davem@...emloft.net>, Vinod Koul <vkoul@...nel.org>, 
 Jonathan Corbet <corbet@....net>, Md Sadre Alam <quic_mdalam@...cinc.com>, 
 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: linux-crypto@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org, 
 linux-doc@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v7 1/8] dmaengine: add DMA_PREP_LOCK and DMA_PREP_UNLOCK
 flag

From: Md Sadre Alam <quic_mdalam@...cinc.com>

Add lock and unlock flags for the command descriptor. With the former set
in the requester pipe, the bam controller will lock all other pipes and
process the request only from requester pipe. Unlocking can only be
performed from the same pipe.

Setting the DMA_PREP_LOCK/DMA_PREP_UNLOCK flags in the command
descriptor means, the caller requests the BAM controller to be locked
for the duration of the transaction. In this case the BAM driver must
set the LOCK/UNLOCK bits in the HW descriptor respectively.

Only BAM IPs version 1.4.0 and above support the LOCK/UNLOCK feature.

Signed-off-by: Md Sadre Alam <quic_mdalam@...cinc.com>
[Bartosz: reworked the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 Documentation/driver-api/dmaengine/provider.rst | 15 +++++++++++++++
 include/linux/dmaengine.h                       |  6 ++++++
 2 files changed, 21 insertions(+)

diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
index 3085f8b460fa..a032e55d0a4f 100644
--- a/Documentation/driver-api/dmaengine/provider.rst
+++ b/Documentation/driver-api/dmaengine/provider.rst
@@ -628,6 +628,21 @@ DMA_CTRL_REUSE
   - This flag is only supported if the channel reports the DMA_LOAD_EOT
     capability.

+- DMA_PREP_LOCK
+
+  - If set, the DMA will lock all other pipes not related to the current
+    pipe group, and keep handling the current pipe only.
+
+  - All pipes not within this group will be locked by this pipe upon lock
+    event.
+
+  - only pipes which are in the same group and relate to the same Environment
+    Execution(EE) will not be locked by a certain pipe.
+
+- DMA_PREP_UNLOCK
+
+  - If set, DMA will release all locked pipes
+
 General Design Notes
 ====================

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 346251bf1026..8ebd43a998a7 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -200,6 +200,10 @@ struct dma_vec {
  *  transaction is marked with DMA_PREP_REPEAT will cause the new transaction
  *  to never be processed and stay in the issued queue forever. The flag is
  *  ignored if the previous transaction is not a repeated transaction.
+ *  @DMA_PREP_LOCK: tell the driver that there is a lock bit set on command
+ *  descriptor.
+ *  @DMA_PREP_UNLOCK: tell the driver that there is a un-lock bit set on command
+ *  descriptor.
  */
 enum dma_ctrl_flags {
 	DMA_PREP_INTERRUPT = (1 << 0),
@@ -212,6 +216,8 @@ enum dma_ctrl_flags {
 	DMA_PREP_CMD = (1 << 7),
 	DMA_PREP_REPEAT = (1 << 8),
 	DMA_PREP_LOAD_EOT = (1 << 9),
+	DMA_PREP_LOCK = (1 << 10),
+	DMA_PREP_UNLOCK = (1 << 11),
 };

 /**

-- 
2.45.2