linux-kernel - [PATCH v2 2/3] bus: mhi: ep: Create mhi_ep_queue

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Message-Id: <20251104-loopback_mhi-v2-2-727a3fd9aa74@oss.qualcomm.com>
Date: Tue, 04 Nov 2025 11:09:06 +0530
From: Sumit Kumar <sumit.kumar@....qualcomm.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
        Akhil Vinod <akhil.vinod@....qualcomm.com>,
        Subramanian Ananthanarayanan <subramanian.ananthanarayanan@....qualcomm.com>,
        linux-kernel@...r.kernel.org, mhi@...ts.linux.dev,
        linux-arm-msm@...r.kernel.org, quic_vpernami@...cinc.com,
        Sumit Kumar <sumit.kumar@....qualcomm.com>
Subject: [PATCH v2 2/3] bus: mhi: ep: Create mhi_ep_queue_buf API for raw
 buffer queuing

Create and export a new mhi_ep_queue_buf() API that allows raw buffer
queuing for client not using skb.

Extract core logic for queuing buffers into a new internal mhi_ep_queue()
function that provides a unified implementation for both mhi_ep_queue_skb()
and mhi_ep_queue_buf(). This internal function uses a cb_buf parameter to
handle both socket buffers and raw buffers through the same code path.
---
 drivers/bus/mhi/ep/main.c | 23 +++++++++++++++++------
 include/linux/mhi_ep.h    | 10 ++++++++++
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index b3eafcf2a2c50d95e3efd3afb27038ecf55552a5..f4b119a8dca2dbfb3ffc24b04c85743fb57088fd 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -544,9 +544,9 @@ static void mhi_ep_skb_completion(struct mhi_ep_buf_info *buf_info)
 
 	mhi_ep_ring_inc_index(ring);
 }
-
 /* TODO: Handle partially formed TDs */
-int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
+static int mhi_ep_queue(struct mhi_ep_device *mhi_dev, void *buf, size_t len,
+			void *cb_buf)
 {
 	struct mhi_ep_cntrl *mhi_cntrl = mhi_dev->mhi_cntrl;
 	struct mhi_ep_chan *mhi_chan = mhi_dev->dl_chan;
@@ -559,7 +559,7 @@ int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
 	u32 tre_len;
 	int ret;
 
-	buf_left = skb->len;
+	buf_left = len;
 	ring = &mhi_cntrl->mhi_chan[mhi_chan->chan].ring;
 
 	mutex_lock(&mhi_chan->lock);
@@ -582,13 +582,13 @@ int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
 		tre_len = MHI_TRE_DATA_GET_LEN(el);
 
 		tr_len = min(buf_left, tre_len);
-		read_offset = skb->len - buf_left;
+		read_offset = len - buf_left;
 
-		buf_info.dev_addr = skb->data + read_offset;
+		buf_info.dev_addr = buf + read_offset;
 		buf_info.host_addr = MHI_TRE_DATA_GET_PTR(el);
 		buf_info.size = tr_len;
 		buf_info.cb = mhi_ep_skb_completion;
-		buf_info.cb_buf = skb;
+		buf_info.cb_buf = cb_buf;
 		buf_info.mhi_dev = mhi_dev;
 
 		/*
@@ -627,8 +627,19 @@ int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
 
 	return ret;
 }
+
+int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
+{
+	return mhi_ep_queue(mhi_dev, skb->data, skb->len, skb);
+}
 EXPORT_SYMBOL_GPL(mhi_ep_queue_skb);
 
+int mhi_ep_queue_buf(struct mhi_ep_device *mhi_dev, void *buf, size_t len)
+{
+	return mhi_ep_queue(mhi_dev, buf, len, buf);
+}
+EXPORT_SYMBOL_GPL(mhi_ep_queue_buf);
+
 static int mhi_ep_cache_host_cfg(struct mhi_ep_cntrl *mhi_cntrl)
 {
 	size_t cmd_ctx_host_size, ch_ctx_host_size, ev_ctx_host_size;
diff --git a/include/linux/mhi_ep.h b/include/linux/mhi_ep.h
index 7b40fc8cbe77ab8419d167e89264b69a817b9fb1..7186eb667b081009927af48513519084fb0be3a6 100644
--- a/include/linux/mhi_ep.h
+++ b/include/linux/mhi_ep.h
@@ -302,4 +302,14 @@ bool mhi_ep_queue_is_empty(struct mhi_ep_device *mhi_dev, enum dma_data_directio
  */
 int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb);
 
+/**
+ * mhi_ep_queue_buf - Send buffer to host over MHI Endpoint
+ * @mhi_dev: Device associated with the DL channel
+ * @buf: Buffer to be queued
+ * @len: Size of the buffer
+ *
+ * Return: 0 if the buffer has been sent successfully, a negative error code otherwise.
+ */
+int mhi_ep_queue_buf(struct mhi_ep_device *mhi_dev, void *buf, size_t len);
+
 #endif

-- 
2.34.1