net: qrtr: Add MHI transport layer

MHI is the transport layer used for communicating to the external modems.
Hence, this commit adds MHI transport layer support to QRTR for
transferring the QMI messages over IPC Router.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 127 insertions, 0 deletions

diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
new file mode 100644
index 000000000000..ff0c41467fc1
--- /dev/null
+++ b/net/qrtr/mhi.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/mhi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+
+#include "qrtr.h"
+
+struct qrtr_mhi_dev {
+	struct qrtr_endpoint ep;
+	struct mhi_device *mhi_dev;
+	struct device *dev;
+};
+
+/* From MHI to QRTR */
+static void qcom_mhi_qrtr_dl_callback(struct mhi_device *mhi_dev,
+				      struct mhi_result *mhi_res)
+{
+	struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev);
+	int rc;
+
+	if (!qdev || mhi_res->transaction_status)
+		return;
+
+	rc = qrtr_endpoint_post(&qdev->ep, mhi_res->buf_addr,
+				mhi_res->bytes_xferd);
+	if (rc == -EINVAL)
+		dev_err(qdev->dev, "invalid ipcrouter packet\n");
+}
+
+/* From QRTR to MHI */
+static void qcom_mhi_qrtr_ul_callback(struct mhi_device *mhi_dev,
+				      struct mhi_result *mhi_res)
+{
+	struct sk_buff *skb = mhi_res->buf_addr;
+
+	if (skb->sk)
+		sock_put(skb->sk);
+	consume_skb(skb);
+}
+
+/* Send data over MHI */
+static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
+{
+	struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep);
+	int rc;
+
+	rc = skb_linearize(skb);
+	if (rc)
+		goto free_skb;
+
+	rc = mhi_queue_skb(qdev->mhi_dev, DMA_TO_DEVICE, skb, skb->len,
+			   MHI_EOT);
+	if (rc)
+		goto free_skb;
+
+	if (skb->sk)
+		sock_hold(skb->sk);
+
+	return rc;
+
+free_skb:
+	kfree_skb(skb);
+
+	return rc;
+}
+
+static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
+			       const struct mhi_device_id *id)
+{
+	struct qrtr_mhi_dev *qdev;
+	int rc;
+
+	qdev = devm_kzalloc(&mhi_dev->dev, sizeof(*qdev), GFP_KERNEL);
+	if (!qdev)
+		return -ENOMEM;
+
+	qdev->mhi_dev = mhi_dev;
+	qdev->dev = &mhi_dev->dev;
+	qdev->ep.xmit = qcom_mhi_qrtr_send;
+
+	dev_set_drvdata(&mhi_dev->dev, qdev);
+	rc = qrtr_endpoint_register(&qdev->ep, QRTR_EP_NID_AUTO);
+	if (rc)
+		return rc;
+
+	dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");
+
+	return 0;
+}
+
+static void qcom_mhi_qrtr_remove(struct mhi_device *mhi_dev)
+{
+	struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev);
+
+	qrtr_endpoint_unregister(&qdev->ep);
+	dev_set_drvdata(&mhi_dev->dev, NULL);
+}
+
+static const struct mhi_device_id qcom_mhi_qrtr_id_table[] = {
+	{ .chan = "IPCR" },
+	{}
+};
+MODULE_DEVICE_TABLE(mhi, qcom_mhi_qrtr_id_table);
+
+static struct mhi_driver qcom_mhi_qrtr_driver = {
+	.probe = qcom_mhi_qrtr_probe,
+	.remove = qcom_mhi_qrtr_remove,
+	.dl_xfer_cb = qcom_mhi_qrtr_dl_callback,
+	.ul_xfer_cb = qcom_mhi_qrtr_ul_callback,
+	.id_table = qcom_mhi_qrtr_id_table,
+	.driver = {
+		.name = "qcom_mhi_qrtr",
+	},
+};
+
+module_mhi_driver(qcom_mhi_qrtr_driver);
+
+MODULE_AUTHOR("Chris Lew <clew@codeaurora.org>");
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
+MODULE_DESCRIPTION("Qualcomm IPC-Router MHI interface driver");
+MODULE_LICENSE("GPL v2");