Date:   Wed, 1 Apr 2020 22:49:18 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     gregkh@...uxfoundation.org, davem@...emloft.net,
        smohanad@...eaurora.org, jhugo@...eaurora.org,
        kvalo@...eaurora.org, hemantk@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        clew@...eaurora.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 2/3] net: qrtr: Add MHI transport layer

On Wed 01 Apr 22:36 PDT 2020, Manivannan Sadhasivam wrote:

> 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@...aro.org>

Regards,
Bjorn

> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: netdev@...r.kernel.org
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  net/qrtr/Kconfig  |   7 +++
>  net/qrtr/Makefile |   2 +
>  net/qrtr/mhi.c    | 126 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 135 insertions(+)
>  create mode 100644 net/qrtr/mhi.c
> 
> diff --git a/net/qrtr/Kconfig b/net/qrtr/Kconfig
> index 63f89cc6e82c..8eb876471564 100644
> --- a/net/qrtr/Kconfig
> +++ b/net/qrtr/Kconfig
> @@ -29,4 +29,11 @@ config QRTR_TUN
>  	  implement endpoints of QRTR, for purpose of tunneling data to other
>  	  hosts or testing purposes.
>  
> +config QRTR_MHI
> +	tristate "MHI IPC Router channels"
> +	depends on MHI_BUS
> +	help
> +	  Say Y here to support MHI based ipcrouter channels. MHI is the
> +	  transport used for communicating to external modems.
> +
>  endif # QRTR
> diff --git a/net/qrtr/Makefile b/net/qrtr/Makefile
> index 32d4e923925d..1b1411d158a7 100644
> --- a/net/qrtr/Makefile
> +++ b/net/qrtr/Makefile
> @@ -5,3 +5,5 @@ obj-$(CONFIG_QRTR_SMD) += qrtr-smd.o
>  qrtr-smd-y	:= smd.o
>  obj-$(CONFIG_QRTR_TUN) += qrtr-tun.o
>  qrtr-tun-y	:= tun.o
> +obj-$(CONFIG_QRTR_MHI) += qrtr-mhi.o
> +qrtr-mhi-y	:= mhi.o
> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> new file mode 100644
> index 000000000000..2f604dff93cd
> --- /dev/null
> +++ b/net/qrtr/mhi.c
> @@ -0,0 +1,126 @@
> +// 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 = (struct sk_buff *)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) {
> +		kfree_skb(skb);
> +		return rc;
> +	}
> +
> +	rc = mhi_queue_skb(qdev->mhi_dev, DMA_TO_DEVICE, skb, skb->len,
> +			   MHI_EOT);
> +	if (rc) {
> +		kfree_skb(skb);
> +		return rc;
> +	}
> +
> +	if (skb->sk)
> +		sock_hold(skb->sk);
> +
> +	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@...eaurora.org>");
> +MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>");
> +MODULE_DESCRIPTION("Qualcomm IPC-Router MHI interface driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.17.1
> 

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