linux-kernel - Re: [RFC PATCH v2 4/6] remoteproc: virtio: Create platform device for the remoteproc

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Date:   Thu, 6 Jan 2022 11:53:09 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com
Subject: Re: [RFC PATCH v2 4/6] remoteproc: virtio: Create platform device
 for the remoteproc_virtio

On Wed, Dec 22, 2021 at 09:23:47AM +0100, Arnaud Pouliquen wrote:
> Define a platform driver to prepare for the management of
> remoteproc virtio devices as platform devices.
> 
> The platform device allows to pass rproc_vdev_data platform data to
> specify properties that are stored in the rproc_vdev structure.
> 
> Such approach will allow to preserve legacy remoteproc virtio device
> creation but also to probe the device using device tree mechanism.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> ---
> Update vs previous revision:
>   - Fix commit and rename rproc_vdev_data to rproc_vdev_pdata
> ---
>  drivers/remoteproc/remoteproc_internal.h |  6 +++
>  drivers/remoteproc/remoteproc_virtio.c   | 65 ++++++++++++++++++++++++
>  include/linux/remoteproc.h               |  2 +
>  3 files changed, 73 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h
> index e9e9a551a8c2..6f511c50a15d 100644
> --- a/drivers/remoteproc/remoteproc_internal.h
> +++ b/drivers/remoteproc/remoteproc_internal.h
> @@ -24,6 +24,12 @@ struct rproc_debug_trace {
>  	struct rproc_mem_entry trace_mem;
>  };
>  
> +struct rproc_vdev_pdata {
> +	u32 rsc_offset;
> +	unsigned int id;
> +	unsigned int index;
> +};
> +
>  /* from remoteproc_core.c */
>  void rproc_release(struct kref *kref);
>  int rproc_of_parse_firmware(struct device *dev, int index,
> diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> index 51d415744fc6..5f8005caeb6e 100644
> --- a/drivers/remoteproc/remoteproc_virtio.c
> +++ b/drivers/remoteproc/remoteproc_virtio.c
> @@ -4,6 +4,7 @@
>   *
>   * Copyright (C) 2011 Texas Instruments, Inc.
>   * Copyright (C) 2011 Google, Inc.
> + * Copyright (C) 2021 STMicroelectronics
>   *
>   * Ohad Ben-Cohen <ohad@...ery.com>
>   * Brian Swetland <swetland@...gle.com>
> @@ -13,6 +14,7 @@
>  #include <linux/dma-map-ops.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/export.h>
> +#include <linux/of_platform.h>
>  #include <linux/of_reserved_mem.h>
>  #include <linux/remoteproc.h>
>  #include <linux/virtio.h>
> @@ -575,3 +577,66 @@ void rproc_vdev_release(struct kref *ref)
>  
>  	rproc_rvdev_remove_device(rvdev);
>  }
> +
> +static int rproc_virtio_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct rproc_vdev_pdata *vdev_data = dev->platform_data;
> +	struct rproc_vdev *rvdev;
> +	struct rproc *rproc;
> +
> +	if (!vdev_data)
> +		return -EINVAL;
> +
> +	rvdev = devm_kzalloc(dev, sizeof(*rvdev), GFP_KERNEL);
> +	if (!rvdev)
> +		return -ENOMEM;
> +
> +	rproc = container_of(dev->parent, struct rproc, dev);
> +
> +	rvdev->rsc_offset = vdev_data->rsc_offset;
> +	rvdev->id = vdev_data->id;
> +	rvdev->index = vdev_data->index;
> +
> +	rvdev->pdev = pdev;
> +	rvdev->rproc = rproc;
> +
> +	platform_set_drvdata(pdev, rvdev);
> +
> +	return rproc_rvdev_add_device(rvdev);
> +}
> +
> +static int rproc_virtio_remove(struct platform_device *pdev)
> +{
> +	struct rproc_vdev *rvdev = dev_get_drvdata(&pdev->dev);
> +	struct rproc *rproc = rvdev->rproc;
> +	struct rproc_vring *rvring;
> +	int id;
> +
> +	for (id = 0; id < ARRAY_SIZE(rvdev->vring); id++) {
> +		rvring = &rvdev->vring[id];
> +		rproc_free_vring(rvring);
> +	}
> +
> +	rproc_remove_subdev(rproc, &rvdev->subdev);
> +	rproc_unregister_rvdev(rvdev);
> +	dev_dbg(&pdev->dev, "virtio dev %d removed\n",  rvdev->index);
> +

Function rproc_virtio_remove() doesn't do the opposite of rproc_virtio_probe(),
making it hard for people to wrap their head around what is happening.  This may
get cleaned up as part of the error path problem we already talked about...  If not
this is something to improve one.

I am done reviewing this set.

Thanks,
Mathieu

> +	return 0;
> +}
> +
> +/* Platform driver */
> +static const struct of_device_id rproc_virtio_match[] = {
> +	{ .compatible = "rproc-virtio", },
> +	{},
> +};
> +
> +static struct platform_driver rproc_virtio_driver = {
> +	.probe		= rproc_virtio_probe,
> +	.remove		= rproc_virtio_remove,
> +	.driver		= {
> +		.name	= "rproc-virtio",
> +		.of_match_table	= rproc_virtio_match,
> +	},
> +};
> +builtin_platform_driver(rproc_virtio_driver);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e0600e1e5c17..542a3d4664f2 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -616,6 +616,7 @@ struct rproc_vring {
>   * struct rproc_vdev - remoteproc state for a supported virtio device
>   * @refcount: reference counter for the vdev and vring allocations
>   * @subdev: handle for registering the vdev as a rproc subdevice
> + * @pdev: remoteproc virtio platform device
>   * @dev: device struct used for reference count semantics
>   * @id: virtio device id (as in virtio_ids.h)
>   * @node: list node
> @@ -628,6 +629,7 @@ struct rproc_vdev {
>  	struct kref refcount;
>  
>  	struct rproc_subdev subdev;
> +	struct platform_device *pdev;
>  	struct device dev;
>  
>  	unsigned int id;
> -- 
> 2.17.1
>