Re: [RFC PATCH v3 4/4] remoteproc: virtio: Create platform device for the remoteproc_virtio

Mathieu Poirier
2022-03-04T18:53:16Z

On Wed, Jan 26, 2022 at 05:24:05PM +0100, Arnaud Pouliquen wrote:
> Define a platform driver to manage the remoteproc virtio device as
> a 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.
>
> remoteproc_virtio.c update:
> - Add rproc_virtio_driver platform driver. The probe/remove ops replace
> the rproc_rvdev_add_device/rproc_rvdev_remove_device functions.
> - All reference to the rvdev->dev has been updated to rvdev-pdev->dev.
> - rproc_rvdev_release is removed as associated to the rvdev device.
> - The use of rvdev->kref counter is replaced by get/put_device on the
> remoteproc virtio platform device.
> - The vdev device no longer increments rproc device counter.
> increment/decrement is done in rproc_virtio_probe/rproc_virtio_remove
> function in charge of the vrings allocation/free.
>
> remoteproc_core.c update:
> Migrate from the rvdev device to the rvdev platform device.
> From this patch, when a vdev resource is found in the resource table
> the remoteproc core register a platform device.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
> Update vs previous revision:
> - squash following two patches
> - [4/6] remoteproc: virtio: Create platform device for the remoteproc_virtio
> https://lkml.org/lkml/2021/12/22/112
> - [6/6] remoteproc: Instantiate the new remoteproc virtio platform device
> https://lkml.org/lkml/2021/12/22/114
> ---
> drivers/remoteproc/remoteproc_core.c | 23 +++-
> drivers/remoteproc/remoteproc_internal.h | 3 -
> drivers/remoteproc/remoteproc_virtio.c | 151 +++++++++++------------
> include/linux/remoteproc.h | 6 +-
> 4 files changed, 93 insertions(+), 90 deletions(-)
>
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index eb6b43b71c2b..5b864c9c6244 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -467,6 +467,7 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> struct device *dev = &rproc->dev;
> struct rproc_vdev *rvdev;
> struct rproc_vdev_data rvdev_data;
> + struct platform_device *pdev;
>
> /* make sure resource isn't truncated */
> if (struct_size(rsc, vring, rsc->num_of_vrings) + rsc->config_len >
> @@ -495,9 +496,23 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> rvdev_data.rsc_offset = offset;
> rvdev_data.rsc = rsc;
>
> - rvdev = rproc_rvdev_add_device(rproc, &rvdev_data);
> - if (IS_ERR(rvdev))
> - return PTR_ERR(rvdev);
> + pdev = platform_device_register_data(dev, "rproc-virtio", rvdev_data.index, &rvdev_data,
> + sizeof(rvdev_data));
> + if (IS_ERR(pdev)) {
> + dev_err(rproc->dev.parent,
> + "failed to create rproc-virtio device\n");
> + return PTR_ERR(pdev);
> + }
> +
> + /*
> + * At this point the registered remoteproc virtio platform device should have been probed.
> + * Get the associated rproc_vdev struct to assign the vrings.
> + */
> + rvdev = platform_get_drvdata(pdev);
> + if (!rvdev) {
> + platform_device_unregister(pdev);
> + return -EINVAL;
> + }

I can't find a reason to justify this check... Any error condition should be
handled in rproc_virtio_probe() and reported by IS_ERR(pdev) above.

Otherwise this patchset is holding together.

Thanks,
Mathieu

>
> return 0;
> }
> @@ -1237,7 +1252,7 @@ void rproc_resource_cleanup(struct rproc *rproc)
>
> /* clean up remote vdev entries */
> list_for_each_entry_safe(rvdev, rvtmp, &rproc->rvdevs, node)
> - kref_put(&rvdev->refcount, rproc_vdev_release);
> + platform_device_unregister(rvdev->pdev);
>
> rproc_coredump_cleanup(rproc);
> }
> diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h
> index 7725b404afc6..175e64a1f3a1 100644
> --- a/drivers/remoteproc/remoteproc_internal.h
> +++ b/drivers/remoteproc/remoteproc_internal.h
> @@ -45,10 +45,7 @@ int rproc_of_parse_firmware(struct device *dev, int index,
> const char **fw_name);
>
> /* from remoteproc_virtio.c */
> -struct rproc_vdev *rproc_rvdev_add_device(struct rproc *rproc, struct rproc_vdev_data *rvdev_data);
> -void rproc_rvdev_remove_device(struct rproc_vdev *rvdev);
> irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int vq_id);
> -void rproc_vdev_release(struct kref *ref);
>
> /* from remoteproc_debugfs.c */
> void rproc_remove_trace_file(struct dentry *tfile);
> diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> index 1c4fd79ac1c5..de9f12fcd044 100644
> --- a/drivers/remoteproc/remoteproc_virtio.c
> +++ b/drivers/remoteproc/remoteproc_virtio.c
> @@ -13,6 +13,7 @@
> #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>
> @@ -46,7 +47,11 @@ static int copy_dma_range_map(struct device *to, struct device *from)
>
> static struct rproc_vdev *vdev_to_rvdev(struct virtio_device *vdev)
> {
> - return container_of(vdev->dev.parent, struct rproc_vdev, dev);
> + struct platform_device *pdev;
> +
> + pdev = container_of(vdev->dev.parent, struct platform_device, dev);
> +
> + return platform_get_drvdata(pdev);
> }
>
> static struct rproc *vdev_to_rproc(struct virtio_device *vdev)
> @@ -341,13 +346,10 @@ static void rproc_virtio_dev_release(struct device *dev)
> {
> struct virtio_device *vdev = dev_to_virtio(dev);
> struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
> - struct rproc *rproc = vdev_to_rproc(vdev);
>
> kfree(vdev);
>
> - kref_put(&rvdev->refcount, rproc_vdev_release);
> -
> - put_device(&rproc->dev);
> + put_device(&rvdev->pdev->dev);
> }
>
> /**
> @@ -363,7 +365,7 @@ static void rproc_virtio_dev_release(struct device *dev)
> static int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
> {
> struct rproc *rproc = rvdev->rproc;
> - struct device *dev = &rvdev->dev;
> + struct device *dev = &rvdev->pdev->dev;
> struct virtio_device *vdev;
> struct rproc_mem_entry *mem;
> int ret;
> @@ -433,18 +435,8 @@ static int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
> vdev->dev.parent = dev;
> vdev->dev.release = rproc_virtio_dev_release;
>
> - /*
> - * We're indirectly making a non-temporary copy of the rproc pointer
> - * here, because drivers probed with this vdev will indirectly
> - * access the wrapping rproc.
> - *
> - * Therefore we must increment the rproc refcount here, and decrement
> - * it _only_ when the vdev is released.
> - */
> - get_device(&rproc->dev);
> -
> /* Reference the vdev and vring allocations */
> - kref_get(&rvdev->refcount);
> + get_device(dev);
>
> ret = register_virtio_device(vdev);
> if (ret) {
> @@ -486,78 +478,57 @@ static int rproc_vdev_do_start(struct rproc_subdev *subdev)
> static void rproc_vdev_do_stop(struct rproc_subdev *subdev, bool crashed)
> {
> struct rproc_vdev *rvdev = container_of(subdev, struct rproc_vdev, subdev);
> + struct device *dev = &rvdev->pdev->dev;
> int ret;
>
> - ret = device_for_each_child(&rvdev->dev, NULL, rproc_remove_virtio_dev);
> + ret = device_for_each_child(dev, NULL, rproc_remove_virtio_dev);
> if (ret)
> - dev_warn(&rvdev->dev, "can't remove vdev child device: %d\n", ret);
> -}
> -
> -/**
> - * rproc_rvdev_release() - release the existence of a rvdev
> - *
> - * @dev: the subdevice's dev
> - */
> -static void rproc_rvdev_release(struct device *dev)
> -{
> - struct rproc_vdev *rvdev = container_of(dev, struct rproc_vdev, dev);
> -
> - of_reserved_mem_device_release(dev);
> -
> - kfree(rvdev);
> + dev_warn(dev, "can't remove vdev child device: %d\n", ret);
> }
>
> -struct rproc_vdev *
> -rproc_rvdev_add_device(struct rproc *rproc, struct rproc_vdev_data *rvdev_data)
> +static int rproc_virtio_probe(struct platform_device *pdev)
> {
> + struct device *dev = &pdev->dev;
> + struct rproc_vdev_data *rvdev_data = dev->platform_data;
> struct rproc_vdev *rvdev;
> - struct fw_rsc_vdev *rsc = rvdev_data->rsc;
> - char name[16];
> + struct rproc *rproc = container_of(dev->parent, struct rproc, dev);
> + struct fw_rsc_vdev *rsc;
> int i, ret;
>
> - rvdev = kzalloc(sizeof(*rvdev), GFP_KERNEL);
> - if (!rvdev)
> - return ERR_PTR(-ENOMEM);
> + if (!rvdev_data)
> + return -EINVAL;
>
> - kref_init(&rvdev->refcount);
> + rvdev = devm_kzalloc(dev, sizeof(*rvdev), GFP_KERNEL);
> + if (!rvdev)
> + return -ENOMEM;
>
> rvdev->id = rvdev_data->id;
> rvdev->rproc = rproc;
> rvdev->index = rvdev_data->index;
>
> - /* Initialise vdev subdevice */
> - snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
> - rvdev->dev.parent = &rproc->dev;
> - rvdev->dev.release = rproc_rvdev_release;
> - dev_set_name(&rvdev->dev, "%s#%s", dev_name(rvdev->dev.parent), name);
> - dev_set_drvdata(&rvdev->dev, rvdev);
> -
> - ret = device_register(&rvdev->dev);
> - if (ret) {
> - put_device(&rvdev->dev);
> - return ERR_PTR(ret);
> - }
> -
> - ret = copy_dma_range_map(&rvdev->dev, rproc->dev.parent);
> + ret = copy_dma_range_map(dev, rproc->dev.parent);
> if (ret)
> - goto free_rvdev;
> + return ret;
>
> /* Make device dma capable by inheriting from parent's capabilities */
> - set_dma_ops(&rvdev->dev, get_dma_ops(rproc->dev.parent));
> + set_dma_ops(dev, get_dma_ops(rproc->dev.parent));
>
> - ret = dma_coerce_mask_and_coherent(&rvdev->dev,
> - dma_get_mask(rproc->dev.parent));
> + ret = dma_coerce_mask_and_coherent(dev, dma_get_mask(rproc->dev.parent));
> if (ret) {
> - dev_warn(&rvdev->dev,
> - "Failed to set DMA mask %llx. Trying to continue... (%pe)\n",
> + dev_warn(dev, "Failed to set DMA mask %llx. Trying to continue... (%pe)\n",
> dma_get_mask(rproc->dev.parent), ERR_PTR(ret));
> }
>
> + platform_set_drvdata(pdev, rvdev);
> + rvdev->pdev = pdev;
> +
> + rsc = rvdev_data->rsc;
> +
> /* parse the vrings */
> for (i = 0; i < rsc->num_of_vrings; i++) {
> ret = rproc_parse_vring(rvdev, rsc, i);
> if (ret)
> - goto free_rvdev;
> + return ret;
> }
>
> /* remember the resource offset*/
> @@ -577,18 +548,30 @@ rproc_rvdev_add_device(struct rproc *rproc, struct rproc_vdev_data *rvdev_data)
>
> rproc_add_subdev(rproc, &rvdev->subdev);
>
> - return rvdev;
> + dev_dbg(dev, "virtio dev %d added\n", rvdev->index);
> +
> + /*
> + * We're indirectly making a non-temporary copy of the rproc pointer
> + * here, because the platform devicer or the vdev device will indirectly
> + * access the wrapping rproc.
> + *
> + * Therefore we must increment the rproc refcount here, and decrement
> + * it _only_ on platform remove.
> + */
> + get_device(&rproc->dev);
> +
> + return 0;
>
> unwind_vring_allocations:
> for (i--; i >= 0; i--)
> rproc_free_vring(&rvdev->vring[i]);
> -free_rvdev:
> - device_unregister(&rvdev->dev);
> - return ERR_PTR(ret);
> +
> + return ret;
> }
>
> -void rproc_rvdev_remove_device(struct rproc_vdev *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;
> @@ -600,19 +583,29 @@ void rproc_rvdev_remove_device(struct rproc_vdev *rvdev)
>
> rproc_remove_subdev(rproc, &rvdev->subdev);
> rproc_unregister_rvdev(rvdev);
> - device_unregister(&rvdev->dev);
> -}
>
> -void rproc_vdev_release(struct kref *ref)
> -{
> - struct rproc_vdev *rvdev = container_of(ref, struct rproc_vdev, refcount);
> - struct rproc_vring *rvring;
> - int id;
> + of_reserved_mem_device_release(&pdev->dev);
>
> - for (id = 0; id < ARRAY_SIZE(rvdev->vring); id++) {
> - rvring = &rvdev->vring[id];
> - rproc_free_vring(rvring);
> - }
> + dev_dbg(&pdev->dev, "virtio dev %d removed\n", rvdev->index);
>
> - rproc_rvdev_remove_device(rvdev);
> + /* The remote proc device can be removed */
> + put_device(&rproc->dev);
> +
> + 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..7951a3e2b62a 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -614,9 +614,8 @@ 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
> - * @dev: device struct used for reference count semantics
> + * @pdev: remoteproc virtio platform device
> * @id: virtio device id (as in virtio_ids.h)
> * @node: list node
> * @rproc: the rproc handle
> @@ -625,10 +624,9 @@ struct rproc_vring {
> * @index: vdev position versus other vdev declared in resource table
> */
> struct rproc_vdev {
> - struct kref refcount;
>
> struct rproc_subdev subdev;
> - struct device dev;
> + struct platform_device *pdev;
>
> unsigned int id;
> struct list_head node;
> --
> 2.25.1
>