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

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