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

Arnaud Pouliquen
2022-01-26T16:25:40Z

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;
+ }

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