[PATCH 0/2] Attach DT nodes to existing PCI devices

[PATCH 0/2] Attach DT nodes to existing PCI devices

[Herve Codina]

Hi,

The commit 407d1a51921e ("PCI: Create device tree node for bridge")
creates of_node for PCI devices.
During the insertion handling of these new DT nodes done by of_platform,
new devices (struct device) are created.
For each PCI devices a struct device is already present (created and
handled by the PCI core).
Creating a new device from a DT node leads to some kind of wrong struct
device duplication to represent the exact same PCI device.

This patch series first introduces device_{add,remove}_of_node() in
order to add or remove a newly created of_node to an already existing
device.
Then it fixes the DT node creation for PCI devices to add or remove the
created node to the existing PCI device without any new device creation.

Best regards,
Hervé

Herve Codina (2):
  driver core: Introduce device_{add,remove}_of_node()
  PCI: of: Attach created of_node to existing device

 drivers/base/core.c    | 74 ++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/of.c       | 15 +++++++--
 include/linux/device.h |  2 ++
 3 files changed, 89 insertions(+), 2 deletions(-)

-- 
2.42.0

[PATCH 1/2] driver core: Introduce device_{add,remove}_of_node()

[Herve Codina]

An of_node can be duplicated from an existing device using
device_set_of_node_from_dev() or initialized using device_set_node()
In both cases, these functions have to be called before the device_add()
call in order to have the of_node link created in the device sysfs
directory. Further more, these function cannot prevent any of_node
and/or fwnode overwrites.

When adding an of_node on an already present device, the following
operations need to be done:
- Attach the of_node if no of_node were already attached
- Attach the of_node as a fwnode if no fwnode were already attached
- Create the of_node sysfs link if needed

This is the purpose of device_add_of_node().
device_remove_of_node() reverts the operations done by
device_add_of_node().

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
 drivers/base/core.c    | 74 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/device.h |  2 ++
 2 files changed, 76 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 2926f3b1f868..ac026187ac6a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -5046,6 +5046,80 @@ void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
 }
 EXPORT_SYMBOL_GPL(set_secondary_fwnode);
 
+/**
+ * device_remove_of_node - Remove an of_node from a device
+ * @dev: device whose device-tree node is being removed
+ */
+void device_remove_of_node(struct device *dev)
+{
+	dev = get_device(dev);
+	if (!dev)
+		return;
+
+	if (!dev->of_node)
+		goto end;
+
+	sysfs_remove_link(&dev->kobj, "of_node");
+
+	if (dev->fwnode == of_fwnode_handle(dev->of_node))
+		dev->fwnode = NULL;
+
+	of_node_put(dev->of_node);
+	dev->of_node = NULL;
+
+end:
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(device_remove_of_node);
+
+/**
+ * device_add_of_node - Add an of_node to an existing device
+ * @dev: device whose device-tree node is being added
+ * @of_node: of_node to add
+ */
+void device_add_of_node(struct device *dev, struct device_node *of_node)
+{
+	int ret;
+
+	if (!of_node)
+		return;
+
+	dev = get_device(dev);
+	if (!dev)
+		return;
+
+	if (dev->of_node) {
+		dev_warn(dev, "Replace node %pOF with %pOF\n", dev->of_node, of_node);
+		device_remove_of_node(dev);
+	}
+
+	dev->of_node = of_node_get(of_node);
+
+	if (!dev->fwnode)
+		dev->fwnode = of_fwnode_handle(of_node);
+
+	if (!dev->p) {
+		/*
+		 * device_add() was not previously called.
+		 * The of_node link will be created when device_add() is called.
+		 */
+		goto end;
+	}
+
+	/*
+	 * device_add() was previously called and so the of_node link was not
+	 * created by device_add_class_symlinks().
+	 * Create this link now.
+	 */
+	ret = sysfs_create_link(&dev->kobj, of_node_kobj(of_node), "of_node");
+	if (ret)
+		dev_warn(dev, "Error %d creating of_node link\n", ret);
+
+end:
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(device_add_of_node);
+
 /**
  * device_set_of_node_from_dev - reuse device-tree node of another device
  * @dev: device whose device-tree node is being set
diff --git a/include/linux/device.h b/include/linux/device.h
index d7a72a8749ea..2b093e62907a 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1128,6 +1128,8 @@ int device_offline(struct device *dev);
 int device_online(struct device *dev);
 void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode);
 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode);
+void device_add_of_node(struct device *dev, struct device_node *of_node);
+void device_remove_of_node(struct device *dev);
 void device_set_of_node_from_dev(struct device *dev, const struct device *dev2);
 void device_set_node(struct device *dev, struct fwnode_handle *fwnode);
 
-- 
2.42.0

[PATCH 2/2] PCI: of: Attach created of_node to existing device

[Herve Codina]

The commit 407d1a51921e ("PCI: Create device tree node for bridge")
creates of_node for PCI devices.
During the insertion handling of these new DT nodes done by of_platform,
new devices (struct device) are created.
For each PCI devices a struct device is already present (created and
handled by the PCI core).
Having a second struct device to represent the exact same PCI device is
not correct.

On the of_node creation, tell the of_platform that there is no need to
create a device for this node (OF_POPULATED flag), link this newly
created of_node to the already present device and tell fwnode that the
device attached to this of_node is ready (fwnode_dev_initialized()).

With this fix, the of_node are available in the sysfs device tree:
/sys/devices/platform/soc/d0070000.pcie/
+ of_node -> .../devicetree/base/soc/pcie@d0070000
+ pci0000:00
  + 0000:00:00.0
    + of_node -> .../devicetree/base/soc/pcie@d0070000/pci@0,0
    + 0000:01:00.0
      + of_node -> .../devicetree/base/soc/pcie@d0070000/pci@0,0/dev@0,0

On the of_node removal, revert the operations.

Fixes: 407d1a51921e ("PCI: Create device tree node for bridge")
Cc: stable@vger.kernel.org
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
 drivers/pci/of.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 51e3dd0ea5ab..5afd2731e876 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -615,7 +615,8 @@ void of_pci_remove_node(struct pci_dev *pdev)
 	np = pci_device_to_OF_node(pdev);
 	if (!np || !of_node_check_flag(np, OF_DYNAMIC))
 		return;
-	pdev->dev.of_node = NULL;
+
+	device_remove_of_node(&pdev->dev);
 
 	of_changeset_revert(np->data);
 	of_changeset_destroy(np->data);
@@ -668,12 +669,22 @@ void of_pci_make_dev_node(struct pci_dev *pdev)
 	if (ret)
 		goto out_free_node;
 
+	/*
+	 * This of_node will be added to an existing device.
+	 * Avoid any device creation and use the existing device
+	 */
+	of_node_set_flag(np, OF_POPULATED);
+	np->fwnode.dev = &pdev->dev;
+	fwnode_dev_initialized(&np->fwnode, true);
+
 	ret = of_changeset_apply(cset);
 	if (ret)
 		goto out_free_node;
 
 	np->data = cset;
-	pdev->dev.of_node = np;
+
+	/* Add the of_node to the existing device */
+	device_add_of_node(&pdev->dev, np);
 	kfree(name);
 
 	return;
-- 
2.42.0

Re: [PATCH 2/2] PCI: of: Attach created of_node to existing device

[Greg Kroah-Hartman]

On Thu, Nov 30, 2023 at 04:24:04PM +0100, Herve Codina wrote:
> The commit 407d1a51921e ("PCI: Create device tree node for bridge")
> creates of_node for PCI devices.
> During the insertion handling of these new DT nodes done by of_platform,
> new devices (struct device) are created.
> For each PCI devices a struct device is already present (created and
> handled by the PCI core).
> Having a second struct device to represent the exact same PCI device is
> not correct.
> 
> On the of_node creation, tell the of_platform that there is no need to
> create a device for this node (OF_POPULATED flag), link this newly
> created of_node to the already present device and tell fwnode that the
> device attached to this of_node is ready (fwnode_dev_initialized()).
> 
> With this fix, the of_node are available in the sysfs device tree:
> /sys/devices/platform/soc/d0070000.pcie/
> + of_node -> .../devicetree/base/soc/pcie@d0070000
> + pci0000:00
>   + 0000:00:00.0
>     + of_node -> .../devicetree/base/soc/pcie@d0070000/pci@0,0
>     + 0000:01:00.0
>       + of_node -> .../devicetree/base/soc/pcie@d0070000/pci@0,0/dev@0,0
> 
> On the of_node removal, revert the operations.
> 
> Fixes: 407d1a51921e ("PCI: Create device tree node for bridge")
> Cc: stable@vger.kernel.org

How can this be cc: stable when the api it relies on is not?

confused,

greg k-h

Re: [PATCH 2/2] PCI: of: Attach created of_node to existing device

[Herve Codina]

Hi Greg,

On Thu, 30 Nov 2023 16:18:58 +0000
Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:

> On Thu, Nov 30, 2023 at 04:24:04PM +0100, Herve Codina wrote:
> > The commit 407d1a51921e ("PCI: Create device tree node for bridge")
> > creates of_node for PCI devices.
> > During the insertion handling of these new DT nodes done by of_platform,
> > new devices (struct device) are created.
> > For each PCI devices a struct device is already present (created and
> > handled by the PCI core).
> > Having a second struct device to represent the exact same PCI device is
> > not correct.
> > 
> > On the of_node creation, tell the of_platform that there is no need to
> > create a device for this node (OF_POPULATED flag), link this newly
> > created of_node to the already present device and tell fwnode that the
> > device attached to this of_node is ready (fwnode_dev_initialized()).
> > 
> > With this fix, the of_node are available in the sysfs device tree:
> > /sys/devices/platform/soc/d0070000.pcie/
> > + of_node -> .../devicetree/base/soc/pcie@d0070000
> > + pci0000:00
> >   + 0000:00:00.0
> >     + of_node -> .../devicetree/base/soc/pcie@d0070000/pci@0,0
> >     + 0000:01:00.0
> >       + of_node -> .../devicetree/base/soc/pcie@d0070000/pci@0,0/dev@0,0
> > 
> > On the of_node removal, revert the operations.
> > 
> > Fixes: 407d1a51921e ("PCI: Create device tree node for bridge")
> > Cc: stable@vger.kernel.org  
> 
> How can this be cc: stable when the api it relies on is not?
> 
> confused,

My bad, I will add cc: stable in the other patch needed.

Sorry about that.
Hervé

-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com